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Sample records for implantable neural microelectrodes

  1. Implantable liquid metal-based flexible neural microelectrode array and its application in recovering animal locomotion functions

    Guo, Rui; Liu, Jing

    2017-10-01

    With significant advantages in rapidly restoring the nerve function, electrical stimulation of nervous tissue is a crucial treatment of peripheral nerve injuries leading to common movement disorder. However, the currently available stimulating electrodes generally based on rigid conductive materials would cause a potential mechanical mismatch with soft neural tissues which thus reduces long-term effects of electrical stimulation. Here, we proposed and fabricated a flexible neural microelectrode array system based on the liquid metal GaIn alloy (75.5% Ga and 24.5% In by weight) and via printing approach. Such an alloy with a unique low melting point (10.35 °C) owns excellent electrical conductivity and high compliance, which are beneficial to serve as implantable flexible neural electrodes. The flexible neural microelectrode array embeds four liquid metal electrodes and stretchable interconnects in a PDMS membrane (500 µm in thickness) that possess a lower elastic modulus (1.055 MPa), which is similar to neural tissues with elastic moduli in the 0.1-1.5 MPa range. The electrical experiments indicate that the liquid metal interconnects could sustain over 7000 mechanical stretch cycles with resistance approximately staying at 4 Ω. Over the conceptual experiments on animal sciatic nerve electrical stimulation, the dead bullfrog implanted with flexible neural microelectrode array could even rhythmically contract and move its lower limbs under the electrical stimulations from the implant. This demonstrates a highly efficient way for quickly recovering biological nerve functions. Further, the good biocompatibility of the liquid metal material was justified via a series of biological experiments. This liquid metal modality for neural stimulation is expected to play important roles as biologic electrodes to overcome the fundamental mismatch in mechanics between biological tissues and electronic devices in the coming time.

  2. Implantable liquid metal-based flexible neural microelectrode array and its application in recovering animal locomotion functions

    Guo, Rui; Liu, Jing

    2017-01-01

    With significant advantages in rapidly restoring the nerve function, electrical stimulation of nervous tissue is a crucial treatment of peripheral nerve injuries leading to common movement disorder. However, the currently available stimulating electrodes generally based on rigid conductive materials would cause a potential mechanical mismatch with soft neural tissues which thus reduces long-term effects of electrical stimulation. Here, we proposed and fabricated a flexible neural microelectrode array system based on the liquid metal GaIn alloy (75.5% Ga and 24.5% In by weight) and via printing approach. Such an alloy with a unique low melting point (10.35 °C) owns excellent electrical conductivity and high compliance, which are beneficial to serve as implantable flexible neural electrodes. The flexible neural microelectrode array embeds four liquid metal electrodes and stretchable interconnects in a PDMS membrane (500 µ m in thickness) that possess a lower elastic modulus (1.055 MPa), which is similar to neural tissues with elastic moduli in the 0.1–1.5 MPa range. The electrical experiments indicate that the liquid metal interconnects could sustain over 7000 mechanical stretch cycles with resistance approximately staying at 4 Ω. Over the conceptual experiments on animal sciatic nerve electrical stimulation, the dead bullfrog implanted with flexible neural microelectrode array could even rhythmically contract and move its lower limbs under the electrical stimulations from the implant. This demonstrates a highly efficient way for quickly recovering biological nerve functions. Further, the good biocompatibility of the liquid metal material was justified via a series of biological experiments. This liquid metal modality for neural stimulation is expected to play important roles as biologic electrodes to overcome the fundamental mismatch in mechanics between biological tissues and electronic devices in the coming time. (paper)

  3. Estimation of neural energy in microelectrode signals

    Gaumond, R. P.; Clement, R.; Silva, R.; Sander, D.

    2004-09-01

    We considered the problem of determining the neural contribution to the signal recorded by an intracortical electrode. We developed a linear least-squares approach to determine the energy fraction of a signal attributable to an arbitrary number of autocorrelation-defined signals buried in noise. Application of the method requires estimation of autocorrelation functions Rap(tgr) characterizing the action potential (AP) waveforms and Rn(tgr) characterizing background noise. This method was applied to the analysis of chronically implanted microelectrode signals from motor cortex of rat. We found that neural (AP) energy consisted of a large-signal component which grows linearly with the number of threshold-detected neural events and a small-signal component unrelated to the count of threshold-detected AP signals. The addition of pseudorandom noise to electrode signals demonstrated the algorithm's effectiveness for a wide range of noise-to-signal energy ratios (0.08 to 39). We suggest, therefore, that the method could be of use in providing a measure of neural response in situations where clearly identified spike waveforms cannot be isolated, or in providing an additional 'background' measure of microelectrode neural activity to supplement the traditional AP spike count.

  4. Long-term neural recordings using MEMS based moveable microelectrodes in the brain

    Nathan Jackson

    2010-06-01

    Full Text Available One of the critical requirements of the emerging class of neural prosthetic devices is to maintain good quality neural recordings over long time periods. We report here a novel (Micro-ElectroMechanical Systems based technology that can move microelectrodes in the event of deterioration in neural signal to sample a new set of neurons. Microscale electro-thermal actuators are used to controllably move microelectrodes post-implantation in steps of approximately 9 µm. In this study, a total of 12 moveable microelectrode chips were individually implanted in adult rats. Two of the 12 moveable microelectrode chips were not moved over a period of 3 weeks and were treated as control experiments. During the first three weeks of implantation, moving the microelectrodes led to an improvement in the average SNR from 14.61 ± 5.21 dB before movement to 18.13 ± 4.99 dB after movement across all microelectrodes and all days. However, the average RMS values of noise amplitudes were similar at 2.98 ± 1.22 µV and 3.01 ± 1.16 µV before and after microelectrode movement. Beyond three weeks, the primary observed failure mode was biological rejection of the PMMA (dental cement based skull mount resulting in the device loosening and eventually falling from the skull. Additionally, the average SNR for functioning devices beyond three weeks was 11.88 ± 2.02 dB before microelectrode movement and was significantly different (p<0.01 from the average SNR of 13.34 ± 0.919 dB after movement. The results of this study demonstrate that MEMS based technologies can move microelectrodes in rodent brains in long-term experiments resulting in improvements in signal quality. Further improvements in packaging and surgical techniques will potentially enable movable microelectrodes to record cortical neuronal activity in chronic experiments.

  5. Discovery of Undescribed Brain Tissue Changes Around Implanted Microelectrode Arrays

    Himanshi Desai

    2012-01-01

    Full Text Available Brain-implantable microelectrode arrays are devicesdesigned to record or electrically stimulate the activity ofneurons in the brain. These devices hold the potential tohelp treat epilepsy, paralysis, blindness, and deafness, andalso provide researchers with insights into a varietyof neural processes, such as memory formation.While these devices have a very promising future,researchers are discovering that their long-termfunctionality is greatly limited by the brain’s naturalimmune response to foreign objects. To improve thefunctional lifetime of these devices, one solution lies infully characterizing and understanding this tissue response.Roles for microglia and astrocytes in this biologicalresponse have been characterized. However, changesto oligodendrocytes, cells that myelinate axons, remainpoorly understood. These cells provide insulationto the axons, which is required for proper neuralfunctioning. Here we report on the changes that occurwith oligodendrocyte processes in tissue aroundmicroelectrode implants in the brain.Six rats were surgically implanted with microelectrodearrays and allowed to recover for 1, 2, or 4 weeks.Subjects were then sacrificed and the brain tissue wasprocessed using our recently developed method, Device-Capture Histology. Immunohistochemistry and confocalmicroscopy was employed to assess the responsearound the device. Results indicated a decrease inoligodendrocyte density and a loss in typical directionalorientation of oligodendrocyte processes in tissue near thedevice. These results suggest alterations in the underlyingneuronal networks around these devices, which maygreatly impact the current functional utility of thesepromising devices.

  6. Polycrystalline-Diamond MEMS Biosensors Including Neural Microelectrode-Arrays

    Donna H. Wang

    2011-08-01

    Full Text Available Diamond is a material of interest due to its unique combination of properties, including its chemical inertness and biocompatibility. Polycrystalline diamond (poly-C has been used in experimental biosensors that utilize electrochemical methods and antigen-antibody binding for the detection of biological molecules. Boron-doped poly-C electrodes have been found to be very advantageous for electrochemical applications due to their large potential window, low background current and noise, and low detection limits (as low as 500 fM. The biocompatibility of poly-C is found to be comparable, or superior to, other materials commonly used for implants, such as titanium and 316 stainless steel. We have developed a diamond-based, neural microelectrode-array (MEA, due to the desirability of poly-C as a biosensor. These diamond probes have been used for in vivo electrical recording and in vitro electrochemical detection. Poly-C electrodes have been used for electrical recording of neural activity. In vitro studies indicate that the diamond probe can detect norepinephrine at a 5 nM level. We propose a combination of diamond micro-machining and surface functionalization for manufacturing diamond pathogen-microsensors.

  7. Analysis of Al2O3—parylene C bilayer coatings and impact of microelectrode topography on long term stability of implantable neural arrays

    Caldwell, Ryan; Mandal, Himadri; Sharma, Rohit; Solzbacher, Florian; Tathireddy, Prashant; Rieth, Loren

    2017-08-01

    Objective. Performance of many dielectric coatings for neural electrodes degrades over time, contributing to loss of neural signals and evoked percepts. Studies using planar test substrates have found that a novel bilayer coating of atomic-layer deposited (ALD) Al2O3 and parylene C is a promising candidate for neural electrode applications, exhibiting superior stability to parylene C alone. However, initial results from bilayer encapsulation testing on non-planar devices have been less positive. Our aim was to evaluate ALD Al2O3-parylene C coatings using novel test paradigms, to rigorously evaluate dielectric coatings for neural electrode applications by incorporating neural electrode topography into test structure design. Approach. Five test devices incorporated three distinct topographical features common to neural electrodes, derived from the utah electrode array (UEA). Devices with bilayer (52 nm Al2O3  +  6 µm parylene C) were evaluated against parylene C controls (N  ⩾  6 per device type). Devices were aged in phosphate buffered saline at 67 °C for up to 311 d, and monitored through: (1) leakage current to evaluate encapsulation lifetimes (>1 nA during 5VDC bias indicated failure), and (2) wideband (1-105 Hz) impedance. Main results. Mean-times-to-failure (MTTFs) ranged from 12 to 506 d for bilayer-coated devices, versus 10 to  >2310 d for controls. Statistical testing (log-rank test, α  =  0.05) of failure rates gave mixed results but favored the control condition. After failure, impedance loss for bilayer devices continued for months and manifested across the entire spectrum, whereas the effect was self-limiting after several days, and restricted to frequencies  physiological fluids may improve performance. Testing frameworks which take neural electrode complexities into account will be well suited to reliably evaluate such encapsulation schemes.

  8. Microfabrication, characterization and in vivo MRI compatibility of diamond microelectrodes array for neural interfacing

    Hébert, Clément, E-mail: clement.hebert@cea.fr [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Warnking, Jan; Depaulis, Antoine [INSERM, U836, Grenoble Institut des Neurosciences, Grenoble (France); Garçon, Laurie Amandine [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); CEA/INAC/SPrAM/CREAB, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Mermoux, Michel [Université Grenoble Alpes, LEPMI, F-38000 Grenoble (France); CNRS, LEPMI, F-38000 Grenoble (France); Eon, David [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Mailley, Pascal [CEA-LETI-DTBS Minatec, 17 rue des Martyres, 38054 Grenoble (France); Omnès, Franck [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France)

    2015-01-01

    Neural interfacing still requires highly stable and biocompatible materials, in particular for in vivo applications. Indeed, most of the currently used materials are degraded and/or encapsulated by the proximal tissue leading to a loss of efficiency. Here, we considered boron doped diamond microelectrodes to address this issue and we evaluated the performances of a diamond microelectrode array. We described the microfabrication process of the device and discuss its functionalities. We characterized its electrochemical performances by cyclic voltammetry and impedance spectroscopy in saline buffer and observed the typical diamond electrode electrochemical properties, wide potential window and low background current, allowing efficient electrochemical detection. The charge storage capacitance and the modulus of the electrochemical impedance were found to remain in the same range as platinum electrodes used for standard commercial devices. Finally we observed a reduced Magnetic Resonance Imaging artifact when the device was implanted on a rat cortex, suggesting that boron doped-diamond is a very promising electrode material allowing functional imaging. - Highlights: • Microfabrication of all-diamond microelectrode array • Evaluation of as-grown nanocrystalline boron-doped diamond for electrical neural interfacing • MRI compatibility of nanocrystalline boron-doped diamond.

  9. An implantable integrated low-power amplifier-microelectrode array for Brain-Machine Interfaces.

    Patrick, Erin; Sankar, Viswanath; Rowe, William; Sanchez, Justin C; Nishida, Toshikazu

    2010-01-01

    One of the important challenges in designing Brain-Machine Interfaces (BMI) is to build implantable systems that have the ability to reliably process the activity of large ensembles of cortical neurons. In this paper, we report the design, fabrication, and testing of a polyimide-based microelectrode array integrated with a low-power amplifier as part of the Florida Wireless Integrated Recording Electrode (FWIRE) project at the University of Florida developing a fully implantable neural recording system for BMI applications. The electrode array was fabricated using planar micromachining MEMS processes and hybrid packaged with the amplifier die using a flip-chip bonding technique. The system was tested both on bench and in-vivo. Acute and chronic neural recordings were obtained from a rodent for a period of 42 days. The electrode-amplifier performance was analyzed over the chronic recording period with the observation of a noise floor of 4.5 microVrms, and an average signal-to-noise ratio of 3.8.

  10. Microfabrication, characterization and in vivo MRI compatibility of diamond microelectrodes array for neural interfacing.

    Hébert, Clément; Warnking, Jan; Depaulis, Antoine; Garçon, Laurie Amandine; Mermoux, Michel; Eon, David; Mailley, Pascal; Omnès, Franck

    2015-01-01

    Neural interfacing still requires highly stable and biocompatible materials, in particular for in vivo applications. Indeed, most of the currently used materials are degraded and/or encapsulated by the proximal tissue leading to a loss of efficiency. Here, we considered boron doped diamond microelectrodes to address this issue and we evaluated the performances of a diamond microelectrode array. We described the microfabrication process of the device and discuss its functionalities. We characterized its electrochemical performances by cyclic voltammetry and impedance spectroscopy in saline buffer and observed the typical diamond electrode electrochemical properties, wide potential window and low background current, allowing efficient electrochemical detection. The charge storage capacitance and the modulus of the electrochemical impedance were found to remain in the same range as platinum electrodes used for standard commercial devices. Finally we observed a reduced Magnetic Resonance Imaging artifact when the device was implanted on a rat cortex, suggesting that boron doped-diamond is a very promising electrode material allowing functional imaging. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Microfabrication of an Implantable silicone Microelectrode array for an epiretinal prosthesis

    Maghribi, Mariam Nader [Univ. of California, Davis, CA (United States)

    2003-06-10

    Millions of people suffering from diseases such as retinitis pigmentosa and macular degeneration are legally blind due to the loss of photoreceptor function. Fortunately a large percentage of the neural cells connected to the photoreceptors remain viable, and electrical stimulation of these cells has been shown to result in visual perception. These findings have generated worldwide efforts to develop a retinal prosthesis device, with the hope of restoring vision. Advances in microfabrication, integrated circuits, and wireless technologies provide the means to reach this challenging goal. This dissertation describes the development of innovative silicone-based microfabrication techniques for producing an implantable microelectrode array. The microelectrode array is a component of an epiretinal prosthesis being developed by a multi-laboratory consortium. This array will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces. Because the array is intended as a long-term implant, vital biological and physical design requirements must be met. A retinal implant poses difficult engineering challenges due to the size of the intraocular cavity and the delicate retina. Not only does it have to be biocompatible in terms of cytotoxicity and degradation, but it also has to be structurally biocompatible, with regard to smooth edges and high conformability; basically mimicking the biological tissue. This is vital to minimize stress and prevent physical damage to the retina. Also, the device must be robust to withstand the forces imposed on it during fabrication and implantation. In order to meet these biocompatibility needs, the use of non-conventional microfabrication materials such as silicone is required. This mandates the enhancement of currently available polymer-based fabrication techniques and the development of new microfabrication methods. Through an iterative process, devices

  12. Correlations between histology and neuronal activity recorded by microelectrodes implanted chronically in the cerebral cortex

    McCreery, Douglas; Cogan, Stuart; Kane, Sheryl; Pikov, Victor

    2016-06-01

    Objective. To quantify relations between the neuronal activity recorded with chronically-implanted intracortical microelectrodes and the histology of the surrounding tissue, using radial distance from the tip sites and time after array implantation as parameters. Approach. ‘Utah’-type intracortical microelectrode arrays were implanted into cats’ sensorimotor cortex for 275-364 days. The brain tissue around the implants was immuno-stained for the neuronal marker NeuN and for the astrocyte marker GFAP. Pearson’s product-moment correlations were used to quantify the relations between these markers and the amplitudes of the recorded neuronal action potentials (APs) and their signal-to-noise ratios (S/N). Main results. S/N was more stable over post-implant time than was AP amplitude, but its increased correlation with neuronal density after many months indicates ongoing loss of neurons around the microelectrodes. S/N was correlated with neuron density out to at least 140 μm from the microelectrodes, while AP amplitude was correlated with neuron density and GFAP density within ˜80 μm. Correlations between AP amplitude and histology markers (GFAP and NeuN density) were strongest immediately after implantation, while correlation between the neuron density and S/N was strongest near the time the animals were sacrificed. Unlike AP amplitude, there was no significant correlation between S/N and density of GFAP around the tip sites. Significance. Our findings indicate an evolving interaction between changes in the tissue surrounding the microelectrodes and the microelectrode’s electrical properties. Ongoing loss of neurons around recording microelectrodes, and the interactions between their delayed electrical deterioration and early tissue scarring around the tips appear to pose the greatest threats to the microelectrodes’ long-term functionality.

  13. Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates

    Barrese, James C.; Aceros, Juan; Donoghue, John P.

    2016-04-01

    Objective. Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. Approach. We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. Main results. SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. Significance. These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does

  14. Surface-modified microelectrode array with flake nanostructure for neural recording and stimulation

    Kim, Ju-Hyun; Choi, Yang-Kyu [Nano-Oriented Bio-Electronics Lab, Department of Electrical Engineering, College of Information Science and Technology, KAIST, Daejeon 305-701 (Korea, Republic of); Kang, Gyumin; Nam, Yoonkey, E-mail: ynam@kaist.ac.kr, E-mail: ykchoi@ee.kaist.ac.kr [Department of Bio and Brain Engineering, KAIST, KAIST Institute for Nano-Century, Daejeon 305-701 (Korea, Republic of)

    2010-02-26

    A novel microelectrode modification method is reported for neural electrode engineering with a flake nanostructure (nanoflake). The nanoflake-modified electrodes are fabricated by combining conventional lithography and electrochemical deposition to implement a microelectrode array (MEA) on a glass substrate. The unique geometrical properties of nanoflake sharp tips and valleys are studied by optical, electrochemical and electrical methods in order to verify the advantages of using nanoflakes for neural recording devices. The in vitro recording and stimulation of cultured hippocampal neurons are demonstrated on the nanoflake-modified MEA and the clear action potentials are observed due to the nanoflake impedance reduction effect.

  15. Characterization of Early Cortical Neural Network Development in Multiwell Microelectrode Array Plates

    We examined the development of neural network activity using microelectrode array (MEA) recordings made in multi-well MEA plates (mwMEAs) over the first 12 days in vitro (DIV). In primary cortical cultures made from postnatal rats, action potential spiking activity was essentiall...

  16. Bio-inspired hybrid microelectrodes: a hybrid solution to improve long-term performance of chronic intracortical implants.

    De Faveri, Sara; Maggiolini, Emma; Miele, Ermanno; De Angelis, Francesco; Cesca, Fabrizia; Benfenati, Fabio; Fadiga, Luciano

    2014-01-01

    The use of implants that allow chronic electrical stimulation and recording in the brain of human patients is currently limited by a series of events that cause the deterioration over time of both the electrode surface and the surrounding tissue. The main reason of failure is the tissue inflammatory reaction that eventually causes neuronal loss and glial encapsulation, resulting in a progressive increase of the electrode-electrolyte impedance. Here, we describe a new method to create bio-inspired electrodes to mimic the mechanical properties and biological composition of the host tissue. This combination has a great potential to increase the implant lifetime by reducing tissue reaction and improving electrical coupling. Our method implies coating the electrode with reprogrammed neural or glial cells encapsulated within a hydrogel layer. We chose fibrin as a hydrogel and primary hippocampal neurons or astrocytes from rat brain as cellular layer. We demonstrate that fibrin coating is highly biocompatible, forms uniform coatings of controllable thickness, does not alter the electrochemical properties of the microelectrode and allows good quality recordings. Moreover, it reduces the amount of host reactive astrocytes - over time - compared to a bare wire and is fully reabsorbed by the surrounding tissue within 7 days after implantation, avoiding the common problem of hydrogels swelling. Both astrocytes and neurons could be successfully grown onto the electrode surface within the fibrin hydrogel without altering the electrochemical properties of the microelectrode. This bio-hybrid device has therefore a good potential to improve the electrical integration at the neuron-electrode interface and support the long-term success of neural prostheses.

  17. Bio-inspired hybrid microelectrodes. A hybrid solution to improve long-term performance of chronic intracortical implants.

    Sara eDe Faveri

    2014-04-01

    Full Text Available The use of implants that allow chronic electrical stimulation and recording in the brain of human patients is currently limited by a series of events that cause the deterioration over time of both the electrode surface and the surrounding tissue. The main reason of failure is the tissue inflammatory reaction that eventually causes neuronal loss and glial encapsulation, resulting in a progressive increase of the electrode-electrolyte impedance. Here, we describe a new method to create bio-inspired electrodes to mimic the mechanical properties and biological composition of the host tissue. This combination has a great potential to increase the implant lifetime by reducing tissue reaction and improving electrical coupling. Our method implies coating the electrode with reprogrammed neural or glial cells encapsulated within a hydrogel layer. We chose fibrin as a hydrogel and primary hippocampal neurons or astrocytes from rat brain as cellular layer. We demonstrate that fibrin coating is highly biocompatible, forms uniform coatings of controllable thickness, does not alter the electrochemical properties of the microelectrode and allows good quality recordings. Moreover, it reduces the amount of host reactive astrocytes - over time - compared to a bare wire and is fully reabsorbed by the surrounding tissue within 7 days after implantation, avoiding the common problem of hydrogels swelling. Both astrocytes and neurons could be successfully grown onto the electrode surface within the fibrin hydrogel without altering the electrochemical properties of the microelectrode. This bio-hybrid device has therefore a good potential to improve the electrical integration at the neuron-electrode interface and support the long-term success of neural prostheses.

  18. A wideband wireless neural stimulation platform for high-density microelectrode arrays.

    Myers, Frank B; Simpson, Jim A; Ghovanloo, Maysam

    2006-01-01

    We describe a system that allows researchers to control an implantable neural microstimulator from a PC via a USB 2.0 interface and a novel dual-carrier wireless link, which provides separate data and power transmission. Our wireless stimulator, Interestim-2B (IS-2B), is a modular device capable of generating controlled-current stimulation pulse trains across 32 sites per module with support for a variety of stimulation schemes (biphasic/monophasic, bipolar/monopolar). We have developed software to generate multi-site stimulation commands for the IS-2B based on streaming data from artificial sensory devices such as cameras and microphones. For PC interfacing, we have developed a USB 2.0 microcontroller-based interface. Data is transmitted using frequency-shift keying (FSK) at 6/12 MHz to achieve a data rate of 3 Mb/s via a pair of rectangular coils. Power is generated using a class-E power amplifier operating at 1 MHz and transmitted via a separate pair of spiral planar coils which are oriented perpendicular to the data coils to minimize cross-coupling. We have successfully demonstrated the operation of the system by applying it as a visual prosthesis. Pulse-frequency modulated stimuli are generated in real-time based on a grayscale image from a webcam. These pulses are projected onto an 11x11 LED matrix that represents a 2D microelectrode array.

  19. Corrosion of tungsten microelectrodes used in neural recording applications.

    Patrick, Erin; Orazem, Mark E; Sanchez, Justin C; Nishida, Toshikazu

    2011-06-15

    In neuroprosthetic applications, long-term electrode viability is necessary for robust recording of the activity of neural populations used for generating communication and control signals. The corrosion of tungsten microwire electrodes used for intracortical recording applications was analyzed in a controlled bench-top study and compared to the corrosion of tungsten microwires used in an in vivo study. Two electrolytes were investigated for the bench-top electrochemical analysis: 0.9% phosphate buffered saline (PBS) and 0.9% PBS containing 30 mM of hydrogen peroxide. The oxidation and reduction reactions responsible for corrosion were found by measurement of the open circuit potential and analysis of Pourbaix diagrams. Dissolution of tungsten to form the tungstic ion was found to be the corrosion mechanism. The corrosion rate was estimated from the polarization resistance, which was extrapolated from the electrochemical impedance spectroscopy data. The results show that tungsten microwires in an electrolyte of PBS have a corrosion rate of 300-700 μm/yr. The corrosion rate for tungsten microwires in an electrolyte containing PBS and 30 mM H₂O₂ is accelerated to 10,000-20,000 μm/yr. The corrosion rate was found to be controlled by the concentration of the reacting species in the cathodic reaction (e.g. O₂ and H₂O₂). The in vivo corrosion rate, averaged over the duration of implantation, was estimated to be 100 μm/yr. The reduced in vivo corrosion rate as compared to the bench-top rate is attributed to decreased rate of oxygen diffusion caused by the presence of a biological film and a reduced concentration of available oxygen in the brain. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Implantable Neural Interfaces for Sharks

    2007-05-01

    technology for recording and stimulating from the auditory and olfactory sensory nervous systems of the awake, swimming nurse shark , G. cirratum (Figures...overlay of the central nervous system of the nurse shark on a horizontal MR image. Implantable Neural Interfaces for Sharks ...Neural Interfaces for Characterizing Population Responses to Odorants and Electrical Stimuli in the Nurse Shark , Ginglymostoma cirratum.” AChemS Abs

  1. Listening to Brain Microcircuits for Interfacing With External World-Progress in Wireless Implantable Microelectronic Neuroengineering Devices: Experimental systems are described for electrical recording in the brain using multiple microelectrodes and short range implantable or wearable broadcasting units.

    Nurmikko, Arto V; Donoghue, John P; Hochberg, Leigh R; Patterson, William R; Song, Yoon-Kyu; Bull, Christopher W; Borton, David A; Laiwalla, Farah; Park, Sunmee; Ming, Yin; Aceros, Juan

    2010-01-01

    Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature's amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic "brain-interfaces" within the body, a point of special emphasis of this paper.

  2. Implantation of Neural Probes in the Brain Elicits Oxidative Stress

    Evon S. Ereifej

    2018-02-01

    Full Text Available Clinical implantation of intracortical microelectrodes has been hindered, at least in part, by the perpetual inflammatory response occurring after device implantation. The neuroinflammatory response observed after device implantation has been correlated to oxidative stress that occurs due to neurological injury and disease. However, there has yet to be a definitive link of oxidative stress to intracortical microelectrode implantation. Thus, the objective of this study is to give direct evidence of oxidative stress following intracortical microelectrode implantation. This study also aims to identify potential molecular targets to attenuate oxidative stress observed postimplantation. Here, we implanted adult rats with silicon non-functional microelectrode probes for 4 weeks and compared the oxidative stress response to no surgery controls through postmortem gene expression analysis and qualitative histological observation of oxidative stress markers. Gene expression analysis results at 4 weeks postimplantation indicated that EH domain-containing 2, prion protein gene (Prnp, and Stearoyl-Coenzyme A desaturase 1 (Scd1 were all significantly higher for animals implanted with intracortical microelectrode probes compared to no surgery control animals. To the contrary, NADPH oxidase activator 1 (Noxa1 relative gene expression was significantly lower for implanted animals compared to no surgery control animals. Histological observation of oxidative stress showed an increased expression of oxidized proteins, lipids, and nucleic acids concentrated around the implant site. Collectively, our results reveal there is a presence of oxidative stress following intracortical microelectrode implantation compared to no surgery controls. Further investigation targeting these specific oxidative stress linked genes could be beneficial to understanding potential mechanisms and downstream therapeutics that can be utilized to reduce oxidative stress-mediated damage

  3. In-Vivo Characterization of Glassy Carbon Micro-Electrode Arrays for Neural Applications and Histological Analysis of the Brain Tissue

    Vomero, Maria

    The aim of this work is to fabricate and characterize glassy carbon Microelectrode Arrays (MEAs) for sensing and stimulating neural activity, and conduct histological analysis of the brain tissue after the implant to determine long-term performance. Neural applications often require robust electrical and electrochemical response over a long period of time, and for those applications we propose to replace the commonly used noble metals like platinum, gold and iridium with glassy carbon. We submit that such material has the potential to improve the performances of traditional neural prostheses, thanks to better charge transfer capabilities and higher electrochemical stability. Great interest and attention is given in this work, in particular, to the investigation of tissue response after several weeks of implants in rodents' brain motor cortex and the associated materials degradation. As part of this work, a new set of devices for Electrocorticography (ECoG) has been designed and fabricated to improve durability and quality of the previous generation of devices, designed and manufactured by the same research group in 2014. In-vivo long-term impedance measurements and brain activity recordings were performed to test the functionality of the neural devices. In-vitro electrical characterization of the carbon electrodes, as well as the study of the adhesion mechanisms between glassy carbon and different substrates is also part of the research described in this book.

  4. Modulation of cultured neural networks using neurotrophin release from hydrogel-coated microelectrode arrays

    Jun, Sang Beom; Hynd, Matthew R.; Dowell-Mesfin, Natalie M.; Al-Kofahi, Yousef; Roysam, Badrinath; Shain, William; Kim, Sung June

    2008-06-01

    Polyacrylamide and poly(ethylene glycol) diacrylate hydrogels were synthesized and characterized for use as drug release and substrates for neuron cell culture. Protein release kinetics was determined by incorporating bovine serum albumin (BSA) into hydrogels during polymerization. To determine if hydrogel incorporation and release affect bioactivity, alkaline phosphatase was incorporated into hydrogels and a released enzyme activity determined using the fluorescence-based ELF-97 assay. Hydrogels were then used to deliver a brain-derived neurotrophic factor (BDNF) from hydrogels polymerized over planar microelectrode arrays (MEAs). Primary hippocampal neurons were cultured on both control and neurotrophin-containing hydrogel-coated MEAs. The effect of released BDNF on neurite length and process arborization was investigated using automated image analysis. An increased spontaneous activity as a response to the released BDNF was recorded from the neurons cultured on the top of hydrogel layers. These results demonstrate that proteins of biological interest can be incorporated into hydrogels to modulate development and function of cultured neural networks. These results also set the stage for development of hydrogel-coated neural prosthetic devices for local delivery of various biologically active molecules.

  5. Spatial and temporal characteristics of V1 microstimulation during chronic implantation of a microelectrode array in a behaving macaque

    Davis, T. S.; Parker, R. A.; House, P. A.; Bagley, E.; Wendelken, S.; Normann, R. A.; Greger, B.

    2012-12-01

    Objective. It has been hypothesized that a vision prosthesis capable of evoking useful visual percepts can be based upon electrically stimulating the primary visual cortex (V1) of a blind human subject via penetrating microelectrode arrays. As a continuation of earlier work, we examined several spatial and temporal characteristics of V1 microstimulation. Approach. An array of 100 penetrating microelectrodes was chronically implanted in V1 of a behaving macaque monkey. Microstimulation thresholds were measured using a two-alternative forced choice detection task. Relative locations of electrically-evoked percepts were measured using a memory saccade-to-target task. Main results. The principal finding was that two years after implantation we were able to evoke behavioural responses to electric stimulation across the spatial extent of the array using groups of contiguous electrodes. Consistent responses to stimulation were evoked at an average threshold current per electrode of 204 ± 49 µA (mean ± std) for groups of four electrodes and 91 ± 25 µA for groups of nine electrodes. Saccades to electrically-evoked percepts using groups of nine electrodes showed that the animal could discriminate spatially distinct percepts with groups having an average separation of 1.6 ± 0.3 mm (mean ± std) in cortex and 1.0° ± 0.2° in visual space. Significance. These results demonstrate chronic perceptual functionality and provide evidence for the feasibility of a cortically-based vision prosthesis for the blind using penetrating microelectrodes.

  6. Sub-meninges implantation reduces immune response to neural implants.

    Markwardt, Neil T; Stokol, Jodi; Rennaker, Robert L

    2013-04-15

    Glial scar formation around neural interfaces inhibits their ability to acquire usable signals from the surrounding neurons. To improve neural recording performance, the inflammatory response and glial scarring must be minimized. Previous work has indicated that meningeally derived cells participate in the immune response, and it is possible that the meninges may grow down around the shank of a neural implant, contributing to the formation of the glial scar. This study examines whether the glial scar can be reduced by placing a neural probe completely below the meninges. Rats were implanted with sets of loose microwire implants placed either completely below the meninges or implanted conventionally with the upper end penetrating the meninges, but not attached to the skull. Histological analysis was performed 4 weeks following surgical implantation to evaluate the glial scar. Our results found that sub-meninges implants showed an average reduction in reactive astrocyte activity of 63% compared to trans-meninges implants. Microglial activity was also reduced for sub-meninges implants. These results suggest that techniques that isolate implants from the meninges offer the potential to reduce the encapsulation response which should improve chronic recording quality and stability. Published by Elsevier B.V.

  7. A Chip for an Implantable Neural Stimulator

    Gudnason, Gunnar; Bruun, Erik; Haugland, Morten

    2000-01-01

    This paper describes a chip for a multichannel neural stimulator for functional electrical stimulation (FES). The purpose of FES is to restore muscular control in disabled patients. The chip performs all the signal processing required in an implanted neural stimulator. The power and digital data...

  8. Using Arrays of Microelectrodes Implanted in Residual Peripheral Nerves to Provide Dextrous Control of, and Modulated Sensory Feedback from, a Hand Prosthesis

    2015-10-01

    extended that work by investigating multiple aspects important for developing future bidirectional neural prostheses based on high-count microelectrode...Fan J M, Kao J C, Stavisky S D, Ryu S and Shenoy K 2012 A recurrent neural network for closed-loop intracortical brain-machine interface decoders J...Peripheral Nerve Interface, Prosthetic Hand, Neural Prosthesis, Sensory Feedback, Micro-stimulation, Electrophysiology, Action Potentials, Micro

  9. Brain machine interfaces combining microelectrode arrays with nanostructured optical biochemical sensors

    Hajj-Hassan, Mohamad; Gonzalez, Timothy; Ghafer-Zadeh, Ebrahim; Chodavarapu, Vamsy; Musallam, Sam; Andrews, Mark

    2009-02-01

    Neural microelectrodes are an important component of neural prosthetic systems which assist paralyzed patients by allowing them to operate computers or robots using their neural activity. These microelectrodes are also used in clinical settings to localize the locus of seizure initiation in epilepsy or to stimulate sub-cortical structures in patients with Parkinson's disease. In neural prosthetic systems, implanted microelectrodes record the electrical potential generated by specific thoughts and relay the signals to algorithms trained to interpret these thoughts. In this paper, we describe novel elongated multi-site neural electrodes that can record electrical signals and specific neural biomarkers and that can reach depths greater than 8mm in the sulcus of non-human primates (monkeys). We hypothesize that additional signals recorded by the multimodal probes will increase the information yield when compared to standard probes that record just electropotentials. We describe integration of optical biochemical sensors with neural microelectrodes. The sensors are made using sol-gel derived xerogel thin films that encapsulate specific biomarker responsive luminophores in their nanostructured pores. The desired neural biomarkers are O2, pH, K+, and Na+ ions. As a prototype, we demonstrate direct-write patterning to create oxygen-responsive xerogel waveguide structures on the neural microelectrodes. The recording of neural biomarkers along with electrical activity could help the development of intelligent and more userfriendly neural prosthesis/brain machine interfaces as well as aid in providing answers to complex brain diseases and disorders.

  10. All-diamond functional surface micro-electrode arrays for brain-slice neural analysis

    Vahidpour, F.; Curley, L.; Biró, I.; McDonald, M.; Croux, D.; Pobedinskas, P.; Haenen, K.; Giugliano, M.; Vlčková Živcová, Zuzana; Kavan, Ladislav; Nesládek, M.

    2017-01-01

    Roč. 214, č. 2 (2017), č. článku 1532347. ISSN 1862-6300 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 Keywords : impedance spectroscopy * microelectrode arrays * surface termination Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 1.775, year: 2016

  11. A fully implantable rodent neural stimulator

    Perry, D. W. J.; Grayden, D. B.; Shepherd, R. K.; Fallon, J. B.

    2012-02-01

    The ability to electrically stimulate neural and other excitable tissues in behaving experimental animals is invaluable for both the development of neural prostheses and basic neurological research. We developed a fully implantable neural stimulator that is able to deliver two channels of intra-cochlear electrical stimulation in the rat. It is powered via a novel omni-directional inductive link and includes an on-board microcontroller with integrated radio link, programmable current sources and switching circuitry to generate charge-balanced biphasic stimulation. We tested the implant in vivo and were able to elicit both neural and behavioural responses. The implants continued to function for up to five months in vivo. While targeted to cochlear stimulation, with appropriate electrode arrays the stimulator is well suited to stimulating other neurons within the peripheral or central nervous systems. Moreover, it includes significant on-board data acquisition and processing capabilities, which could potentially make it a useful platform for telemetry applications, where there is a need to chronically monitor physiological variables in unrestrained animals.

  12. Compact microelectrode array system: tool for in situ monitoring of drug effects on neurotransmitter release from neural cells.

    Chen, Yu; Guo, Chunxian; Lim, Layhar; Cheong, Serchoong; Zhang, Qingxin; Tang, Kumcheong; Reboud, Julien

    2008-02-15

    This paper presents a compact microelectrode array (MEA) system, to study potassium ion-induced dopamine release from PC12 neural cells, without relying on a micromanipulator and a microscope. The MEA chip was integrated with a custom-made "test jig", which provides a robust electrical interfacing tool between the microchip and the macroenvironment, together with a potentiostat and a microfluidic syringe pump. This integrated system significantly simplifies the operation procedures, enhances sensing performance, and reduces fabrication costs. The achieved detection limit for dopamine is 3.8 x 10-2 muM (signal/noise, S/N = 3) and the dopamine linear calibration range is up to 7.39 +/- 0.06 muM (mean +/- SE). The effects of the extracelluar matrix collagen coating of the microelectrodes on dopamine sensing behaviors, as well as the influences of K+ and l-3,4-digydroxyphenylalanine concentrations and incubation times on dopamine release, were extensively studied. The results show that our system is well suited for biologists to study chemical release from living cells as well as drug effects on secreting cells. The current system also shows a potential for further improvements toward a multichip array system for drug screening applications.

  13. Microelectrode Array-evaluation of Neurotoxic Effects of Magnesium as an Implantable Biomaterial.

    Huang, Ting; Wang, Zhonghai; Wei, Lina; Kindy, Mark; Zheng, Yufeng; Xi, Tingfei; Gao, Bruce Z

    2016-01-01

    Magnesium (Mg)-based biomaterials have shown great potential in clinical applications. However, the cytotoxic effects of excessive Mg 2+ and the corrosion products from Mg-based biomaterials, particularly their effects on neurons, have been little studied. Although viability tests are most commonly used, a functional evaluation is critically needed. Here, both methyl thiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) assays were used to test the effect of Mg 2+ and Mg-extract solution on neuronal viability. Microelectrode arrays (MEAs), which provide long-term, real-time recording of extracellular electrophysiological signals of in vitro neuronal networks, were used to test for toxic effects. The minimum effective concentrations (EC min ) of Mg 2+ from the MTT and LDH assays were 3 mmol/L and 100 mmol/L, respectively, while the EC min obtained from the MEA assay was 0.1 mmol/L. MEA data revealed significant loss of neuronal network activity when the culture was exposed to 25% Mg-extract solution, a concentration that did not affect neuronal viability. For evaluating the biocompatibility of Mg-based biomaterials with neurons, MEA electrophysiological testing is a more precise method than basic cell-viability testing.

  14. Unsupervised neural spike sorting for high-density microelectrode arrays with convolutive independent component analysis.

    Leibig, Christian; Wachtler, Thomas; Zeck, Günther

    2016-09-15

    Unsupervised identification of action potentials in multi-channel extracellular recordings, in particular from high-density microelectrode arrays with thousands of sensors, is an unresolved problem. While independent component analysis (ICA) achieves rapid unsupervised sorting, it ignores the convolutive structure of extracellular data, thus limiting the unmixing to a subset of neurons. Here we present a spike sorting algorithm based on convolutive ICA (cICA) to retrieve a larger number of accurately sorted neurons than with instantaneous ICA while accounting for signal overlaps. Spike sorting was applied to datasets with varying signal-to-noise ratios (SNR: 3-12) and 27% spike overlaps, sampled at either 11.5 or 23kHz on 4365 electrodes. We demonstrate how the instantaneity assumption in ICA-based algorithms has to be relaxed in order to improve the spike sorting performance for high-density microelectrode array recordings. Reformulating the convolutive mixture as an instantaneous mixture by modeling several delayed samples jointly is necessary to increase signal-to-noise ratio. Our results emphasize that different cICA algorithms are not equivalent. Spike sorting performance was assessed with ground-truth data generated from experimentally derived templates. The presented spike sorter was able to extract ≈90% of the true spike trains with an error rate below 2%. It was superior to two alternative (c)ICA methods (≈80% accurately sorted neurons) and comparable to a supervised sorting. Our new algorithm represents a fast solution to overcome the current bottleneck in spike sorting of large datasets generated by simultaneous recording with thousands of electrodes. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Conductive nanogel-interfaced neural microelectrode arrays with electrically controlled in-situ delivery of manganese ions enabling high-resolution MEMRI for synchronous neural tracing with deep brain stimulation.

    Huang, Wei-Chen; Lo, Yu-Chih; Chu, Chao-Yi; Lai, Hsin-Yi; Chen, You-Yin; Chen, San-Yuan

    2017-04-01

    Chronic brain stimulation has become a promising physical therapy with increased efficacy and efficiency in the treatment of neurodegenerative diseases. The application of deep brain electrical stimulation (DBS) combined with manganese-enhanced magnetic resonance imaging (MEMRI) provides an unbiased representation of the functional anatomy, which shows the communication between areas of the brain responding to the therapy. However, it is challenging for the current system to provide a real-time high-resolution image because the incorporated MnCl 2 solution through microinjection usually results in image blurring or toxicity due to the uncontrollable diffusion of Mn 2+ . In this study, we developed a new type of conductive nanogel-based neural interface composed of amphiphilic chitosan-modified poly(3,4 -ethylenedioxythiophene) (PMSDT) that can exhibit biomimic structural/mechanical properties and ionic/electrical conductivity comparable to that of Au. More importantly, the PMSDT enables metal-ligand bonding with Mn 2+ ions, so that the system can release Mn 2+ ions rather than MnCl 2 solution directly and precisely controlled by electrical stimulation (ES) to achieve real-time high-resolution MEMRI. With the integration of PMSDT nanogel-based coating in polyimide-based microelectrode arrays, the post-implantation DBS enables frequency-dependent MR imaging in vivo, as well as small focal imaging in response to channel site-specific stimulation on the implant. The MR imaging of the implanted brain treated with 5-min electrical stimulation showed a thalamocortical neuronal pathway after 36 h, confirming the effective activation of a downstream neuronal circuit following DBS. By eliminating the susceptibility to artifact and toxicity, this system, in combination with a MR-compatible implant and a bio-compliant neural interface, provides a harmless and synchronic functional anatomy for DBS. The study demonstrates a model of MEMRI-functionalized DBS based on functional

  16. Seven years of recording from monkey cortex with a chronically implanted multiple microelectrode

    Jürgen Krüger

    2010-05-01

    Full Text Available A brush of 64 microwires was chronically implanted in the ventral premotor cortex of a macaque monkey. Contrary to common approaches, the wires were inserted from the white matter side. This approach, by avoiding mechanical pressure on the dura and pia mater during penetration, disturbed only minimally the cortical recording site. With this approach isolated potentials and multiunit activity were recorded for more than seven years in about one third of electrodes. The indirect insertion method also provided an excellent stability within each recording session, and in some cases even allowed recording from the same neurons for several years. Histological examination of the implanted brain region shows only a very marginal damage the recording area. Advantages and problems related to long-term recording are discussed.

  17. Neural Implants, Packaging for Biocompatible Implants, and Improving Fabricated Capacitors

    Agger, Elizabeth Rose

    We have completed the circuit design and packaging procedure for an NIH-funded neural implant, called a MOTE (Microscale Optoelectronically Transduced Electrode). Neural recording implants for mice have greatly advanced neuroscience, but they are often damaging and limited in their recording location. This project will result in free-floating implants that cause less damage, provide rapid electronic recording, and increase range of recording across the cortex. A low-power silicon IC containing amplification and digitization sub-circuits is powered by a dual-function gallium arsenide photovoltaic and LED. Through thin film deposition, photolithography, and chemical and physical etching, the Molnar Group and the McEuen Group (Applied and Engineering Physics department) will package the IC and LED into a biocompatible implant approximately 100microm3. The IC and LED are complete and we have begun refining this packaging procedure in the Cornell NanoScale Science & Technology Facility. ICs with 3D time-resolved imaging capabilities can image microorganisms and other biological samples given proper packaging. A portable, flat, easily manufactured package would enable scientists to place biological samples on slides directly above the Molnar group's imaging chip. We have developed a packaging procedure using laser cutting, photolithography, epoxies, and metal deposition. Using a flip-chip method, we verified the process by aligning and adhering a sample chip to a holder wafer. In the CNF, we have worked on a long-term metal-insulator-metal (MIM) capacitor characterization project. Former Fellow and continuing CNF user Kwame Amponsah developed the original procedure for the capacitor fabrication, and another former fellow, Jonilyn Longenecker, revised the procedure and began the arduous process of characterization. MIM caps are useful to clean room users as testing devices to verify electronic characteristics of their active circuitry. This project's objective is to

  18. Selective comparison of gelling agents as neural cell culture matrices for long-term microelectrode array electrophysiology

    Wilk Nicolai

    2016-01-01

    Full Text Available In classic monolayer cell culture, the world is flat. In contrast, tissue-embedded cells experience a three-dimensional context to interact with. We assessed a selection of natural gelling agents of non-animal origin (ι- and κ-carrageenan, gellan gum, guar gum, locust bean gum, sodium alginate, tragacanth and xanthan gum in serum-free medium at 1–4% (w/v concentration for their suitability as a more natural 3D culture environment for brain-derived cells. Their biophysical properties (viscosity, texture, transparency, gelling propensity resemble those of the extracellular matrix (ECM. Gels provide the neurons with a 3D scaffold to interact with and allow for an increase of the overall cell density compared to classical monolayer 2D culture. They not only protect neurons in cell culture from shear forces and medium evaporation, but stabilize the microenvironment around them for efficient glial proliferation, tissue-analog neural differentiation and neural communication. We report on their properties (viscosity, transparency, their ease of handling in a cell culture context and their possible use modalities (cell embedment, as a cell cover or as a cell culture substrate. Among the selected gels, guar gum and locust bean gum with intercalated laminin allowed for cortical cell embedment. Neurons plated on and migrating into gellan gum survived and differentiated even without the addition of laminin. Sodium alginate with laminin was a suitable cell cover. Finally, we exemplarily demonstrate how guar gum supported the functional survival of a cortical culture over a period of 79 days in a proof-of-concept long-term microelectrode array (MEA electrophysiology study.

  19. An implantable wireless neural interface for recording cortical circuit dynamics in moving primates

    Borton, David A.; Yin, Ming; Aceros, Juan; Nurmikko, Arto

    2013-04-01

    Objective. Neural interface technology suitable for clinical translation has the potential to significantly impact the lives of amputees, spinal cord injury victims and those living with severe neuromotor disease. Such systems must be chronically safe, durable and effective. Approach. We have designed and implemented a neural interface microsystem, housed in a compact, subcutaneous and hermetically sealed titanium enclosure. The implanted device interfaces the brain with a 510k-approved, 100-element silicon-based microelectrode array via a custom hermetic feedthrough design. Full spectrum neural signals were amplified (0.1 Hz to 7.8 kHz, 200× gain) and multiplexed by a custom application specific integrated circuit, digitized and then packaged for transmission. The neural data (24 Mbps) were transmitted by a wireless data link carried on a frequency-shift-key-modulated signal at 3.2 and 3.8 GHz to a receiver 1 m away by design as a point-to-point communication link for human clinical use. The system was powered by an embedded medical grade rechargeable Li-ion battery for 7 h continuous operation between recharge via an inductive transcutaneous wireless power link at 2 MHz. Main results. Device verification and early validation were performed in both swine and non-human primate freely-moving animal models and showed that the wireless implant was electrically stable, effective in capturing and delivering broadband neural data, and safe for over one year of testing. In addition, we have used the multichannel data from these mobile animal models to demonstrate the ability to decode neural population dynamics associated with motor activity. Significance. We have developed an implanted wireless broadband neural recording device evaluated in non-human primate and swine. The use of this new implantable neural interface technology can provide insight into how to advance human neuroprostheses beyond the present early clinical trials. Further, such tools enable mobile

  20. Acute human brain responses to intracortical microelectrode arrays: Challenges and future prospects

    Eduardo eFernandez

    2014-07-01

    Full Text Available The emerging field of neuroprosthetics is focused on the development of new therapeutic interventions that will be able to restore some lost neural function by selective electrical stimulation or by harnessing activity recorded from populations of neurons. As more and more patients benefit from these approaches, the interest in neural interfaces has grown significantly and a new generation of penetrating microelectrode arrays are providing unprecedented access to the neurons of the CNS. These microelectrodes have active tip dimensions that are similar in size to neurons and because they penetrate the nervous system, they provide selective access to these cells (within a few microns. However, the very long-term viability of chronically implanted microelectrodes and the capability of recording the same spiking activity over long time periods still remain to be established and confirmed in human studies. Here we review the main responses to acute implantation of microelectrode arrays, and emphasize that it will become essential to control the neural tissue damage induced by these intracortical microelectrodes in order to achieve the high clinical potentials accompanying this technology.

  1. Flexible microelectrode array for interfacing with the surface of neural ganglia

    Sperry, Zachariah J.; Na, Kyounghwan; Parizi, Saman S.; Chiel, Hillel J.; Seymour, John; Yoon, Euisik; Bruns, Tim M.

    2018-06-01

    Objective. The dorsal root ganglia (DRG) are promising nerve structures for sensory neural interfaces because they provide centralized access to primary afferent cell bodies and spinal reflex circuitry. In order to harness this potential, new electrode technologies are needed which take advantage of the unique properties of DRG, specifically the high density of neural cell bodies at the dorsal surface. Here we report initial in vivo results from the development of a flexible non-penetrating polyimide electrode array interfacing with the surface of ganglia. Approach. Multiple layouts of a 64-channel iridium electrode (420 µm2) array were tested, with pitch as small as 25 µm. The buccal ganglia of invertebrate sea slug Aplysia californica were used to develop handling and recording techniques with ganglionic surface electrode arrays (GSEAs). We also demonstrated the GSEA’s capability to record single- and multi-unit activity from feline lumbosacral DRG related to a variety of sensory inputs, including cutaneous brushing, joint flexion, and bladder pressure. Main results. We recorded action potentials from a variety of Aplysia neurons activated by nerve stimulation, and units were observed firing simultaneously on closely spaced electrode sites. We also recorded single- and multi-unit activity associated with sensory inputs from feline DRG. We utilized spatial oversampling of action potentials on closely-spaced electrode sites to estimate the location of neural sources at between 25 µm and 107 µm below the DRG surface. We also used the high spatial sampling to demonstrate a possible spatial sensory map of one feline’s DRG. We obtained activation of sensory fibers with low-amplitude stimulation through individual or groups of GSEA electrode sites. Significance. Overall, the GSEA has been shown to provide a variety of information types from ganglia neurons and to have significant potential as a tool for neural mapping and interfacing.

  2. Physicochemical properties of peptide-coated microelectrode arrays and their in vitro effects on neuroblast cells

    Ghane-Motlagh, Bahareh, E-mail: bahar.ghane@gmail.com [Polystim Neurotechnologies Laboratory, Department of Electrical Engineering, Polytechnique Montreal, QC H3C 3A7 (Canada); Javanbakht, Taraneh; Shoghi, Fatemeh; Wilkinson, Kevin J.; Martel, Richard [Department of Chemistry, University of Montreal, QC H3C 3J7 (Canada); Sawan, Mohamad [Polystim Neurotechnologies Laboratory, Department of Electrical Engineering, Polytechnique Montreal, QC H3C 3A7 (Canada)

    2016-11-01

    Silicon micromachined neural electrode arrays, which act as an interface between bioelectronic devices and neural tissues, play an important role in chronic implants, in vivo. The biological compatibility of chronic microelectrode arrays (MEA) is an essential factor that must be taken into account in their design and fabrication. In order to improve biocompatibility of the MEAs, the surface of the electrodes was coated with polyethylene glycol (PEG) and parylene-C, which are biocompatible polymers. An in vitro study was performed to test the capacity of poly-D-lysine (PDL) to improve neural-cell adhesion and proliferation. Increased proliferation of the neuroblast cells on the microelectrodes was observed in the presence of the PDL. The presence of the peptide on the electrode surface was confirmed using Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The impedance of the electrodes was not changed significantly before and after PDL deposition. Mouse neuroblast cells were seeded and cultured on the PDL coated and uncoated neural MEAs with different tip-coatings such as platinum, molybdenum, gold, sputtered iridium oxide, and carbon nanotubes. The neuroblast cells grew preferentially on and around peptide coated-microelectrode tips, as compared to the uncoated microelectrodes. - Highlights: • A novel high-density microelectrode array (MEA) for intracortical 3D recording and stimulation was designed and fabricated. • In order to improve neural-cell adhesion and proliferation, the surface of the electrodes was coated with poly-D-lysine (PDL). • An in vitro study was performed to test the capacity of PDL to improve cell adhesion and proliferation. • The neuroblast cells grew preferentially on peptide-coated microelectrode tips compared to the uncoated microelectrodes.

  3. Electrode impedance analysis of chronic tungsten microwire neural implants: understanding abiotic vs. biotic contributions

    Viswanath eSankar

    2014-05-01

    Full Text Available Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially.

  4. Simultaneous recording of brain extracellular glucose, spike and local field potential in real time using an implantable microelectrode array with nano-materials

    Wei, Wenjing; Song, Yilin; Fan, Xinyi; Zhang, Song; Wang, Li; Xu, Shengwei; Wang, Mixia; Cai, Xinxia

    2016-03-01

    Glucose is the main substrate for neurons in the central nervous system. In order to efficiently characterize the brain glucose mechanism, it is desirable to determine the extracellular glucose dynamics as well as the corresponding neuroelectrical activity in vivo. In the present study, we fabricated an implantable microelectrode array (MEA) probe composed of platinum electrochemical and electrophysiology microelectrodes by standard micro electromechanical system (MEMS) processes. The MEA probe was modified with nano-materials and implanted in a urethane-anesthetized rat for simultaneous recording of striatal extracellular glucose, local field potential (LFP) and spike on the same spatiotemporal scale when the rat was in normoglycemia, hypoglycemia and hyperglycemia. During these dual-mode recordings, we observed that increase of extracellular glucose enhanced the LFP power and spike firing rate, while decrease of glucose had an opposite effect. This dual mode MEA probe is capable of examining specific spatiotemporal relationships between electrical and chemical signaling in the brain, which will contribute significantly to improve our understanding of the neuron physiology.

  5. Simultaneous recording of brain extracellular glucose, spike and local field potential in real time using an implantable microelectrode array with nano-materials

    Wei, Wenjing; Song, Yilin; Fan, Xinyi; Zhang, Song; Wang, Li; Xu, Shengwei; Wang, Mixia; Cai, Xinxia

    2016-01-01

    Glucose is the main substrate for neurons in the central nervous system. In order to efficiently characterize the brain glucose mechanism, it is desirable to determine the extracellular glucose dynamics as well as the corresponding neuroelectrical activity in vivo. In the present study, we fabricated an implantable microelectrode array (MEA) probe composed of platinum electrochemical and electrophysiology microelectrodes by standard micro electromechanical system (MEMS) processes. The MEA probe was modified with nano-materials and implanted in a urethane-anesthetized rat for simultaneous recording of striatal extracellular glucose, local field potential (LFP) and spike on the same spatiotemporal scale when the rat was in normoglycemia, hypoglycemia and hyperglycemia. During these dual-mode recordings, we observed that increase of extracellular glucose enhanced the LFP power and spike firing rate, while decrease of glucose had an opposite effect. This dual mode MEA probe is capable of examining specific spatiotemporal relationships between electrical and chemical signaling in the brain, which will contribute significantly to improve our understanding of the neuron physiology. (paper)

  6. A novel method for the fabrication of a high-density carbon nanotube microelectrode array

    Adam Khalifa

    2015-09-01

    Full Text Available We present a novel method for fabricating a high-density carbon nanotube microelectrode array (MEA chip. Vertically aligned carbon nanotubes (VACNTs were synthesized by microwave plasma-enhanced chemical vapor deposition and thermal chemical vapor deposition. The device was characterized using electrochemical experiments such as cyclic voltammetry, impedance spectroscopy and potential transient measurements. Through-silicon vias (TSVs were fabricated and partially filled with polycrystalline silicon to allow electrical connection from the high-density electrodes to a stimulator microchip. In response to the demand for higher resolution implants, we have developed a unique process to obtain a high-density electrode array by making the microelectrodes smaller in size and designing new ways of routing the electrodes to current sources. Keywords: Microelectrode array, Neural implant, Carbon nanotubes, Through-silicon via interconnects, Microfabrication

  7. Implantable neurotechnologies: a review of integrated circuit neural amplifiers.

    Ng, Kian Ann; Greenwald, Elliot; Xu, Yong Ping; Thakor, Nitish V

    2016-01-01

    Neural signal recording is critical in modern day neuroscience research and emerging neural prosthesis programs. Neural recording requires the use of precise, low-noise amplifier systems to acquire and condition the weak neural signals that are transduced through electrode interfaces. Neural amplifiers and amplifier-based systems are available commercially or can be designed in-house and fabricated using integrated circuit (IC) technologies, resulting in very large-scale integration or application-specific integrated circuit solutions. IC-based neural amplifiers are now used to acquire untethered/portable neural recordings, as they meet the requirements of a miniaturized form factor, light weight and low power consumption. Furthermore, such miniaturized and low-power IC neural amplifiers are now being used in emerging implantable neural prosthesis technologies. This review focuses on neural amplifier-based devices and is presented in two interrelated parts. First, neural signal recording is reviewed, and practical challenges are highlighted. Current amplifier designs with increased functionality and performance and without penalties in chip size and power are featured. Second, applications of IC-based neural amplifiers in basic science experiments (e.g., cortical studies using animal models), neural prostheses (e.g., brain/nerve machine interfaces) and treatment of neuronal diseases (e.g., DBS for treatment of epilepsy) are highlighted. The review concludes with future outlooks of this technology and important challenges with regard to neural signal amplification.

  8. In vivo monitoring of glial scar proliferation on chronically implanted neural electrodes by fiber optical coherence tomography

    Xie, Yijing; Martini, Nadja; Hassler, Christina; Kirch, Robert D.; Stieglitz, Thomas; Seifert, Andreas; Hofmann, Ulrich G.

    2014-01-01

    In neural prosthetics and stereotactic neurosurgery, intracortical electrodes are often utilized for delivering therapeutic electrical pulses, and recording neural electrophysiological signals. Unfortunately, neuroinflammation impairs the neuron-electrode-interface by developing a compact glial encapsulation around the implants in long term. At present, analyzing this immune reaction is only feasible with post-mortem histology; currently no means for specific in vivo monitoring exist and most applicable imaging modalities can not provide information in deep brain regions. Optical coherence tomography (OCT) is a well established imaging modality for in vivo studies, providing cellular resolution and up to 1.2 mm imaging depth in brain tissue. A fiber based spectral domain OCT was shown to be capable of minimally invasive brain imaging. In the present study, we propose to use a fiber based spectral domain OCT to monitor the progression of the tissue's immune response through scar encapsulation progress in a rat animal model. A fine fiber catheter was implanted in rat brain together with a flexible polyimide microelectrode in sight both of which acts as a foreign body and induces the brain tissue immune reaction. OCT signals were collected from animals up to 12 weeks after implantation and thus gliotic scarring in vivo monitored for that time. Preliminary data showed a significant enhancement of the OCT backscattering signal during the first 3 weeks after implantation, and increased attenuation factor of the sampled tissue due to the glial scar formation. PMID:25191264

  9. Further Evaluation of DNT Hazard Screening using Neural Networks from Rat Cortical Neurons on Multi-well Microelectrode Arrays

    Thousands of chemicals have not been characterized for their DNT potential. Due to the need for DNT hazard identification, efforts to develop screening assays for DNT potential is a high priority. Multi-well microelectrode arrays (MEA) measure the spontaneous activity of electr...

  10. Chronic in vivo stability assessment of carbon fiber microelectrode arrays

    Patel, Paras R.; Zhang, Huanan; Robbins, Matthew T.; Nofar, Justin B.; Marshall, Shaun P.; Kobylarek, Michael J.; Kozai, Takashi D. Y.; Kotov, Nicholas A.; Chestek, Cynthia A.

    2016-12-01

    Objective. Individual carbon fiber microelectrodes can record unit activity in both acute and semi-chronic (∼1 month) implants. Additionally, new methods have been developed to insert a 16 channel array of carbon fiber microelectrodes. Before assessing the in vivo long-term viability of these arrays, accelerated soak tests were carried out to determine the most stable site coating material. Next, a multi-animal, multi-month, chronic implantation study was carried out with carbon fiber microelectrode arrays and silicon electrodes. Approach. Carbon fibers were first functionalized with one of two different formulations of PEDOT and subjected to accelerated aging in a heated water bath. After determining the best PEDOT formula to use, carbon fiber arrays were chronically implanted in rat motor cortex. Some rodents were also implanted with a single silicon electrode, while others received both. At the end of the study a subset of animals were perfused and the brain tissue sliced. Tissue sections were stained for astrocytes, microglia, and neurons. The local reactive responses were assessed using qualitative and quantitative methods. Main results. Electrophysiology recordings showed the carbon fibers detecting unit activity for at least 3 months with average amplitudes of ∼200 μV. Histology analysis showed the carbon fiber arrays with a minimal to non-existent glial scarring response with no adverse effects on neuronal density. Silicon electrodes showed large glial scarring that impacted neuronal counts. Significance. This study has validated the use of carbon fiber microelectrode arrays as a chronic neural recording technology. These electrodes have demonstrated the ability to detect single units with high amplitude over 3 months, and show the potential to record for even longer periods. In addition, the minimal reactive response should hold stable indefinitely, as any response by the immune system may reach a steady state after 12 weeks.

  11. An Implantable Mixed Analog/Digital Neural Stimulator Circuit

    Gudnason, Gunnar; Bruun, Erik; Haugland, Morten

    1999-01-01

    This paper describes a chip for a multichannel neural stimulator for functional electrical stimulation. The chip performs all the signal processing required in an implanted neural stimulator. The power and signal transmission to the stimulator is carried out via an inductive link. From the signals...... electrical stimulation is to restore various bodily functions (e.g. motor functions) in patients who have lost them due to injury or disease....

  12. Resistive and reactive changes to the impedance of intracortical microelectrodes can be mitigated with polyethylene glycol under acute in vitro and in vivo settings

    Salah eSommakia

    2014-08-01

    Full Text Available The reactive response of brain tissue to implantable intracortical microelectrodes is thought to negatively affect their recordable signal quality and impedance, resulting in unreliable longitudinal performance. The relationship between the progression of the reactive tissue into a glial scar and the decline in device performance is unclear. We show that exposure to a model protein solution in vitro and acute implantation result in both resistive and capacitive changes to electrode impedance, rather than purely resistive changes. We also show that applying 4000 MW polyethylene glycol (PEG prevents impedance increases in vitro, and reduces the percent change in impedance in vivo following implantation. Our results highlight the importance of considering the contributions of non-cellular components to the decline in neural microelectrode performance, and present a proof of concept for using a simple dip-coated PEG film to modulate changes in microelectrode impedance.

  13. Fractal Interfaces for Stimulating and Recording Neural Implants

    Watterson, William James

    From investigating movement in an insect to deciphering cognition in a human brain to treating Parkinson's disease, hearing loss, or even blindness, electronic implants are an essential tool for understanding the brain and treating neural diseases. Currently, the stimulating and recording resolution of these implants remains low. For instance, they can record all the neuron activity associated with movement in an insect, but are quite far from recording, at an individual neuron resolution, the large volumes of brain tissue associated with cognition. Likewise, there is remarkable success in the cochlear implant restoring hearing due to the relatively simple anatomy of the auditory nerves, but are failing to restore vision to the blind due to poor signal fidelity and transmission in stimulating the more complex anatomy of the visual nerves. The critically important research needed to improve the resolution of these implants is to optimize the neuron-electrode interface. This thesis explores geometrical and material modifications to both stimulating and recording electrodes which can improve the neuron-electrode interface. First, we introduce a fractal electrode geometry which radically improves the restored visual acuity achieved by retinal implants and leads to safe, long-term operation of the implant. Next, we demonstrate excellent neuron survival and neurite outgrowth on carbon nanotube electrodes, thus providing a safe biomaterial which forms a strong connection between the electrode and neurons. Additional preliminary evidence suggests carbon nanotubes patterned into a fractal geometry will provide further benefits in improving the electrode-neuron interface. Finally, we propose a novel implant based off field effect transistor technology which utilizes an interconnecting fractal network of semiconducting carbon nanotubes to record from thousands of neurons simutaneously at an individual neuron resolution. Taken together, these improvements have the potential to

  14. Properties of Retinal Precursor Cells Grown on Vertically Aligned Multiwalled Carbon Nanotubes Generated for the Modification of Retinal Implant-Embedded Microelectrode Arrays.

    Johnen, Sandra; Meißner, Frank; Krug, Mario; Baltz, Thomas; Endler, Ingolf; Mokwa, Wilfried; Walter, Peter

    2016-01-01

    Background. To analyze the biocompatibility of vertically aligned multiwalled carbon nanotubes (MWCNT), used as nanomodification to optimize the properties of prostheses-embedded microelectrodes that induce electrical stimulation of surviving retinal cells. Methods. MWCNT were synthesized on silicon wafers. Their growth was achieved by iron particles (Fe) or mixtures of iron-platinum (Fe-Pt) and iron-titanium (Fe-Ti) acting as catalysts. Viability, growth, adhesion, and gene expression of L-929 and retinal precursor (R28) cells were analyzed after nondirect and direct contact. Results. Nondirect contact had almost no influence on cell growth, as measured in comparison to reference materials with defined levels of cytotoxicity. Both cell types exhibited good proliferation properties on each MWCNT-coated wafer. Viability ranged from 95.9 to 99.8%, in which better survival was observed for nonfunctionalized MWCNT generated with the Fe-Pt and Fe-Ti catalyst mixtures. R28 cells grown on the MWCNT-coated wafers showed a decreased gene expression associated with neural and glial properties. Expression of the cell cycle-related genes CCNC, MYC, and TP53 was slightly downregulated. Cultivation on plasma-treated MWCNT did not lead to additional changes. Conclusions. All tested MWCNT-covered slices showed good biocompatibility profiles, confirming that this nanotechnology is a promising tool to improve prostheses bearing electrodes which connect with retinal tissue.

  15. Properties of Retinal Precursor Cells Grown on Vertically Aligned Multiwalled Carbon Nanotubes Generated for the Modification of Retinal Implant-Embedded Microelectrode Arrays

    Sandra Johnen

    2016-01-01

    Full Text Available Background. To analyze the biocompatibility of vertically aligned multiwalled carbon nanotubes (MWCNT, used as nanomodification to optimize the properties of prostheses-embedded microelectrodes that induce electrical stimulation of surviving retinal cells. Methods. MWCNT were synthesized on silicon wafers. Their growth was achieved by iron particles (Fe or mixtures of iron-platinum (Fe-Pt and iron-titanium (Fe-Ti acting as catalysts. Viability, growth, adhesion, and gene expression of L-929 and retinal precursor (R28 cells were analyzed after nondirect and direct contact. Results. Nondirect contact had almost no influence on cell growth, as measured in comparison to reference materials with defined levels of cytotoxicity. Both cell types exhibited good proliferation properties on each MWCNT-coated wafer. Viability ranged from 95.9 to 99.8%, in which better survival was observed for nonfunctionalized MWCNT generated with the Fe-Pt and Fe-Ti catalyst mixtures. R28 cells grown on the MWCNT-coated wafers showed a decreased gene expression associated with neural and glial properties. Expression of the cell cycle-related genes CCNC, MYC, and TP53 was slightly downregulated. Cultivation on plasma-treated MWCNT did not lead to additional changes. Conclusions. All tested MWCNT-covered slices showed good biocompatibility profiles, confirming that this nanotechnology is a promising tool to improve prostheses bearing electrodes which connect with retinal tissue.

  16. Toward multi-area distributed network of implanted neural interrogators

    Powell, Marc P.; Hou, Xiaoxiao; Galligan, Craig; Ashe, Jeffrey; Borton, David A.

    2017-08-01

    As we aim to improve our understanding of the brain, it is critical that researchers have simultaneous multi-area, large-scale access to the brain. Information processing in the brain occurs through close and distant coupling of functional sub-domains, as opposed to within isolated single neurons. However, commercially available neural interfaces capable of sensing electrophysiology of single neurons, currently allow access to only a small, mm3 volume of cortical cells, are not scalable to recording from orders of magnitude more neurons, and leverage bulky, skull mounted hardware and cabling sensitive to relative movements of the skull and brain. In this work, we propose a system capable of recording from many individual distributed neural interrogator nodes, untethered from any external electronics. Using an array of epidural inductive coils to wirelessly power the implanted electronics, the system is intended to be agnostic to the surgical placement of any individual node. Here, we demonstrate the ability to transmit nearly 15mW of power with greater than 50% power transfer efficiency, benchtop testing of individual subcircuit system components showing successful digitization of neural signals, and wireless transmission currently supporting a data rate of 3.84Mbps. We leverage a software defined radio based RF receiver to demodulate the data which can be stored in memory for later retrieval. Finally, we introduce a packaging technology capable of isolating active electronics from the surrounding tissue while providing capability for electrical feed-through assemblies for external neural interfacing. We expect, based on the presented preliminary findings, that the system can be integrated into a platform technology for the study of the intricate interactions between cortical domains.

  17. Electrical Characterization of 3D Au Microelectrodes for Use in Retinal Prostheses.

    Lee, Sangmin; Ahn, Jae Hyun; Seo, Jong-Mo; Chung, Hum; Cho, Dong-Il Dan

    2015-06-17

    In order to provide high-quality visual information to patients who have implanted retinal prosthetic devices, the number of microelectrodes should be large. As the number of microelectrodes is increased, the dimensions of each microelectrode must be decreased, which in turn results in an increased microelectrode interface impedance and decreased injection current dynamic range. In order to improve the trade-off envelope between the number of microelectrodes and the current injection characteristics, a 3D microelectrode structure can be used as an alternative. In this paper, the electrical characteristics of 2D and 3D Au microelectrodes were investigated. In order to examine the effects of the structural difference, 2D and 3D Au microelectrodes with different base areas but similar effective surface areas were fabricated and evaluated. Interface impedances were measured and similar dynamic ranges were obtained for both 2D and 3D Au microelectrodes. These results indicate that more electrodes can be implemented in the same area if 3D designs are used. Furthermore, the 3D Au microelectrodes showed substantially enhanced electrical durability characteristics against over-injected stimulation currents, withstanding electrical currents that are much larger than the limit measured for 2D microelectrodes of similar area. This enhanced electrical durability property of 3D Au microelectrodes is a new finding in microelectrode research, and makes 3D microelectrodes very desirable devices.

  18. Electrical Characterization of 3D Au Microelectrodes for Use in Retinal Prostheses

    Sangmin Lee

    2015-06-01

    Full Text Available In order to provide high-quality visual information to patients who have implanted retinal prosthetic devices, the number of microelectrodes should be large. As the number of microelectrodes is increased, the dimensions of each microelectrode must be decreased, which in turn results in an increased microelectrode interface impedance and decreased injection current dynamic range. In order to improve the trade-off envelope between the number of microelectrodes and the current injection characteristics, a 3D microelectrode structure can be used as an alternative. In this paper, the electrical characteristics of 2D and 3D Au microelectrodes were investigated. In order to examine the effects of the structural difference, 2D and 3D Au microelectrodes with different base areas but similar effective surface areas were fabricated and evaluated. Interface impedances were measured and similar dynamic ranges were obtained for both 2D and 3D Au microelectrodes. These results indicate that more electrodes can be implemented in the same area if 3D designs are used. Furthermore, the 3D Au microelectrodes showed substantially enhanced electrical durability characteristics against over-injected stimulation currents, withstanding electrical currents that are much larger than the limit measured for 2D microelectrodes of similar area. This enhanced electrical durability property of 3D Au microelectrodes is a new finding in microelectrode research, and makes 3D microelectrodes very desirable devices.

  19. Construction of implantable optical fibers for long-term optogenetic manipulation of neural circuits.

    Sparta, Dennis R; Stamatakis, Alice M; Phillips, Jana L; Hovelsø, Nanna; van Zessen, Ruud; Stuber, Garret D

    2011-12-08

    In vivo optogenetic strategies have redefined our ability to assay how neural circuits govern behavior. Although acutely implanted optical fibers have previously been used in such studies, long-term control over neuronal activity has been largely unachievable. Here we describe a method to construct implantable optical fibers to readily manipulate neural circuit elements with minimal tissue damage or change in light output over time (weeks to months). Implanted optical fibers readily interface with in vivo electrophysiological arrays or electrochemical detection electrodes. The procedure described here, from implant construction to the start of behavioral experimentation, can be completed in approximately 2-6 weeks. Successful use of implantable optical fibers will allow for long-term control of mammalian neural circuits in vivo, which is integral to the study of the neurobiology of behavior.

  20. A novel flexible cuff-like microelectrode for dual purpose, acute and chronic electrical interfacing with the mouse cervical vagus nerve

    Caravaca, A. S.; Tsaava, T.; Goldman, L.; Silverman, H.; Riggott, G.; Chavan, S. S.; Bouton, C.; Tracey, K. J.; Desimone, R.; Boyden, E. S.; Sohal, H. S.; Olofsson, P. S.

    2017-12-01

    Objective. Neural reflexes regulate immune responses and homeostasis. Advances in bioelectronic medicine indicate that electrical stimulation of the vagus nerve can be used to treat inflammatory disease, yet the understanding of neural signals that regulate inflammation is incomplete. Current interfaces with the vagus nerve do not permit effective chronic stimulation or recording in mouse models, which is vital to studying the molecular and neurophysiological mechanisms that control inflammation homeostasis in health and disease. We developed an implantable, dual purpose, multi-channel, flexible ‘microelectrode’ array, for recording and stimulation of the mouse vagus nerve. Approach. The array was microfabricated on an 8 µm layer of highly biocompatible parylene configured with 16 sites. The microelectrode was evaluated by studying the recording and stimulation performance. Mice were chronically implanted with devices for up to 12 weeks. Main results. Using the microelectrode in vivo, high fidelity signals were recorded during physiological challenges (e.g potassium chloride and interleukin-1β), and electrical stimulation of the vagus nerve produced the expected significant reduction of blood levels of tumor necrosis factor (TNF) in endotoxemia. Inflammatory cell infiltration at the microelectrode 12 weeks of implantation was limited according to radial distribution analysis of inflammatory cells. Significance. This novel device provides an important step towards a viable chronic interface for cervical vagus nerve stimulation and recording in mice.

  1. An Implantable Wireless Neural Interface System for Simultaneous Recording and Stimulation of Peripheral Nerve with a Single Cuff Electrode.

    Shon, Ahnsei; Chu, Jun-Uk; Jung, Jiuk; Kim, Hyungmin; Youn, Inchan

    2017-12-21

    Recently, implantable devices have become widely used in neural prostheses because they eliminate endemic drawbacks of conventional percutaneous neural interface systems. However, there are still several issues to be considered: low-efficiency wireless power transmission; wireless data communication over restricted operating distance with high power consumption; and limited functionality, working either as a neural signal recorder or as a stimulator. To overcome these issues, we suggest a novel implantable wireless neural interface system for simultaneous neural signal recording and stimulation using a single cuff electrode. By using widely available commercial off-the-shelf (COTS) components, an easily reconfigurable implantable wireless neural interface system was implemented into one compact module. The implantable device includes a wireless power consortium (WPC)-compliant power transmission circuit, a medical implant communication service (MICS)-band-based radio link and a cuff-electrode path controller for simultaneous neural signal recording and stimulation. During in vivo experiments with rabbit models, the implantable device successfully recorded and stimulated the tibial and peroneal nerves while communicating with the external device. The proposed system can be modified for various implantable medical devices, especially such as closed-loop control based implantable neural prostheses requiring neural signal recording and stimulation at the same time.

  2. An Implantable Wireless Neural Interface System for Simultaneous Recording and Stimulation of Peripheral Nerve with a Single Cuff Electrode

    Ahnsei Shon

    2017-12-01

    Full Text Available Recently, implantable devices have become widely used in neural prostheses because they eliminate endemic drawbacks of conventional percutaneous neural interface systems. However, there are still several issues to be considered: low-efficiency wireless power transmission; wireless data communication over restricted operating distance with high power consumption; and limited functionality, working either as a neural signal recorder or as a stimulator. To overcome these issues, we suggest a novel implantable wireless neural interface system for simultaneous neural signal recording and stimulation using a single cuff electrode. By using widely available commercial off-the-shelf (COTS components, an easily reconfigurable implantable wireless neural interface system was implemented into one compact module. The implantable device includes a wireless power consortium (WPC-compliant power transmission circuit, a medical implant communication service (MICS-band-based radio link and a cuff-electrode path controller for simultaneous neural signal recording and stimulation. During in vivo experiments with rabbit models, the implantable device successfully recorded and stimulated the tibial and peroneal nerves while communicating with the external device. The proposed system can be modified for various implantable medical devices, especially such as closed-loop control based implantable neural prostheses requiring neural signal recording and stimulation at the same time.

  3. OptoZIF Drive: a 3D printed implant and assembly tool package for neural recording and optical stimulation in freely moving mice

    Freedman, David S.; Schroeder, Joseph B.; Telian, Gregory I.; Zhang, Zhengyang; Sunil, Smrithi; Ritt, Jason T.

    2016-12-01

    Objective. Behavioral neuroscience studies in freely moving rodents require small, light-weight implants to facilitate neural recording and stimulation. Our goal was to develop an integrated package of 3D printed parts and assembly aids for labs to rapidly fabricate, with minimal training, an implant that combines individually positionable microelectrodes, an optical fiber, zero insertion force (ZIF-clip) headstage connection, and secondary recording electrodes, e.g. for electromyography (EMG). Approach. Starting from previous implant designs that position recording electrodes using a control screw, we developed an implant where the main drive body, protective shell, and non-metal components of the microdrives are 3D printed in parallel. We compared alternative shapes and orientations of circuit boards for electrode connection to the headstage, in terms of their size, weight, and ease of wire insertion. We iteratively refined assembly methods, and integrated additional assembly aids into the 3D printed casing. Main results. We demonstrate the effectiveness of the OptoZIF Drive by performing real time optogenetic feedback in behaving mice. A novel feature of the OptoZIF Drive is its vertical circuit board, which facilities direct ZIF-clip connection. This feature requires angled insertion of an optical fiber that still can exit the drive from the center of a ring of recording electrodes. We designed an innovative 2-part protective shell that can be installed during the implant surgery to facilitate making additional connections to the circuit board. We use this feature to show that facial EMG in mice can be used as a control signal to lock stimulation to the animal’s motion, with stable EMG signal over several months. To decrease assembly time, reduce assembly errors, and improve repeatability, we fabricate assembly aids including a drive holder, a drill guide, an implant fixture for microelectode ‘pinning’, and a gold plating fixture. Significance. The

  4. The consequences of neural degeneration regarding optimal cochlear implant position in scala tympani: a model approach.

    Briaire, Jeroen J; Frijns, Johan H M

    2006-04-01

    Cochlear implant research endeavors to optimize the spatial selectivity, threshold and dynamic range with the objective of improving the speech perception performance of the implant user. One of the ways to achieve some of these goals is by electrode design. New cochlear implant electrode designs strive to bring the electrode contacts into close proximity to the nerve fibers in the modiolus: this is done by placing the contacts on the medial side of the array and positioning the implant against the medial wall of scala tympani. The question remains whether this is the optimal position for a cochlea with intact neural fibers and, if so, whether it is also true for a cochlea with degenerated neural fibers. In this study a computational model of the implanted human cochlea is used to investigate the optimal position of the array with respect to threshold, dynamic range and spatial selectivity for a cochlea with intact nerve fibers and for degenerated nerve fibers. In addition, the model is used to evaluate the predictive value of eCAP measurements for obtaining peri-operative information on the neural status. The model predicts improved threshold, dynamic range and spatial selectivity for the peri-modiolar position at the basal end of the cochlea, with minimal influence of neural degeneration. At the apical end of the array (1.5 cochlear turns), the dynamic range and the spatial selectivity are limited due to the occurrence of cross-turn stimulation, with the exception of the condition without neural degeneration and with the electrode array along the lateral wall of scala tympani. The eCAP simulations indicate that a large P(0) peak occurs before the N(1)P(1) complex when the fibers are not degenerated. The absence of this peak might be used as an indicator for neural degeneration.

  5. Modeling and Simulation of Microelectrode-Retina Interactions

    Beckerman, M

    2002-11-30

    The goal of the retinal prosthesis project is the development of an implantable microelectrode array that can be used to supply visually-driven electrical input to cells in the retina, bypassing nonfunctional rod and cone cells, thereby restoring vision to blind individuals. This goal will be achieved through the study of the fundamentals of electrical engineering, vision research, and biomedical engineering with the aim of acquiring the knowledge needed to engineer a high-density microelectrode-tissue hybrid sensor that will restore vision to millions of blind persons. The modeling and simulation task within this project is intended to address the question how best to stimulate, and communicate with, cells in the retina using implanted microelectrodes.

  6. Wireless power transfer and data communication for neural implants case study : epilepsy monitoring

    Yilmaz, Gürkan

    2017-01-01

    This book presents new circuits and systems for implantable biomedical applications targeting neural recording. The authors describe a system design adapted to conform to the requirements of an epilepsy monitoring system. Throughout the book, these requirements are reflected in terms of implant size, power consumption, and data rate. In addition to theoretical background which explains the relevant technical challenges, the authors provide practical, step-by-step solutions to these problems. Readers will gain understanding of the numerical values in such a system, enabling projections for feasibility of new projects. Provides complete, system-level perspective for implantable batteryless biomedical system; Extends design example to implementation and long term in-vitro validation; Discusses system design concerns regarding wireless power transmission and wireless data communication, particularly for systems in which both are performed on the same channel/frequency; Presents fully-integrated, implantable syste...

  7. Multi-microelectrode devices for intrafascicular use in peripheral nerve

    Rutten, Wim

    1996-01-01

    This minisymposium paper gives an overview of experimental, modeling, design and microfabrication steps which lead towards the University of Twente three-dimensional 128-fold silicon microelectrode device. The device is meant for implantation in peripheral nerve for neuromuscular control purposes

  8. Using Arrays of Microelectrodes Implanted in Residual Peripheral Nerves to Provide Dexterous Control of, and Modulated Sensory Feedback from, a Hand Prosthesis

    2017-10-01

    systems integration) and the software for offline analysis and real- time decoding and stimulation . They have had experience performing...microstimulation sessions). All experimental sessions were recorded with a video camera, which was time -stamped to the neural recording or stimulation data. 2.5...evoked an ‘electric shock’ like quality, and lower frequencies (1–25 Hz) and longer stimulation times (up to 60 s) could evoke more physiological

  9. Residual neural processng of musical sound features in adult cochlear implant users

    Timm, Lydia; Vuust, Peter; Brattico, Elvira

    2014-01-01

    setting lasting only 20 min. The presentation of stimuli did not require the participants' attention, allowing the study of the early automatic stage of feature processing in the auditory cortex. For the CI users, we obtained mismatch negativity (MMN) brain responses to five feature changes...... neural skills for music processing even in CI users who have been implanted in adolescence or adulthood. HIGHLIGHTS: -Automatic brain responses to musical feature changes reflect the limitations of central auditory processing in adult Cochlear Implant users.-The brains of adult CI users automatically...

  10. Monitoring the evolution of boron doped porous diamond electrode on flexible retinal implant by OCT and in vivo impedance spectroscopy

    Hébert, Clément; Cottance, Myline; Degardin, Julie; Scorsone, Emmanuel; Rousseau, Lionel; Lissorgues, Gaelle; Bergonzo, Philippe; Picaud, Serge

    2016-01-01

    Nanocrystalline Boron doped Diamond proved to be a very attractive material for neural interfacing, especially with the retina, where reduce glia growth is observed with respect to other materials, thus facilitating neuro-stimulation over long terms. In the present study, we integrated diamond microelectrodes on a polyimide substrate and investigated their performances for the development of neural prosthesis. A full description of the microfabrication of the implants is provided and their functionalities are assessed using cyclic voltammetry and electrochemical impedance spectroscopy. A porous structure of the electrode surface was thus revealed and showed promising properties for neural recording or stimulation. Using the flexible implant, we showed that is possible to follow in vivo the evolution of the electric contact between the diamond electrodes and the retina over 4 months by using electrochemical impedance spectroscopy. The position of the implant was also monitored by optical coherence tomography to corroborate the information given by the impedance measurements. The results suggest that diamond microelectrodes are very good candidates for retinal prosthesis. - Highlights: • Microfabrication of porous diamond electrode on flexible retinal implant • Electrochemical characterization of microelectrode for neural interfacing • In vivo impedance spectroscopy of retinal tissue

  11. Monitoring the evolution of boron doped porous diamond electrode on flexible retinal implant by OCT and in vivo impedance spectroscopy

    Hébert, Clément, E-mail: clement.hebert@icn2.cat [CEA-LIST, Diamond Sensors Laboratory, Gif-sur-Yvette 91191 (France); Cottance, Myline [Université Paris-Est, ESYCOM-ESIEE Paris, Noisy le Grand (France); Degardin, Julie [INSERM, U968, Institut de la Vision, Paris (France); Scorsone, Emmanuel [CEA-LIST, Diamond Sensors Laboratory, Gif-sur-Yvette 91191 (France); Rousseau, Lionel; Lissorgues, Gaelle [Université Paris-Est, ESYCOM-ESIEE Paris, Noisy le Grand (France); Bergonzo, Philippe [CEA-LIST, Diamond Sensors Laboratory, Gif-sur-Yvette 91191 (France); Picaud, Serge [INSERM, U968, Institut de la Vision, Paris (France)

    2016-12-01

    Nanocrystalline Boron doped Diamond proved to be a very attractive material for neural interfacing, especially with the retina, where reduce glia growth is observed with respect to other materials, thus facilitating neuro-stimulation over long terms. In the present study, we integrated diamond microelectrodes on a polyimide substrate and investigated their performances for the development of neural prosthesis. A full description of the microfabrication of the implants is provided and their functionalities are assessed using cyclic voltammetry and electrochemical impedance spectroscopy. A porous structure of the electrode surface was thus revealed and showed promising properties for neural recording or stimulation. Using the flexible implant, we showed that is possible to follow in vivo the evolution of the electric contact between the diamond electrodes and the retina over 4 months by using electrochemical impedance spectroscopy. The position of the implant was also monitored by optical coherence tomography to corroborate the information given by the impedance measurements. The results suggest that diamond microelectrodes are very good candidates for retinal prosthesis. - Highlights: • Microfabrication of porous diamond electrode on flexible retinal implant • Electrochemical characterization of microelectrode for neural interfacing • In vivo impedance spectroscopy of retinal tissue.

  12. Cycle Training Using Implanted Neural Prostheses: Team Cleveland.

    McDaniel, John; Lombardo, Lisa M; Foglyano, Kevin M; Marasco, Paul D; J Triolo, Ronald

    2017-12-05

    Recently our laboratory team focused on training five individuals with complete spinal cord injuries for an overground FES bike race in the 2016 Cybathlon held in Zurich Switzerland. A unique advantage team Cleveland had over other teams was the use of implanted pulse generators that provide more selective activation of muscles compared to standard surface stimulation. The advancements in muscle strength and endurance and ultimately cycling power our pilots made during this training period helped propel our competing pilot to win gold at the Cybathlon and allowed our pilots to ride their bikes outside within their communities. Such positive outcomes has encouraged us to further explore more widespread use of FES overground cycling as a rehabilitative tool for those with spinal cord injuries. This review will describes our approach to this race including information on the pilots, stimulation strategy, bike details and training program.

  13. Cycle Training Using Implanted Neural Prostheses: Team Cleveland

    John McDaniel

    2017-12-01

    Full Text Available Recently our laboratory team focused on training five individuals with complete spinal cord injuries for an overground FES bike race in the 2016 Cybathlon held in Zurich Switzerland. A unique advantage team Cleveland had over other teams was the use of implanted pulse generators that provide more selective activation of muscles compared to standard surface stimulation. The advancements in muscle strength and endurance and ultimately cycling power our pilots made during this training period helped propel our competing pilot to win gold at the Cybathlon and allowed our pilots to ride their bikes outside within their communities. Such positive outcomes has encouraged us to further explore more widespread use of FES overground cycling as a rehabilitative tool for those with spinal cord injuries. This review will describes our approach to this race including information on the pilots, stimulation strategy, bike details and training program.

  14. A Chronically Implantable Bidirectional Neural Interface for Non-human Primates

    Misako Komatsu

    2017-09-01

    Full Text Available Optogenetics has potential applications in the study of epilepsy and neuroprostheses, and for studies on neural circuit dynamics. However, to achieve translation to clinical usage, optogenetic interfaces that are capable of chronic stimulation and monitoring with minimal brain trauma are required. We aimed to develop a chronically implantable device for photostimulation of the brain of non-human primates. We used a micro-light-emitting diode (LED array with a flexible polyimide film. The array was combined with a whole-cortex electrocorticographic (ECoG electrode array for simultaneous photostimulation and recording. Channelrhodopsin-2 (ChR2 was virally transduced into the cerebral cortex of common marmosets, and then the device was epidurally implanted into their brains. We recorded the neural activity during photostimulation of the awake monkeys for 4 months. The neural responses gradually increased after the virus injection for ~8 weeks and remained constant for another 8 weeks. The micro-LED and ECoG arrays allowed semi-invasive simultaneous stimulation and recording during long-term implantation in the brains of non-human primates. The development of this device represents substantial progress in the field of optogenetic applications.

  15. A preferential design approach for energy-efficient and robust implantable neural signal processing hardware.

    Narasimhan, Seetharam; Chiel, Hillel J; Bhunia, Swarup

    2009-01-01

    For implantable neural interface applications, it is important to compress data and analyze spike patterns across multiple channels in real time. Such a computational task for online neural data processing requires an innovative circuit-architecture level design approach for low-power, robust and area-efficient hardware implementation. Conventional microprocessor or Digital Signal Processing (DSP) chips would dissipate too much power and are too large in size for an implantable system. In this paper, we propose a novel hardware design approach, referred to as "Preferential Design" that exploits the nature of the neural signal processing algorithm to achieve a low-voltage, robust and area-efficient implementation using nanoscale process technology. The basic idea is to isolate the critical components with respect to system performance and design them more conservatively compared to the noncritical ones. This allows aggressive voltage scaling for low power operation while ensuring robustness and area efficiency. We have applied the proposed approach to a neural signal processing algorithm using the Discrete Wavelet Transform (DWT) and observed significant improvement in power and robustness over conventional design.

  16. Neural signal processing and closed-loop control algorithm design for an implanted neural recording and stimulation system.

    Hamilton, Lei; McConley, Marc; Angermueller, Kai; Goldberg, David; Corba, Massimiliano; Kim, Louis; Moran, James; Parks, Philip D; Sang Chin; Widge, Alik S; Dougherty, Darin D; Eskandar, Emad N

    2015-08-01

    A fully autonomous intracranial device is built to continually record neural activities in different parts of the brain, process these sampled signals, decode features that correlate to behaviors and neuropsychiatric states, and use these features to deliver brain stimulation in a closed-loop fashion. In this paper, we describe the sampling and stimulation aspects of such a device. We first describe the signal processing algorithms of two unsupervised spike sorting methods. Next, we describe the LFP time-frequency analysis and feature derivation from the two spike sorting methods. Spike sorting includes a novel approach to constructing a dictionary learning algorithm in a Compressed Sensing (CS) framework. We present a joint prediction scheme to determine the class of neural spikes in the dictionary learning framework; and, the second approach is a modified OSort algorithm which is implemented in a distributed system optimized for power efficiency. Furthermore, sorted spikes and time-frequency analysis of LFP signals can be used to generate derived features (including cross-frequency coupling, spike-field coupling). We then show how these derived features can be used in the design and development of novel decode and closed-loop control algorithms that are optimized to apply deep brain stimulation based on a patient's neuropsychiatric state. For the control algorithm, we define the state vector as representative of a patient's impulsivity, avoidance, inhibition, etc. Controller parameters are optimized to apply stimulation based on the state vector's current state as well as its historical values. The overall algorithm and software design for our implantable neural recording and stimulation system uses an innovative, adaptable, and reprogrammable architecture that enables advancement of the state-of-the-art in closed-loop neural control while also meeting the challenges of system power constraints and concurrent development with ongoing scientific research designed

  17. Freeze Drying Improves the Shelf-Life of Conductive Polymer Modified Neural Electrodes

    Himadri S. Mandal

    2015-08-01

    Full Text Available Coating microelectrodes with conductive polymer is widely recognized to decrease impedance and improve performance of implantable neural devices during recording and stimulation. A concern for wide-spread use of this approach is shelf-life, i.e., the electrochemical stability of the coated microelectrodes prior to use. In this work, we investigated the possibility of using the freeze-drying process in order to retain the native low impedance state and, thereby, improve the shelf-life of conductive polymer poly(3,4-ethylenedioxythiophene (PEDOT-PSS modified neural electrodes. Control PEDOT-PSS coated microelectrodes demonstrated a significant increase in impedance at 1 kHz after 41–50 days of room temperature storage. Based on equivalent circuit modeling derived from electrochemical impedance spectroscopy, this increase in impedance could be largely attributed to a decrease in the interfacial capacitance consistent with a collapse and closing of the porous structure of the polymeric coating. Time-dependent electrochemical impedance measurements revealed higher stability of the freeze-dried coated microelectrodes compared to the controls, such that impedance values after 41–50 days appeared to be indistinguishable from the initial levels. This suggests that freeze drying PEDOT-PSS coated microelectrodes correlates with enhanced electrochemical stability during shelf storage.

  18. A novel method for extraction of neural response from single channel cochlear implant auditory evoked potentials.

    Sinkiewicz, Daniel; Friesen, Lendra; Ghoraani, Behnaz

    2017-02-01

    Cortical auditory evoked potentials (CAEP) are used to evaluate cochlear implant (CI) patient auditory pathways, but the CI device produces an electrical artifact, which obscures the relevant information in the neural response. Currently there are multiple methods, which attempt to recover the neural response from the contaminated CAEP, but there is no gold standard, which can quantitatively confirm the effectiveness of these methods. To address this crucial shortcoming, we develop a wavelet-based method to quantify the amount of artifact energy in the neural response. In addition, a novel technique for extracting the neural response from single channel CAEPs is proposed. The new method uses matching pursuit (MP) based feature extraction to represent the contaminated CAEP in a feature space, and support vector machines (SVM) to classify the components as normal hearing (NH) or artifact. The NH components are combined to recover the neural response without artifact energy, as verified using the evaluation tool. Although it needs some further evaluation, this approach is a promising method of electrical artifact removal from CAEPs. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  19. Studies in RF power communication, SAR, and temperature elevation in wireless implantable neural interfaces.

    Yujuan Zhao

    Full Text Available Implantable neural interfaces are designed to provide a high spatial and temporal precision control signal implementing high degree of freedom real-time prosthetic systems. The development of a Radio Frequency (RF wireless neural interface has the potential to expand the number of applications as well as extend the robustness and longevity compared to wired neural interfaces. However, it is well known that RF signal is absorbed by the body and can result in tissue heating. In this work, numerical studies with analytical validations are performed to provide an assessment of power, heating and specific absorption rate (SAR associated with the wireless RF transmitting within the human head. The receiving antenna on the neural interface is designed with different geometries and modeled at a range of implanted depths within the brain in order to estimate the maximum receiving power without violating SAR and tissue temperature elevation safety regulations. Based on the size of the designed antenna, sets of frequencies between 1 GHz to 4 GHz have been investigated. As expected the simulations demonstrate that longer receiving antennas (dipole and lower working frequencies result in greater power availability prior to violating SAR regulations. For a 15 mm dipole antenna operating at 1.24 GHz on the surface of the brain, 730 uW of power could be harvested at the Federal Communications Commission (FCC SAR violation limit. At approximately 5 cm inside the head, this same antenna would receive 190 uW of power prior to violating SAR regulations. Finally, the 3-D bio-heat simulation results show that for all evaluated antennas and frequency combinations we reach FCC SAR limits well before 1 °C. It is clear that powering neural interfaces via RF is possible, but ultra-low power circuit designs combined with advanced simulation will be required to develop a functional antenna that meets all system requirements.

  20. Telemetria de resposta neural intra-operatória em usuários de implante coclear Neural response telemetry measures in patients implanted with Nucleus 24®

    Mariana Cardoso Guedes

    2005-10-01

    Full Text Available A possibilidade de realizar o implante coclear em crianças pequenas torna necessário o uso de medidas objetivas para auxiliar a programação do processador de fala. Telemetria é a propriedade que permite, no Nucleus 24®, a obtenção do potencial de ação composto evocado do VIII par (EAP utilizando o implante como instrumento de estimulação e gravação para o estudo das propriedades neurais remanescentes. OBJETIVO: Descrever a utilização do sistema de telemetria para a gravação do EAP, caracterizando as respostas obtidas e a sua prevalência na condição intraoperatória. FORMA DE ESTUDO: clínico com coorte transversal. MATERIAL E MÉTODO: Medidas das impedâncias dos eletrodos e do EAP em um grupo de 17 indivíduos usuários do implante Nucleus 24® durante a cirurgia. Análise das respostas de acordo com a etiologia, o tempo de duração da surdez e a posição dos eletrodos dentro da cóclea. RESULTADOS: Maior prevalência nos eletrodos apicais e limiares mais elevados nos casos de meningite e otosclerose. CONCLUSÃO: A telemetria é eficiente para a verificação da integridade dos eletrodos na condição intraoperatória e para a gravação do EAP, apresentando alta prevalência na população estudada.Cochlear implantation has been recommended for children under 24 months of age. The use of objective measures is needed to help speech processor programming. The electrically evoked compound potential (EAP, which can be assessed by neural response telemetry (NRT, is one of those objective measures. AIM: to determine how often the EAP can be recorded by NRT system during surgery and to describe the responses. STUDY DESIGN: clinical with transversal cohort. MATERIAL AND METHOD: the impedances and NRT were measured in a group of 17 Nucleus 24 ® implant users. The responses were analyzed and compared to the etiology, hearing loss duration and electrode array position. RESULTS: The EAP was easily recorded in the apical electrodes

  1. Antibacterial, anti-inflammatory and neuroprotective layer-by-layer coatings for neural implants

    Zhang, Zhiling; Nong, Jia; Zhong, Yinghui

    2015-08-01

    Objective. Infection, inflammation, and neuronal loss are common issues that seriously affect the functionality and longevity of chronically implanted neural prostheses. Minocycline hydrochloride (MH) is a broad-spectrum antibiotic and effective anti-inflammatory drug that also exhibits potent neuroprotective activities. In this study, we investigated the development of biocompatible thin film coatings capable of sustained release of MH for improving the long term performance of implanted neural electrodes. Approach. We developed a novel magnesium binding-mediated drug delivery mechanism for controlled and sustained release of MH from an ultrathin hydrophilic layer-by-layer (LbL) coating and characterized the parameters that control MH loading and release. The anti-biofilm, anti-inflammatory and neuroprotective potencies of the LbL coating and released MH were also examined. Main results. Sustained release of physiologically relevant amount of MH for 46 days was achieved from the Mg2+-based LbL coating at a thickness of 1.25 μm. In addition, MH release from the LbL coating is pH-sensitive. The coating and released MH demonstrated strong anti-biofilm, anti-inflammatory, and neuroprotective potencies. Significance. This study reports, for the first time, the development of a bioactive coating that can target infection, inflammation, and neuroprotection simultaneously, which may facilitate the translation of neural interfaces to clinical applications.

  2. Toward a distributed free-floating wireless implantable neural recording system.

    Pyungwoo Yeon; Xingyuan Tong; Byunghun Lee; Mirbozorgi, Abdollah; Ash, Bruce; Eckhardt, Helmut; Ghovanloo, Maysam

    2016-08-01

    To understand the complex correlations between neural networks across different regions in the brain and their functions at high spatiotemporal resolution, a tool is needed for obtaining long-term single unit activity (SUA) across the entire brain area. The concept and preliminary design of a distributed free-floating wireless implantable neural recording (FF-WINeR) system are presented, which can enabling SUA acquisition by dispersedly implanting tens to hundreds of untethered 1 mm3 neural recording probes, floating with the brain and operating wirelessly across the cortical surface. For powering FF-WINeR probes, a 3-coil link with an intermediate high-Q resonator provides a minimum S21 of -22.22 dB (in the body medium) and -21.23 dB (in air) at 2.8 cm coil separation, which translates to 0.76%/759 μW and 0.6%/604 μW of power transfer efficiency (PTE) / power delivered to a 9 kΩ load (PDL), in body and air, respectively. A mock-up FF-WINeR is implemented to explore microassembly method of the 1×1 mm2 micromachined silicon die with a bonding wire-wound coil and a tungsten micro-wire electrode. Circuit design methods to fit the active circuitry in only 0.96 mm2 of die area in a 130 nm standard CMOS process, and satisfy the strict power and performance requirements (in simulations) are discussed.

  3. Chronic behavior evaluation of a micro-machined neural implant with optimized design based on an experimentally derived model.

    Andrei, Alexandru; Welkenhuysen, Marleen; Ameye, Lieveke; Nuttin, Bart; Eberle, Wolfgang

    2011-01-01

    Understanding the mechanical interactions between implants and the surrounding tissue is known to have an important role for improving the bio-compatibility of such devices. Using a recently developed model, a particular micro-machined neural implant design aiming the reduction of insertion forces dependence on the insertion speed was optimized. Implantations with 10 and 100 μm/s insertion speeds showed excellent agreement with the predicted behavior. Lesion size, gliosis (GFAP), inflammation (ED1) and neuronal cells density (NeuN) was evaluated after 6 week of chronic implantation showing no insertion speed dependence.

  4. Design, implementation and testing of an implantable impedance-based feedback-controlled neural gastric stimulator

    Arriagada, A J; Jurkov, A S; Mintchev, M P; Neshev, E; Andrews, C N; Muench, G

    2011-01-01

    Functional neural gastrointestinal electrical stimulation (NGES) is a methodology of gastric electrical stimulation that can be applied as a possible treatment for disorders such as obesity and gastroparesis. NGES is capable of generating strong lumen-occluding local contractions that can produce retrograde or antegrade movement of gastric content. A feedback-controlled implantable NGES system has been designed, implemented and tested both in laboratory conditions and in an acute animal setting. The feedback system, based on gastric tissue impedance change, is aimed at reducing battery energy requirements and managing the phenomenon of gastric tissue accommodation. Acute animal testing was undertaken in four mongrel dogs (2 M, 2 F, weight 25.53 ± 7.3 kg) that underwent subserosal two-channel electrode implantation. Three force transducers sutured serosally along the gastric axis and a wireless signal acquisition system were utilized to record stimulation-generated contractions and tissue impedance variations respectively. Mechanically induced contractions in the stomach were utilized to indirectly generate a tissue impedance change that was detected by the feedback system. Results showed that increasing or decreasing impedance changes were detected by the implantable stimulator and that therapy can be triggered as a result. The implantable feedback system brings NGES one step closer to long term treatment of burdening gastric motility disorders in humans

  5. Design and evaluation of carbon nanofiber and silicon materials for neural implant applications

    McKenzie, Janice L.

    Reduction of glial scar tissue around central nervous system implants is necessary for improved efficacy in chronic applications. Design of materials that possess tunable properties inspired by native biological tissue and elucidation of pertinent cellular interactions with these materials was the motivation for this study. Since nanoscale carbon fibers possess the fundamental dimensional similarities to biological tissue and have attractive material properties needed for neural biomaterial implants, this present study explored cytocompatibility of these materials as well as modifications to traditionally used silicon. On silicon materials, results indicated that nanoscale surface features reduced astrocyte functions, and could be used to guide neurite extension from PC12 cells. Similarly, it was determined that astrocyte functions (key cells in glial scar tissue formation) were reduced on smaller diameter carbon fibers (125 nm or less) while PC12 neurite extension was enhanced on smaller diameter carbon fibers (100 nm or less). Further studies implicated laminin adsorption as a key mechanism in enhancing astrocyte adhesion to larger diameter fibers and at the same time encouraging neurite extension on smaller diameter fibers. Polycarbonate urethane (PCU) was then used as a matrix material for the smaller diameter carbon fibers (100 and 60 nm). These composites proved very versatile since electrical and mechanical properties as well as cell functions and directionality could be influenced by changing bulk and surface composition and features of these matrices. When these composites were modified to be smooth at the micronscale and only rough at the nanoscale, P19 cells actually submerged philopodia, extensions, or whole cells bodies beneath the PCU in order to interact with the carbon nanofibers. These carbon nanofiber composites that have been formulated are a promising material to coat neural probes and thereby enhance functionality at the tissue interface. This

  6. Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

    Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

    2011-10-01

    In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.

  7. Residual Neural Processing of Musical Sound Features in Adult Cochlear Implant Users

    Timm, Lydia; Vuust, Peter; Brattico, Elvira; Agrawal, Deepashri; Debener, Stefan; Büchner, Andreas; Dengler, Reinhard; Wittfoth, Matthias

    2014-01-01

    Auditory processing in general and music perception in particular are hampered in adult cochlear implant (CI) users. To examine the residual music perception skills and their underlying neural correlates in CI users implanted in adolescence or adulthood, we conducted an electrophysiological and behavioral study comparing adult CI users with normal-hearing age-matched controls (NH controls). We used a newly developed musical multi-feature paradigm, which makes it possible to test automatic auditory discrimination of six different types of sound feature changes inserted within a musical enriched setting lasting only 20 min. The presentation of stimuli did not require the participants’ attention, allowing the study of the early automatic stage of feature processing in the auditory cortex. For the CI users, we obtained mismatch negativity (MMN) brain responses to five feature changes but not to changes of rhythm, whereas we obtained MMNs for all the feature changes in the NH controls. Furthermore, the MMNs to deviants of pitch of CI users were reduced in amplitude and later than those of NH controls for changes of pitch and guitar timber. No other group differences in MMN parameters were found to changes in intensity and saxophone timber. Furthermore, the MMNs in CI users reflected the behavioral scores from a respective discrimination task and were correlated with patients’ age and speech intelligibility. Our results suggest that even though CI users are not performing at the same level as NH controls in neural discrimination of pitch-based features, they do possess potential neural abilities for music processing. However, CI users showed a disrupted ability to automatically discriminate rhythmic changes compared with controls. The current behavioral and MMN findings highlight the residual neural skills for music processing even in CI users who have been implanted in adolescence or adulthood. Highlights: -Automatic brain responses to musical feature changes

  8. Biofunctionalization of diamond microelectrodes

    Reitinger, Andreas Adam; Lud, Simon Quartus; Stutzmann, Martin; Garrido, Jose Antonio [Walter Schottky Institut, TU Muenchen (Germany); Hutter, Naima Aurelia; Richter, Gerhard; Jordan, Rainer [WACKER-Chair of Macromolecular Chemistry, TU Muenchen (Germany)

    2010-07-01

    In this work we present two main routes for the biofunctionalization of nanocrystalline diamond films, aiming at the application of diamond microelectrodes as amperometric biosensors. We report on direct covalent grafting of biomolecules on nanocrystalline diamond films via diazonium monophenyls and biphenyls as well as other linker molecules, forming self-assembled monolayers on the diamond surface. Monolayers with different functional head groups have been characterized. Patterning of the available functional groups using electron beam-induced chemical lithography allows the selective preparation of well-localized docking sites for the immobilization of biomolecules. Furthermore, polymer brushes are expected to enable novel paths for designing more advanced biosensing schemes, incorporating multifunctional groups and a higher loading capacity for biomolecules. Here, we focus on the preparation of polymer grafts by self-initiated photografting and photopolymerization. Further chemical modification of the grafted polymer brushes results in the introduction of additional functional molecules, paving the way for the incorporation of more complex molecular structures such as proteins. In a comparative study we investigate the advantages and disadvantages of both approaches.

  9. A comparison between neural response telemetry via cochleostomy or the round window approach in cochlear implantation.

    Hamerschmidt, Rogério; Schuch, Luiz Henrique; Rezende, Rodrigo Kopp; Wiemes, Gislaine Richter Minhoto; Oliveira, Adriana Kosma Pires de; Mocellin, Marcos

    2012-01-01

    There are two techniques for cochlear implant (CI) electrode placement: cochleostomy and the round window (RW) approach. This study aims to compare neural response telemetry (NRT) results immediately after surgery to check for possible differences on auditory nerve stimulation between these two techniques. This is a prospective cross-sectional study. Twenty-three patients were enrolled. Six patients underwent surgery by cochleostomy and 17 had it through the RW approach. Mean charge units (MCU) for high frequency sounds: patients submitted to the RW approach had a mean value of 190.4 (± 29.2) while cochleostomy patients averaged 187.8 (± 32.7); p = 0.71. MCU for mid frequency sounds: patients submitted to the RW approach had a mean value of 192.5 (± 22) while cochleostomy patients averaged 178.5 (± 18.5); p = 0.23. MCU for low frequency sounds: patients submitted to the RW approach had a mean value of 183.3 (± 25) while cochleostomy patients averaged 163.8 (± 19.3); p = 0.19. This study showed no differences in the action potential of the distal portion of the auditory nerve in patients with multichannel cochlear implants submitted to surgery by cochleostomy or through the RW approach, using the implant itself to generate stimuli and record responses. Both techniques equally stimulate the cochlear nerve. Therefore, the choice of approach can be made based on the surgeon's own preference and experience.

  10. A review on mechanical considerations for chronically-implanted neural probes

    Lecomte, Aziliz; Descamps, Emeline; Bergaud, Christian

    2018-06-01

    This review intends to present a comprehensive analysis of the mechanical considerations for chronically-implanted neural probes. Failure of neural electrical recordings or stimulation over time has shown to arise from foreign body reaction and device material stability. It seems that devices that match most closely with the mechanical properties of the brain would be more likely to reduce the mechanical stress at the probe/tissue interface, thus improving body acceptance. The use of low Young’s modulus polymers instead of hard substrates is one way to enhance this mechanical mimetism, though compliance can be achieved through a variety of means. The reduction of probe width and thickness in comparison to a designated length, the use of soft hydrogel coatings and the release in device tethering to the skull, can also improve device compliance. Paradoxically, the more compliant the device, the more likely it will fail during the insertion process in the brain. Strategies have multiplied this past decade to offer partial or temporary stiffness to the device to overcome this buckling effect. A detailed description of the probe insertion mechanisms is provided to analyze potential sources of implantation failure and the need for a mechanically-enhancing structure. This leads us to present an overview of the strategies that have been put in place over the last ten years to overcome buckling issues. Particularly, great emphasis is put on bioresorbable polymers and their assessment for neural applications. Finally, a discussion is provided on some of the key features for the design of mechanically-reliable, polymer-based next generation of chronic neuroprosthetic devices.

  11. Carbon fiber on polyimide ultra-microelectrodes

    Gillis, Winthrop F.; Lissandrello, Charles A.; Shen, Jun; Pearre, Ben W.; Mertiri, Alket; Deku, Felix; Cogan, Stuart; Holinski, Bradley J.; Chew, Daniel J.; White, Alice E.; Otchy, Timothy M.; Gardner, Timothy J.

    2018-02-01

    Objective. Most preparations for making neural recordings degrade over time and eventually fail due to insertion trauma and reactive tissue response. The magnitudes of these responses are thought to be related to the electrode size (specifically, the cross-sectional area), the relative stiffness of the electrode, and the degree of tissue tolerance for the material. Flexible carbon fiber ultra-microelectrodes have a much smaller cross-section than traditional electrodes and low tissue reactivity, and thus may enable improved longevity of neural recordings in the central and peripheral nervous systems. Only two carbon fiber array designs have been described previously, each with limited channel densities due to limitations of the fabrication processes or interconnect strategies. Here, we describe a method for assembling carbon fiber electrodes on a flexible polyimide substrate that is expected to facilitate the construction of high-density recording and stimulating arrays. Approach. Individual carbon fibers were aligned using an alignment tool that was 3D-printed with sub-micron resolution using direct laser writing. Indium deposition on the carbon fibers, followed by low-temperature microsoldering, provided a robust and reliable method of electrical connection to the polyimide interconnect. Main results. Spontaneous multiunit activity and stimulation-evoked compound responses with SNR  >10 and  >120, respectively, were recorded from a small (125 µm) peripheral nerve. We also improved the typically poor charge injection capacity of small diameter carbon fibers by electrodepositing 100 nm-thick iridium oxide films, making the carbon fiber arrays usable for electrical stimulation as well as recording. Significance. Our innovations in fabrication technique pave the way for further miniaturization of carbon fiber ultra-microelectrode arrays. We believe these advances to be key steps to enable a shift from labor intensive, manual assembly to a more automated

  12. Neuron cell positioning on polystyrene in culture by silver-negative ion implantation and region control of neural outgrowth

    Tsuji, Hiroshi; Sato, Hiroko; Baba, Takahiro; Ikemura, Shin'ichi; Gotoh, Yasuhito; Ishikawa, Junzo

    2000-01-01

    A new method to control the position of neuron cell attachment and extension region of neural outgrowth has been developed by using a pattering ion implantation with silver-negative ions into polystyrene dishes. This technique offers a promising method to form an artificially designed neural network in cell culture in vitro. Silver-negative ions were implanted into non-treated polystyrene dishes (NTPS) at conditions of 20 keV and 3x10 15 ions/cm 2 through a pattering mask, which had as many as 67 slits of 60 μm in width and 4 mm in length with a spacing of 60 μm. For cell culture in vitro, nerve cells of PC-12h (rat adrenal phechromocytoma) were used because they respond to a nerve growth factor (NGF). In the first 2 days in culture without NGF, we observed a selective cell attachment only to the ion-implanted region in patterning Ag - implanted polystyrene sample (p-Ag/NTPS). In another 2 days in culture with NGF, the nerve cells expanded neurites only over the ion-implanted region. For collagen-coated p-Ag/NTPS sample of which collagen was coated after the ion implantation (Collagen/p-Ag/NTPS), most nerve cells were also attached on the ion-implanted region. However, neurites expanded in both ion-implanted and unimplanted regions. The contact angle of NTPS decreased after the ion implantation from 86 deg. to 74 deg. . The region selectivity of neuron attachment and neurite extension is considered to be due to contact angle lowering by the ion implantation as radiation effect on the surface

  13. An ovine model of cerebral catheter venography for implantation of an endovascular neural interface.

    Oxley, Thomas James; Opie, Nicholas Lachlan; Rind, Gil Simon; Liyanage, Kishan; John, Sam Emmanuel; Ronayne, Stephen; McDonald, Alan James; Dornom, Anthony; Lovell, Timothy John Haynes; Mitchell, Peter John; Bennett, Iwan; Bauquier, Sebastien; Warne, Leon Norris; Steward, Chris; Grayden, David Bruce; Desmond, Patricia; Davis, Stephen M; O'Brien, Terence John; May, Clive N

    2018-04-01

    OBJECTIVE Neural interface technology may enable the development of novel therapies to treat neurological conditions, including motor prostheses for spinal cord injury. Intracranial neural interfaces currently require a craniotomy to achieve implantation and may result in chronic tissue inflammation. Novel approaches are required that achieve less invasive implantation methods while maintaining high spatial resolution. An endovascular stent electrode array avoids direct brain trauma and is able to record electrocorticography in local cortical tissue from within the venous vasculature. The motor area in sheep runs in a parasagittal plane immediately adjacent to the superior sagittal sinus (SSS). The authors aimed to develop a sheep model of cerebral venography that would enable validation of an endovascular neural interface. METHODS Cerebral catheter venography was performed in 39 consecutive sheep. Contrast-enhanced MRI of the brain was performed on 13 animals. Multiple telescoping coaxial catheter systems were assessed to determine the largest wide-bore delivery catheter that could be delivered into the anterior SSS. Measurements of SSS diameter and distance from the motor area were taken. The location of the motor area was determined in relation to lateral and superior projections of digital subtraction venography images and confirmed on MRI. RESULTS The venous pathway from the common jugular vein (7.4 mm) to the anterior SSS (1.2 mm) was technically challenging to selectively catheterize. The SSS coursed immediately adjacent to the motor cortex (SSS. Attempted access with 5-Fr and 6-Fr delivery catheters was associated with longer procedure times and higher complication rates. A 4-Fr catheter (internal lumen diameter 1.1 mm) was successful in accessing the SSS in 100% of cases with no associated complications. Complications included procedure-related venous dissection in two major areas: the torcular herophili, and the anterior formation of the SSS. The

  14. Implications of chronic daily anti-oxidant administration on the inflammatory response to intracortical microelectrodes

    Potter-Baker, Kelsey A.; Stewart, Wade G.; Tomaszewski, William H.; Wong, Chun T.; Meador, William D.; Ziats, Nicholas P.; Capadona, Jeffrey R.

    2015-08-01

    Objective. Oxidative stress events have been implicated to occur and facilitate multiple failure modes of intracortical microelectrodes. The goal of the present study was to evaluate the ability of a sustained concentration of an anti-oxidant and to reduce oxidative stress-mediated neurodegeneration for the application of intracortical microelectrodes. Approach. Non-functional microelectrodes were implanted into the cortex of male Sprague Dawley rats for up to sixteen weeks. Half of the animals received a daily intraperitoneal injection of the natural anti-oxidant resveratrol, at 30 mg kg-1. The study was designed to investigate the biodistribution of the resveratrol, and the effects on neuroinflammation/neuroprotection following device implantation. Main results. Daily maintenance of a sustained range of resveratrol throughout the implantation period resulted in fewer degenerating neurons in comparison to control animals at both two and sixteen weeks post implantation. Initial and chronic improvements in neuronal viability in resveratrol-dosed animals were correlated with significant reductions in local superoxide anion accumulation around the implanted device at two weeks after implantation. Controls, receiving only saline injections, were also found to have reduced amounts of accumulated superoxide anion locally and less neurodegeneration than controls at sixteen weeks post-implantation. Despite observed benefits, thread-like adhesions were found between the liver and diaphragm in resveratrol-dosed animals. Significance. Overall, our chronic daily anti-oxidant dosing scheme resulted in improvements in neuronal viability surrounding implanted microelectrodes, which could result in improved device performance. However, due to the discovery of thread-like adhesions, further work is still required to optimize a chronic anti-oxidant dosing regime for the application of intracortical microelectrodes.

  15. A three dimensional in vitro glial scar model to investigate the local strain effects from micromotion around neural implants.

    Spencer, Kevin C; Sy, Jay C; Falcón-Banchs, Roberto; Cima, Michael J

    2017-02-28

    Glial scar formation remains a significant barrier to the long term success of neural probes. Micromotion coupled with mechanical mismatch between the probe and tissue is believed to be a key driver of the inflammatory response. In vitro glial scar models present an intermediate step prior to conventional in vivo histology experiments as they enable cell-device interactions to be tested on a shorter timescale, with the ability to conduct broader biochemical assays. No established in vitro models have incorporated methods to assess device performance with respect to mechanical factors. In this study, we describe an in vitro glial scar model that combines high-precision linear actuators to simulate axial micromotion around neural implants with a 3D primary neural cell culture in a collagen gel. Strain field measurements were conducted to visualize the local displacement within the gel in response to micromotion. Primary brain cell cultures were found to be mechanically responsive to micromotion after one week in culture. Astrocytes, as determined by immunohistochemical staining, were found to have significantly increased in cell areas and perimeters in response to micromotion compared to static control wells. These results demonstrate the importance of micromotion when considering the chronic response to neural implants. Going forward, this model provides advantages over existing in vitro models as it will enable critical mechanical design factors of neural implants to be evaluated prior to in vivo testing.

  16. Assessment of functional recovery after autologous implantation of neural progenitor cells for the treatment of traumatic brain injury

    Wu Xing; Zhang Dong; Zuo Zhuantao; Ge Feng; Zhu Jianhong; Zhou Liangfu

    2005-01-01

    Objective: To assess the functional recovery in the patients with traumatic brain injury (TBI) after autologous implantation of neural progenitor cells, and 7 counterparts with matched age, injury location and extent were chosen as the control. Methods: Neural progenitor cells were isolated from exposed brain tissue and propagated for 25 to 30 d, then implanted the autologous neural progenitor cells at seven points around the traumatic regions with MRI-stereotactic guiding device for 7 patients. All recruited patients underwent 18 F-fluorodeox-yglucose (FDG) PET imaging, function MRI (fMRI) and assessment of Glasgow outcome scale extended (GOSE) after operation for open brain trauma. The examinations were repeated one month after neural progenitor cell implantation and then repeated every 3 months during follow-up in the first year, and every 6 months in the second year. The same examinations were performed on untreated counterparts at similar intervals for avoiding deviations of spontaneous recovery. The data were analyzed with region of interest (ROI) and statistical parametric mapping (SPM). Results: At the third month of follow-up, mean tracer uptake in the damaged territory in implantation group increased significantly (P 18 F-FDG in the top of precentral gyrus was significantly increased in implantation group, and the metabolism of 18 F-FDG in the frontal lobe was significantly elevated postoperation according to paired SPM analysis. The activation in fMRI maps was seen in the motor cortex since the third month after implantation, whereas no active signals were detected before implantation or in control group. At the 6th month of follow-up, mean score of GOSE in the group of implantation was 6.63±0.52, whereas the mean score was 4.50 ±0.76 in control group (P 18 F-FDG uptake in the injured area was 3 months prior to the elevation of GOSE. Conclusions: The results of the study show that 18 F-FDG PET and fMRI both showed significantly increased neurological

  17. Lower layers in the motor cortex are more effective targets for penetrating microelectrodes in cortical prostheses

    Parikh, Hirak; Marzullo, Timothy C.; Kipke, Daryl R.

    2009-04-01

    Improving cortical prostheses requires the development of recording neural interfaces that are efficient in terms of providing maximal control information with minimal interface complexity. While the typical approaches have targeted neurons in the motor cortex with multiple penetrating shanks, an alternative approach is to determine an efficient distribution of electrode sites within the layers of the cortex with fewer penetrating shanks. The objective of this study was to compare unit activity in the upper and lower layers of the cortex with respect to movement and direction in order to inform the design of penetrating microelectrodes. Four rats were implanted bilaterally with multi-site single-shank silicon microelectrode arrays in the neck/shoulder region of the motor cortex. We simultaneously recorded unit activity across all layers of the motor cortex while the animal was engaged in a movement direction task. Localization of the electrode array within the different layers of the cortex was determined by histology. We denoted units from layers 2 and 3 and units as upper layer units, and units from layers 5 and 6 as lower layer units. Analysis of unit spiking activity demonstrated that both the upper and lower layers encode movement and direction information. Unit responses in either cortical layer of the cortex were not preferentially associated with contralateral or ipsilateral movement. Aggregate analysis (633 neurons) and best session analysis (75 neurons) indicated that units in the lower layers (layers 5, 6) are more likely to encode direction information when compared to units in the upper layers (layers 2, 3) (p< 0.05). These results suggest that electrode sites clustered in the lower layers provide access to more salient control information for cortical neuroprostheses.

  18. Soldering of Nanotubes onto Microelectrodes

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing sold...... bonds were consistently found to be mechanically stronger than the carbon nanotubes.......Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing solder...... bonds were formed at the intersection of the nanotube and the electrodes. Current-voltage curves indicated metallic conduction of the nanotubes, with resistances in the range of 9-29 kOmega. Bridges made entirely of the soldering material exhibited resistances on the order of 100 Omega, and the solder...

  19. Conducting polymer 3D microelectrodes

    Sasso, Luigi; Vazquez, Patricia; Vedarethinam, Indumathi

    2010-01-01

    Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained...... showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared...

  20. Modeling the electrode-neuron interface of cochlear implants: effects of neural survival, electrode placement, and the partial tripolar configuration.

    Goldwyn, Joshua H; Bierer, Steven M; Bierer, Julie Arenberg

    2010-09-01

    The partial tripolar electrode configuration is a relatively novel stimulation strategy that can generate more spatially focused electric fields than the commonly used monopolar configuration. Focused stimulation strategies should improve spectral resolution in cochlear implant users, but may also be more sensitive to local irregularities in the electrode-neuron interface. In this study, we develop a practical computer model of cochlear implant stimulation that can simulate neural activation in a simplified cochlear geometry and we relate the resulting patterns of neural activity to basic psychophysical measures. We examine how two types of local irregularities in the electrode-neuron interface, variations in spiral ganglion nerve density and electrode position within the scala tympani, affect the simulated neural activation patterns and how these patterns change with electrode configuration. The model shows that higher partial tripolar fractions activate more spatially restricted populations of neurons at all current levels and require higher current levels to excite a given number of neurons. We find that threshold levels are more sensitive at high partial tripolar fractions to both types of irregularities, but these effects are not independent. In particular, at close electrode-neuron distances, activation is typically more spatially localized which leads to a greater influence of neural dead regions. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  1. Multi-scale, multi-modal analysis uncovers complex relationship at the brain tissue-implant neural interface: new emphasis on the biological interface

    Michelson, Nicholas J.; Vazquez, Alberto L.; Eles, James R.; Salatino, Joseph W.; Purcell, Erin K.; Williams, Jordan J.; Cui, X. Tracy; Kozai, Takashi D. Y.

    2018-06-01

    Objective. Implantable neural electrode devices are important tools for neuroscience research and have an increasing range of clinical applications. However, the intricacies of the biological response after implantation, and their ultimate impact on recording performance, remain challenging to elucidate. Establishing a relationship between the neurobiology and chronic recording performance is confounded by technical challenges related to traditional electrophysiological, material, and histological limitations. This can greatly impact the interpretations of results pertaining to device performance and tissue health surrounding the implant. Approach. In this work, electrophysiological activity and immunohistological analysis are compared after controlling for motion artifacts, quiescent neuronal activity, and material failure of devices in order to better understand the relationship between histology and electrophysiological outcomes. Main results. Even after carefully accounting for these factors, the presence of viable neurons and lack of glial scarring does not convey single unit recording performance. Significance. To better understand the biological factors influencing neural activity, detailed cellular and molecular tissue responses were examined. Decreases in neural activity and blood oxygenation in the tissue surrounding the implant, shift in expression levels of vesicular transporter proteins and ion channels, axon and myelin injury, and interrupted blood flow in nearby capillaries can impact neural activity around implanted neural interfaces. Combined, these tissue changes highlight the need for more comprehensive, basic science research to elucidate the relationship between biology and chronic electrophysiology performance in order to advance neural technologies.

  2. Chronic multisite brain recordings from a totally implantable bidirectional neural interface: experience in 5 patients with Parkinson's disease.

    Swann, Nicole C; de Hemptinne, Coralie; Miocinovic, Svjetlana; Qasim, Salman; Ostrem, Jill L; Galifianakis, Nicholas B; Luciano, Marta San; Wang, Sarah S; Ziman, Nathan; Taylor, Robin; Starr, Philip A

    2018-02-01

    OBJECTIVE Dysfunction of distributed neural networks underlies many brain disorders. The development of neuromodulation therapies depends on a better understanding of these networks. Invasive human brain recordings have a favorable temporal and spatial resolution for the analysis of network phenomena but have generally been limited to acute intraoperative recording or short-term recording through temporarily externalized leads. Here, the authors describe their initial experience with an investigational, first-generation, totally implantable, bidirectional neural interface that allows both continuous therapeutic stimulation and recording of field potentials at multiple sites in a neural network. METHODS Under a physician-sponsored US Food and Drug Administration investigational device exemption, 5 patients with Parkinson's disease were implanted with the Activa PC+S system (Medtronic Inc.). The device was attached to a quadripolar lead placed in the subdural space over motor cortex, for electrocorticography potential recordings, and to a quadripolar lead in the subthalamic nucleus (STN), for both therapeutic stimulation and recording of local field potentials. Recordings from the brain of each patient were performed at multiple time points over a 1-year period. RESULTS There were no serious surgical complications or interruptions in deep brain stimulation therapy. Signals in both the cortex and the STN were relatively stable over time, despite a gradual increase in electrode impedance. Canonical movement-related changes in specific frequency bands in the motor cortex were identified in most but not all recordings. CONCLUSIONS The acquisition of chronic multisite field potentials in humans is feasible. The device performance characteristics described here may inform the design of the next generation of totally implantable neural interfaces. This research tool provides a platform for translating discoveries in brain network dynamics to improved neurostimulation

  3. Stab injury and device implantation within the brain results in inversely multiphasic neuroinflammatory and neurodegenerative responses

    Potter, Kelsey A.; Buck, Amy C.; Self, Wade K.; Capadona, Jeffrey R.

    2012-08-01

    An estimated 25 million people in the US alone rely on implanted medical devices, ˜2.5 million implanted within the nervous system. Even though many devices perform adequately for years, the host response to medical devices often severely limits tissue integration and long-term performance. This host response is believed to be particularly limiting in the case of intracortical microelectrodes, where it has been shown that glial cell encapsulation and localized neuronal cell loss accompany intracortical microelectrode implantation. Since neuronal ensembles must be within ˜50 µm of the electrode to obtain neuronal spikes and local field potentials, developing a better understanding of the molecular and cellular environment at the device-tissue interface has been the subject of significant research. Unfortunately, immunohistochemical studies of scar maturation in correlation to device function have been inconclusive. Therefore, here we present a detailed quantitative study of the cellular events and the stability of the blood-brain barrier (BBB) following intracortical microelectrode implantation and cortical stab injury in a chronic survival model. We found two distinctly inverse multiphasic profiles for neuronal survival in device-implanted tissue compared to stab-injured animals. For chronically implanted animals, we observed a biphasic paradigm between blood-derived/trauma-induced and CNS-derived inflammatory markers driving neurodegeneration at the interface. In contrast, stab injured animals demonstrated a CNS-mediated neurodegenerative environment. Collectively these data provide valuable insight to the possibility of multiple roles of chronic neuroinflammatory events on BBB disruption and localized neurodegeneration, while also suggesting the importance to consider multiphasic neuroinflammatory kinetics in the design of therapeutic strategies for stabilizing neural interfaces.

  4. Pyrolytic 3D Carbon Microelectrodes for Electrochemistry

    Hemanth, Suhith; Caviglia, Claudia; Amato, Letizia

    2016-01-01

    This work presents the fabrication and characterization of suspended three-dimensional (3D) pyrolytic carbon microelectrodes for electrochemical applications. For this purpose, an optimized process with multiple steps of UV photolithography with the negative tone photoresist SU-8 followed...... by pyrolysis at 900ºC for 1h was developed. With this process, microelectrode chips with a three electrode configuration were fabricated and characterized with cyclic voltammetry (CV) using a 10mM potassium ferri-ferrocyanide redox probe in a custom made batch system with magnetic clamping. The 3D pyrolytic...... carbon microelectrodes displayed twice the higher peak current compared to 2D....

  5. An implantable two axis micromanipulator made with a 3D printer for recording neural activity in free-swimming fish.

    Rogers, Loranzie S; Van Wert, Jacey C; Mensinger, Allen F

    2017-08-15

    Chronically implanted electrodes allow monitoring neural activity from free moving animals. While a wide variety of implanted headstages, microdrives and electrodes exist for terrestrial animals, few have been developed for use with aquatic animals. A two axis micromanipulator was fabricated with a Formlabs 3D printer for implanting electrodes into free-swimming oyster toadfish (Opsanus tau). The five piece manipulator consisted of a base, body, electrode holder, manual screw drive and locking nut. The manipulator measured approximately 25×20×30mm (l×w×h) and weighed 5.28g after hand assembly. Microwire electrodes were inserted successfully with the manipulator to record high fidelity signals from the anterior lateral line nerve of the toadfish. The micromanipulator allowed the chronically implanted electrodes to be repositioned numerous times to record from multiple sites and extended successful recording time in the toadfish by several days. Three dimensional printing allowed an inexpensive (<$US 5 material), two axis micromanipulator to be printed relatively rapidly (<2h) to successfully record from multiple sites in the anterior lateral line nerve of free-swimming toadfish. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. [The application of artificial neural network on the assessment of lexical tone production of pediatric cochlear implant users].

    Mao, Y T; Chen, Z M; Xu, L

    2017-08-07

    Objective: The present study was carried out to explore the tone production ability of the Mandarin-speaking children with cochlear implants (CI) by using an artificial neural network model and to examine the potential contributing factors underlining their tone production performance. The results of this study might provide useful guidelines for post-operative rehabilitation processes of pediatric CI users. Methods: Two hundred and seventy-eight prelingually deafened children who received unilateral CI participated in this study. As controls, 170 similarly-aged children with normal hearing (NH) were recruited. A total of 36 Chinese monosyllabic words were selected as the tone production targets. Vocal production samples were recorded and the fundamental frequency (F0) contour of each syllable was extracted using an auto-correlation algorithm followed by manual correction. An artificial neural network was created in MATLAB to classify the tone production. The relationships between tone production and several demographic factors were evaluated. Results: Pediatric CI users produced Mandarin tones much less accurately than did the NH children (58.8% vs. 91.5% correct). Tremendous variability in tone production performance existed among the CI children. Tones 2 and 3 were produced less accurately than tones 1 and 4 for both groups. For the CI group, all tones when in error tended to be judged as tone 1. The tone production accuracy was negatively correlated with age at implantation and positively correlated with CI use duration with correlation coefficients ( r ) of -0.215 ( P =0.003) and 0.203 ( P =0.005), respectively. Age was one of the determinants of tonal ability for NH children. Conclusions: For children with severe to profound hearing loss, early implantation and persistent use of CI are beneficial to their tone production development. Artificial neural network is a convenient and reliable assessment tool for the development of tonal ability of hearing

  7. Conducting Polymer 3D Microelectrodes

    Jenny Emnéus

    2010-12-01

    Full Text Available Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements.

  8. Band-type microelectrodes for amperometric immunoassays

    Lee, Ga-Yeon; Chang, Young Wook; Ko, Hyuk [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of); Kang, Min-Jung [Korea Institute of Science and Technology (KIST), Seoul (Korea, Republic of); Pyun, Jae-Chul, E-mail: jcpyun@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of)

    2016-07-20

    A band-type microelectrode was made using a parylene-N film as a passivation layer. A circular-type, mm-scale electrode with the same diameter as the band-type microelectrode was also made with an electrode area that was 5000 times larger than the band-type microelectrode. By comparing the amperometric signals of 3,5,3′,5′-tetramethylbenzidine (TMB) samples at different optical density (OD) values, the band-type microelectrode was determined to be 9 times more sensitive than the circular-type electrode. The properties of the circular-type and the band-type electrodes (e.g., the shape of their cyclic voltammograms, the type of diffusion layer used, and the diffusion layer thickness per unit electrode area) were characterized according to their electrode area using the COMSOL Multiphysics software. From these simulations, the band-type electrode was estimated to have the conventional microelectrode properties, even when the electrode area was 100 times larger than a conventional circular-type electrode. These results show that both the geometry and the area of an electrode can influence the properties of the electrode. Finally, amperometric analysis based on a band-type electrode was applied to commercial ELISA kits to analyze human hepatitis B surface antigen (hHBsAg) and human immunodeficiency virus (HIV) antibodies. - Highlights: • A band-type microelectrode was made using a parylene-N film as a passivation layer. • The band-type microelectrode was 14-times more sensitive than circular-type electrode. • The influence of geometry on microelectrode properties was simulated using COMSOL. • The band-type electrode was applied to ELISA kits for hHBsAg and hHIV-antibodies.

  9. Advances in cochlear implant telemetry: evoked neural responses, electrical field imaging, and technical integrity.

    Mens, L.H.M.

    2007-01-01

    During the last decade, cochlear implantation has evolved into a well-established treatment of deafness, predominantly because of many improvements in speech processing and the controlled excitation of the auditory nerve. Cochlear implants now also feature telemetry, which is highly useful to

  10. Towards a closed-loop cochlear implant system: application of embedded monitoring of peripheral and central neural activity.

    Mc Laughlin, Myles; Lu, Thomas; Dimitrijevic, Andrew; Zeng, Fan-Gang

    2012-07-01

    Although the cochlear implant (CI) is widely considered the most successful neural prosthesis, it is essentially an open-loop system that requires extensive initial fitting and frequent tuning to maintain a high, but not necessarily optimal, level of performance. Two developments in neuroscience and neuroengineering now make it feasible to design a closed-loop CI. One development is the recording and interpretation of evoked potentials (EPs) from the peripheral to the central nervous system. The other is the embedded hardware and software of a modern CI that allows recording of EPs. We review EPs that are pertinent to behavioral functions from simple signal detection and loudness growth to speech discrimination and recognition. We also describe signal processing algorithms used for electric artifact reduction and cancellation, critical to the recording of electric EPs. We then present a conceptual design for a closed-loop CI that utilizes in an innovative way the embedded implant receiver and stimulators to record short latency compound action potentials ( ~1 ms), auditory brainstem responses (1-10 ms) and mid-to-late cortical potentials (20-300 ms). We compare EPs recorded using the CI to EPs obtained using standard scalp electrodes recording techniques. Future applications and capabilities are discussed in terms of the development of a new generation of closed-loop CIs and other neural prostheses.

  11. Failure Mechanisms of a Gold Microelectrode in Bioelectronics Applications

    Jonghun Kim

    2015-01-01

    Full Text Available The generation, growth, and collapse of tiny bubbles are inevitable for a microelectrode working in aqueous environment, thus resulting in physical damages on the microelectrode. The failure mechanisms of a microelectrode induced by tiny bubble collapsing are investigated by generating tiny hydrogen bubbles on a gold microelectrode through deionized water electrolysis. The surface of the microelectrode is modified with a thiol-functionalized arginine-glycine-aspartic acid peptide to generate perfectly spherical bubbles in proximity of the surface. The failure of an Au microelectrode is governed by two damage mechanisms, depending on the thickness of the microelectrode: a water-hammer pressure due to the violent collapse of a single large bubble, formed through merging of small bubbles, for ultrathin Au microelectrodes of 40–60 nm in thickness, and an energy accumulation resulting from the repetitive collapse of tiny bubbles for thick Au microelectrodes of 100–120 nm.

  12. Perianal implantation of bioengineered human internal anal sphincter constructs intrinsically innervated with human neural progenitor cells.

    Raghavan, Shreya; Miyasaka, Eiichi A; Gilmont, Robert R; Somara, Sita; Teitelbaum, Daniel H; Bitar, Khalil N

    2014-04-01

    The internal anal sphincter (IAS) is a major contributing factor to pressure within the anal canal and is required for maintenance of rectoanal continence. IAS damage or weakening results in fecal incontinence. We have demonstrated that bioengineered, intrinsically innervated, human IAS tissue replacements possess key aspects of IAS physiology, such as the generation of spontaneous basal tone and contraction/relaxation in response to neurotransmitters. The objective of this study is to demonstrate the feasibility of implantation of bioengineered IAS constructs in the perianal region of athymic rats. Human IAS tissue constructs were bioengineered from isolated human IAS circular smooth muscle cells and human enteric neuronal progenitor cells. After maturation of the bioengineered constructs in culture, they were implanted operatively into the perianal region of athymic rats. Platelet-derived growth factor was delivered to the implanted constructs through a microosmotic pump. Implanted constructs were retrieved from the animals 4 weeks postimplantation. Animals tolerated the implantation well, and there were no early postoperative complications. Normal stooling was observed during the implantation period. At harvest, implanted constructs were adherent to the perirectal rat tissue and appeared healthy and pink. Immunohistochemical analysis revealed neovascularization. Implanted smooth muscle cells maintained contractile phenotype. Bioengineered constructs responded in vitro in a tissue chamber to neuronally evoked relaxation in response to electrical field stimulation and vasoactive intestinal peptide, indicating the preservation of neuronal networks. Our results indicate that bioengineered innervated IAS constructs can be used to augment IAS function in an animal model. This is a regenerative medicine based therapy for fecal incontinence that would directly address the dysfunction of the IAS muscle. Copyright © 2014 Mosby, Inc. All rights reserved.

  13. Comparação da telemetria de resposta neural via cocleostomia ou via janela redonda no implante coclear A comparison between neural response telemetry via cochleostomy or the round window approach in cochlear implantation

    Rogério Hamerschmidt

    2012-08-01

    Full Text Available Existem duas técnicas para inserção dos eletrodos do implante coclear (IC: Via cocleostomia ou via janela redonda (JR. OBJETIVO: Comparar a telemetria de resposta neural (NRT no pós-operatório imediato, verificando se há diferenças na estimulação do nervo auditivo entre estas duas técnicas. MÉTODOS: Prospectivo e transversal. Foram avaliados 23 pacientes. Seis submetidos à cirurgia via cocleostomia e 17 via JR. RESULTADOS: Comparação das unidades de corrente médias (UCM para sons agudos: via JR com média de 190,4 (± 29,2 e via cocleostomia 187,8 (± 32,7, p = 0,71. Comparação das UCM para sons intermediários: via JR, média de 192,5 (± 22 e via cocleostomia 178,5 (± 18.5, p = 0,23. Comparação das UCM para sons graves: via JR, média de 183,3 (± 25 e via cocleostomia 163,8 (± 19,3, p = 0,19. CONCLUSÃO: Este estudo não mostrou diferença na captação do potencial de ação da porção distal do nervo auditivo em pacientes usuários do implante coclear multicanal submetidos à cirurgia via cocleostomia ou via JR, utilizando o próprio implante para eliciar o estímulo e gravar as respostas. Portanto, ambas as técnicas estimulam de maneira igual o nervo coclear, e baseado nisto conclui-se, também, que realizar o implante coclear via cocleostomia ou RW é uma escolha que depende da experiência cirúrgica e opção do cirurgião.There are two techniques for cochlear implant (CI electrode placement: cochleostomy and the round window (RW approach. OBJECTIVE: This study aims to compare neural response telemetry (NRT results immediately after surgery to check for possible differences on auditory nerve stimulation between these two techniques. MATERIALS AND METHODS: This is a prospective cross-sectional study. Twenty-three patients were enrolled. Six patients underwent surgery by cochleostomy and 17 had it through the RW approach. RESULTS: Mean charge units (MCU for high frequency sounds: patients submitted to the RW

  14. Electrical Neural Stimulation and Simultaneous in Vivo Monitoring with Transparent Graphene Electrode Arrays Implanted in GCaMP6f Mice.

    Park, Dong-Wook; Ness, Jared P; Brodnick, Sarah K; Esquibel, Corinne; Novello, Joseph; Atry, Farid; Baek, Dong-Hyun; Kim, Hyungsoo; Bong, Jihye; Swanson, Kyle I; Suminski, Aaron J; Otto, Kevin J; Pashaie, Ramin; Williams, Justin C; Ma, Zhenqiang

    2018-01-23

    Electrical stimulation using implantable electrodes is widely used to treat various neuronal disorders such as Parkinson's disease and epilepsy and is a widely used research tool in neuroscience studies. However, to date, devices that help better understand the mechanisms of electrical stimulation in neural tissues have been limited to opaque neural electrodes. Imaging spatiotemporal neural responses to electrical stimulation with minimal artifact could allow for various studies that are impossible with existing opaque electrodes. Here, we demonstrate electrical brain stimulation and simultaneous optical monitoring of the underlying neural tissues using carbon-based, fully transparent graphene electrodes implanted in GCaMP6f mice. Fluorescence imaging of neural activity for varying electrical stimulation parameters was conducted with minimal image artifact through transparent graphene electrodes. In addition, full-field imaging of electrical stimulation verified more efficient neural activation with cathode leading stimulation compared to anode leading stimulation. We have characterized the charge density limitation of capacitive four-layer graphene electrodes as 116.07-174.10 μC/cm 2 based on electrochemical impedance spectroscopy, cyclic voltammetry, failure bench testing, and in vivo testing. This study demonstrates the transparent ability of graphene neural electrodes and provides a method to further increase understanding and potentially improve therapeutic electrical stimulation in the central and peripheral nervous systems.

  15. Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system.

    Cafarelli-Dees, D.; Dillier, N.; Lai, W.K.; Wallenberg, E. von; Dijk, B. van; Akdas, F.; Aksit, M.; Batman, C.; Beynon, A.J.; Burdo, S.; Chanal, J.M.; Collet, L.; Conway, M.; Coudert, C.; Craddock, L.; Cullington, H.; Deggouj, N.; Fraysse, B.; Grabel, S.; Kiefer, J.; Kiss, J.G.; Lenarz, T.; Mair, A.; Maune, S.; Muller-Deile, J.; Piron, J.P.; Razza, S.; Tasche, C.; Thai-Van, H.; Toth, F.; Truy, E.; Uziel, A.; Smoorenburg, G.F.

    2005-01-01

    One hundred and forty-seven adult recipients of the Nucleus 24 cochlear implant system, from 13 different European countries, were tested using neural response telemetry to measure the electrically evoked compound action potential (ECAP), according to a standardised postoperative measurement

  16. Chronic, percutaneous connector for electrical recording and stimulation with microelectrode arrays.

    Shah, Kedar G; Lee, Kye Young; Tolosa, Vanessa; Tooker, Angela; Felix, Sarah; Benett, William; Pannu, Satinderpall

    2014-01-01

    The translation of advances in neural stimulation and recording research into clinical practice hinges on the ability to perform chronic experiments in awake and behaving animal models. Advances in microelectrode array technology, most notably flexible polymer arrays, have significantly improved reliability of the neural interface. However, electrical connector technology has lagged and is prone to failure from non-biocompatibility, large size, contamination, corrosion, and difficulty of use. We present a novel chronic, percutaneous electrical connector system that is suitable for neural stimulation and recording. This system features biocompatible materials, low connect and disconnect forces, passive alignment, and a protective cap during non-use. We have successfully designed, assembled, and tested in vitro both a 16-channel system and a high density 64-channel system. Custom, polyimide, 16-channel, microelectrode arrays were electrically assembled with the connector system and tested using cyclic voltammetry and electrochemical impedance spectroscopy. This connector system is versatile and can be used with a variety of microelectrode array technologies for chronic studies.

  17. Batch fabrication of nanotubes suspended between microelectrodes

    Mateiu, Ramona Valentina; Stöckli, T.; Knapp, H. F.

    2007-01-01

    be done with a simple lift-off process with standard photolithographic resist. An applied electric field is sustained between the microelectrodes during CVD to guide the nanotube growth. Comparison with simulations shows that the location and the orientation of the grown carbon nanotubes (CNT) correspond...... to the regions of maximum electric field, enabling accurate positioning of a nanotube by controlling the shape of the microelectrodes. The CNT bridges are deflected tens of nm when a DC voltage is applied between the nanotube and a gate microelectrode indicating that the clamping through the catalyst particles...... is not only mechanically stable but also electrical conducting. This method could be used to fabricate nanoelectromechanical systems based on suspended double clamped CNTs depending only on photolithography and standard Cleanroom processes....

  18. Characterizing Enzymatic Deposition for Microelectrode Neurotransmitter Detection

    Hosein, W. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yorita, A. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tolosa, V. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-12

    The enzyme immobilization process, one step in creating an enzymatic biosensor, was characterized and analyzed as a function of its physical properties. The neural glutamic biosensor is a flexible device, effectively minimizing trauma to the area of implantation. The Multielectrode Array (MEA) is composed primarily of a proprietary polymer which has been successfully implanted into human subjects in recent years. This polymer allows the device the pliability that other devices normally lack, though this poses some challenges to implantation. The electrodes are made of Platinum (Pt), and can range in number from eight to thirty two electrodes per device. These electrodes are electroplated with a semipermeable polymer layer to improve selectivity of the electrode to the neurotransmitter of interest, in this case glutamate. A signal is created from the interaction of glutamate in the brain with the glutamate oxidase (GluOx) which is immobilized on the surface of the electrode by using crosslinking chemistry in conjunction with glutaraldehyde and Bovine Serum Albumin (BSA). The glutamate is oxidized by glutamate oxidase, producing α-ketoglutarate and hydrogen peroxide (H2O2) as a by-product. The production of H2O2 is crucial for detection of the presence of the glutamate within the enzymatic coating, as it diffuses through the enzyme layer and oxidizes at the surface of the electrode. This oxidation is detectable by measurable change in the current using amperometry. Hence, the MEA allows for in vivo monitoring of neurotransmitter activity in real time. The sensitivity of the sensor to these neurotransmitters is dependent on the thickness of the layer, which is investigated in these experiments in order to optimize the efficacy of the device to detecting the substrate, once implanted.

  19. Implantable neurotechnologies: bidirectional neural interfaces--applications and VLSI circuit implementations.

    Greenwald, Elliot; Masters, Matthew R; Thakor, Nitish V

    2016-01-01

    A bidirectional neural interface is a device that transfers information into and out of the nervous system. This class of devices has potential to improve treatment and therapy in several patient populations. Progress in very large-scale integration has advanced the design of complex integrated circuits. System-on-chip devices are capable of recording neural electrical activity and altering natural activity with electrical stimulation. Often, these devices include wireless powering and telemetry functions. This review presents the state of the art of bidirectional circuits as applied to neuroprosthetic, neurorepair, and neurotherapeutic systems.

  20. Feature extraction using extrema sampling of discrete derivatives for spike sorting in implantable upper-limb neural prostheses.

    Zamani, Majid; Demosthenous, Andreas

    2014-07-01

    Next generation neural interfaces for upper-limb (and other) prostheses aim to develop implantable interfaces for one or more nerves, each interface having many neural signal channels that work reliably in the stump without harming the nerves. To achieve real-time multi-channel processing it is important to integrate spike sorting on-chip to overcome limitations in transmission bandwidth. This requires computationally efficient algorithms for feature extraction and clustering suitable for low-power hardware implementation. This paper describes a new feature extraction method for real-time spike sorting based on extrema analysis (namely positive peaks and negative peaks) of spike shapes and their discrete derivatives at different frequency bands. Employing simulation across different datasets, the accuracy and computational complexity of the proposed method are assessed and compared with other methods. The average classification accuracy of the proposed method in conjunction with online sorting (O-Sort) is 91.6%, outperforming all the other methods tested with the O-Sort clustering algorithm. The proposed method offers a better tradeoff between classification error and computational complexity, making it a particularly strong choice for on-chip spike sorting.

  1. Inhibition of the cluster of differentiation 14 innate immunity pathway with IAXO-101 improves chronic microelectrode performance

    Hermann, John K.; Ravikumar, Madhumitha; Shoffstall, Andrew J.; Ereifej, Evon S.; Kovach, Kyle M.; Chang, Jeremy; Soffer, Arielle; Wong, Chun; Srivastava, Vishnupriya; Smith, Patrick; Protasiewicz, Grace; Jiang, Jingle; Selkirk, Stephen M.; Miller, Robert H.; Sidik, Steven; Ziats, Nicholas P.; Taylor, Dawn M.; Capadona, Jeffrey R.

    2018-04-01

    Objective. Neuroinflammatory mechanisms are hypothesized to contribute to intracortical microelectrode failures. The cluster of differentiation 14 (CD14) molecule is an innate immunity receptor involved in the recognition of pathogens and tissue damage to promote inflammation. The goal of the study was to investigate the effect of CD14 inhibition on intracortical microelectrode recording performance and tissue integration. Approach. Mice implanted with intracortical microelectrodes in the motor cortex underwent electrophysiological characterization for 16 weeks, followed by endpoint histology. Three conditions were examined: (1) wildtype control mice, (2) knockout mice lacking CD14, and (3) wildtype control mice administered a small molecule inhibitor to CD14 called IAXO-101. Main results. The CD14 knockout mice exhibited acute but not chronic improvements in intracortical microelectrode performance without significant differences in endpoint histology. Mice receiving IAXO-101 exhibited significant improvements in recording performance over the entire 16 week duration without significant differences in endpoint histology. Significance. Full removal of CD14 is beneficial at acute time ranges, but limited CD14 signaling is beneficial at chronic time ranges. Innate immunity receptor inhibition strategies have the potential to improve long-term intracortical microelectrode performance.

  2. Versatile, modular 3D microelectrode arrays for neuronal ensemble recordings: from design to fabrication, assembly, and functional validation in non-human primates

    Barz, F.; Livi, A.; Lanzilotto, M.; Maranesi, M.; Bonini, L.; Paul, O.; Ruther, P.

    2017-06-01

    Objective. Application-specific designs of electrode arrays offer an improved effectiveness for providing access to targeted brain regions in neuroscientific research and brain machine interfaces. The simultaneous and stable recording of neuronal ensembles is the main goal in the design of advanced neural interfaces. Here, we describe the development and assembly of highly customizable 3D microelectrode arrays and demonstrate their recording performance in chronic applications in non-human primates. Approach. System assembly relies on a microfabricated stacking component that is combined with Michigan-style silicon-based electrode arrays interfacing highly flexible polyimide cables. Based on the novel stacking component, the lead time for implementing prototypes with altered electrode pitches is minimal. Once the fabrication and assembly accuracy of the stacked probes have been characterized, their recording performance is assessed during in vivo chronic experiments in awake rhesus macaques (Macaca mulatta) trained to execute reaching-grasping motor tasks. Main results. Using a single set of fabrication tools, we implemented three variants of the stacking component for electrode distances of 250, 300 and 350 µm in the stacking direction. We assembled neural probes with up to 96 channels and an electrode density of 98 electrodes mm-2. Furthermore, we demonstrate that the shank alignment is accurate to a few µm at an angular alignment better than 1°. Three 64-channel probes were chronically implanted in two monkeys providing single-unit activity on more than 60% of all channels and excellent recording stability. Histological tissue sections, obtained 52 d after implantation from one of the monkeys, showed minimal tissue damage, in accordance with the high quality and stability of the recorded neural activity. Significance. The versatility of our fabrication and assembly approach should significantly support the development of ideal interface geometries for a broad

  3. Adaptive quantization of local field potentials for wireless implants in freely moving animals: an open-source neural recording device

    Martinez, Dominique; Clément, Maxime; Messaoudi, Belkacem; Gervasoni, Damien; Litaudon, Philippe; Buonviso, Nathalie

    2018-04-01

    Objective. Modern neuroscience research requires electrophysiological recording of local field potentials (LFPs) in moving animals. Wireless transmission has the advantage of removing the wires between the animal and the recording equipment but is hampered by the large number of data to be sent at a relatively high rate. Approach. To reduce transmission bandwidth, we propose an encoder/decoder scheme based on adaptive non-uniform quantization. Our algorithm uses the current transmitted codeword to adapt the quantization intervals to changing statistics in LFP signals. It is thus backward adaptive and does not require the sending of side information. The computational complexity is low and similar at the encoder and decoder sides. These features allow for real-time signal recovery and facilitate hardware implementation with low-cost commercial microcontrollers. Main results. As proof-of-concept, we developed an open-source neural recording device called NeRD. The NeRD prototype digitally transmits eight channels encoded at 10 kHz with 2 bits per sample. It occupies a volume of 2  ×  2  ×  2 cm3 and weighs 8 g with a small battery allowing for 2 h 40 min of autonomy. The power dissipation is 59.4 mW for a communication range of 8 m and transmission losses below 0.1%. The small weight and low power consumption offer the possibility of mounting the entire device on the head of a rodent without resorting to a separate head-stage and battery backpack. The NeRD prototype is validated in recording LFPs in freely moving rats at 2 bits per sample while maintaining an acceptable signal-to-noise ratio (>30 dB) over a range of noisy channels. Significance. Adaptive quantization in neural implants allows for lower transmission bandwidths while retaining high signal fidelity and preserving fundamental frequencies in LFPs.

  4. A Wireless and Batteryless Microsystem with Implantable Grid Electrode/3-Dimensional Probe Array for ECoG and Extracellular Neural Recording in Rats

    Chih-Wei Chang

    2013-04-01

    Full Text Available This paper presents the design and implementation of an integrated wireless microsystem platform that provides the possibility to support versatile implantable neural sensing devices in free laboratory rats. Inductive coupled coils with low dropout regulator design allows true long-term recording without limitation of battery capacity. A 16-channel analog front end chip located on the headstage is designed for high channel account neural signal conditioning with low current consumption and noise. Two types of implantable electrodes including grid electrode and 3D probe array are also presented for brain surface recording and 3D biopotential acquisition in the implanted target volume of tissue. The overall system consumes less than 20 mA with small form factor, 3.9 × 3.9 cm2 mainboard and 1.8 × 3.4 cm2 headstage, is packaged into a backpack for rats. Practical in vivo recordings including auditory response, brain resection tissue and PZT-induced seizures recording demonstrate the correct function of the proposed microsystem. Presented achievements addressed the aforementioned properties by combining MEMS neural sensors, low-power circuit designs and commercial chips into system-level integration.

  5. Modeling and Characterization of Capacitive Elements With Tissue as Dielectric Material for Wireless Powering of Neural Implants.

    Erfani, Reza; Marefat, Fatemeh; Sodagar, Amir M; Mohseni, Pedram

    2018-05-01

    This paper reports on the modeling and characterization of capacitive elements with tissue as the dielectric material, representing the core building block of a capacitive link for wireless power transfer to neural implants. Each capacitive element consists of two parallel plates that are aligned around the tissue layer and incorporate a grounded, guarded, capacitive pad to mitigate the adverse effect of stray capacitances and shield the plates from external interfering electric fields. The plates are also coated with a biocompatible, insulating, coating layer on the inner side of each plate in contact with the tissue. A comprehensive circuit model is presented that accounts for the effect of the coating layers and is validated by measurements of the equivalent capacitance as well as impedance magnitude/phase of the parallel plates over a wide frequency range of 1 kHz-10 MHz. Using insulating coating layers of Parylene-C at a thickness of and Parylene-N at a thickness of deposited on two sets of parallel plates with different sizes and shapes of the guarded pad, our modeling and characterization results accurately capture the effect of the thickness and electrical properties of the coating layers on the behavior of the capacitive elements over frequency and with different tissues.

  6. Vertically aligned carbon nanotubes for microelectrode arrays applications.

    Castro Smirnov, J R; Jover, Eric; Amade, Roger; Gabriel, Gemma; Villa, Rosa; Bertran, Enric

    2012-09-01

    In this work a methodology to fabricate carbon nanotube based electrodes using plasma enhanced chemical vapour deposition has been explored and defined. The final integrated microelectrode based devices should present specific properties that make them suitable for microelectrode arrays applications. The methodology studied has been focused on the preparation of highly regular and dense vertically aligned carbon nanotube (VACNT) mat compatible with the standard lithography used for microelectrode arrays technology.

  7. Ultra-nanocrystalline diamond electrodes: optimization towards neural stimulation applications.

    Garrett, David J; Ganesan, Kumaravelu; Stacey, Alastair; Fox, Kate; Meffin, Hamish; Prawer, Steven

    2012-02-01

    Diamond is well known to possess many favourable qualities for implantation into living tissue including biocompatibility, biostability, and for some applications hardness. However, conducting diamond has not, to date, been exploited in neural stimulation electrodes due to very low electrochemical double layer capacitance values that have been previously reported. Here we present electrochemical characterization of ultra-nanocrystalline diamond electrodes grown in the presence of nitrogen (N-UNCD) that exhibit charge injection capacity values as high as 163 µC cm(-2) indicating that N-UNCD is a viable material for microelectrode fabrication. Furthermore, we show that the maximum charge injection of N-UNCD can be increased by tailoring growth conditions and by subsequent electrochemical activation. For applications requiring yet higher charge injection, we show that N-UNCD electrodes can be readily metalized with platinum or iridium, further increasing charge injection capacity. Using such materials an implantable neural stimulation device fabricated from a single piece of bio-permanent material becomes feasible. This has significant advantages in terms of the physical stability and hermeticity of a long-term bionic implant.

  8. A Multimodal, SU-8 - Platinum - Polyimide Microelectrode Array for Chronic In Vivo Neurophysiology.

    Gergely Márton

    Full Text Available Utilization of polymers as insulator and bulk materials of microelectrode arrays (MEAs makes the realization of flexible, biocompatible sensors possible, which are suitable for various neurophysiological experiments such as in vivo detection of local field potential changes on the surface of the neocortex or unit activities within the brain tissue. In this paper the microfabrication of a novel, all-flexible, polymer-based MEA is presented. The device consists of a three dimensional sensor configuration with an implantable depth electrode array and brain surface electrodes, allowing the recording of electrocorticographic (ECoG signals with laminar ones, simultaneously. In vivo recordings were performed in anesthetized rat brain to test the functionality of the device under both acute and chronic conditions. The ECoG electrodes recorded slow-wave thalamocortical oscillations, while the implanted component provided high quality depth recordings. The implants remained viable for detecting action potentials of individual neurons for at least 15 weeks.

  9. Neurosurgical interventions in the treatment of idiopathic Parkinson disease: neurostimulation and neural implantation.

    Kupsch, A; Earl, C

    1999-01-01

    With the exception of thalamotomy for drug-refractory tremor, surgical therapy for Parkinson's disease has been almost abandoned as treatment for Parkinsonian symptoms between 1965 and 1985. Reasons for this development relate to inconsistent postoperative results, complications associated with stereotactic surgical techniques and, most importantly, the advent of levodopa, which is still considered to be the gold standard in pharmacotherapy for Parkinson's disease. However, both, the long-term experience with L-DOPA therapy on the one hand and the progress of advanced stereotactic techniques and fetal graft research on the other hand have lead to reconsideration of surgical therapy in Parkinson's disease for patients, who can not be treated satisfactorily with medication. Both lesions (via thermocoagulation) and/or neurostimulation (via chronic intracerebral implantation of electrodes) in thalamic nuclei (nucleus ventralis oralis posterior/intermedialis thalami; VOP/VIM) may alleviate rest tremor in PD patients. In principle neurostimulation has the significant advantage of reversibility with regard to side effects in comparison to lesion surgery. Furthermore ventro-posterior pallidotomy or chronic stimulation in this structures may ameliorate bradykinesia and levodopa-induced dyskinesias. Additionally, "switching-off" the subthalamic nucleus by neurostimulation has been reported to reduce rigidity, bradykinesia and levodopa-induced ON-OFF-fluctuations. On the other hand, neuronal transplantation of fetal nigral dopamine precursor cells aims at restoring the striatal dopamine deficit. Both animal and clinical experiments have shown that fetal grafts survive intrastriatal transplantation and may ensue moderate to satisfactory improvements, especially in regard to bradykinesia and ON-OFF-fluctuations. Further progress in the field of neuronal transplantation will largely depend on the development of alternative cell resources.

  10. Efeitos do potencial de ação neural sobre a percepção de fala em usuários de implante coclear Influence of evoked compound action potential on speech perception in cochlear implant users

    Mariana Cardoso Guedes

    2007-08-01

    Full Text Available O Potencial de Ação Composto Evocado Eletricamente reflete a atividade do nervo auditivo, podendo ser registrado através dos eletrodos do implante coclear. A determinação dos elementos neurais estimuláveis pode contribuir para explicar a variabilidade de desempenho entre indivíduos implantados. OBJETIVO: Comparar o desempenho nos testes de percepção da fala entre pacientes que apresentaram e que não apresentaram potencial de ação composto evocado eletricamente no momento intra-operatório. MATERIAL E MÉTODO: Estudo prospectivo no qual 100 indivíduos usuários do implante coclear Nucleus 24 foram divididos em dois grupos de acordo com a presença ou ausência do potencial de ação intra-operatório. Após 6 meses de uso do dispositivo, os resultados dos testes de percepção de fala foram comparados entre os grupos. RESULTADOS: O potencial foi observado em 72% dos pacientes. A percepção no teste de frases em formato aberto foi melhor nos indivíduos com presença de potencial (média 82,8% contra 41,0%, p = 0,005. Houve associação entre ausência do potencial e etiologia da surdez por meningite. CONCLUSÃO: Ausência de potencial neural intraoperatório esteve associada ao pior desempenho na percepção da fala e à etiologia da surdez por meningite. Por outro lado, a presença do potencial de ação intraoperatório sugere ótimo prognóstico.Electrically Evoked Compound Action Potential is a measure of synchronous cochlear nerve fibers activity elicited by electrical stimulation of the cochlear implant. The electrophysiological nerve responses may contribute to explain the variability in individual performance of cochlear implant recipients. AIM: To compare speech perception tests’ performances of cochlear implant users according to the presence or absence of intraoperative neural telemetry responses. MATERIAL AND METHOD: Prospective study design with 100 "Nucleus 24" cochlear implant users divided in two groups according

  11. A CMOS frontend chip for implantable neural recording with wide voltage supply range

    Liu Jialin; Zhang Xu; Hu Xiaohui; Li Peng; Liu Ming; Chen Hongda; Guo Yatao; Li Bin

    2015-01-01

    A design for a CMOS frontend integrated circuit (chip) for neural signal acquisition working at wide voltage supply range is presented in this paper. The chip consists of a preamplifier, a serial instrumental amplifier (IA) and a cyclic analog-to-digital converter (CADC). The capacitive-coupled and capacitive-feedback topology combined with MOS-bipolar pseudo-resistor element is adopted in the preamplifier to create a −3 dB upper cut-off frequency less than 1 Hz without using a ponderous discrete device. A dual-amplifier instrumental amplifier is used to provide a low output impedance interface for ADC as well as to boost the gain. The preamplifier and the serial instrumental amplifier together provide a midband gain of 45.8 dB and have an input-referred noise of 6.7 μV rms integrated from 1 Hz to 5 kHz. The ADC digitizes the amplified signal at 12-bits precision with a highest sampling rate of 130 kS/s. The measured effective number of bits (ENOB) of the ADC is 8.7 bits. The entire circuit draws 165 to 216 μA current from the supply voltage varied from 1.34 to 3.3 V. The prototype chip is fabricated in the 0.18-μm CMOS process and occupies an area of 1.23 mm 2 (including pads). In-vitro recording was successfully carried out by the proposed frontend chip. (paper)

  12. A CMOS frontend chip for implantable neural recording with wide voltage supply range

    Jialin, Liu; Xu, Zhang; Xiaohui, Hu; Yatao, Guo; Peng, Li; Ming, Liu; Bin, Li; Hongda, Chen

    2015-10-01

    A design for a CMOS frontend integrated circuit (chip) for neural signal acquisition working at wide voltage supply range is presented in this paper. The chip consists of a preamplifier, a serial instrumental amplifier (IA) and a cyclic analog-to-digital converter (CADC). The capacitive-coupled and capacitive-feedback topology combined with MOS-bipolar pseudo-resistor element is adopted in the preamplifier to create a -3 dB upper cut-off frequency less than 1 Hz without using a ponderous discrete device. A dual-amplifier instrumental amplifier is used to provide a low output impedance interface for ADC as well as to boost the gain. The preamplifier and the serial instrumental amplifier together provide a midband gain of 45.8 dB and have an input-referred noise of 6.7 μVrms integrated from 1 Hz to 5 kHz. The ADC digitizes the amplified signal at 12-bits precision with a highest sampling rate of 130 kS/s. The measured effective number of bits (ENOB) of the ADC is 8.7 bits. The entire circuit draws 165 to 216 μA current from the supply voltage varied from 1.34 to 3.3 V. The prototype chip is fabricated in the 0.18-μm CMOS process and occupies an area of 1.23 mm2 (including pads). In-vitro recording was successfully carried out by the proposed frontend chip. Project supported by the National Natural Science Foundation of China (Nos. 61474107, 61372060, 61335010, 61275200, 61178051) and the Key Program of the Chinese Academy of Sciences (No. KJZD-EW-L11-01).

  13. Fabrication of three-dimensional carbon microelectrodes for electrochemical sensing

    Hemanth, Suhith

    Carbon microelectrodes have a wide range of applications because of their unique material properties and biocompatibility. The aim of the research work carried out in this thesis was to develop three-dimensional (3D) carbon microelectrodes for electrochemical applications. Three different fabrica...

  14. Electric potential microelectrode for studies of electrobiogeophysics

    Damgaard, Lars Riis; Risgaard-Petersen, Nils; Nielsen, Lars Peter

    2014-01-01

    were needle-shaped, shielded Ag/AgCl half-cells that were rendered insensitive to redox-active species in the environment. Tip diameters of 40 to 100 μm and signal resolution of approximately 10 μV were achieved. A test in marine sediments with active cable bacteria showed an electric potential......Spatially separated electron donors and acceptors in sediment can be exploited by the so-called “cable bacteria.” Electric potential microelectrodes (EPMs) were constructed to measure the electric fields that should appear when cable bacteria conduct electrons over centimeter distances. The EPMs...

  15. EDITORIAL: Special issue containing contributions from the 39th Neural Interfaces Conference Special issue containing contributions from the 39th Neural Interfaces Conference

    Weiland, James D.

    2011-07-01

    strategy that can potentially optimize dosing, reduce side effects and extend implant battery life. The article by Liang et al investigates methods for closed loop control of epilepsy, using neural recording to detect imminent seizures and stimulation to halt the aberrant neural activity leading to seizure. Liu et al report on a model of basal ganglia function that could lead to optimized, closed-loop stimulation to reduce symptoms of Parkinson's disease while avoiding side effects. Our laboratory, as described in Ray et al, is investigating the interface between stimulating microelectrodes and the retina, to inform the design of a high-resolution retinal prosthesis. Three contributions address the issue of long-term stability of cortical recording, which remains a major hurdle to implementation of neural recording systems. The Utah group reports on the in vitro testing of a completely implantable, wireless neural recording system, demonstrating almost one year of reliable performance under simulated implant conditions. Shenoy's laboratory at Stanford demonstrates that useful signals can be recorded from research animals for over 2.5 years. Lempka et al describe a modeling approach to analyzing intracortical microelectrode recordings. These findings represent real and significant progress towards overcoming the final barriers to implementation of a reliable cortical interface. Planning is well underway for the 40th Neural Interfaces Conference, which will be held in Salt Lake City, Utah, in June 2012. The conference promises to continue the NIC tradition of showcasing the latest results from clinical trials of neural interface therapies while providing ample time for dynamic exchange amongst the interdisciplinary audience of engineers, scientists and clinicians.

  16. Screening metal nanoparticles using boron-doped diamond microelectrodes

    Ivandini, Tribidasari A., E-mail: ivandini.tri@sci.ui.ac.id; Rangkuti, Prasmita K. [Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Einaga, Yasuaki [Department of Chemistry, Faculty of Science and Technology, Keio University (Japan); JST ACCEL, 3-14-1 Hiyoshi, Yokohama 223-8522 (Japan)

    2016-04-19

    Boron-doped diamond (BDD) microelectrodes were used to observe the correlation between electrocatalytic currents caused by individual Pt nanoparticle (Pt-np) collisions at the electrode. The BDD microelectrodes, ∼20 µm diameter and ∼2 µm particle size, were fabricated at the surface of tungsten wires. Pt-np with a size of 1 to 5 nm with agglomerations up to 20 nm was used for observation. The electrolytic currents were observed via catalytic reaction of 15 mM hydrazine in 50 mM phosphate buffer solution at Pt-np at 0.4 V when it collides with the surface of the microelectrodes. The low current noise and wider potential window in the measurements using BDD microelectrode produced a better results, which represents a better correlation to the TEM result of the Pt-np, compared to when gold microelectrodes was used.

  17. Screening metal nanoparticles using boron-doped diamond microelectrodes

    Ivandini, Tribidasari A.; Rangkuti, Prasmita K.; Einaga, Yasuaki

    2016-01-01

    Boron-doped diamond (BDD) microelectrodes were used to observe the correlation between electrocatalytic currents caused by individual Pt nanoparticle (Pt-np) collisions at the electrode. The BDD microelectrodes, ∼20 µm diameter and ∼2 µm particle size, were fabricated at the surface of tungsten wires. Pt-np with a size of 1 to 5 nm with agglomerations up to 20 nm was used for observation. The electrolytic currents were observed via catalytic reaction of 15 mM hydrazine in 50 mM phosphate buffer solution at Pt-np at 0.4 V when it collides with the surface of the microelectrodes. The low current noise and wider potential window in the measurements using BDD microelectrode produced a better results, which represents a better correlation to the TEM result of the Pt-np, compared to when gold microelectrodes was used.

  18. Nanostructured gold microelectrodes for extracellular recording

    Brueggemann, Dorothea; Wolfrum, Bernhard; Maybeck, Vanessa; Offenhaeusser, Andreas [CNI Center of Nanoelectronic Systems for Information Technology and Institute of Bio- and Nanosystems 2, Forschungszentrum Juelich (Germany)

    2010-07-01

    Electrophysiological activity of electrogenic cells is currently recorded with planar bioelectronic interfaces such as microelectrode arrays (MEAs). In this work, a novel concept of biocompatible nanostructured gold MEAs for extracellular signal recording is presented. MEAs were fabricated using clean room technologies, e.g. photolithography and metallization. Subsequently, they were modified with gold nanopillars of approximately 300 to 400 nm in height and 60 nm width. The nanostructuring process was carried out with a template-assisted approach using nanoporous aluminium oxide. Impedance spectroscopy of the resulting nanostructures showed higher capacitances compared to planar gold. This confirmed the expected increase of the surface area via nanostructuring. We used the nanostructured microelectrodes to record extracellular potentials from heart muscle cells (HL1), which were plated onto the chips. Good coupling between the HL1 cells and the nanostructured electrodes was observed. The resulting signal-to-noise ratio of nanopillar-MEAs was increased by a factor of 2 compared to planar MEAs. In future applications this nanopillar concept can be adopted for distinct interface materials and coupling to cellular and molecular sensing components.

  19. Microfluidic Actuation of Carbon Nanotube Fibers for Neural Recordings

    Vercosa, Daniel G.

    Implantable devices to record and stimulate neural circuits have led to breakthroughs in neuroscience; however, technologies capable of electrical recording at the cellular level typically rely on rigid metals that poorly match the mechanical properties of soft brain tissue. As a result these electrodes often cause extensive acute and chronic injury, leading to short electrode lifetime. Recently, flexible electrodes such as Carbon Nanotube fibers (CNTf) have emerged as an attractive alternative to conventional electrodes and studies have shown that these flexible electrodes reduce neuro-inflammation and increase the quality and longevity of neural recordings. Insertion of these new compliant electrodes, however, remains challenge. The stiffening agents necessary to make the electrodes rigid enough to be inserted increases device footprint, which exacerbates brain damage during implantation. To overcome this challenge we have developed a novel technology to precisely implant and actuate high-performance, flexible carbon nanotube fiber (CNTf) microelectrodes without using a stiffening agents or shuttles. Instead, our technology uses drag forces within a microfluidic device to drive electrodes into tissue while minimizing the amount of fluid that is ejected into the tissue. In vitro experiments in brain phantoms, show that microfluidic actuated CNTf can be implanted at least 4.5 mm depth with 30 microm precision, while keeping the total volume of fluid ejected below 0.1 microL. As proof of concept, we inserted CNTfs in the small cnidarian Hydra littoralis and observed compound action potentials corresponding to contractions and in agreement with the literature. Additionally, brain slices extracted from transgenic mice were used to show that our device can be used to record spontaneous and light evoked activity from the cortex and deep brain regions such as the thalamic reticular nucleus (TRN). Overall our microfluidic actuation technology provides a platform for

  20. Dual-side and three-dimensional microelectrode arrays fabricated from ultra-thin silicon substrates

    Du, Jiangang; Masmanidis, Sotiris C; Roukes, Michael L

    2009-01-01

    A method for fabricating planar implantable microelectrode arrays was demonstrated using a process that relied on ultra-thin silicon substrates, which ranged in thickness from 25 to 50 µm. The challenge of handling these fragile materials was met via a temporary substrate support mechanism. In order to compensate for putative electrical shielding of extracellular neuronal fields, separately addressable electrode arrays were defined on each side of the silicon device. Deep reactive ion etching was employed to create sharp implantable shafts with lengths of up to 5 mm. The devices were flip-chip bonded onto printed circuit boards (PCBs) by means of an anisotropic conductive adhesive film. This scalable assembly technique enabled three-dimensional (3D) integration through formation of stacks of multiple silicon and PCB layers. Simulations and measurements of microelectrode noise appear to suggest that low impedance surfaces, which could be formed by electrodeposition of gold or other materials, are required to ensure an optimal signal-to-noise ratio as well a low level of interchannel crosstalk

  1. A novel combinational pH-PCO2 microelectrode.

    Rao, X; Ma, Y

    1993-07-01

    A novel combinational pH-PCO2 microelectrode based on a neutral carrier hydrogen ion exchanger is described. It is easy to fabricate and allows pH and PCO2 to be measured simultaneously. The microelectrode has a 5-microns tip. The PCO2 microelectrode exhibits a linear response in the range 1.75 x 10(-5)-10(-2) mol/liter with a Nernstian slope of 57.0 mV/decade at 25 degrees C. The detection limit is 10(-5) mol/liter. The pH microelectrode exhibits a linear response in the range pH 4-12 with a Nernstian slope of 60.0 mV/decade at 25 degrees C. The 95% steady-state response time of the PCO2 microelectrode is about 2 min, while it is about 10 s for pH microelectrode. The electromotive force drift is 4.3 mV/h (PCO2) and 2.6 mV/h (pH), respectively. The lifetime is 3 to 4 days. The microelectrode can measure pH and PCO2 in body fluids simultaneously with satisfactory results. It is also a good basic electrode for enzyme microelectrolysis.

  2. Apparatus and method of inserting a microelectrode in body tissue or the like using vibration means

    Feldstein, C.; Crawford, D. W.; Kanabus, E. W. (Inventor)

    1979-01-01

    An arrangement for and method of inserting a glass microelectrode having a tip in the micron range into body tissue is presented. The arrangement includes a microelectrode. The top of the microelectrode is attached to the diaphragm center of a first speaker. The microelectrode tip is brought into contact with the tissue by controlling a micromanipulator. Thereafter, an audio signal is applied to the speaker to cause the microelectrode to vibrate and thereby pierce the tissue surface without breaking the microelectrode tip. Thereafter, the tip is inserted into the tissue to the desired depth by operating the micromanipulator with the microelectrode in a vibratory or non-vibratory state.

  3. Improving Impedance of Implantable Microwire Multi-Electrode Arrays by Ultrasonic Electroplating of Durable Platinum Black

    Desai, Sharanya Arcot; Rolston, John D.; Guo, Liang; Potter, Steve M.

    2010-01-01

    Implantable microelectrode arrays (MEAs) have been a boon for neural stimulation and recording experiments. Commercially available MEAs have high impedances, due to their low surface area and small tip diameters, which are suitable for recording single unit activity. Lowering the electrode impedance, but preserving the small diameter, would provide a number of advantages, including reduced stimulation voltages, reduced stimulation artifacts and improved signal-to-noise ratio. Impedance reductions can be achieved by electroplating the MEAs with platinum (Pt) black, which increases the surface area but has little effect on the physical extent of the electrodes. However, because of the low durability of Pt black plating, this method has not been popular for chronic use. Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry. This method has not previously been characterized for MEAs used in chronic neural implants. We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods. We also show the improved stimulation and recording performance that can be achieved in an in vivo implantation study with the sonicoplated low-impedance MMEAs, compared to high-impedance unplated electrodes. PMID:20485478

  4. Pyrolytic 3D Carbon Microelectrodes for Electrochemistry

    Hemanth, Suhith; Caviglia, Claudia; Amato, Letizia

    2016-01-01

    electrochemical activity, chemical stability, and ease in surface functionalization [1]. The most common carbon microfabrication techniques (i.e. screen printing) produce two-dimensional (2D) electrodes, which limit the detection sensitivity. Hence several 3D microfabrication techniques have been explored......This work presents the fabrication and characterization of multi-layered three-dimensional (3D) pyrolysed carbon microelectrodes for electrochemical applications. For this purpose, an optimized UV photolithography and pyrolysis process with the negative tone photoresist SU-8 has been developed...... carbon [2]. This process enables fabrication of 2D and 3D electrodes with possibility for tailoring ad-hoc designs and unique sensitivities for specific applications. Due to this, pyrolysed carbon is becoming increasingly attractive for numerous applications, such as novel sensors and scaffolds for cell...

  5. Partially flexible MEMS neural probe composed of polyimide and sucrose gel for reducing brain damage during and after implantation

    Jeon, Myounggun; Yoon, Eui-Sung; Cho, Il-Joo; Cho, Jeiwon; Jung, Dahee; Kim, Yun Kyung; Shin, Sehyun

    2014-01-01

    This paper presents a flexible microelectromechanical systems (MEMS) neural probe that minimizes neuron damage and immune response, suitable for chronic recording applications. MEMS neural probes with various features such as high electrode densities have been actively investigated for neuron stimulation and recording to study brain functions. However, successful recording of neural signals in chronic application using rigid silicon probes still remains challenging because of cell death and macrophages accumulated around the electrodes over time from continuous brain movement. Thus, in this paper, we propose a new flexible MEMS neural probe that consists of two segments: a polyimide-based, flexible segment for connection and a rigid segment composed of thin silicon for insertion. While the flexible connection segment is designed to reduce the long-term chronic neuron damage, the thin insertion segment is designed to minimize the brain damage during the insertion process. The proposed flexible neural probe was successfully fabricated using the MEMS process on a silicon on insulator wafer. For a successful insertion, a biodegradable sucrose gel is coated on the flexible segment to temporarily increase the probe stiffness to prevent buckling. After the insertion, the sucrose gel dissolves inside the brain exposing the polyimide probe. By performing an insertion test, we confirm that the flexible probe has enough stiffness. In addition, by monitoring immune responses and brain histology, we successfully demonstrate that the proposed flexible neural probe incurs fivefold less neural damage than that incurred by a conventional silicon neural probe. Therefore, the presented flexible neural probe is a promising candidate for recording stable neural signals for long-time chronic applications. (paper)

  6. Suspended 3D pyrolytic carbon microelectrodes for electrochemistry

    Hemanth, Suhith; Caviglia, Claudia; Keller, Stephan Sylvest

    2017-01-01

    with cyclic voltammetry (CV) and impedance spectroscopy (EIS) using potassium ferri-ferrocyanide redox probe in a custom made batch system with magnetic clamping. Different 3D pyrolytic carbon microelectrodes were compared and the optimal design displayed twice the peak current and half the charge transfer......Carbon microelectrodes have a wide range of applications because of their unique material properties and biocompatibility. This work presents the fabrication and characterization of suspended pyrolytic carbon microstructures serving as three-dimensional (3D) carbon microelectrodes...... for electrochemical applications. A 3D polymer template in epoxy based photoresist (SU-8) was fabricated with multiple steps of UV photolithography and pyrolysed at 900 °C to obtain 3D carbon microelectrodes. The pyrolytic carbon microstructures were characterized by SEM, Raman spectroscopy and XPS to determine...

  7. Sonochemically Fabricated Microelectrode Arrays for Use as Sensing Platforms

    Stuart D. Collyer

    2010-05-01

    Full Text Available The development, manufacture, modification and subsequent utilisation of sonochemically-formed microelectrode arrays is described for a range of applications. Initial fabrication of the sensing platform utilises ultrasonic ablation of electrochemically insulating polymers deposited upon conductive carbon substrates, forming an array of up to 70,000 microelectrode pores cm–2. Electrochemical and optical analyses using these arrays, their enhanced signal response and stir-independence area are all discussed. The growth of conducting polymeric “mushroom” protrusion arrays with entrapped biological entities, thereby forming biosensors is detailed. The simplicity and inexpensiveness of this approach, lending itself ideally to mass fabrication coupled with unrivalled sensitivity and stir independence makes commercial viability of this process a reality. Application of microelectrode arrays as functional components within sensors include devices for detection of chlorine, glucose, ethanol and pesticides. Immunosensors based on microelectrode arrays are described within this monograph for antigens associated with prostate cancer and transient ischemic attacks (strokes.

  8. Techniques for extracting single-trial activity patterns from large-scale neural recordings

    Churchland, Mark M; Yu, Byron M; Sahani, Maneesh; Shenoy, Krishna V

    2008-01-01

    Summary Large, chronically-implanted arrays of microelectrodes are an increasingly common tool for recording from primate cortex, and can provide extracellular recordings from many (order of 100) neurons. While the desire for cortically-based motor prostheses has helped drive their development, such arrays also offer great potential to advance basic neuroscience research. Here we discuss the utility of array recording for the study of neural dynamics. Neural activity often has dynamics beyond that driven directly by the stimulus. While governed by those dynamics, neural responses may nevertheless unfold differently for nominally identical trials, rendering many traditional analysis methods ineffective. We review recent studies – some employing simultaneous recording, some not – indicating that such variability is indeed present both during movement generation, and during the preceding premotor computations. In such cases, large-scale simultaneous recordings have the potential to provide an unprecedented view of neural dynamics at the level of single trials. However, this enterprise will depend not only on techniques for simultaneous recording, but also on the use and further development of analysis techniques that can appropriately reduce the dimensionality of the data, and allow visualization of single-trial neural behavior. PMID:18093826

  9. Glass pipette-carbon fiber microelectrodes for evoked potential recordings

    Moraes M.F.D.

    1997-01-01

    Full Text Available Current methods for recording field potentials with tungsten electrodes make it virtually impossible to use the same recording electrode also as a lesioning electrode, for example for histological confirmation of the recorded site, because the lesioning procedure usually wears off the tungsten tip. Therefore, the electrode would have to be replaced after each lesioning procedure, which is a very high cost solution to the problem. We present here a low cost, easy to make, high quality glass pipette-carbon fiber microelectrode that shows resistive, signal/noise and electrochemical coupling advantages over tungsten electrodes. Also, currently used carbon fiber microelectrodes often show problems with electrical continuity, especially regarding electrochemical applications using a carbon-powder/resin mixture, with consequent low performance, besides the inconvenience of handling such a mixture. We propose here a new method for manufacturing glass pipette-carbon fiber microelectrodes with several advantages when recording intracerebral field potentials

  10. Combined Reactor and Microelectrode Measurements in Laboratory Grown Biofilms

    Larsen, Tove; Harremoës, Poul

    1994-01-01

    A combined biofilm reactor-/microelectrode experimental set-up has been constructed, allowing for simultaneous reactor mass balances and measurements of concentration profiles within the biofilm. The system consists of an annular biofilm reactor equipped with an oxygen microelectrode. Experiments...... were carried out with aerobic glucose and starch degrading biofilms. The well described aerobic glucose degradation biofilm system was used to test the combined reactor set-up. Results predicted from known biofilm kinetics were obtained. In the starch degrading biofilm, basic assumptions were tested...... with the microelectrode measurements. It was established, that even with a high molecular weight, non-diffusible substrate, degradation took place in the depths of the biofilm. Intrinsic enzymatic hydrolysis was not limiting and the volumetric removal rate of oxygen was zero order....

  11. Outcomes of Interventional-MRI Versus Microelectrode Recording-Guided Subthalamic Deep Brain Stimulation

    Philip S. Lee

    2018-04-01

    Full Text Available In deep brain stimulation (DBS of the subthalamic nucleus (STN for Parkinson’s disease (PD, there is debate concerning the use of neuroimaging alone to confirm correct anatomic placement of the DBS lead into the STN, versus the use of microelectrode recording (MER to confirm functional placement. We performed a retrospective study of a contemporaneous cohort of 45 consecutive patients who underwent either interventional-MRI (iMRI or MER-guided DBS lead implantation. We compared radial lead error, motor and sensory side effect, and clinical benefit programming thresholds, and pre- and post-operative unified PD rating scale scores, and levodopa equivalent dosages. MER-guided surgery was associated with greater radial error compared to the intended target. In general, side effect thresholds during initial programming were slightly lower in the MER group, but clinical benefit thresholds were similar. No significant difference in the reduction of clinical symptoms or medication dosage was observed. In summary, iMRI lead implantation occurred with greater anatomic accuracy, in locations demonstrated to be the appropriate functional region of the STN, based on the observation of similar programming side effect and benefit thresholds obtained with MER. The production of equivalent clinical outcomes suggests that surgeon and patient preference can be used to guide the decision of whether to recommend iMRI or MER-guided DBS lead implantation to appropriate patients with PD.

  12. Data-driven model comparing the effects of glial scarring and interface interactions on chronic neural recordings in non-human primates

    Malaga, Karlo A.; Schroeder, Karen E.; Patel, Paras R.; Irwin, Zachary T.; Thompson, David E.; Bentley, J. Nicole; Lempka, Scott F.; Chestek, Cynthia A.; Patil, Parag G.

    2016-02-01

    Objective. We characterized electrode stability over twelve weeks of impedance and neural recording data from four chronically-implanted Utah arrays in two rhesus macaques, and investigated the effects of glial scarring and interface interactions at the electrode recording site on signal quality using a computational model. Approach. A finite-element model of a Utah array microelectrode in neural tissue was coupled with a multi-compartmental model of a neuron to quantify the effects of encapsulation thickness, encapsulation resistivity, and interface resistivity on electrode impedance and waveform amplitude. The coupled model was then reconciled with the in vivo data. Histology was obtained seventeen weeks post-implantation to measure gliosis. Main results. From week 1-3, mean impedance and amplitude increased at rates of 115.8 kΩ/week and 23.1 μV/week, respectively. This initial ramp up in impedance and amplitude was observed across all arrays, and is consistent with biofouling (increasing interface resistivity) and edema clearing (increasing tissue resistivity), respectively, in the model. Beyond week 3, the trends leveled out. Histology showed that thin scars formed around the electrodes. In the model, scarring could not match the in vivo data. However, a thin interface layer at the electrode tip could. Despite having a large effect on impedance, interface resistivity did not have a noticeable effect on amplitude. Significance. This study suggests that scarring does not cause an electrical problem with regard to signal quality since it does not appear to be the main contributor to increasing impedance or significantly affect amplitude unless it displaces neurons. This, in turn, suggests that neural signals can be obtained reliably despite scarring as long as the recording site has sufficiently low impedance after accumulating a thin layer of biofouling. Therefore, advancements in microelectrode technology may be expedited by focusing on improvements to the

  13. Microelectrodes as novel research tools for environmental biofilm studies

    Yu, T.; Lu, R.; Bishop, L.

    2002-01-01

    Biofilm processes are widely utilized in environmental engineering for biodegradation of contaminated waters, gases and soils. It is important to understand the structure and functions of biofilms. Microelectrodes are novel experimental tools for environmental biofilm studies. The authors reviewed the techniques of oxygen, sulfide, redox potential and pH microelectrode. These microelectrodes have tip diameters of 3 to 20 μm, resulting a high spatial resolution. They enable us directly measure the chemical conditions as results of microbial activities in biofilms. The authors also reported the laboratory and field studies of wastewater biofilms using microelectrode techniques. The results of these studies provided experimental evidence on the stratification of microbial processes and the associated redox potential change in wastewater biofilms: (1) The oxygen penetration depth was only a fraction of the biofilm thickness. This observation, first made under laboratory conditions, has been confirmed under field conditions. (2) The biofilms with both aerobic oxidation and sulfate reduction had a clearly stratified structure. This was evidenced by a sharp decrease of redox potential near the interface between the aerobic zone and the sulfate reduction zone within the biofilm. In this type of biofilms, aerobic oxidation took place only in a shallow layer near the biofilm surface and sulfate reduction occurred in the deeper anoxic zone. (3) The redox potential changed with the shift of primary microbial process in biofilms, indicating that it is possible to use redox potential to help illustrate the structure and functions of biofilms. (author)

  14. Microelectrode measurements of the activity distribution in nitrifying bacterial aggregates

    Beer, de D.; Heuvel, van den J.C.; Ottengraf, S.P.P.

    1993-01-01

    Microelectrodes for ammonium, oxygen, nitrate, and pH were used to study nitrifying aggregates grown in a fluidized-bed reactor. Local reactant fluxes and distribution of microbial activity could be detd. from the microprofiles. The interfacial fluxes of the reactants closely reflected the

  15. Integration of Polymer Micro-Electrodes for Bio-Sensing

    Argyraki, Aikaterini; Larsen, Simon Tylsgaard; Tanzi, Simone

    We present the fabrication of PEDOT and pyrolyzed micro-electrodes for the detection of neurotransmitter exocytosis from single cells. The patterns of the electrodes are defined with photolithography. The micro-electro-fluidic-chips were fabricated by bonding two injection molded TOPAS parts. Pol...

  16. A Platform for Manufacturable Stretchable Micro-electrode Arrays

    Khoshfetrat Pakazad, S.; Savov, A.; Braam, S.R.; Dekker, R.

    2012-01-01

    A platform for the batch fabrication of pneumatically actuated Stretchable Micro-Electrode Arrays (SMEAs) by using state-of-the-art micro-fabrication techniques and materials is demonstrated. The proposed fabrication process avoids the problems normally associated with processing of thin film

  17. AFM cantilever with in situ renewable mercury microelectrode

    Schön, Peter Manfred; Geerlings, J.; Tas, Niels Roelof; Sarajlic, Edin

    2013-01-01

    We report here first results obtained on a novel, in situ renewable mercury microelectrode integrated into an atomic force microscopy (AFM) cantilever. Our approach is based on a fountain pen probe with appropriate dimensions enabling reversible filling with(nonwetting) mercury under changing the

  18. Lability criteria for metal complexes in micro-electrode voltammetry

    Leeuwen, van H.P.; Pinheiro, J.P.

    1999-01-01

    Theoretical expressions are derived for the voltammetric lability criteria of metal complexes in the micro-electrode regime. The treatment includes three limiting situations: (i) the macro-electrode limit, where both the diffusion layer and the dissociation reaction layer are linear; (ii) an

  19. Biocompatible implants and methods of making and attaching the same

    Rowley, Adrian P; Laude, Lucien D; Humayun, Mark S; Weiland, James D; Lotfi, Atoosa; Markland, Jr., Francis S

    2014-10-07

    The invention provides a biocompatible silicone implant that can be securely affixed to living tissue through interaction with integral membrane proteins (integrins). A silicone article containing a laser-activated surface is utilized to make the implant. One example is an implantable prosthesis to treat blindness caused by outer retinal degenerative diseases. The device bypasses damaged photoreceptors and electrically stimulates the undamaged neurons of the retina. Electrical stimulation is achieved using a silicone microelectrode array (MEA). A safe, protein adhesive is used in attaching the MEA to the retinal surface and assist in alleviating focal pressure effects. Methods of making and attaching such implants are also provided.

  20. Signal processing methods for reducing artifacts in microelectrode brain recordings caused by functional electrical stimulation

    Young, D.; Willett, F.; Memberg, W. D.; Murphy, B.; Walter, B.; Sweet, J.; Miller, J.; Hochberg, L. R.; Kirsch, R. F.; Ajiboye, A. B.

    2018-04-01

    Objective. Functional electrical stimulation (FES) is a promising technology for restoring movement to paralyzed limbs. Intracortical brain-computer interfaces (iBCIs) have enabled intuitive control over virtual and robotic movements, and more recently over upper extremity FES neuroprostheses. However, electrical stimulation of muscles creates artifacts in intracortical microelectrode recordings that could degrade iBCI performance. Here, we investigate methods for reducing the cortically recorded artifacts that result from peripheral electrical stimulation. Approach. One participant in the BrainGate2 pilot clinical trial had two intracortical microelectrode arrays placed in the motor cortex, and thirty-six stimulating intramuscular electrodes placed in the muscles of the contralateral limb. We characterized intracortically recorded electrical artifacts during both intramuscular and surface stimulation. We compared the performance of three artifact reduction methods: blanking, common average reference (CAR) and linear regression reference (LRR), which creates channel-specific reference signals, composed of weighted sums of other channels. Main results. Electrical artifacts resulting from surface stimulation were 175  ×  larger than baseline neural recordings (which were 110 µV peak-to-peak), while intramuscular stimulation artifacts were only 4  ×  larger. The artifact waveforms were highly consistent across electrodes within each array. Application of LRR reduced artifact magnitudes to less than 10 µV and largely preserved the original neural feature values used for decoding. Unmitigated stimulation artifacts decreased iBCI decoding performance, but performance was almost completely recovered using LRR, which outperformed CAR and blanking and extracted useful neural information during stimulation artifact periods. Significance. The LRR method was effective at reducing electrical artifacts resulting from both intramuscular and surface FES, and

  1. Microelectrode array-induced neuronal alignment directs neurite outgrowth: analysis using a fast Fourier transform (FFT).

    Radotić, Viktorija; Braeken, Dries; Kovačić, Damir

    2017-12-01

    Many studies have shown that the topography of the substrate on which neurons are cultured can promote neuronal adhesion and guide neurite outgrowth in the same direction as the underlying topography. To investigate this effect, isotropic substrate-complementary metal-oxide-semiconductor (CMOS) chips were used as one example of microelectrode arrays (MEAs) for directing neurite growth of spiral ganglion neurons. Neurons were isolated from 5 to 7-day-old rat pups, cultured 1 day in vitro (DIV) and 4 DIV, and then fixed with 4% paraformaldehyde. For analysis of neurite alignment and orientation, fast Fourier transformation (FFT) was used. Results revealed that on the micro-patterned surface of a CMOS chip, neurons orient their neurites along three directional axes at 30, 90, and 150° and that neurites aligned in straight lines between adjacent pillars and mostly followed a single direction while occasionally branching perpendicularly. We conclude that the CMOS substrate guides neurites towards electrodes by means of their structured pillar organization and can produce electrical stimulation of aligned neurons as well as monitoring their neural activities once neurites are in the vicinity of electrodes. These findings are of particular interest for neural tissue engineering with the ultimate goal of developing a new generation of MEA essential for improved electrical stimulation of auditory neurons.

  2. Electrochemical measurements on a droplet using gold microelectrodes

    Jenabi, Amin; Souri, Asma; Rastkhadiv, Ali

    2016-03-01

    Facile methods of ion recognition are important for the fabrication of electronic tongue systems. In this work, we demonstrate performing pulsed conductometry on microliter electrolyte droplets dropped on gold microelectrodes vapor deposited on soda lime glass slides. A droplet is dropped between two microelectrodes when a voltage waveform from a preprogramed power supply is applied on them. The temporal variation of the electric current passing through the droplet is recorded, digitized and stored. The obtained data are compared with the database formed out of the previous experiences for the classification of the sample electrolytes. It is shown that the shape of the voltage waveform is the important parameter of the process. We devised a method for the optimization of the voltage waveform profile for obtaining the maximum of discriminating information from the recorded current variations.

  3. Electrochemical measurements on a droplet using gold microelectrodes

    Jenabi, Amin; Souri, Asma; Rastkhadiv, Ali

    2016-01-01

    Facile methods of ion recognition are important for the fabrication of electronic tongue systems. In this work, we demonstrate performing pulsed conductometry on microliter electrolyte droplets dropped on gold microelectrodes vapor deposited on soda lime glass slides. A droplet is dropped between two microelectrodes when a voltage waveform from a preprogramed power supply is applied on them. The temporal variation of the electric current passing through the droplet is recorded, digitized and stored. The obtained data are compared with the database formed out of the previous experiences for the classification of the sample electrolytes. It is shown that the shape of the voltage waveform is the important parameter of the process. We devised a method for the optimization of the voltage waveform profile for obtaining the maximum of discriminating information from the recorded current variations. (paper)

  4. Stretchable microelectrode array using room-temperature liquid alloy interconnects

    Wei, P; Ziaie, B; Taylor, R; Chung, C; Higgs, G; Pruitt, B L; Ding, Z; Abilez, O J

    2011-01-01

    In this paper, we present a stretchable microelectrode array for studying cell behavior under mechanical strain. The electrode array consists of gold-plated nail-head pins (250 µm tip diameter) or tungsten micro-wires (25.4 µm in diameter) inserted into a polydimethylsiloxane (PDMS) platform (25.4 × 25.4 mm 2 ). Stretchable interconnects to the outside were provided by fusible indium-alloy-filled microchannels. The alloy is liquid at room temperature, thus providing the necessary stretchability and electrical conductivity. The electrode platform can withstand strains of up to 40% and repeated (100 times) strains of up to 35% did not cause any failure in the electrodes or the PDMS substrate. We confirmed biocompatibility of short-term culture, and using the gold pin device, we demonstrated electric field pacing of adult murine heart cells. Further, using the tungsten microelectrode device, we successfully measured depolarizations of differentiated murine heart cells from embryoid body clusters

  5. Comparison of microelectrode sensing configurations for impedimetric cell monitoring

    Caviglia, Claudia; Heiskanen, Arto; Andresen, Thomas Lars

    2012-01-01

    interdigitated microelectrodes using a versatile custom-made monitoring platform including a 24-channel miniaturized potentiostat. As expected, characterization of bare microelectrodes in buffer and tracking experiments with HeLa cells over 16 hours demonstrate that the coplanar configuration provides a higher......A theoretical and experimental comparison between vertical and coplanar interdigitated sensing configurations for impedimetric cell growth tracking is presented. For the first time, these widely-adopted approaches are quantitatively compared on the same cell populations and on the same 10μm...... sensitivity to cell adhesion and spreading (Cell Index = 1.6 vs. 0.4) albeit at a higher frequency of maximum sensitivity (100kHz vs. 24 kHz)....

  6. Microstimulation with Chronically Implanted Intracortical Electrodes

    McCreery, Douglas

    Stimulating microelectrodes that penetrate into the brain afford a means of accessing the basic functional units of the central nervous system. Microstimulation in the region of the cerebral cortex that subserve vision may be an alternative, or an adjunct, to a retinal prosthesis, and may be particularly attractive as a means of restoring a semblance of high-resolution central vision. There also is the intriguing possibility that such a prosthesis could convey higher order visual percepts, many of which are mediated by neural circuits in the secondary or "extra-striate" visual areas that surround the primary visual cortex. The technologies of intracortical stimulating microelectrodes and investigations of the effects of microstimulation on neural tissue have advanced to the point where a cortical-level prosthesis is at least feasible. The imperative of protecting neural tissue from stimulation-induced damage imposes constraints on the selection of stimulus parameters, as does the requirement that the stimulation not greatly affect the electrical excitability of the neurons that are to be activated. The latter is especially likely to occur when many adjacent microelectrodes are pulsed, as will be necessary in a visual prosthesis. However, data from animal studies indicates that these restrictions on stimulus parameter are compatible with those that can evoke visual percepts in humans and in experimental animals. These findings give cause to be optimistic about the prospects for realizing a visual prosthesis utilizing intracortical microstimulation.

  7. Pencil lead microelectrode and the application on cell dielectrophoresis

    Hsieh, Bo-Chuan; Cheng, Tzong-Jih; Shih, Syuan-He [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, 136 Chou-Shan Rd., Taipei City 106, Taiwan (China); Chen, Richie L.C., E-mail: rlcchen@ntu.edu.tw [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, 136 Chou-Shan Rd., Taipei City 106, Taiwan (China)

    2011-11-30

    A microelectrode was fabricated by electrochemical etching of a pencil lead (0.5 mm in diameter) in 1.0 M NaOH aqueous solution. The pencil lead was dipped into the solution and then an ac voltage (3.0 V{sub rms} for 10 min) was imposed against a stainless plate under mild stirring (450 rpm). The electrochemically sharpened pencil tip was about 10 {mu}m in diameter (12 {+-} 3 {mu}m, n = 5), and the lateral part was insulated within a polypropylene micro-pipette tip (2-200 {mu}L volume range). The cyclic voltammograms conducted in 2.0 mM ferricyanide/ferrocyanide buffer solution (pH 7.0) are with low capacitive current and a typical sigmoidal signal of micro-sized electrodes. The microelectrode was used to perform dielectrophoresis of polystyrene latex microbeads (nominal diameter of 3 {mu}m) and human red blood cells. A conducting glass (indium tin oxide coated glass, 40 mm x 40 mm x 1 mm) served as the counter electrode (0.5 mm beneath the microelectrode) to generate the asymmetrical electric field and also as the window for microscopic observation. With the sinusoidal bias voltage (30 V{sub rms}) ranged from 20 Hz to 2 MHz, positive and negative dielectrophoretic phenomena were identified.

  8. Glassy carbon MEMS for novel origami-styled 3D integrated intracortical and epicortical neural probes

    Goshi, Noah; Castagnola, Elisa; Vomero, Maria; Gueli, Calogero; Cea, Claudia; Zucchini, Elena; Bjanes, David; Maggiolini, Emma; Moritz, Chet; Kassegne, Sam; Ricci, Davide; Fadiga, Luciano

    2018-06-01

    We report on a novel technology for microfabricating 3D origami-styled micro electro-mechanical systems (MEMS) structures with glassy carbon (GC) features and a supporting polymer substrate. GC MEMS devices that open to form 3D microstructures are microfabricated from GC patterns that are made through pyrolysis of polymer precursors on high-temperature resisting substrates like silicon or quartz and then transferring the patterned devices to a flexible substrate like polyimide followed by deposition of an insulation layer. The devices on flexible substrate are then folded into 3D form in an origami-fashion. These 3D MEMS devices have tunable mechanical properties that are achieved by selectively varying the thickness of the polymeric substrate and insulation layers at any desired location. This technology opens new possibilities by enabling microfabrication of a variety of 3D GC MEMS structures suited to applications ranging from biochemical sensing to implantable microelectrode arrays. As a demonstration of the technology, a neural signal recording microelectrode array platform that integrates both surface (cortical) and depth (intracortical) GC microelectrodes onto a single flexible thin-film device is introduced. When the device is unfurled, a pre-shaped shank of polyimide automatically comes off the substrate and forms the penetrating part of the device in a 3D fashion. With the advantage of being highly reproducible and batch-fabricated, the device introduced here allows for simultaneous recording of electrophysiological signals from both the brain surface (electrocorticography—ECoG) and depth (single neuron). Our device, therefore, has the potential to elucidate the roles of underlying neurons on the different components of µECoG signals. For in vivo validation of the design capabilities, the recording sites are coated with a poly(3,4-ethylenedioxythiophene)—polystyrene sulfonate—carbon nanotube composite, to improve the electrical conductivity of the

  9. Carbon Nanotube-based microelectrodes for enhanced detection of neurotransmitters

    Jacobs, Christopher B.

    Fast-scan cyclic voltammetry (FSCV) is one of the common techniques used for rapid measurement of neurotransmitters in vivo. Carbon-fiber microelectrodes (CFMEs) are typically used for neurotransmitter detection because of sub-second measurement capabilities, ability to measure changes in neurotransmitter concentration during neurotransmission, and the small size electrode diameter, which limits the amount of damage caused to tissue. Cylinder CFMEs, typically 50 -- 100 microm long, are commonly used for in vivo experiments because the electrode sensitivity is directly related to the electrode surface area. However the length of the electrode can limit the spatial resolution of neurotransmitter detection, which can restrict experiments in Drosophila and other small model systems. In addition, the electrode sensitivity toward dopamine and serotonin detection drops significantly for measurements at rates faster than 10 Hz, limiting the temporal resolution of CFMEs. While the use of FSCV at carbon-fiber microelectrodes has led to substantial strides in our understanding of neurotransmission, techniques that expand the capabilities of CFMEs are crucial to fully maximize the potential uses of FSCV. This dissertation introduces new methods to integrate carbon nanotubes (CNT) into microelectrodes and discusses the electrochemical enhancements of these CNT-microelectrodes. The electrodes are specifically designed with simple fabrication procedures so that highly specialized equipment is not necessary, and they utilize commercially available materials so that the electrodes could be easily integrated into existing systems. The electrochemical properties of CNT modified CFMEs are characterized using FSCV and the effect of CNT functionalization on these properties is explored in Chapter 2. For example, CFME modification using carboxylic acid functionalized CNTs yield about a 6-fold increase in dopamine oxidation current, but modification with octadecylamine CNTs results in a

  10. A hardware-algorithm co-design approach to optimize seizure detection algorithms for implantable applications.

    Raghunathan, Shriram; Gupta, Sumeet K; Markandeya, Himanshu S; Roy, Kaushik; Irazoqui, Pedro P

    2010-10-30

    Implantable neural prostheses that deliver focal electrical stimulation upon demand are rapidly emerging as an alternate therapy for roughly a third of the epileptic patient population that is medically refractory. Seizure detection algorithms enable feedback mechanisms to provide focally and temporally specific intervention. Real-time feasibility and computational complexity often limit most reported detection algorithms to implementations using computers for bedside monitoring or external devices communicating with the implanted electrodes. A comparison of algorithms based on detection efficacy does not present a complete picture of the feasibility of the algorithm with limited computational power, as is the case with most battery-powered applications. We present a two-dimensional design optimization approach that takes into account both detection efficacy and hardware cost in evaluating algorithms for their feasibility in an implantable application. Detection features are first compared for their ability to detect electrographic seizures from micro-electrode data recorded from kainate-treated rats. Circuit models are then used to estimate the dynamic and leakage power consumption of the compared features. A score is assigned based on detection efficacy and the hardware cost for each of the features, then plotted on a two-dimensional design space. An optimal combination of compared features is used to construct an algorithm that provides maximal detection efficacy per unit hardware cost. The methods presented in this paper would facilitate the development of a common platform to benchmark seizure detection algorithms for comparison and feasibility analysis in the next generation of implantable neuroprosthetic devices to treat epilepsy. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Nanoporous gold microelectrode prepared from potential modulated electrochemical alloying–dealloying in ionic liquid

    Jiang, Junhua; Wang, Xinying; Zhang, Lei

    2013-01-01

    Highlights: • A green chemistry method for producing nanoporous gold microelectrode was studied. • An ionic liquid plating bath was utilized for electrochemical alloying–dealloying. • Nanostructures of gold surface layers can be tuned by modulating potential. • Nanoporous gold microelectrode has high surface area and merit of a microelectrode. • Nitrite oxidation and reduction on nanoporous gold microelectrode were studied. -- Abstract: Nanoporous gold (NPG) microelectrodes with high surface area and open pore network were successfully prepared by applying modulated potential to a polycrystalline Au-disk microelectrode in ionic liquid electrolyte containing ZnCl 2 at elevated temperature. During cathodic process, Zn is electrodeposited and interacted with Au microdisk substrate to form a AuZn alloy phase. During subsequent anodic process, Zn is selectively dissolved from the alloy phase, leading to the formation of a NPG layer which can grow with repetitive potential modulation. Scanning-electron microscope and energy dispersive X-ray microscope measurements show that the NPG microelectrodes possessing nanoporous structures can be tuned via potential modulation, and chemically contain a small amount of Zn whose presence has no obvious influence on electrochemical responses of the electrodes. Steady-state and cyclic voltammetric studies suggest that the NPG microelectrodes have high surface area and keep diffusional properties of a microelectrode. Electrochemical nitrite reduction and oxidation are studied as model reactions to demonstrate potential applications of the NPG microelectrodes in electrocatalysis and electroanalysis. These facts suggest that the potential-modulated electrochemical alloying/dealloying in ionic liquid electrolyte offers a convenient green-chemistry method for the preparation of nanoporous microelectrodes

  12. Acute in vivo testing of a conformal polymer microelectrode array for multi-region hippocampal recordings

    Xu, Huijing; Weltman Hirschberg, Ahuva; Scholten, Kee; Berger, Theodore William; Song, Dong; Meng, Ellis

    2018-02-01

    Objective. The success of a cortical prosthetic device relies upon its ability to attain resolvable spikes from many neurons in particular neural networks over long periods of time. Traditionally, lifetimes of neural recordings are greatly limited by the body’s immune response against the foreign implant which causes neuronal death and glial scarring. This immune reaction is posited to be exacerbated by micromotion between the implant, which is often rigid, and the surrounding, soft brain tissue, and attenuates the quality of recordings over time. Approach. In an attempt to minimize the foreign body response to a penetrating neural array that records from multiple brain regions, Parylene C, a flexible, biocompatible polymer was used as the substrate material for a functional, proof-of-concept neural array with a reduced elastic modulus. This probe array was designed and fabricated to have 64 electrodes positioned to match the anatomy of the rat hippocampus and allow for simultaneous recordings between two cell-body layers of interest. A dissolvable brace was used for deep-brain penetration of the flexible array. Main results. Arrays were electrochemically characterized at the benchtop, and a novel insertion technique that restricts acute insertion injury enabled accurate target placement of four, bare, flexible arrays to greater than 4 mm deep into the rat brain. Arrays were tested acutely and in vivo recordings taken intra-operatively reveal spikes in both targeted regions of the hippocampus with spike amplitudes and noise levels similar to those recorded with microwires. Histological staining of a sham array implanted for one month reveals limited astrocytic scarring and neuronal death around the implant. Significance. This work represents one of the first examples of a penetrating polymer probe array that records from individual neurons in structures that lie deep within the brain.

  13. Brain Computer Interface Learning for Systems Based on Electrocorticography and Intracortical Microelectrode Arrays

    Shivayogi V Hiremath

    2015-06-01

    Full Text Available A brain-computer interface (BCI system transforms neural activity into control signals for external devices in real time. A BCI user needs to learn to generate specific cortical activity patterns to control external devices effectively. We call this process BCI learning, and it often requires significant effort and time. Therefore, it is important to study this process and develop novel and efficient approaches to accelerate BCI learning. This article reviews major approaches that have been used for BCI learning, including computer-assisted learning, co-adaptive learning, operant conditioning, and sensory feedback. We focus on BCIs based on electrocorticography and intracortical microelectrode arrays for restoring motor function. This article also explores the possibility of brain modulation techniques in promoting BCI learning, such as electrical cortical stimulation, transcranial magnetic stimulation, and optogenetics. Furthermore, as proposed by recent BCI studies, we suggest that BCI learning is in many ways analogous to motor and cognitive skill learning, and therefore skill learning should be a useful metaphor to model BCI learning.

  14. Brain computer interface learning for systems based on electrocorticography and intracortical microelectrode arrays.

    Hiremath, Shivayogi V; Chen, Weidong; Wang, Wei; Foldes, Stephen; Yang, Ying; Tyler-Kabara, Elizabeth C; Collinger, Jennifer L; Boninger, Michael L

    2015-01-01

    A brain-computer interface (BCI) system transforms neural activity into control signals for external devices in real time. A BCI user needs to learn to generate specific cortical activity patterns to control external devices effectively. We call this process BCI learning, and it often requires significant effort and time. Therefore, it is important to study this process and develop novel and efficient approaches to accelerate BCI learning. This article reviews major approaches that have been used for BCI learning, including computer-assisted learning, co-adaptive learning, operant conditioning, and sensory feedback. We focus on BCIs based on electrocorticography and intracortical microelectrode arrays for restoring motor function. This article also explores the possibility of brain modulation techniques in promoting BCI learning, such as electrical cortical stimulation, transcranial magnetic stimulation, and optogenetics. Furthermore, as proposed by recent BCI studies, we suggest that BCI learning is in many ways analogous to motor and cognitive skill learning, and therefore skill learning should be a useful metaphor to model BCI learning.

  15. Nanostructured gold microelectrodes for extracellular recording from electrogenic cells

    Brueggemann, D; Wolfrum, B; Maybeck, V; Mourzina, Y; Jansen, M; Offenhaeusser, A, E-mail: a.offenhaeusser@fz-juelich.de [Institute of Complex Systems and Peter Gruenberg Institute: Bioelectronics (ICS8/PGI8), Forschungszentrum Juelich GmbH, Leo-Brandt-Strasse, 52428 Juelich (Germany); Juelich-Aachen Research Alliance-Fundamental of Future Information Technology (JARA-FIT) (Germany)

    2011-07-01

    We present a new biocompatible nanostructured microelectrode array for extracellular signal recording from electrogenic cells. Microfabrication techniques were combined with a template-assisted approach using nanoporous aluminum oxide to develop gold nanopillar electrodes. The nanopillars were approximately 300-400 nm high and had a diameter of 60 nm. Thus, they yielded a higher surface area of the electrodes resulting in a decreased impedance compared to planar electrodes. The interaction between the large-scale gold nanopillar arrays and cardiac muscle cells (HL-1) was investigated via focused ion beam milling. In the resulting cross-sections we observed a tight coupling between the HL-1 cells and the gold nanostructures. However, the cell membranes did not bend into the cleft between adjacent nanopillars due to the high pillar density. We performed extracellular potential recordings from HL-1 cells with the nanostructured microelectrode arrays. The maximal amplitudes recorded with the nanopillar electrodes were up to 100% higher than those recorded with planar gold electrodes. Increasing the aspect ratio of the gold nanopillars and changing the geometrical layout can further enhance the signal quality in the future.

  16. A Single Platinum Microelectrode for Identifying Soft Drink Samples

    Lígia Bueno

    2012-01-01

    Full Text Available Cyclic voltammograms recorded with a single platinum microelectrode were used along with a non-supervised pattern recognition, namely, Principal Component Analysis, to conduct a qualitative analysis of sixteen different brands of carbonated soft drinks (Kuat, Soda Antarctica, H2OH!, Sprite 2.0, Guarana Antarctica, Guarana Antarctica Zero, Coca-Cola, Coca-Cola Zero, Coca-Cola Plus, Pepsi, Pepsi Light, Pepsi Twist, Pepsi Twist Light, Pepsi Twist 3, Schin Cola, and Classic Dillar’s. In this analysis, soft drink samples were not subjected to pre-treatment. Good differentiation among all the analysed soft drinks was achieved using the voltammetric data. An analysis of the loading plots shows that the potentials of −0.65 V, −0.4 V, 0.4 V, and 0.750 V facilitated the discrimination process. The electrochemical processes related to this potential are the reduction of hydrogen ions and inhibition of the platinum oxidation by the caffeine adsorption on the electrode surface. Additionally, the single platinum microelectrode was useful for the quality control of the soft drink samples, as it helped to identify the time at which the beverage was opened.

  17. Nanostructured gold microelectrodes for extracellular recording from electrogenic cells.

    Brüggemann, D; Wolfrum, B; Maybeck, V; Mourzina, Y; Jansen, M; Offenhäusser, A

    2011-07-01

    We present a new biocompatible nanostructured microelectrode array for extracellular signal recording from electrogenic cells. Microfabrication techniques were combined with a template-assisted approach using nanoporous aluminum oxide to develop gold nanopillar electrodes. The nanopillars were approximately 300-400 nm high and had a diameter of 60 nm. Thus, they yielded a higher surface area of the electrodes resulting in a decreased impedance compared to planar electrodes. The interaction between the large-scale gold nanopillar arrays and cardiac muscle cells (HL-1) was investigated via focused ion beam milling. In the resulting cross-sections we observed a tight coupling between the HL-1 cells and the gold nanostructures. However, the cell membranes did not bend into the cleft between adjacent nanopillars due to the high pillar density. We performed extracellular potential recordings from HL-1 cells with the nanostructured microelectrode arrays. The maximal amplitudes recorded with the nanopillar electrodes were up to 100% higher than those recorded with planar gold electrodes. Increasing the aspect ratio of the gold nanopillars and changing the geometrical layout can further enhance the signal quality in the future.

  18. ORGANIC ELECTRODE COATINGS FOR NEXT-GENERATION NEURAL INTERFACES

    Ulises A Aregueta-Robles

    2014-05-01

    Full Text Available Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes.

  19. Ion implantation

    Dearnaley, Geoffrey

    1975-01-01

    First, ion implantation in semiconductors is discussed: ion penetration, annealing of damage, gettering, ion implanted semiconductor devices, equipement requirements for ion implantation. The importance of channeling for ion implantation is studied. Then, some applications of ion implantation in metals are presented: study of the corrosion of metals and alloys; influence or ion implantation on the surface-friction and wear properties of metals; hyperfine interactions in implanted metals

  20. Experiments on pumping of liquids using arrays of microelectrodes subjected to travelling wave potentials

    Garcia-Sanchez, P; Ramos, A [Dpto. de Electronica y Electromagnetismo, Universidad de Sevilla, 41012 Sevilla (Spain); Green, Nicolas G; Morgan, H [School of Electronics and Computer Science, University of Southampton, SO17 1BJ Southampton (United Kingdom)], E-mail: pablogarcia@us.es

    2008-12-01

    Net fluid flow of electrolytes driven on an array of microelectrodes subjected to a travelling-wave potential is presented. Two sizes of platinum microelectrodes have been studied. In both arrays, at low voltages the liquid flows according to the prediction given by ac electroosmotic theory. At voltages above a threshold the fluid flow is reversed. Measurements of the electrical current when the microelectrode array is pumping the liquid are also reported. Transient behaviours in both electrical current and fluid velocity have been observed.

  1. Experiments on pumping of liquids using arrays of microelectrodes subjected to travelling wave potentials

    Garcia-Sanchez, P; Ramos, A; Green, Nicolas G; Morgan, H

    2008-01-01

    Net fluid flow of electrolytes driven on an array of microelectrodes subjected to a travelling-wave potential is presented. Two sizes of platinum microelectrodes have been studied. In both arrays, at low voltages the liquid flows according to the prediction given by ac electroosmotic theory. At voltages above a threshold the fluid flow is reversed. Measurements of the electrical current when the microelectrode array is pumping the liquid are also reported. Transient behaviours in both electrical current and fluid velocity have been observed.

  2. Micro-fabrication of three dimensional pyrolysed carbon microelectrodes

    2017-01-01

    ; soft baking the photoresist layer; performing a full depth exposure with UV light through a first mask; performing a partial depth exposure with UV light through a second mask; wherein the full depth exposure and the partial depth exposure are aligned to ensure that the first and second latent images...... are connected to each other; post-exposure baking the photoresist layer; and developing the microscale patterned resist template as a free-standing structure of cross-linked resist with lateral hanging structures that are supported by vertical support structures at a free height above the substrate. The method...... is characterized by a soft baking temperature below 70 °C. Repetitive coating and partial depth exposure allows for the fabrication of multiple level laterally interconnected structures. Carbonization of the resist template provides truly three-dimensional carbon microelectrode structures....

  3. Thin film microelectrodes for electrochemical detection of neurotransmitters

    Larsen, Simon Tylsgaard

    An important signaling process in the nervous system is the release of chemical messengers called neurotransmitters from neurons. In this thesis alternative thin film electrode materials for applications targeting electrochemical detection of neurotransmitters in chip devices were evaluated...... and conductive polymer microelectrodes made of Pedot:Pss were also fabricated and used successfully to measure transmitter release from cells. The use of different thin film electrodes for low-noise amperometric measurements of single events of transmitter release from neuronal cells was studied....... For this application a very low current noise is needed together with a large temporal resolution. It was shown, that resistive and capacitive properties of thin film electrode materials are determining their usefulness in low-noise amperometric measurements. An analytical expression for the noise was derived...

  4. A 3-D Microelectrode System for Dielectrophoretic Manipulation of Microparticles

    Chen, D F; Du, H; Gong, H Q; Li, W H

    2006-01-01

    This paper presents a microfluidic system for manipulation and separation of micron-sized particles based on the combined use of negative dielectrophoresis (DEP) and hydrodynamic forces. A 3-D microelectrode structure (so called paired electrode array) are constructed face to face on the top and bottom sides of the microchannel and driven with highfrequency AC voltage to generate dielectrophoretic gates. Depending on the relative strengths of the two forces, particles such as polystyrene beads or cells carrying by a laminar flow can either penetrate the gate or settle there. This gives rise to certain applications including selectively concentrating particles from the flow, separating particles depending on their sizes or dielectric properties, and automatically positioning particles to selective locations. For this purpose, a microfluidic device consisting of the paired electrode array sitting on the channel has been fabricated using microfabrication techniques. Polystyrene beads were used to study the performance of the device. Experimental results including the concentration and separation of particles are presented

  5. Potential for thermal damage to the blood–brain barrier during craniotomy: implications for intracortical recording microelectrodes

    Shoffstall, Andrew J.; Paiz, Jen E.; Miller, David M.; Rial, Griffin M.; Willis, Mitchell T.; Menendez, Dhariyat M.; Hostler, Stephen R.; Capadona, Jeffrey R.

    2018-06-01

    Objective. Our objective was to determine how readily disruption of the blood–brain barrier (BBB) occurred as a result of bone drilling during a craniotomy to implant microelectrodes in rat cortex. While the phenomenon of heat production during bone drilling is well known, practices to evade damage to the underlying brain tissue are inconsistently practiced and reported in the literature. Approach. We conducted a review of the intracortical microelectrode literature to summarize typical approaches to mitigate drill heating during rodent craniotomies. Post mortem skull-surface and transient brain-surface temperatures were experimentally recorded using an infrared camera and thermocouple, respectively. A number of drilling conditions were tested, including varying drill speed and continuous versus intermittent contact. In vivo BBB permeability was assayed 1 h after the craniotomy procedure using Evans blue dye. Main results. Of the reviewed papers that mentioned methods to mitigate thermal damage during craniotomy, saline irrigation was the most frequently cited (in six of seven papers). In post mortem tissues, we observed increases in skull-surface temperature ranging from  +3 °C to  +21 °C, dependent on drill speed. In vivo, pulsed-drilling (2 s-on/2 s-off) and slow-drilling speeds (1000 r.p.m.) were the most effective methods we studied to mitigate heating effects from drilling, while inconclusive results were obtained with saline irrigation. Significance. Neuroinflammation, initiated by damage to the BBB and perpetuated by the foreign body response, is thought to play a key role in premature failure of intracortical recording microelectrodes. This study demonstrates the extreme sensitivity of the BBB to overheating caused by bone drilling. To avoid damage to the BBB, the authors recommend that craniotomies be drilled with slow speeds and/or with intermittent drilling with complete removal of the drill from the skull during ‘off’ periods. While

  6. A three-dimensional microelectrode array composed of vertically aligned ultra-dense carbon nanotube networks

    Nick, C.; Yadav, S.; Joshi, R.; Schneider, J. J.; Thielemann, C.

    2015-07-01

    Electrodes based on carbon nanotubes are a promising approach to manufacture highly sensitive sensors with a low limit of signal detection and a high signal-to-noise ratio. This is achieved by dramatically increasing the electrochemical active surface area without increasing the overall geometrical dimensions. Typically, carbon nanotube electrodes are nearly planar and composed of randomly distributed carbon nanotube networks having a limited surface gain for a specific geometrical surface area. To overcome this limitation, we have introduced vertically aligned carbon nanotube (VACNT) networks as electrodes, which are arranged in a microelectrode pattern of 60 single electrodes. Each microelectrode features a very high aspect ratio of more than 300 and thus a dramatically increased surface area. These microelectrodes composed of VACNT networks display dramatically decreased impedance over the entire frequency range compared to planar microelectrodes caused by the enormous capacity increase. This is experimentally verified by electrochemical impedance spectroscopy and cyclic voltammetry.

  7. Low Frequency Activity of Cortical Networks on Microelectrode Arrays is Differentially Altered by Bicuculline and Carbaryl

    Thousands of chemicals need to be characterized for their neurotoxicity potential. Neurons grown on microelectrode arrays (MEAs) are an in vitro model used to screen chemicals for functional effects on neuronal networks. Typically, after removal of low frequency components, effec...

  8. Conductive Polymer Microelectrodes for on-chip measurement of transmitter release from living cells

    Larsen, Simon Tylsgaard; Matteucci, Marco; Taboryski, Rafael J.

    2012-01-01

    driven cell trapping inside closed chip devices. Conductive polymer microelectrodes were used to measure transmitter release using electrochemical methods such as cyclic voltammetry and constant potential amperometry. By measuring the oxidation current at a cyclic voltammogram, the concentration...

  9. A microfluidic cell culture device with integrated microelectrodes for barrier studies

    Tan, Hsih-Yin; Dufva, Martin; Kutter, Jörg P.

    We present an eight cell culture microfluidic device fabricated using thiol-ene ‘click’ chemistry with embedded microelectrodes for evaluating barrier properties of human intestinal epithelial cells. The capability of the microelectrodes for trans-epithelial electrical resistance (TEER) measureme......) measurements was demonstrated by using confluent human colorectal epithelial cells (Caco-2) and rat fibroblast (CT 26) cells cultured in the microfluidic device....

  10. Power Conditioning and Stimulation for Wireless Neural Interface ICs

    Biederman, William

    2014-01-01

    Brain machine interfaces have the potential to revolutionize our understanding of the brain, restore motor function, and improve the quality of life to patients with neurological con- ditions. In recent human trials, control of robotic prostheses has been demonstrated using micro-electrode arrays, which provide high spatio-temporal resolution and an electrical feed- back path to the brain. However, after implantation, scar tissue degrades the recording signal-to-noise ratio and limits the use...

  11. Implantable optical-electrode device for stimulation of spinal motoneurons

    Matveev, M V; Erofeev, A I; Zakharova, O A; Vlasova, O L; Pyatyshev, E N; Kazakin, A N

    2016-01-01

    Recent years, optogenetic method of scientific research has proved its effectiveness in the nerve cell stimulation tasks. In our article we demonstrate an implanted device for the spinal optogenetic motoneurons activation. This work is carried out in the Laboratory of Molecular Neurodegeneration of the Peter the Great St. Petersburg Polytechnic University, together with Nano and Microsystem Technology Laboratory. The work of the developed device is based on the principle of combining fiber optic light stimulation of genetically modified cells with the microelectrode multichannel recording of neurons biopotentials. The paper presents a part of the electrode implant manufacturing technique, combined with the optical waveguide of ThorLabs (USA). (paper)

  12. Carbon-Ring Microelectrode Arrays for Electrochemical Imaging of Single Cell Exocytosis: Fabrication and Characterization

    Lin, Yuqing; Trouillon, Raphaël; Svensson, Maria I.; Keighron, Jacqueline D.; Cans, Ann-Sofie; Ewing, Andrew G.

    2012-01-01

    Fabrication of carbon microelectrode arrays, with up to 15 electrodes in total tips as small as 10 to 50 μm, is presented. The support structures of microelectrodes were obtained by pulling multiple quartz capillaries together to form hollow capillary arrays before carbon deposition. Carbon ring microelectrodes were deposited by pyrolysis of acetylene in the lumen of these quartz capillary arrays. Each carbon deposited array tip was filled with epoxy, followed by beveling of the tip of the array to form a deposited carbon-ring microelectrode array (CRMA). Both the number of the microelectrodes in the array and the tip size are independently tunable. These CRMAs have been characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, and electrogenerated chemiluminescence. Additionally, the electrochemical properties were investigated with steady-state voltammetry. In order to demonstrate the utility of these fabricated microelectrodes in neurochemistry, CRMAs containing eight microring electrodes were used for electrochemical monitoring of exocytotic events from single PC12 cells. Subcellular temporal heterogeneities in exocytosis (ie. cold spots vs. hot spots) were successfully detected with the CRMAs. PMID:22339586

  13. Cell culture chamber with gas supply for prolonged recording of human neuronal cells on microelectrode array.

    Kreutzer, Joose; Ylä-Outinen, Laura; Mäki, Antti-Juhana; Ristola, Mervi; Narkilahti, Susanna; Kallio, Pasi

    2017-03-15

    Typically, live cell analyses are performed outside an incubator in an ambient air, where the lack of sufficient CO 2 supply results in a fast change of pH and the high evaporation causes concentration drifts in the culture medium. That limits the experiment time for tens of minutes. In many applications, e.g. in neurotoxicity studies, a prolonged measurement of extracellular activity is, however, essential. We demonstrate a simple cell culture chamber that enables stable culture conditions during prolonged extracellular recordings on a microelectrode array (MEA) outside an incubator. The proposed chamber consists of a gas permeable silicone structure that enables gas transfer into the chamber. We show that the culture chamber supports the growth of the human embryonic stem cell (hESC)-derived neurons both inside and outside an incubator. The structure provides very low evaporation, stable pH and osmolarity, and maintains strong signaling of hESC-derived neuronal networks over three-day MEA experiments. Existing systems are typically complex including continuous perfusion of medium or relatively large amount of gas to supply. The proposed chamber requires only a supply of very low flow rate (1.5ml/min) of non-humidified 5% CO 2 gas. Utilizing dry gas supply makes the proposed chamber simple to use. Using the proposed culture structure on top of MEA, we can maintain hESC-derived neural networks over three days outside an incubator. Technically, the structure requires very low flow rate of dry gas supporting, however, low evaporation and maintaining the pH of the culture. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. A review of organic and inorganic biomaterials for neural interfaces.

    Fattahi, Pouria; Yang, Guang; Kim, Gloria; Abidian, Mohammad Reza

    2014-03-26

    Recent advances in nanotechnology have generated wide interest in applying nanomaterials for neural prostheses. An ideal neural interface should create seamless integration into the nervous system and performs reliably for long periods of time. As a result, many nanoscale materials not originally developed for neural interfaces become attractive candidates to detect neural signals and stimulate neurons. In this comprehensive review, an overview of state-of-the-art microelectrode technologies provided fi rst, with focus on the material properties of these microdevices. The advancements in electro active nanomaterials are then reviewed, including conducting polymers, carbon nanotubes, graphene, silicon nanowires, and hybrid organic-inorganic nanomaterials, for neural recording, stimulation, and growth. Finally, technical and scientific challenges are discussed regarding biocompatibility, mechanical mismatch, and electrical properties faced by these nanomaterials for the development of long-lasting functional neural interfaces.

  15. Applying a foil queue micro-electrode in micro-EDM to fabricate a 3D micro-structure

    Xu, Bin; Guo, Kang; Wu, Xiao-yu; Lei, Jian-guo; Liang, Xiong; Guo, Deng-ji; Ma, Jiang; Cheng, Rong

    2018-05-01

    Applying a 3D micro-electrode in a micro electrical discharge machining (micro-EDM) can fabricate a 3D micro-structure with an up and down reciprocating method. However, this processing method has some shortcomings, such as a low success rate and a complex process for fabrication of 3D micro-electrodes. By focusing on these shortcomings, this paper proposed a novel 3D micro-EDM process based on the foil queue micro-electrode. Firstly, a 3D micro-electrode was discretized into several foil micro-electrodes and these foil micro-electrodes constituted a foil queue micro-electrode. Then, based on the planned process path, foil micro-electrodes were applied in micro-EDM sequentially and the micro-EDM results of each foil micro-electrode were able to superimpose the 3D micro-structure. However, the step effect will occur on the 3D micro-structure surface, which has an adverse effect on the 3D micro-structure. To tackle this problem, this paper proposes to reduce this adverse effect by rounded corner wear at the end of the foil micro-electrode and studies the impact of machining parameters on rounded corner wear and the step effect on the micro-structure surface. Finally, using a wire cutting voltage of 80 V, a current of 0.5 A and a pulse width modulation ratio of 1:4, the foil queue micro-electrode was fabricated by wire electrical discharge machining. Also, using a pulse width of 100 ns, a pulse interval of 200 ns, a voltage of 100 V and workpiece material of 304# stainless steel, the foil queue micro-electrode was applied in micro-EDM for processing of a 3D micro-structure with hemispherical features, which verified the feasibility of this process.

  16. Investigating brain functional evolution and plasticity using microelectrode array technology.

    Napoli, Alessandro; Obeid, Iyad

    2015-10-01

    The aim of this work was to investigate long and short-term plasticity responsible for memory formation in dissociated neuronal networks. In order to address this issue, a set of experiments was designed and implemented in which the microelectrode array electrode grid was divided into four quadrants, two of which were chronically stimulated, every two days for one hour with a stimulation paradigm that varied over time. Overall network and quadrant responses were then analyzed to quantify what level of plasticity took place in the network and how this was due to the stimulation interruption. The results demonstrate that there were no spatial differences in the stimulus-evoked activity within quadrants. Furthermore, the implemented stimulation protocol induced depression effects in the neuronal networks as demonstrated by the consistently lower network activity following stimulation sessions. Finally, the analysis demonstrated that the inhibitory effects of the stimulation decreased over time, thus suggesting a habituation phenomenon. These findings are sufficient to conclude that electrical stimulation is an important tool to interact with dissociated neuronal cultures, but localized stimuli are not enough to drive spatial synaptic potentiation or depression. On the contrary, the ability to modulate synaptic temporal plasticity was a feasible task to achieve by chronic network stimulation. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Study of the Behavior of the Mercury on Diverse Microelectrodes with Cell of Continuous Flow

    Cruz Valldeperas, F

    2001-01-01

    A comparative study of six types of microelectrodes in two different support electrolytes was developed using a new analytic technique for analysis of mercury in liquid samples in the ambit of parts by million. For it, a new system of cell of continuous flow and platinum microelectrodes and of platinum with gold film was implemented using volt-amperemetry of anodized spoil with square wave. In a preliminary study, some parameters that characterize the analysis with this new cell were optimized, for example the sample's speed flow and the time of electrodeposition. The calibration curves were made for the different types of microelectrode that were used in an ambit of concentrations of 1-10 ppm. According to the obtained results, the microelectrode that better works is the platinum disk for possessing bigger superficial area exposed to the dissolution, which increases the analite's currents of pick. And as a support electrolyte, potassium tiocianato is recommended because of its effectiveness to solve the analytic sign of the mercury. Studies of answer of the current of mercury regarding the quantity of the placed sample and studies of interferences of the analysis with this type of microelectrode were also carried out. With regard to the study of the quantity of sample, it was obtained that the electrochemical answer of the cell is directly proportional to the concentration of the analite placed in it. In the study of interference, it was found that the copper, lead, and zinc ions affect the analysis of mercury in concentrations of 0.1 ppm and on in the case of the microelectrode of platinum disk. And in case that the same microelectrode is used recovered with gold, it only affects the copper in concentrations over 5 ppm, for what is necessary to take into account a previous treatment of the sample in the event of containing some of the interfering ions [es

  18. Effective long-term immunosuppression in rats by subcutaneously implanted sustained-release tacrolimus pellet: Effect on spinally grafted human neural precursor survival

    Ševc, J.; Goldberg, D.; van Gorp, S.; Leerink, M.; Juhás, Štefan; Juhásová, Jana; Marsala, S.; Hruška-Plocháň, Marian; Hefferan, M. P.; Motlík, Jan; Rypáček, František; Machová, Luďka; Kakinohana, O.; Santucci, C.; Johe, K.; Lukáčová, N.; Yamada, K.; Bui, J. D.; Marsala, M.

    2013-01-01

    Roč. 248, October (2013), s. 85-99 ISSN 0014-4886 R&D Projects: GA TA ČR TA01011466; GA MŠk ED2.1.00/03.0124 Institutional support: RVO:67985904 ; RVO:61389013 Keywords : immunosuppression * xenograft * human neural precursors Subject RIV: FH - Neurology; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.617, year: 2013

  19. [Positions of the implanted stimulating electrodes for artificial facial nerve for inducing contraction of the orbicularis oris muscle in rabbit with peripheral facial paralysis].

    Xu, D Y; Zhao, N J; Zhao, Y X; Luo, D; Sun, Y J; Li, K Y

    2017-11-07

    Objective: To explore the optimal positions of the implanted stimulating eletrodes for artificial facial nerve (AFN) for inducing contraction of the orbicularis oris muscle (OOM) in rabbit with peripheral facial paralysis. Methods: According to the four microelectrodes of the AFN stimulating side, four modes of the implanted positions were divided. In line with different modes, the electrodes were implanted into the affected OOM of the rabbits with unilateral peripheral facial paralysis. AFN output electric stimulation to induce contraction of the affected OOM with uniform stimulating frequency and pulse length in vitro. Then compared the stimulus threshold amplitude and the peak amplitude separately among different modes by SAS 9.3 version statistical software. Results: The differences of the stimulus threshold amplitude and the peak amplitude had no statistically significant separately between the first mode and the second mode ( P >0.05), but there were statistically significant differences between the third mode and the fourth mode ( P <0.05). Both kinds of the amplitudes were approximated between the first mode and the second mode respectively, and higher than those in the third mode or the fourth mode. Furthermore, both kinds of the amplitudes in the fourth mode were higher than those in the third mode. Conclusions: The microelectrodes of the AFN stimulating lateral are implanted into the upper lip with a public microelectrode and an output microelectrode, into the lower lip with an output microelectrode, and into the way, which is located to the angle 40° to 45° about the line joining between the midpoint of the ipsilateral auricle root and the corner of the mouth with an output microelectrode. This is the third positional mode which requires lowest effective stimulus current intensity. Thus the mode is suitable as the optimal placement programme.

  20. Chitosan coated carbon fiber microelectrode for selective in vivo detection of neurotransmitters in live zebrafish embryos

    Ozel, Rifat Emrah; Wallace, Kenneth N.; Andreescu, Silvana

    2011-01-01

    Graphical abstract: Chitosan coated fiber electrodes are sensitive to serotonin detection while rejecting physiological levels of ascorbic acid interferences. - Abstract: We report the development of a chitosan modified carbon fiber microelectrode for in vivo detection of serotonin. We find that chitosan has the ability to reject physiological levels of ascorbic acid interferences and facilitate selective and sensitive detection of in vivo levels of serotonin, a common catecholamine neurotransmitter. Presence of chitosan on the microelectrode surface was investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrode was characterized using differential pulse voltammetry (DPV). A detection limit of 1.6 nM serotonin with a sensitivity of 5.12 nA/μM, a linear range from 2 to 100 nM and a reproducibility of 6.5% for n = 6 electrodes were obtained. Chitosan modified microelectrodes selectively measure serotonin in presence of physiological levels of ascorbic acid. In vivo measurements were performed to measure concentration of serotonin in the live embryonic zebrafish intestine. The sensor quantifies in vivo intestinal levels of serotonin while successfully rejecting ascorbic acid interferences. We demonstrate that chitosan can be used as an effective coating to reject ascorbic acid interferences at carbon fiber microelectrodes, as an alternative to Nafion, and that chitosan modified microelectrodes are reliable tools for in vivo monitoring of changes in neurotransmitter levels.

  1. Chitosan coated carbon fiber microelectrode for selective in vivo detection of neurotransmitters in live zebrafish embryos

    Ozel, Rifat Emrah [Department of Chemistry and Biomolecular Science, 8 Clarkson Ave, Potsdam, NY 136995810 (United States); Wallace, Kenneth N. [Department of Biology, Clarkson University, Potsdam, NY 136995810 (United States); Andreescu, Silvana, E-mail: eandrees@clarkson.edu [Department of Chemistry and Biomolecular Science, 8 Clarkson Ave, Potsdam, NY 136995810 (United States)

    2011-06-10

    Graphical abstract: Chitosan coated fiber electrodes are sensitive to serotonin detection while rejecting physiological levels of ascorbic acid interferences. - Abstract: We report the development of a chitosan modified carbon fiber microelectrode for in vivo detection of serotonin. We find that chitosan has the ability to reject physiological levels of ascorbic acid interferences and facilitate selective and sensitive detection of in vivo levels of serotonin, a common catecholamine neurotransmitter. Presence of chitosan on the microelectrode surface was investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrode was characterized using differential pulse voltammetry (DPV). A detection limit of 1.6 nM serotonin with a sensitivity of 5.12 nA/{mu}M, a linear range from 2 to 100 nM and a reproducibility of 6.5% for n = 6 electrodes were obtained. Chitosan modified microelectrodes selectively measure serotonin in presence of physiological levels of ascorbic acid. In vivo measurements were performed to measure concentration of serotonin in the live embryonic zebrafish intestine. The sensor quantifies in vivo intestinal levels of serotonin while successfully rejecting ascorbic acid interferences. We demonstrate that chitosan can be used as an effective coating to reject ascorbic acid interferences at carbon fiber microelectrodes, as an alternative to Nafion, and that chitosan modified microelectrodes are reliable tools for in vivo monitoring of changes in neurotransmitter levels.

  2. Preparation of metal nanoband microelectrode on poly(dimethylsiloxane) for chip-based amperometric detection

    Chen Shaopeng; Wu Jian; Yu Xiaodong [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Xu Jingjuan, E-mail: xujj@nju.edu.cn [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen Hongyuan [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2010-04-30

    We proposed herein a novel approach for fabricating nanoband microelectrodes for electrochemical detection on an electrophoresis microchip. The metal films were first obtained via region-selective electroless deposition of gold or copper films on PDMS substrates by selective region plasma oxidation through shadow masking. Both metal films show uniform surfaces with the thickness at the level of 100 nm. By casting another PDMS layer on the metal films, the cross section of the sandwich structures can be used as nanoband microelectrodes, which can be renewed just by cutting. These nanoband microelectrodes are successfully used as electrochemical detectors in microchip electrophoresis for the detection of amino acids, proteins and neurotransmitter molecules. Moreover, integrating an Au-Cu double-metal detector with a double-channel electrophoresis system, we can easily distinguish electroactive amino acids from that of non-electroactive amino acids.

  3. Chronic microelectrode investigations of normal human brain physiology using a hybrid depth electrode.

    Howard, M A; Volkov, I O; Noh, M D; Granner, M A; Mirsky, R; Garell, P C

    1997-01-01

    Neurosurgeons have unique access to in vivo human brain tissue, and in the course of clinical treatment important scientific advances have been made that further our understanding of normal brain physiology. In the modern era, microelectrode recordings have been used to systematically investigate the cellular properties of lateral temporal cerebral cortex. The current report describes a hybrid depth electrode (HDE) recording technique that was developed to enable neurosurgeons to simultaneously investigate normal cellular physiology during chronic intracranial EEG recordings. The HDE combines microelectrode and EEG recordings sites on a single shaft. Multiple microelectrode recordings are obtained from MRI defined brain sites and single-unit activity is discriminated from these data. To date, over 60 HDEs have been placed in 20 epilepsy surgery patients. Unique physiologic data have been gathered from neurons in numerous brain regions, including amygdala, hippocampus, frontal lobe, insula and Heschl's gyrus. Functional activation studies were carried out without risking patient safety or comfort.

  4. Cochlear Implants

    ... implant, including: • How long a person has been deaf, •The number of surviving auditory nerve fibers, and • ... Implant, Severe Sensoryneurial Hearing Loss Get Involved Professional Development Practice Management ENT Careers Marketplace Privacy Policy Terms ...

  5. Strain response of stretchable micro-electrodes: Controlling sensitivity with serpentine designs and encapsulation

    Gutruf, Philipp; Walia, Sumeet; Nur Ali, Md; Sriram, Sharath; Bhaskaran, Madhu

    2014-01-01

    The functionality of flexible electronics relies on stable performance of thin film micro-electrodes. This letter investigates the behavior of gold thin films on polyimide, a prevalent combination in flexible devices. The dynamic behavior of gold micro-electrodes has been studied by subjecting them to stress while monitoring their resistance in situ. The shape of the electrodes was systematically varied to examine resistive strain sensitivity, while an additional encapsulation was applied to characterize multilayer behavior. The realized designs show remarkable tolerance to repetitive strain, demonstrating that curvature and encapsulation are excellent approaches for minimizing resistive strain sensitivity to enable durable flexible electronics

  6. Fast prototyping of conducting polymer microelectrodes using resistance-controlled high precision drilling

    Kafka, Jan Robert; Geschke, Oliver; Skaarup, Steen

    2011-01-01

    We present a straightforward method for fast prototyping of microelectrode arrays in the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Microelectrode arrays were produced by electrical resistance-controlled microdrilling through an insulating polymer layer (TOPAS® 5013...... approach the steady state currents predicted from modeling, but at a much slower rate than expected. This is shown to be caused by the use of electroactive PEDOT electrodes. Subtraction of the latter contribution gives approach to steady state currents within a few seconds, which is in very good agreement...

  7. Microelectrode for energy and current control of nanotip field electron emitters

    Lüneburg, S.; Müller, M.; Paarmann, A.; Ernstorfer, R.

    2013-01-01

    Emerging experiments and applications in electron microscopy, holography, and diffraction benefit from miniaturized electron guns for compact experimental setups. We present a highly compact microelectrode integrated field emitter that consists of a tungsten nanotip coated with a few micrometers thick polyimide film followed by a several nanometers thick gold film, both positioned behind the exposed emitter apex by approximately 10–30 μm. The control of the electric field strength at the nanometer scale tip apex allows suppression, extraction, and energy tuning of field-emitted electrons. The performance of the microelectrode is demonstrated experimentally and supported by numerical simulations

  8. Reach and grasp by people with tetraplegia using a neurally controlled robotic arm

    Hochberg, Leigh R.; Bacher, Daniel; Jarosiewicz, Beata; Masse, Nicolas Y.; Simeral, John D.; Vogel, Joern; Haddadin, Sami; Liu, Jie; Cash, Sydney S.; van der Smagt, Patrick; Donoghue, John P.

    2012-01-01

    Paralysis following spinal cord injury (SCI), brainstem stroke, amyotrophic lateral sclerosis (ALS) and other disorders can disconnect the brain from the body, eliminating the ability to carry out volitional movements. A neural interface system (NIS)1–5 could restore mobility and independence for people with paralysis by translating neuronal activity directly into control signals for assistive devices. We have previously shown that people with longstanding tetraplegia can use an NIS to move and click a computer cursor and to control physical devices6–8. Able-bodied monkeys have used an NIS to control a robotic arm9, but it is unknown whether people with profound upper extremity paralysis or limb loss could use cortical neuronal ensemble signals to direct useful arm actions. Here, we demonstrate the ability of two people with long-standing tetraplegia to use NIS-based control of a robotic arm to perform three-dimensional reach and grasp movements. Participants controlled the arm over a broad space without explicit training, using signals decoded from a small, local population of motor cortex (MI) neurons recorded from a 96-channel microelectrode array. One of the study participants, implanted with the sensor five years earlier, also used a robotic arm to drink coffee from a bottle. While robotic reach and grasp actions were not as fast or accurate as those of an able-bodied person, our results demonstrate the feasibility for people with tetraplegia, years after CNS injury, to recreate useful multidimensional control of complex devices directly from a small sample of neural signals. PMID:22596161

  9. Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

    Tedesco, Mariateresa; Frega, Monica; Martinoia, Sergio; Pesce, Mattia; Massobrio, Paolo

    2015-01-01

    Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the gold-standard experimental model to study basic neurophysiological mechanisms involved in the formation and maintenance of neuronal cell assemblies. However, in vitro studies have been limited to the recording of the electrophysiological activity generated by bi-dimensional (2D) neural networks. Nonetheless, given the intricate relationship between structure and dynamics, a significant improvement is necessary to investigate the formation and the developing dynamics of three-dimensional (3D) networks. In this work, a novel experimental platform in which 3D hippocampal or cortical networks are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are realized by seeding neurons in a scaffold constituted of glass microbeads (30-40 µm in diameter) on which neurons are able to grow and form complex interconnected 3D assemblies. In this way, it is possible to design engineered 3D networks made up of 5-8 layers with an expected final cell density. The increasing complexity in the morphological organization of the 3D assembly induces an enhancement of the electrophysiological patterns displayed by this type of networks. Compared with the standard 2D networks, where highly stereotyped bursting activity emerges, the 3D structure alters the bursting activity in terms of duration and frequency, as well as it allows observation of more random spiking activity. In this sense, the developed 3D model more closely resembles in vivo neural networks. PMID:26554533

  10. Selective wetting-induced micro-electrode patterning for flexible micro-supercapacitors.

    Kim, Sung-Kon; Koo, Hyung-Jun; Lee, Aeri; Braun, Paul V

    2014-08-13

    Selective wetting-induced micro-electrode patterning is used to fabricate flexible micro-supercapacitors (mSCs). The resulting mSCs exhibit high performance, mechanical stability, stable cycle life, and hold great promise for facile integration into flexible devices requiring on-chip energy storage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Intraneural stimulation using wire-microelectrode arrays: analysis of force steps in recruitment curves

    Smit, J.P.A.; Rutten, Wim; Boom, H.B.K.

    1996-01-01

    In acute experiments on six Wistar rats, a wire-microelectrode array was inserted into the common peroneal nerve. A 5-channel array and a 24-channel array were available. Each electrode in the array was used to generate a twitch contraction force recruitment curve for the extensor digitorum longus

  12. Piezoelectric translator. A simple and inexpensive device to move microelectrodes and micropipettes small distances rapidly.

    Lederer, W J

    1983-09-01

    A device is described that is capable of rapidly moving microelectrodes and micropipettes over distances up to 15 mu. This piezoelectric transLator uses the diaphragm from virtually any available piezoelectric buzzer in combination with simple physical support and drive electronics. All of the necessary details for the construction of this small device are presented. Each finished unit is about 2 cm long with a diameter of 2 cm and can be readily adapted to existing manipulators. The translator has been found useful in aiding the independent penetration by one or more microelectrodes of single cells or of more complicated multicellular preparations (including those that lie behind a connective tissue layer). This new device offers fine control of microelectrode motion that cannot be obtained by the other methods used to aid microelectrode and micropipette penetration of cell membranes (e.g. capacitance overcompensation--"ringing in"' or "tickling"--or tapping the manipulator base). Finally, the device described in this paper is extremely simple and inexpensive to build.

  13. Performance Improvement by Layout Designs of Conductive Polymer Microelectrode Based Impedimetric Biosensors

    Rosati, Giulio; Daprà, Johannes; Cherré, Solène

    2014-01-01

    In this work we present a theoretical, computational, and experimental evaluation of the performance of an impedimetric biosensor based on interdigitated conductive polymer (PEDOT:TsO) microelectrodes in a microfluidic system. The influence of the geometry of the electrodes and microchannels on t...

  14. Investigation of parameters controlling the dielectrophoretic assembly of carbon nanotubes on microelectrodes

    Dimaki, Maria; Bøggild, Peter

    2008-01-01

    Networks of single-walled carbon nanotubes were assembled onto microelectrodes by dielectrophoresis. The dependence of the obtained networks on several assembly parameters such as bias voltage, field application time, frequency, electrode geometry and the nanotube solvent were investigated both s...

  15. A nanoporous alumina microelectrode array for functional cell–chip coupling

    Wesche, Manuel; Hüske, Martin; Yakushenko, Alexey; Brüggemann, Dorothea; Mayer, Dirk; Offenhäusser, Andreas; Wolfrum, Bernhard

    2012-01-01

    The design of electrode interfaces has a strong impact on cell-based bioelectronic applications. We present a new type of microelectrode array chip featuring a nanoporous alumina interface. The chip is fabricated in a combination of top-down and bottom-up processes using state-of-the-art clean room technology and self-assembled generation of nanopores by aluminum anodization. The electrode characteristics are investigated in phosphate buffered saline as well as under cell culture conditions. We show that the modified microelectrodes exhibit decreased impedance compared to planar microelectrodes, which is caused by a nanostructuring effect of the underlying gold during anodization. The stability and biocompatibility of the device are demonstrated by measuring action potentials from cardiomyocyte-like cells growing on top of the chip. Cross sections of the cell–surface interface reveal that the cell membrane seals the nanoporous alumina layer without bending into the sub-50 nm apertures. The nanoporous microelectrode array device may be used as a platform for combining extracellular recording of cell activity with stimulating topographical cues. (paper)

  16. Impedance measurements on Au microelectrodes using controlled atmosphere high temperature scanning probe microscope

    Wu, Yuehua; Hansen, Karin Vels; Jacobsen, Torben

    2011-01-01

    High temperature impedance measurements on Au microelectrodes deposited on polished yttria stabilized zirconia (YSZ) pellets were demonstrated using a newly designed controlled atmosphere high temperature scanning probe microscope (CAHT-SPM). Probes based on Pt0.8Ir0.2 were fabricated and employed...

  17. A hybrid clinical-research depth electrode for acute and chronic in vivo microelectrode recording of human brain neurons. Technical note.

    Howard, M A; Volkov, I O; Granner, M A; Damasio, H M; Ollendieck, M C; Bakken, H E

    1996-01-01

    For several decades, important scientific information has been gained from in vivo microelectrode recordings of individual human cerebral cortical neurons in patients with epilepsy. The experimental methods used, however, are technically complex and require a highly skilled intraoperative team. There are also significant experimental time limitations, as well as constraints on the type of behavioral tests conducted, and the brain regions that may be safely studied. In this report, a new method is described for obtaining in vivo microelectrode recordings using a hybrid depth electrode (HDE). High-impedance research recording contacts are interspersed between low-impedance clinical electroencephalographic (EEG) contacts along the HDE shaft. The HDE has the same external physical properties as a standard clinical depth electrode (DE). Following preclinical laboratory testing, 15 HDEs were used in the evaluation of six patients with medically refractory epilepsy. High-quality EEG recordings were obtained in all cases (two acute intraoperative, four from the chronic epilepsy monitoring unit). Action potentials from individual neurons were successfully recorded during all experimental sessions; however, the chronic preparations were clearly superior. Chronic HDEs are placed using a standard stereotactic system, and the locations of recording contacts are documented on a postimplantation imaging study. The quality of the chronic research recordings was excellent over study periods ranging from 5 to 14 days. The patients rested comfortably on the ward and were able to cooperate with complex experimental instructions. Basic neuroscientists participated fully in all aspects of the chronic investigations. The use of an HDE in place of a standard clinical DE may now allow detailed physiological investigations of any brain region targeted for clinical DE implantation.

  18. Ion implantation

    Johnson, E.

    1986-01-01

    It is the purpose of the present paper to give a review of surface alloy processing by ion implantation. However, rather than covering this vast subject as a whole, the survey is confined to a presentation of the microstructures that can be found in metal surfaces after ion implantation. The presentation is limited to alloys processed by ion implantation proper, that is to processes in which the alloy compositions are altered significantly by direct injection of the implanted ions. The review is introduced by a presentation of the processes taking place during development of the fundamental event in ion implantation - the collision cascade, followed by a summary of the various microstructures which can be formed after ion implantation into metals. This is compared with the variability of microstructures that can be achieved by rapid solidification processing. The microstructures are subsequently discussed in the light of the processes which, as the implantations proceed, take place during and immediately after formation of the individual collision cascades. These collision cascades define the volumes inside which individual ions are slowed down in the implanted targets. They are not only centres for vigorous agitation but also the sources for formation of excess concentrations of point defects, which will influence development of particular microstructures. A final section presents a selection of specific structures which have been observed in different alloy systems. (orig./GSCH)

  19. In Situ Identification and Stratification of Monochloramine Inhibition Effects on Nitrifying Biofilms as Determined by the Use of Microelectrodes

    The nitrifying biofilm grown in an annular biofilm reactor and the microbial deactivation achieved after monochloramine treatment were investigated using microelectrodes. The nitrifying biofilm ammonium microprofile was measured and the effect of monochloramine on nitrifying bio...

  20. 3D silicon neural probe with integrated optical fibers for optogenetic modulation.

    Kim, Eric G R; Tu, Hongen; Luo, Hao; Liu, Bin; Bao, Shaowen; Zhang, Jinsheng; Xu, Yong

    2015-07-21

    Optogenetics is a powerful modality for neural modulation that can be useful for a wide array of biomedical studies. Penetrating microelectrode arrays provide a means of recording neural signals with high spatial resolution. It is highly desirable to integrate optics with neural probes to allow for functional study of neural tissue by optogenetics. In this paper, we report the development of a novel 3D neural probe coupled simply and robustly to optical fibers using a hollow parylene tube structure. The device shanks are hollow tubes with rigid silicon tips, allowing the insertion and encasement of optical fibers within the shanks. The position of the fiber tip can be precisely controlled relative to the electrodes on the shank by inherent design features. Preliminary in vivo rat studies indicate that these devices are capable of optogenetic modulation simultaneously with 3D neural signal recording.

  1. Vertically aligned carbon nanotube-sheathed carbon fibers as pristine microelectrodes for selective monitoring of ascorbate in vivo.

    Xiang, Ling; Yu, Ping; Hao, Jie; Zhang, Meining; Zhu, Lin; Dai, Liming; Mao, Lanqun

    2014-04-15

    Using as-synthesized vertically aligned carbon nanotube-sheathed carbon fibers (VACNT-CFs) as microelectrodes without any postsynthesis functionalization, we have developed in this study a new method for in vivo monitoring of ascorbate with high selectivity and reproducibility. The VACNT-CFs are formed via pyrolysis of iron phthalocyanine (FePc) on the carbon fiber support. After electrochemical pretreatment in 1.0 M NaOH solution, the pristine VACNT-CF microelectrodes exhibit typical microelectrode behavior with fast electron transfer kinetics for electrochemical oxidation of ascorbate and are useful for selective ascorbate monitoring even with other electroactive species (e.g., dopamine, uric acid, and 5-hydroxytryptamine) coexisting in rat brain. Pristine VACNT-CFs are further demonstrated to be a reliable and stable microelectrode for in vivo recording of the dynamic increase of ascorbate evoked by intracerebral infusion of glutamate. Use of a pristine VACNT-CF microelectrode can effectively avoid any manual electrode modification and is free from person-to-person and/or electrode-to-electrode deviations intrinsically associated with conventional CF electrode fabrication, which often involves electrode surface modification with randomly distributed CNTs or other pretreatments, and hence allows easy fabrication of highly selective, reproducible, and stable microelectrodes even by nonelectrochemists. Thus, this study offers a new and reliable platform for in vivo monitoring of neurochemicals (e.g., ascorbate) to largely facilitate future studies on the neurochemical processes involved in various physiological events.

  2. Gold ultra-microelectrode arrays: application to the steady-state voltammetry of hydroxide ion in aqueous solution.

    Ordeig, Olga; Banks, Craig E; Davies, Trevor J; del Campo, F Javier; Muñoz, Francesc Xavier; Compton, Richard G

    2006-05-01

    Gold ultra-microelectrode arrays are used to explore the electrochemical oxidation of hydroxide ions and are shown to be analytical useful. Two types of ultra-microelectrode arrays are used; the first consist of 256 individual electrodes of 5 microm in radius, 170 of which are electrochemically active in a cubic arrangement which are separated from their nearest neighbour by a distance of 100 microm. The second array compromises 2597 electrodes of 2.5 microm in radius and of which 1550 of which are electrochemically active in a hexagonal arrangement separated by the nearest neighbour by 55 microm. Well defined voltammetric waves are found with peak currents proportional to the concentration of hydroxide ions in the range 50 microM to 1 mM. Detection limits of 20 microM using the 170 ultra-microelectrode and 10 microM with the 1550 ultra-microelectrode array are shown to be possible but with a higher sensitivity of 4 mA M(-1) observed using the 1550 ultra-microelectrode array compared to 1.2 mA M(-1) with the 170 ultra-microelectrode array.

  3. Monitoring Ion Activities In and Around Cells Using Ion-Selective Liquid-Membrane Microelectrodes

    Mark D. Parker

    2013-01-01

    Full Text Available Determining the effective concentration (i.e., activity of ions in and around living cells is important to our understanding of the contribution of those ions to cellular function. Moreover, monitoring changes in ion activities in and around cells is informative about the actions of the transporters and/or channels operating in the cell membrane. The activity of an ion can be measured using a glass microelectrode that includes in its tip a liquid-membrane doped with an ion-selective ionophore. Because these electrodes can be fabricated with tip diameters that are less than 1 μm, they can be used to impale single cells in order to monitor the activities of intracellular ions. This review summarizes the history, theory, and practice of ion-selective microelectrode use and brings together a number of classic and recent examples of their usefulness in the realm of physiological study.

  4. Fabrication of gas sensor based on field ionization from SWCNTs with tripolar microelectrode

    Cai, Shengbing; Zhang, Yong; Duan, Zhemin

    2012-12-01

    We report the nanofabrication of a sulfur dioxide (SO2) sensor with a tripolar on-chip microelectrode utilizing a film of single-walled carbon nanotubes (SWCNTs) as the field ionization cathode, where the ion flow current and the partial discharge current generated by the field ionization process of gaseous molecules can be gauged to gas species and concentration. The variation of the sensitivity is less than 4% for all of the tested devices, and the sensor has selectivity against gases such as He, NO2, CO, H2, SO2 and O2. Further, the sensor response presents well-defined and reproducible linear behavior with regard to concentration in the range investigated and a detection limitation of tripolar on-chip microelectrode with SWCNTs as a cathode exhibits an impressive performance with respect to stability and anti-oxidation behavior, which are significantly better than had been possible before in the traditional bipolar sensor under explicit circumstances at room temperature.

  5. Theoretical and experimental comparison of microelectrode sensing configurations for impedimetric cell monitoring

    Carminati, M.; Caviglia, Claudia; Heiskanen, Arto

    2013-01-01

    microelectrodes using a versatile custom-made monitoring platform including a 24-channel miniaturized potentiostat. The characterization of bare microelectrodes in buffer and tracking experiments with HeLa cells over 16 hours demonstrate that the coplanar configuration provides a higher sensitivity to cell......A theoretical and experimental comparison between vertical and coplanar interdigitated sensing configurations for impedimetric cell growth tracking is presented. These widely-adopted approaches are quantitatively compared on the same cell populations and on the same 10 μm interdigitated...... adhesion and spreading (Cell Index = 1.6 vs. 0.4) albeit at a higher frequency of maximum sensitivity (100 kHz vs. 24 kHz) shifting over time. © 2014 Taylor & Francis Group....

  6. Wireless Power Transfer Strategies for Implantable Bioelectronics.

    Agarwal, Kush; Jegadeesan, Rangarajan; Guo, Yong-Xin; Thakor, Nitish V

    2017-01-01

    Neural implants have emerged over the last decade as highly effective solutions for the treatment of dysfunctions and disorders of the nervous system. These implants establish a direct, often bidirectional, interface to the nervous system, both sensing neural signals and providing therapeutic treatments. As a result of the technological progress and successful clinical demonstrations, completely implantable solutions have become a reality and are now commercially available for the treatment of various functional disorders. Central to this development is the wireless power transfer (WPT) that has enabled implantable medical devices (IMDs) to function for extended durations in mobile subjects. In this review, we present the theory, link design, and challenges, along with their probable solutions for the traditional near-field resonant inductively coupled WPT, capacitively coupled short-ranged WPT, and more recently developed ultrasonic, mid-field, and far-field coupled WPT technologies for implantable applications. A comparison of various power transfer methods based on their power budgets and WPT range follows. Power requirements of specific implants like cochlear, retinal, cortical, and peripheral are also considered and currently available IMD solutions are discussed. Patient's safety concerns with respect to electrical, biological, physical, electromagnetic interference, and cyber security from an implanted neurotech device are also explored in this review. Finally, we discuss and anticipate future developments that will enhance the capabilities of current-day wirelessly powered implants and make them more efficient and integrable with other electronic components in IMDs.

  7. Nanowire-templated microelectrodes for high-sensitivity pH detection

    Antohe, V.A.; Radu, Adrian; Mátéfi-Tempfli, Mária

    2009-01-01

    A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features...... by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved...

  8. Static and Dynamic Measurement of Dopamine Adsorption in Carbon Fiber Microelectrodes Using Electrochemical Impedance Spectroscopy.

    Rivera-Serrano, Nilka; Pagan, Miraida; Colón-Rodríguez, Joanisse; Fuster, Christian; Vélez, Román; Almodovar-Faria, Jose; Jiménez-Rivera, Carlos; Cunci, Lisandro

    2018-02-06

    In this study, electrochemical impedance spectroscopy was used for the first time to study the adsorption of dopamine in carbon fiber microelectrodes. In order to show a proof-of-concept, static and dynamic measurements were taken at potentials ranging from -0.4 to 0.8 V versus Ag|AgCl to demonstrate the versatility of this technique to study dopamine without the need of its oxidation. We used electrochemical impedance spectroscopy and single frequency electrochemical impedance to measure different concentrations of dopamine as low as 1 nM. Moreover, the capacitance of the microelectrodes surface was found to decrease due to dopamine adsorption, which is dependent on its concentration. The effect of dissolved oxygen and electrochemical oxidation of the surface in the detection of dopamine was also studied. Nonoxidized and oxidized carbon fiber microelectrodes were prepared and characterized by optical microscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Optimum working parameters of the electrodes, such as frequency and voltage, were obtained for better measurement. Electrochemical impedance of dopamine was determined at different concentration, voltages, and frequencies. Finally, dynamic experiments were conducted using a flow cell and single frequency impedance in order to study continuous and real-time measurements of dopamine.

  9. Field-programmable lab-on-a-chip based on microelectrode dot array architecture.

    Wang, Gary; Teng, Daniel; Lai, Yi-Tse; Lu, Yi-Wen; Ho, Yingchieh; Lee, Chen-Yi

    2014-09-01

    The fundamentals of electrowetting-on-dielectric (EWOD) digital microfluidics are very strong: advantageous capability in the manipulation of fluids, small test volumes, precise dynamic control and detection, and microscale systems. These advantages are very important for future biochip developments, but the development of EWOD microfluidics has been hindered by the absence of: integrated detector technology, standard commercial components, on-chip sample preparation, standard manufacturing technology and end-to-end system integration. A field-programmable lab-on-a-chip (FPLOC) system based on microelectrode dot array (MEDA) architecture is presented in this research. The MEDA architecture proposes a standard EWOD microfluidic component called 'microelectrode cell', which can be dynamically configured into microfluidic components to perform microfluidic operations of the biochip. A proof-of-concept prototype FPLOC, containing a 30 × 30 MEDA, was developed by using generic integrated circuits computer aided design tools, and it was manufactured with standard low-voltage complementary metal-oxide-semiconductor technology, which allows smooth on-chip integration of microfluidics and microelectronics. By integrating 900 droplet detection circuits into microelectrode cells, the FPLOC has achieved large-scale integration of microfluidics and microelectronics. Compared to the full-custom and bottom-up design methods, the FPLOC provides hierarchical top-down design approach, field-programmability and dynamic manipulations of droplets for advanced microfluidic operations.

  10. Novel microelectrode-based online system for monitoring N2O gas emissions during wastewater treatment.

    Marques, Ricardo; Oehmen, Adrian; Pijuan, Maite

    2014-11-04

    Clark-type nitrous oxide (N2O) microelectrodes are commonly used for measuring dissolved N2O levels, but have not previously been tested for gas-phase applications, where the N2O emitted from wastewater systems can be directly quantified. In this study, N2O microelectrodes were tested and validated for online gas measurements, and assessed with respect to their temperature, gas flow, composition dependence, gas pressure, and humidity. An exponential correlation between temperature and sensor signal was found, whereas gas flow, composition, pressure, and humidity did not have any influence on the signal. Two of the sensors were tested at different N2O concentration ranges (0-422.3, 0-50, 0-10, and 0-2 ppmv N2O) and exhibited a linear response over each range. The N2O emission dynamics from two laboratory scale sequencing batch reactors performing ammonia or nitrite oxidation were also monitored using one of the microsensors and results were compared with two other analytical methods. Results show that N2O emissions were accurately described with these microelectrodes and support their application for assessing gaseous N2O emissions from wastewater treatment systems. Advantages of the sensors as compared to conventional measurement techniques include a wider quantification range of N2O fluxes, and a single measurement system that can assess both liquid and gas-phase N2O dynamics.

  11. Carmustine Implant

    ... works by slowing or stopping the growth of cancer cells in your body. ... are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while receiving carmustine implant, call your doctor. Carmustine may harm the fetus.

  12. Cochlear Implants

    ... NIDCD A cochlear implant is a small, complex electronic device that can help to provide a sense ... Hearing Aids Retinitis Pigmentosa - National Eye Institute Telecommunications Relay Services Usher Syndrome Your Baby's Hearing Screening News ...

  13. Time to address the problems at the neural interface

    Durand, Dominique M.; Ghovanloo, Maysam; Krames, Elliot

    2014-04-01

    Neural engineers have made significant, if not remarkable, progress in interfacing with the nervous system in the last ten years. In particular, neuromodulation of the brain has generated significant therapeutic benefits [1-5]. EEG electrodes can be used to communicate with patients with locked-in syndrome [6]. In the central nervous system (CNS), electrode arrays placed directly over or within the cortex can record neural signals related to the intent of the subject or patient [7, 8]. A similar technology has allowed paralyzed patients to control an otherwise normal skeletal system with brain signals [9, 10]. This technology has significant potential to restore function in these and other patients with neural disorders such as stroke [11]. Although there are several multichannel arrays described in the literature, the workhorse for these cortical interfaces has been the Utah array [12]. This 100-channel electrode array has been used in most studies on animals and humans since the 1990s and is commercially available. This array and other similar microelectrode arrays can record neural signals with high quality (high signal-to-noise ratio), but these signals fade and disappear after a few months and therefore the current technology is not reliable for extended periods of time. Therefore, despite these major advances in communicating with the brain, clinical translation cannot be implemented. The reasons for this failure are not known but clearly involve the interface between the electrode and the neural tissue. The Defense Advanced Research Project Agency (DARPA) as well as other federal funding agencies such as the National Science Foundation (NSF) and the National Institutes of Health have provided significant financial support to investigate this problem without much success. A recent funding program from DARPA was designed to establish the failure modes in order to generate a reliable neural interface technology and again was unsuccessful at producing a robust

  14. Localized electron transfer rates and microelectrode-based enrichment of microbial communities within a phototrophic microbial mat

    Jerome eBabauta

    2014-01-01

    Full Text Available Phototrophic microbial mats frequently exhibit sharp, light-dependent redox gradients that regulate microbial respiration on specific electron acceptors as a function of depth. In this work, a benthic phototrophic microbial mat from Hot Lake, a hypersaline, epsomitic lake located near Oroville in north-central Washington, was used to develop a microscale electrochemical method to study local electron transfer processes within the mat. To characterize the physicochemical variables influencing electron transfer, we initially quantified redox potential, pH and dissolved oxygen gradients by depth in the mat under photic and aphotic conditions. We further demonstrated that power output of a mat fuel cell was light-dependent. To study local electron transfer processes, we deployed a microscale electrode (microelectrode with tip size ~20 µm. To enrich a subset of microorganisms capable of interacting with the microelectrode, we anodically polarized the microelectrode in the mat. Subsequently, to characterize the microelectrode-associated community and compare it to the neighboring mat community, we performed amplicon sequencing of the V1-V3 region of the 16S gene. Differences in Bray-Curtis beta diversity, illustrated by large changes in relative abundance at the phylum level, suggested successful enrichment of specific mat community members on the microelectrode surface. The microelectrode-associated community exhibited substantially reduced alpha diversity and elevated relative abundances of Prosthecochloris, Loktanella, Catellibacterium, other unclassified members of Rhodobacteraceae, Thiomicrospira, and Limnobacter, compared with the community at an equivalent depth in the mat. Our results suggest that local electron transfer to an anodically polarized microelectrode selected for a specific microbial population, with substantially more abundance and diversity of sulfur-oxidizing phylotypes compared with the neighboring mat community.

  15. Localized electron transfer rates and microelectrode-based enrichment of microbial communities within a phototrophic microbial mat.

    Babauta, Jerome T; Atci, Erhan; Ha, Phuc T; Lindemann, Stephen R; Ewing, Timothy; Call, Douglas R; Fredrickson, James K; Beyenal, Haluk

    2014-01-01

    Phototrophic microbial mats frequently exhibit sharp, light-dependent redox gradients that regulate microbial respiration on specific electron acceptors as a function of depth. In this work, a benthic phototrophic microbial mat from Hot Lake, a hypersaline, epsomitic lake located near Oroville in north-central Washington, was used to develop a microscale electrochemical method to study local electron transfer processes within the mat. To characterize the physicochemical variables influencing electron transfer, we initially quantified redox potential, pH, and dissolved oxygen gradients by depth in the mat under photic and aphotic conditions. We further demonstrated that power output of a mat fuel cell was light-dependent. To study local electron transfer processes, we deployed a microscale electrode (microelectrode) with tip size ~20 μm. To enrich a subset of microorganisms capable of interacting with the microelectrode, we anodically polarized the microelectrode at depth in the mat. Subsequently, to characterize the microelectrode-associated community and compare it to the neighboring mat community, we performed amplicon sequencing of the V1-V3 region of the 16S gene. Differences in Bray-Curtis beta diversity, illustrated by large changes in relative abundance at the phylum level, suggested successful enrichment of specific mat community members on the microelectrode surface. The microelectrode-associated community exhibited substantially reduced alpha diversity and elevated relative abundances of Prosthecochloris, Loktanella, Catellibacterium, other unclassified members of Rhodobacteraceae, Thiomicrospira, and Limnobacter, compared with the community at an equivalent depth in the mat. Our results suggest that local electron transfer to an anodically polarized microelectrode selected for a specific microbial population, with substantially more abundance and diversity of sulfur-oxidizing phylotypes compared with the neighboring mat community.

  16. Implantation, recoil implantation, and sputtering

    Kelly, R.

    1984-01-01

    The implantation and sputtering mechanisms which are relevant to ion bombardment of surfaces are described. These are: collision, thermal, electronic and photon-induced sputtering. 135 refs.; 36 figs.; 9 tabs

  17. Mathematical modeling of chemotaxis and glial scarring around implanted electrodes

    Silchenko, Alexander N; Tass, Peter A

    2015-01-01

    It is well known that the implantation of electrodes for deep brain stimulation or microelectrode probes for the recording of neuronal activity is always accompanied by the response of the brain’s immune system leading to the formation of a glial scar around the implantation sites. The implantation of electrodes causes massive release of adenosine-5′-triphosphate (ATP) and different cytokines into the extracellular space and activates the microglia. The released ATP and the products of its hydrolysis, such as ADP and adenosine, become the main elements mediating chemotactic sensitivity and motility of microglial cells via subsequent activation of P2Y 2,12 as well as A3A/A2A adenosine receptors. The size and density of an insulating sheath around the electrode, formed by microglial cells, are important criteria for the optimization of the signal-to-noise ratio during microelectrode recordings or parameters of electrical current delivered to the brain tissue. Here, we study a purinergic signaling pathway underlying the chemotactic motion of microglia towards implanted electrodes as well as the possible impact of an anti-inflammatory coating consisting of the interleukin-1 receptor antagonist. We present a model describing the formation of a stable aggregate around the electrode due to the joint chemo-attractive action of ATP and ADP and the mixed influence of extracellular adenosine. The bioactive coating is modeled as a source of chemo-repellent located near the electrode surface. The obtained analytical and numerical results allowed us to reveal the dependences of size and spatial location of the insulating sheath on the amount of released ATP and estimate the impact of immune suppressive coating on the scarring process. (paper)

  18. Importance of cochlear health for implant function.

    Pfingst, Bryan E; Zhou, Ning; Colesa, Deborah J; Watts, Melissa M; Strahl, Stefan B; Garadat, Soha N; Schvartz-Leyzac, Kara C; Budenz, Cameron L; Raphael, Yehoash; Zwolan, Teresa A

    2015-04-01

    Amazing progress has been made in providing useful hearing to hearing-impaired individuals using cochlear implants, but challenges remain. One such challenge is understanding the effects of partial degeneration of the auditory nerve, the target of cochlear implant stimulation. Here we review studies from our human and animal laboratories aimed at characterizing the health of the implanted cochlea and the auditory nerve. We use the data on cochlear and neural health to guide rehabilitation strategies. The data also motivate the development of tissue-engineering procedures to preserve or build a healthy cochlea and improve performance obtained by cochlear implant recipients or eventually replace the need for a cochlear implant. This article is part of a Special Issue entitled . Copyright © 2014 Elsevier B.V. All rights reserved.

  19. NeuroMEMS: Neural Probe Microtechnologies

    Sam Musallam

    2008-10-01

    Full Text Available Neural probe technologies have already had a significant positive effect on our understanding of the brain by revealing the functioning of networks of biological neurons. Probes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain. Neural probes are currently used in many clinical settings for diagnosis of brain diseases such as seizers, epilepsy, migraine, Alzheimer’s, and dementia. We find these devices assisting paralyzed patients by allowing them to operate computers or robots using their neural activity. In recent years, probe technologies were assisted by rapid advancements in microfabrication and microelectronic technologies and thus are enabling highly functional and robust neural probes which are opening new and exciting avenues in neural sciences and brain machine interfaces. With a wide variety of probes that have been designed, fabricated, and tested to date, this review aims to provide an overview of the advances and recent progress in the microfabrication techniques of neural probes. In addition, we aim to highlight the challenges faced in developing and implementing ultralong multi-site recording probes that are needed to monitor neural activity from deeper regions in the brain. Finally, we review techniques that can improve the biocompatibility of the neural probes to minimize the immune response and encourage neural growth around the electrodes for long term implantation studies.

  20. Hip Implant Systems

    ... Implants and Prosthetics Metal-on-Metal Hip Implants Hip Implants Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Hip implants are medical devices intended to restore mobility ...

  1. Breast reconstruction - implants

    Breast implants surgery; Mastectomy - breast reconstruction with implants; Breast cancer - breast reconstruction with implants ... harder to find a tumor if your breast cancer comes back. Getting breast implants does not take as long as breast reconstruction ...

  2. Low-loss microelectrodes fabricated using reverse-side exposure for a tunable ferroelectric capacitor application

    Yoon, Yong-Kyu; Stevenson Kenney, J.; Hunt, Andrew T.; Allen, Mark G.

    2006-02-01

    Narrowly spaced thick microelectrodes are fabricated using a self-aligned multiple reverse-side exposure scheme for an improved quality-factor tunable ferroelectric capacitor. The microelectrodes are fabricated on a functional substrate—a thin film ferroelectric (barium strontium titanate, BST; BaxSr1-xTiO3) coated sapphire substrate, which has an electric-field-dependent dielectric property providing tuning functionality, as well as UV transparency permitting an additional degree of freedom in photolithography steps. The microelectrode process has been applied to interdigitated capacitor fabrication, where a critical challenge is maintaining narrow gaps between electrodes for high tunability, while simultaneously forming thick electrodes to minimize conductor loss. A single mask, self-aligned reverse-side exposure through the transparent substrate achieves both these goals. A single-finger test capacitor with an electrode gap of 1.2 µm and an electrode thickness of 2.2 µm is fabricated and characterized. Tunability (T = 100 × (C0 - Cbias)/C0) of 33% at 10 V has been achieved at 100 kHz. The 2.2 µm thick structure shows improvement of Q-factor compared to that of a 0.1 µm thick structure. To demonstrate the scalability of this process, a 102-finger interdigitated capacitor is fabricated and characterized at 100 kHz and 1 GHz. The structure is embedded in a 25 µm thick epoxy resin SU-8 for passivation. A quality factor decrease of 15-25%, tunability decrease of 2-3% and capacitance increase of 6% are observed due to the expoxy resin after passivation. High frequency performance of the capacitor has been measured to be 15.9 pF of capacitance, 28.1% tunability at 10 V and a quality factor of 16 (at a 10 V dc bias) at 1 GHz.

  3. Modeling microelectrode biosensors: free-flow calibration can substantially underestimate tissue concentrations.

    Newton, Adam J H; Wall, Mark J; Richardson, Magnus J E

    2017-03-01

    Microelectrode amperometric biosensors are widely used to measure concentrations of analytes in solution and tissue including acetylcholine, adenosine, glucose, and glutamate. A great deal of experimental and modeling effort has been directed at quantifying the response of the biosensors themselves; however, the influence that the macroscopic tissue environment has on biosensor response has not been subjected to the same level of scrutiny. Here we identify an important issue in the way microelectrode biosensors are calibrated that is likely to have led to underestimations of analyte tissue concentrations. Concentration in tissue is typically determined by comparing the biosensor signal to that measured in free-flow calibration conditions. In a free-flow environment the concentration of the analyte at the outer surface of the biosensor can be considered constant. However, in tissue the analyte reaches the biosensor surface by diffusion through the extracellular space. Because the enzymes in the biosensor break down the analyte, a density gradient is set up resulting in a significantly lower concentration of analyte near the biosensor surface. This effect is compounded by the diminished volume fraction (porosity) and reduction in the diffusion coefficient due to obstructions (tortuosity) in tissue. We demonstrate this effect through modeling and experimentally verify our predictions in diffusive environments. NEW & NOTEWORTHY Microelectrode biosensors are typically calibrated in a free-flow environment where the concentrations at the biosensor surface are constant. However, when in tissue, the analyte reaches the biosensor via diffusion and so analyte breakdown by the biosensor results in a concentration gradient and consequently a lower concentration around the biosensor. This effect means that naive free-flow calibration will underestimate tissue concentration. We develop mathematical models to better quantify the discrepancy between the calibration and tissue

  4. Neurosecurity: security and privacy for neural devices.

    Denning, Tamara; Matsuoka, Yoky; Kohno, Tadayoshi

    2009-07-01

    An increasing number of neural implantable devices will become available in the near future due to advances in neural engineering. This discipline holds the potential to improve many patients' lives dramatically by offering improved-and in some cases entirely new-forms of rehabilitation for conditions ranging from missing limbs to degenerative cognitive diseases. The use of standard engineering practices, medical trials, and neuroethical evaluations during the design process can create systems that are safe and that follow ethical guidelines; unfortunately, none of these disciplines currently ensure that neural devices are robust against adversarial entities trying to exploit these devices to alter, block, or eavesdrop on neural signals. The authors define "neurosecurity"-a version of computer science security principles and methods applied to neural engineering-and discuss why neurosecurity should be a critical consideration in the design of future neural devices.

  5. DNA-barcode directed capture and electrochemical metabolic analysis of single mammalian cells on a microelectrode array.

    Douglas, Erik S; Hsiao, Sonny C; Onoe, Hiroaki; Bertozzi, Carolyn R; Francis, Matthew B; Mathies, Richard A

    2009-07-21

    A microdevice is developed for DNA-barcode directed capture of single cells on an array of pH-sensitive microelectrodes for metabolic analysis. Cells are modified with membrane-bound single-stranded DNA, and specific single-cell capture is directed by the complementary strand bound in the sensor area of the iridium oxide pH microelectrodes within a microfluidic channel. This bifunctional microelectrode array is demonstrated for the pH monitoring and differentiation of primary T cells and Jurkat T lymphoma cells. Single Jurkat cells exhibited an extracellular acidification rate of 11 milli-pH min(-1), while primary T cells exhibited only 2 milli-pH min(-1). This system can be used to capture non-adherent cells specifically and to discriminate between visually similar healthy and cancerous cells in a heterogeneous ensemble based on their altered metabolic properties.

  6. Electrohydrodynamic actuation of co-flowing liquids by means of microelectrode arrays

    Garcia-Sanchez, Pablo; Ferney, Mathieu; Ramos, Antonio

    2011-01-01

    Electric fields induce forces at the interface between liquids with different electrical properties (conductivity and/or permittivity). We explore how to use these forces for manipulating two coflowing streams of liquids in a microchannel. A microelectrode array is fabricated at the bottom of the channel and one of the two liquids is labelled with a fluorescent dye for observing the phenomenon. The diffuse interface between the two liquids is deflected depending on the ac signal and conductivity (or permittivity) ratio between the liquids. Only a few volts are needed for observing the interface destabilization, in contrast with other electrode configurations where hundreds of volts are applied.

  7. Electrohydrodynamic actuation of co-flowing liquids by means of microelectrode arrays

    Garcia-Sanchez, Pablo; Ferney, Mathieu; Ramos, Antonio, E-mail: pablogarcia@us.es [Depto. de Electronica y Electromagnetismo, University of Sevilla (Spain)

    2011-06-23

    Electric fields induce forces at the interface between liquids with different electrical properties (conductivity and/or permittivity). We explore how to use these forces for manipulating two coflowing streams of liquids in a microchannel. A microelectrode array is fabricated at the bottom of the channel and one of the two liquids is labelled with a fluorescent dye for observing the phenomenon. The diffuse interface between the two liquids is deflected depending on the ac signal and conductivity (or permittivity) ratio between the liquids. Only a few volts are needed for observing the interface destabilization, in contrast with other electrode configurations where hundreds of volts are applied.

  8. Neural networks

    Denby, Bruce; Lindsey, Clark; Lyons, Louis

    1992-01-01

    The 1980s saw a tremendous renewal of interest in 'neural' information processing systems, or 'artificial neural networks', among computer scientists and computational biologists studying cognition. Since then, the growth of interest in neural networks in high energy physics, fueled by the need for new information processing technologies for the next generation of high energy proton colliders, can only be described as explosive

  9. Implantable optoelectronic probes for in vivo optogenetics

    Iseri, Ege; Kuzum, Duygu

    2017-06-01

    More than a decade has passed since optics and genetics came together and lead to the emerging technologies of optogenetics. The advent of light-sensitive opsins made it possible to optically trigger the neurons into activation or inhibition by using visible light. The importance of spatiotemporally isolating a segment of a neural network and controlling nervous signaling in a precise manner has driven neuroscience researchers and engineers to invest great efforts in designing high precision in vivo implantable devices. These efforts have focused on delivery of sufficient power to deep brain regions, while monitoring neural activity with high resolution and fidelity. In this review, we report the progress made in the field of hybrid optoelectronic neural interfaces that combine optical stimulation with electrophysiological recordings. Different approaches that incorporate optical or electrical components on implantable devices are discussed in detail. Advantages of various different designs as well as practical and fundamental limitations are summarized to illuminate the future of neurotechnology development.

  10. Fabrication of gas sensor based on field ionization from SWCNTs with tripolar microelectrode

    Cai, Shengbing; Zhang, Yong; Duan, Zhemin

    2012-01-01

    We report the nanofabrication of a sulfur dioxide (SO 2 ) sensor with a tripolar on-chip microelectrode utilizing a film of single-walled carbon nanotubes (SWCNTs) as the field ionization cathode, where the ion flow current and the partial discharge current generated by the field ionization process of gaseous molecules can be gauged to gas species and concentration. The variation of the sensitivity is less than 4% for all of the tested devices, and the sensor has selectivity against gases such as He, NO 2 , CO, H 2 , SO 2 and O 2 . Further, the sensor response presents well-defined and reproducible linear behavior with regard to concentration in the range investigated and a detection limitation of <∼0.5 ppm for SO 2 . More importantly, a tripolar on-chip microelectrode with SWCNTs as a cathode exhibits an impressive performance with respect to stability and anti-oxidation behavior, which are significantly better than had been possible before in the traditional bipolar sensor under explicit circumstances at room temperature. (paper)

  11. Voltammetric studies on the electrochemical determination of methylmercury in chloride medium at carbon microelectrodes

    Ribeiro, F. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal); Neto, M.M.M. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal) and Departamento de Quimica Agricola e Ambiental, Instituto Superior de Agronomia, Tapada da Ajuda, 1349-017 Lisbon (Portugal)]. E-mail: mm.neto@netcabo.pt; Rocha, M.M. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal); Fonseca, I.T.E. [Centro de Electroquimica e Cinetica da Universidade de Lisboa, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisbon (Portugal)

    2006-10-10

    Electroanalytical techniques have been used to determine methylmercury at low levels in environmental matrices. The electrochemical behaviour of methylmercury at carbon microelectrodes in a hydrochloric acid medium using cyclic, square wave and fast-scan linear-sweep voltammetric techniques has been investigated. The analytical utility of the methylmercury reoxidation peak has been explored, but the recorded peak currents were found to be poorly reproducible. This is ascribed to two factors: the adsorption of insoluble chloromercury compounds on the electrode surface, which appears to be an important contribution to hinder the voltammetric signal of methylmercury; and the competition between the reoxidation of the methylmercury radical and its dimerization reaction, which limits the reproducibility of the methylmercury peak. These problems were successfully overcome by adopting the appropriate experimental conditions. Fast-scan rates were employed and an efficient electrochemical regeneration procedure of the electrode surface was achieved, under potentiostatic conditions in a mercury-free solution containing potassium thiocyanate-a strong complexing agent. The influence of chloride ion concentration was analysed. Interference by metals, such as lead and cadmium, was considered. Calibration plots were obtained in the micromolar and submicromolar concentration ranges, allowing the electrochemical determination of methylmercury in trace amounts. An estuarine water sample was analysed using the new method with a glassy carbon microelectrode.

  12. Development and characterization of a voltammetric carbon-fiber microelectrode pH sensor.

    Makos, Monique A; Omiatek, Donna M; Ewing, Andrew G; Heien, Michael L

    2010-06-15

    This work describes the development and characterization of a modified carbon-fiber microelectrode sensor capable of measuring real-time physiological pH changes in biological microenvironments. The reagentless sensor was fabricated under ambient conditions from voltammetric reduction of the diazonium salt Fast Blue RR onto a carbon-fiber surface in aprotic media. Fast-scan cyclic voltammetry was used to probe redox activity of the p-quinone moiety of the surface-bound molecule as a function of pH. In vitro calibration of the sensor in solutions ranging from pH 6.5 to 8.0 resulted in a pH-dependent anodic peak potential response. Flow-injection analysis was used to characterize the modified microelectrode, revealing sensitivity to acidic and basic changes discernible to 0.005 pH units. Furthermore, the modified electrode was used to measure dynamic in vivo pH changes evoked during neurotransmitter release in the central nervous system of the microanalytical model organism Drosophila melanogaster.

  13. The impact of multichannel microelectrode recording (MER) in deep brain stimulation of the basal ganglia.

    Kinfe, Thomas M; Vesper, Jan

    2013-01-01

    Deep brain stimulation (DBS) of the basal ganglia (Ncl. subthalamicus, Ncl. ventralis intermedius thalami, globus pallidus internus) has become an evidence-based and well-established treatment option in otherwise refractory movement disorders. The Ncl. subthalamicus (STN) is the target of choice in Parkinson's disease.However, a considerable discussion is currently ongoing with regard to the necessity for micro-electrode recording (MER) in DBS surgery.The present review provides an overview on deep brain stimulation and (MER) of the STN in patients with Parkinson's disease. Detailed description is given concerning the multichannel MER systems nowadays available for DBS of the basal ganglia, especially of the STN, as a useful tool for target refinement. Furthermore, an overview is given of the historical aspects, spatial mapping of the STN by MER, and its impact for accuracy and precision in current functional stereotactic neurosurgery.The pros concerning target refinement by MER means on the one hand, and cons including increased bleeding risk, increased operation time, local or general anesthesia, and single versus multichannel microelectrode recording are discussed in detail. Finally, the authors favor the use of MER with intraoperative testing combined with imaging to achieve a more precise electrode placement, aiming to ameliorate clinical outcome in therapy-resistant movement disorders.

  14. Impedance Immunsensor Based on Interdigitated Array Microelectrode and its Experiment Parameter Optimization

    Wen Ping Zhao

    2014-05-01

    Full Text Available This article accounts for a novel impedance immunosensor based on the specificity reaction of the antigen-antibody and the sensitivity of the interdigitated array microelectrode (IDAM for the determination of chlorpyrifos residues. The basic knowledge of immunoassay was in relation to its IDAM electrode surface modification, antibody immobilization, bovine serum albumin (BSA blocking and sample detection. The SPA was dropped onto the surface of IDAM electrode, used for binding antibody Fc fragments. Next, antibody was immobilized on the SPA modified electrode. Finally, BSA was employed to block the possible remaining active sites avoiding any nonspecific adsorption. Target chlorpyrifos was then captured by the immobilized antibody, resulting in a change in the impedance of the IDAM microelectrode surface. The fabrication procedure of the immunosensor and the sample detection were characterized by electrochemical impedance spectroscopy (EIS. The influences of the experiment parameters were investigated. Under optimized conditions, an excellent biosensor was fabricated. Many of the antibodies, enzymes and other reagents integral to immunoassays were very expensive, often hundreds of dollars per milligram, therefore miniaturization reduces reagent costs drastically. In this article the volume of the reagents was micro upgrade, the antibodies, SPA and BSA were 30 mL, the chlorpyrifos sample and detection solution were 50mL. The advantages of the immunosensor were exhibited in its better specificity, stability, selectivity and regeneration. The proposed method was proven to be a feasible quantitative method for chlorpyrifos analysis in vegetables and fruits.

  15. Voltammetric studies on the electrochemical determination of methylmercury in chloride medium at carbon microelectrodes

    Ribeiro, F.; Neto, M.M.M.; Rocha, M.M.; Fonseca, I.T.E.

    2006-01-01

    Electroanalytical techniques have been used to determine methylmercury at low levels in environmental matrices. The electrochemical behaviour of methylmercury at carbon microelectrodes in a hydrochloric acid medium using cyclic, square wave and fast-scan linear-sweep voltammetric techniques has been investigated. The analytical utility of the methylmercury reoxidation peak has been explored, but the recorded peak currents were found to be poorly reproducible. This is ascribed to two factors: the adsorption of insoluble chloromercury compounds on the electrode surface, which appears to be an important contribution to hinder the voltammetric signal of methylmercury; and the competition between the reoxidation of the methylmercury radical and its dimerization reaction, which limits the reproducibility of the methylmercury peak. These problems were successfully overcome by adopting the appropriate experimental conditions. Fast-scan rates were employed and an efficient electrochemical regeneration procedure of the electrode surface was achieved, under potentiostatic conditions in a mercury-free solution containing potassium thiocyanate-a strong complexing agent. The influence of chloride ion concentration was analysed. Interference by metals, such as lead and cadmium, was considered. Calibration plots were obtained in the micromolar and submicromolar concentration ranges, allowing the electrochemical determination of methylmercury in trace amounts. An estuarine water sample was analysed using the new method with a glassy carbon microelectrode

  16. Short Implants: New Horizon in Implant Dentistry.

    Jain, Neha; Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-09-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration.

  17. Some technical nuances for deep brain stimulator implantation

    Cole A. Giller, MD, PhD, MBA

    2015-03-01

    Full Text Available Protocols for deep brain stimulator (DBS implantation vary significantly among movement disorders centers despite the need to address similar operative problems. The general steps of this procedure are well accepted, but there are many seemingly minor, yet important nuances not extensively discussed in published descriptions. A classification and the details of the nuances adopted by a single institution may therefore be helpful in providing a basis for discussion and comparison. We describe operative nuances adopted at the Georgia Regents Medical Center (GRMC for DBS implantation that may not be universally employed. The problems of DBS implantation considered here include stereotactic planning, draping, creation and use of the burhole, physiological testing, anchoring of the electrode, financial considerations, and overall technique. Fourteen categories of operative nuances were identified and described in detail. These include the use of specific anatomical relationships for planning, the use of clear and watertight drapes, countersinking of the burhole, the use of gelfoam and tissue glue to seal the burhole, methods to review the entire microelectrode data simultaneously, blinded communication with the patient during macrostimulation, fluoroscopic marking, MRI compatible protection of the electrode tip, financial considerations effecting choice of operative materials, and restriction to a single operator. The majority of these have not been extensively described but may be in use at other centers. The many operative problems arising during DBS implantation can be addressed with specific technical nuances.

  18. On-Line Monitoring the Growth of E. coli or HeLa Cells Using an Annular Microelectrode Piezoelectric Biosensor

    Feifei Tong

    2016-12-01

    Full Text Available Biological information is obtained from the interaction between the series detection electrode and the organism or the physical field of biological cultures in the non-mass responsive piezoelectric biosensor. Therefore, electric parameter of the electrode will affect the biosensor signal. The electric field distribution of the microelectrode used in this study was simulated using the COMSOL Multiphysics analytical tool. This process showed that the electric field spatial distribution is affected by the width of the electrode finger or the space between the electrodes. In addition, the characteristic response of the piezoelectric sensor constructed serially with an annular microelectrode was tested and applied for the continuous detection of Escherichia coli culture or HeLa cell culture. Results indicated that the piezoelectric biosensor with an annular microelectrode meets the requirements for the real-time detection of E. coli or HeLa cells in culture. Moreover, this kind of piezoelectric biosensor is more sensitive than the sensor with an interdigital microelectrode. Thus, the piezoelectric biosensor acts as an effective analysis tool for acquiring online cell or microbial culture information.

  19. Towards on-chip, in-cell recordings from cultured cardiomyocytes by arrays of gold mushroom-shaped microelectrodes

    Anna eFendyur

    2012-08-01

    Full Text Available Cardiological research greatly rely on the use of cultured primary cardiomyocytes (CM. The prime methodology to assess CM network electrophysiology is based on the use of extracellular recordings by substrate-integrated planar Micro-Electrode Arrays (MEAs. Whereas this methodology permits simultaneous, long-term monitoring of the CM electrical activity, it limits the information to extracellular field potentials (FP. The alternative method of intracellular action potentials (AP recordings by sharp- or patch-microelectrodes is limited to a single cell at a time. Here, we began to merge the advantages of planar MEA and intracellular microelectrodes. To that end we cultured rat CM on micrometer size protruding gold mushroom-shaped microelectrode (gMµE arrays. Cultured CMs engulf the gMµE permitting FPs recordings from individual cells. Local electroporation of a CM converts the extracellular recording configuration to attenuated intracellular APs with shape and duration similar to those recorded intracellularly. The procedure enables to simultaneously record APs from an unlimited number of CMs. The electroporated membrane spontaneously recovers. This allows for repeated recordings from the same CM a number of times (>8 for over 10 days. The further development of CM-gMµE configuration opens up new venues for basic and applied biomedical research.

  20. On-Line Monitoring the Growth of E. coli or HeLa Cells Using an Annular Microelectrode Piezoelectric Biosensor.

    Tong, Feifei; Lian, Yan; Han, Junliang

    2016-12-18

    Biological information is obtained from the interaction between the series detection electrode and the organism or the physical field of biological cultures in the non-mass responsive piezoelectric biosensor. Therefore, electric parameter of the electrode will affect the biosensor signal. The electric field distribution of the microelectrode used in this study was simulated using the COMSOL Multiphysics analytical tool. This process showed that the electric field spatial distribution is affected by the width of the electrode finger or the space between the electrodes. In addition, the characteristic response of the piezoelectric sensor constructed serially with an annular microelectrode was tested and applied for the continuous detection of Escherichia coli culture or HeLa cell culture. Results indicated that the piezoelectric biosensor with an annular microelectrode meets the requirements for the real-time detection of E. coli or HeLa cells in culture. Moreover, this kind of piezoelectric biosensor is more sensitive than the sensor with an interdigital microelectrode. Thus, the piezoelectric biosensor acts as an effective analysis tool for acquiring online cell or microbial culture information.

  1. Evaluation of the Neuroactivity of ToxCast Compounds Using Multi-well Microelectrode Array Recordings in Primary Cortical Neurons

    Evaluation of the Neuroactivity of ToxCast Compounds Using Multi-well Microelectrode Array Recordings in Primary Cortical Neurons P Valdivia1, M Martin2, WR LeFew3, D Hall3, J Ross1, K Houck2 and TJ Shafer3 1Axion Biosystems, Atlanta GA and 2NCCT, 3ISTD, NHEERL, ORD, US EPA, RT...

  2. Implantation, recoil implantation, and sputtering

    Kelly, R.

    1984-01-01

    Underlying ion-beam modification of surfaces is the more basic subject of particle-surface interaction. The ideas can be grouped into forward and backward features, i.e. those affecting the interior of the target and those leading to particle expulsion. Forward effects include the stopping of the incident particles and the deposition of energy, both governed by integral equations which are easily set up but difficult to solve. Closely related is recoil implantation where emphasis is placed not on the stopping of the incident particles but on their interaction with target atoms with resulting implantation of these atoms. Backward effects, all of which are denoted as sputtering, are in general either of collisional, thermal, electronic, or exfoliational origin. (Auth.)

  3. Quantitative Analysis of Rat Dorsal Root Ganglion Neurons Cultured on Microelectrode Arrays Based on Fluorescence Microscopy Image Processing.

    Mari, João Fernando; Saito, José Hiroki; Neves, Amanda Ferreira; Lotufo, Celina Monteiro da Cruz; Destro-Filho, João-Batista; Nicoletti, Maria do Carmo

    2015-12-01

    Microelectrode Arrays (MEA) are devices for long term electrophysiological recording of extracellular spontaneous or evocated activities on in vitro neuron culture. This work proposes and develops a framework for quantitative and morphological analysis of neuron cultures on MEAs, by processing their corresponding images, acquired by fluorescence microscopy. The neurons are segmented from the fluorescence channel images using a combination of segmentation by thresholding, watershed transform, and object classification. The positioning of microelectrodes is obtained from the transmitted light channel images using the circular Hough transform. The proposed method was applied to images of dissociated culture of rat dorsal root ganglion (DRG) neuronal cells. The morphological and topological quantitative analysis carried out produced information regarding the state of culture, such as population count, neuron-to-neuron and neuron-to-microelectrode distances, soma morphologies, neuron sizes, neuron and microelectrode spatial distributions. Most of the analysis of microscopy images taken from neuronal cultures on MEA only consider simple qualitative analysis. Also, the proposed framework aims to standardize the image processing and to compute quantitative useful measures for integrated image-signal studies and further computational simulations. As results show, the implemented microelectrode identification method is robust and so are the implemented neuron segmentation and classification one (with a correct segmentation rate up to 84%). The quantitative information retrieved by the method is highly relevant to assist the integrated signal-image study of recorded electrophysiological signals as well as the physical aspects of the neuron culture on MEA. Although the experiments deal with DRG cell images, cortical and hippocampal cell images could also be processed with small adjustments in the image processing parameter estimation.

  4. Dental Implant Surgery

    ... here to find out more. Dental Implant Surgery Dental Implant Surgery Dental implant surgery is, of course, ... to find out more. Wisdom Teeth Management Wisdom Teeth Management An impacted wisdom tooth can damage neighboring ...

  5. Cochlear Implant

    Mehrnaz Karimi

    1992-04-01

    Full Text Available People with profound hearing loss are not able to use some kinds of conventional amplifiers due to the nature of their loss . In these people, hearing sense is stimulated only when the auditory nerve is activated via electrical stimulation. This stimulation is possible through cochlear implant. In fact, for the deaf people who have good mental health and can not use surgical and medical treatment and also can not benefit from air and bone conduction hearing aids, this device is used if they have normal central auditory system. The basic parts of the device included: Microphone, speech processor, transmitter, stimulator and receiver, and electrode array.

  6. Note: Microelectrode-shielding tip for scanning probe electron energy spectroscopy

    Huang, Wei; Li, Zhean; Xu, Chunkai; Liu, Jian; Xu, Chunye; Chen, Xiangjun

    2018-04-01

    We report a novel microelectrode-shielding tip (ME tip) for scanning probe electron energy spectroscopy (SPEES). The shielding effect of this tip is studied through comparing the detection efficiency with the normal tip by both experiment and simulation. The results show that the backscattering count rate detected by the SPEES instrument using the normal tip begins to decrease as the tip approaches to the sample surface within 21 μm, while that using the ME tip only starts to drop off within 1 μm. This indicates that the electron energy spectra can be measured with the ME tip at a much closer tip-sample distance. Furthermore, it is also demonstrated that the ME tip can be used to obtain topography of the sample surface in situ simultaneously.

  7. Microelectrode generator-collector systems for electrolytic titration: theoretical and practical considerations.

    Bell, Christopher G; Seelanan, Parinya; O'Hare, Danny

    2017-10-23

    Electochemical generator-collector systems, where one electrode is used to generate a reagent, have a potentially large field of application in sensing and measurement. We present a new theoretical description for coplanar microelectrode disc-disc systems where the collector is passive (such as a potentiometric sensor) and the generator is operating at constant flux. This solution is then used to develop a leading order solution for such a system where the reagent reacts reversibly in solution, such as in acid-base titration, where a hydrogen ion flux is generated by electrolysis of water. The principal novel result of the theory is that such devices are constrained by a maximum reagent flux. The hydrogen ion concentration at the collector will only reflect the buffer capacity of the bulk solution if this constraint is met. Both mathematical solutions are evaluated with several microfabricated devices and reasonable agreement with theory is demonstrated.

  8. Characterization of poly(3,4-ethylenedioxythiophene):tosylate conductive polymer microelectrodes for transmitter detection

    Larsen, Simon T.; Vreeland, Richard F.; Heien, Michael L.

    2012-01-01

    applications such as capillary electrophoresis, high-performance liquid chromatography, and constant potential amperometry at living cells. Band electrodes with widths down to 3 μm were fabricated on polymer substrates using UV lithographic methods. The electrodes are electrochemically stable in a range......In this paper we investigate the physical and electrochemical properties of micropatterned poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:tosylate) microelectrodes for neurochemical detection. PEDOT:tosylate is a promising conductive polymer electrode material for chip-based bioanalytical...... between −200 mV and 700 mV vs. Ag/AgCl and show a relatively low resistance. A wide range of transmitters is shown to oxidize readily on the electrodes. Kinetic rate constants and half wave potentials are reported. The capacitance per area was found to be high (1670 ± 130 μF cm−2) compared to other thin...

  9. Microelectrode-assisted low-voltage atmospheric pressure glow discharge in air

    Liu, Wenzheng; Zhao, Shuai; Niu, Jiangqi; Chai, Maolin

    2017-09-01

    During the process of discharge, appropriately changing the paths corresponding to electric field lines and the field strength distribution along these paths, as well as increasing the number of initial electrons, can effectively enhance the uniformity of discharge and inhibit the formation of filamentary discharge. A method is proposed that uses a microelectrode to initiate the macroscopic discharge phenomenon. An asymmetric structure was designed comprising a single electrode of carbon fiber; this electrode structure is of helical-contact type. Benefitting from the special electric field distribution and the microdischarge process, a three-dimensional atmospheric pressure glow discharge was achieved in air, characterized by low discharge voltage, low energy consumption, good diffusion performance, and less ozone generation. The plasma studied is uniform and stable with good diffusion characteristics and low levels of contaminants and hence has potential applications in the field of air purification.

  10. Doped Overoxidized Polypyrrole Microelectrodes as Sensors for the Detection of Dopamine Released from Cell Populations

    Sasso, Luigi; Heiskanen, Arto; Diazzi, Francesco

    2013-01-01

    A surface modification of interdigitated gold microelectrodes (IDEs) with a doped polypyrrole (PPy) film for detection of dopamine released from populations of differentiated PC12 cells is presented. A thin PPy layer was potentiostatically electropolymerized from an 10 aqueous pyrrole solution onto...... electrode surfaces. The conducting polymer film was doped during electropolymerization by introducing counter ions in the monomer solution. Several counter ions were tested and the resulting electrode modifications were characterized electrochemically to find the optimal dopant that increases sensitivity...... to amperometrically detect dopamine released by populations of cells upon triggering cellular exocytosis with an elevated K+ concentration. A comparison between the generated current on bare gold electrodes and gold electrodes modified with overoxidized doped PPy illustrates the clear advantage of the modification...

  11. Hydrogen Peroxide Impedimetric Detection on Poly-Ortho-Phenylenediamine Modified Platinum Disk Microelectrode

    Zainiharyati Mohd Zain; Norazreen Zakaria

    2014-01-01

    This work describes the development of hydrogen peroxide detection based on Poly-ortho-phenylenediamine modified Platinum disk microelectrode (50 μm in diameter). The electrochemical performances of H 2 O 2 detection were studied using Chronoamperometry, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) techniques in Phosphate Buffer Solution (PBS) pH 7.4. Effect of potential, electrode size, and various concentrations of H 2 O 2 , among others, were investigated by tracking the impedance changes at a specific perturbation frequency. To obtain the Charge transfer resistance (R ct ) values, a modified Randles Equivalent Circuit was modelled and fitted to Nyquist Plot. Then, this sensor was further applied in the detection of H 2 O 2 in antiseptic mouthwash with percent recovery of 97 % ± 0.14 (x10 3 kΩ). (author)

  12. Microelectrode Arrays and the Use of PEG-Functionalized Diblock Copolymer Coatings

    Sakshi Uppal

    2014-09-01

    Full Text Available PEG-modified diblock copolymer surfaces have been examined for their compatibility with microelectrode array based analytical methods. The use of PEG-modified polymer surfaces on the arrays was initially problematic because the redox couples used in the experiments were adsorbed by the polymer. This led the current measured by cyclic voltammetry for the redox couple to be unstable and increase with time. However, two key findings allow the experiments to be successful. First, after multiple cyclic voltammograms the current associated with the redox couple does stabilize so that a good baseline current can be established. Second, the rate at which the current stabilizes is consistent every time a particular coated array is used. Hence, multiple analytical experiments can be conducted on an array coated with a PEG-modified diblock copolymer and the data obtained is comparable as long as the data for each experiment is collected at a consistent time point.

  13. Purification of carbon nanotubes through an electric field near the arranged microelectrodes

    Shim, Hyung Cheoul; Lee, Hyung Woo; Yeom, Sujin; Kwak, Yoon Keun; Lee, Seung S; Kim, Soo Hyun

    2007-01-01

    In this work, we attempt to purify multi-walled carbon nanotubes (MWNTs) using electrophoresis induced by the application of an AC electric field to a set of microelectrodes in a microliquid channel. This purifying method is different from conventional methods based on chemical processes. It was observed that most of the MWNTs could pass along the microliquid channel without attaching to the electrode under specific conditions of 1 kHz, at 0.2 V rms μm -1 . On the other hand, the majority of the carbon impurities attached to the electrodes under identical conditions. Field emission scanning electron microscopy (FESEM) images and Raman spectra confirm that this condition is beneficial for removing carbon impurities. The proposed approach has potential applicability in the development of microdevices that can simultaneously perform the purification and fabrication of MWNTs

  14. Addressing of LnCaP Cell Using Magnetic Particles Assisted Impedimetric Microelectrode.

    Nguyen, Dung Thi Xuan; Tran, Trong Binh; Nguyen, Phuong-Diem; Min, Junhong

    2016-03-01

    In this study, we provide a facile, effective technique for a simple isolation and enrichment of low metastatic prostate tumor cell LNCaP using biocompatible, magnetic particles asissted impedimetric sensing system. Hydrophobic cell membrane anchors (BAM) were generated onto magnetic particles which diameters vary from 50 nm to 5 μm and were used to capture LNCaP cells from the suspension. Finally, magnetic particle-LNCaP complex were addressed onto the surface of the interdigitated microelectrode (IDM). Cell viability was monitored by our laboratory developed-technique Electrical Cell Substrate Impedance Sensing (ECIS). The results reavealed that 50 nm-magnetic particles showed best performance in terms of cell separation and cell viability. This technique provides a simple and efficient method for the direct addressing of LNCaP cell on the surface and enhances better understanding of cell behavior for cancer management in the near future.

  15. Complications after cardiac implantable electronic device implantations

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard

    2013-01-01

    Complications after cardiac implantable electronic device (CIED) treatment, including permanent pacemakers (PMs), cardiac resynchronization therapy devices with defibrillators (CRT-Ds) or without (CRT-Ps), and implantable cardioverter defibrillators (ICDs), are associated with increased patient...

  16. Impedimetric microbial biosensor based on single wall carbon nanotube modified microelectrodes for trichloroethylene detection

    Hnaien, M.; Bourigua, S.; Bessueille, F.; Bausells, J.; Errachid, A.; Lagarde, F.; Jaffrezic-Renault, N.

    2011-01-01

    Highlights: ► We propose an impedimetric microbial biosensor for trichloroethylene detection. ► A new transducer modified with carbon nanotubes and Pseudomonas putida is evaluated. ► Functionalization steps are controlled by impedance spectroscopy and AFM. ► The biosensor offers good sensitivity, selectivity, linear range and stability. ► The biosensor is successfully applied to spiked natural water samples. - Abstract: Contamination of soils and groundwaters with persistent organic pollutants is a matter of increasing concern. The most common organic pollutants are chlorinated hydrocarbons such as perchloroethylene and trichloroethylene (TCE). In this study, we developed a bacterial impedimetric biosensor for TCE detection, based on the immobilization of Pseudomonas putida F1 strain on gold microelectrodes functionalized with single wall carbon nanotubes covalently linked to anti-Pseudomonas antibodies. The different steps of microelectrodes functionalization were characterized by electrochemical impedance and atomic force spectroscopies, and analytical performances of the developed microbial biosensor were determined. The impedimetric biosensor response was linear with TCE concentration up to 150 μg L −1 and a low limit of detection (20 μg L −1 ) was achieved. No significant loss of signal was observed after 4 weeks of storage at 4 °C in phosphate buffer saline pH 7 (three to four measurements a week). After 5 weeks, 90% of the initial value still remained. cis-1,2-Dichloroethylene and vinylchloride, the main TCE degradation products, did not significantly interfere with TCE. The microbial sensor was finally applied to the determination of TCE in natural water samples spiked at the 30, 50 and 75 μg L −1 levels. Recoveries were very good, ranging from 100 to 103%.

  17. Neural Networks

    Smith, Patrick I.

    2003-01-01

    Physicists use large detectors to measure particles created in high-energy collisions at particle accelerators. These detectors typically produce signals indicating either where ionization occurs along the path of the particle, or where energy is deposited by the particle. The data produced by these signals is fed into pattern recognition programs to try to identify what particles were produced, and to measure the energy and direction of these particles. Ideally, there are many techniques used in this pattern recognition software. One technique, neural networks, is particularly suitable for identifying what type of particle caused by a set of energy deposits. Neural networks can derive meaning from complicated or imprecise data, extract patterns, and detect trends that are too complex to be noticed by either humans or other computer related processes. To assist in the advancement of this technology, Physicists use a tool kit to experiment with several neural network techniques. The goal of this research is interface a neural network tool kit into Java Analysis Studio (JAS3), an application that allows data to be analyzed from any experiment. As the final result, a physicist will have the ability to train, test, and implement a neural network with the desired output while using JAS3 to analyze the results or output. Before an implementation of a neural network can take place, a firm understanding of what a neural network is and how it works is beneficial. A neural network is an artificial representation of the human brain that tries to simulate the learning process [5]. It is also important to think of the word artificial in that definition as computer programs that use calculations during the learning process. In short, a neural network learns by representative examples. Perhaps the easiest way to describe the way neural networks learn is to explain how the human brain functions. The human brain contains billions of neural cells that are responsible for processing

  18. Evolvable synthetic neural system

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  19. Alkaline biodegradable implants for osteoporotic bone defects--importance of microenvironment pH.

    Liu, W; Wang, T; Yang, C; Darvell, B W; Wu, J; Lin, K; Chang, J; Pan, H; Lu, W W

    2016-01-01

    Change of microenvironment pH by biodegradable implants may ameliorate unbalanced osteoporotic bone remodeling. The present work demonstrated that a weak alkaline condition stimulated osteoblasts differentiation while suppressed osteoclast generation. In vivo, implants with an alkaline microenvironment pH (monitored by a pH microelectrode) exhibited a promising healing effect for the repair of osteoporotic bone defects. Under osteoporotic conditions, the response of the bone microenvironment to an endosseous implant is significantly impaired, and this substantially increases the risk of fracture, non-union and aseptic implant loosening. Acid-base equilibrium is an important factor influencing bone cell behaviour. The present purpose was to study the effect of a series of alkaline biodegradable implant materials on regeneration of osteoporotic bone defect, monitoring the microenvironment pH (μe-pH) over time. The proliferation and differentiation potential of osteoporotic rat bone marrow stromal cells and RAW 264.7 cells were examined under various pH conditions. Ovariectomized rat bone defects were filled with specific biodegradable materials, and μe-pH was measured by pH microelectrode. New osteoid and tartrate-resistant acid phosphatase-positive osteoclast-like cells were examined by Goldner's trichrome and TRAP staining, respectively. The intermediate layer between implants and new bone were studied using energy-dispersive X-ray spectroscopy (EDX) linear scanning. In vitro, weak alkaline conditions stimulated osteoporotic rat bone marrow stromal cells (oBMSC) differentiation, while inhibiting the formation of osteoclasts. In vivo, μe-pH differs from that of the homogeneous peripheral blood and exhibits variations over time particular to each material. Higher initial μe-pH was associated with more new bone formation, late response of TRAP-positive osteoclast-like cells and the development of an intermediate 'apatitic' layer in vivo. EDX suggested that

  20. Cultured Neural Networks: Optimization of Patterned Network Adhesiveness and Characterization of their Neural Activity

    W. L. C. Rutten

    2006-01-01

    Full Text Available One type of future, improved neural interface is the “cultured probe”. It is a hybrid type of neural information transducer or prosthesis, for stimulation and/or recording of neural activity. It would consist of a microelectrode array (MEA on a planar substrate, each electrode being covered and surrounded by a local circularly confined network (“island” of cultured neurons. The main purpose of the local networks is that they act as biofriendly intermediates for collateral sprouts from the in vivo system, thus allowing for an effective and selective neuron–electrode interface. As a secondary purpose, one may envisage future information processing applications of these intermediary networks. In this paper, first, progress is shown on how substrates can be chemically modified to confine developing networks, cultured from dissociated rat cortex cells, to “islands” surrounding an electrode site. Additional coating of neurophobic, polyimide-coated substrate by triblock-copolymer coating enhances neurophilic-neurophobic adhesion contrast. Secondly, results are given on neuronal activity in patterned, unconnected and connected, circular “island” networks. For connected islands, the larger the island diameter (50, 100 or 150 μm, the more spontaneous activity is seen. Also, activity may show a very high degree of synchronization between two islands. For unconnected islands, activity may start at 22 days in vitro (DIV, which is two weeks later than in unpatterned networks.

  1. A Novel Microdialysis Glucose Sensor System Based on Co-immobilizing on AU Micro-Electrode by SOL-GEL Technique

    Yu, Ping

    2001-01-01

    .... The sensor is based on co_immobilizing glucose oxidase (COD) with the catalase by sol-gel technique on the surface of the silicon bases with two pattern of An microelectrodes. A graduated ("sandwich...

  2. Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics.

    Szostak, Katarzyna M; Grand, Laszlo; Constandinou, Timothy G

    2017-01-01

    Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. Although the trend is promising, the long-term reliability of such devices has not yet met the required criteria for chronic human application. The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes-microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges.

  3. Neural Interfaces for Intracortical Recording: Requirements, Fabrication Methods, and Characteristics

    Katarzyna M. Szostak

    2017-12-01

    Full Text Available Implantable neural interfaces for central nervous system research have been designed with wire, polymer, or micromachining technologies over the past 70 years. Research on biocompatible materials, ideal probe shapes, and insertion methods has resulted in building more and more capable neural interfaces. Although the trend is promising, the long-term reliability of such devices has not yet met the required criteria for chronic human application. The performance of neural interfaces in chronic settings often degrades due to foreign body response to the implant that is initiated by the surgical procedure, and related to the probe structure, and material properties used in fabricating the neural interface. In this review, we identify the key requirements for neural interfaces for intracortical recording, describe the three different types of probes—microwire, micromachined, and polymer-based probes; their materials, fabrication methods, and discuss their characteristics and related challenges.

  4. Implantable medical electronics prosthetics, drug delivery, and health monitoring

    Khanna, Vinod Kumar

    2016-01-01

    This book is a comprehensive, interdisciplinary resource for the latest information on implantable medical devices, and is intended for graduate students studying electrical engineering, electronic instrumentation, and biomedical engineering. It is also appropriate for academic researchers, professional engineers, practicing doctors, and paramedical staff. Divided into two sections on Basic Concepts and Principles, and Applications, the first section provides an all-embracing perspective of the electronics background necessary for this work. The second section deals with pacing techniques used for the heart, brain, spinal cord, and the network of nerves that interlink the brain and spinal cord with the major organs, including ear and eye prostheses. The four main offshoots of implantable electronics, which this book discusses, are: The insertion of an implantable neural amplifier for accurate recording of neural signals for neuroengineering studies The use of implantable pulse generators for pacing the activi...

  5. Photosensitive-polyimide based method for fabricating various neural electrode architectures

    Yasuhiro X Kato

    2012-06-01

    Full Text Available An extensive photosensitive polyimide (PSPI-based method for designing and fabricating various neural electrode architectures was developed. The method aims to broaden the design flexibility and expand the fabrication capability for neural electrodes to improve the quality of recorded signals and integrate other functions. After characterizing PSPI’s properties for micromachining processes, we successfully designed and fabricated various neural electrodes even on a non-flat substrate using only one PSPI as an insulation material and without the time-consuming dry etching processes. The fabricated neural electrodes were an electrocorticogram electrode, a mesh intracortical electrode with a unique lattice-like mesh structure to fixate neural tissue, and a guide cannula electrode with recording microelectrodes placed on the curved surface of a guide cannula as a microdialysis probe. In vivo neural recordings using anesthetized rats demonstrated that these electrodes can be used to record neural activities repeatedly without any breakage and mechanical failures, which potentially promises stable recordings for long periods of time. These successes make us believe that this PSPI-based fabrication is a powerful method, permitting flexible design and easy optimization of electrode architectures for a variety of electrophysiological experimental research with improved neural recording performance.

  6. Real-time bladder volume monitoring by the application of a new implantable bladder volume sensor for a small animal model

    Dong Sup Lee

    2011-04-01

    Full Text Available Although real-time monitoring of bladder volume together with intravesical pressure can provide more information for understanding the functional changes of the urinary bladder, it still entails difficulties in the accurate prediction of real-time bladder volume in urodynamic studies with small animal models. We studied a new implantable bladder volume monitoring device with eight rats. During cystometry, microelectrodes prepared by the microelectromechanical systems process were placed symmetrically on both lateral walls of the bladder, and the expanded bladder volume was calculated. Immunohistological study was done after 1 week and after 4 weeks to evaluate the biocompatibility of the microelectrode. From the point that infused saline volume into the bladder was higher than 0.6 mL, estimated bladder volume was statistically correlated with the volume of saline injected (p<0.01. Additionally, the microelectromechanical system microelectrodes used in this study showed reliable biocompatibility. Therefore, the device can be used to evaluate changes in bladder volume in studies with small animals, and it may help to provide more information about functional changes in the bladder in laboratory studies. Furthermore, owing to its biocompatibility, the device could be chronically implanted in conscious ambulating animals, thus allowing a novel longitudinal study to be performed for a specific purpose.

  7. Retrograde peri-implantitis

    Mohamed Jumshad

    2010-01-01

    Full Text Available Retrograde peri-implantitis constitutes an important cause for implant failure. Retrograde peri-implantitis may sometimes prove difficult to identify and hence institution of early treatment may not be possible. This paper presents a report of four cases of (the implant placed developing to retrograde peri-implantitis. Three of these implants were successfully restored to their fully functional state while one was lost due to extensive damage. The paper highlights the importance of recognizing the etiopathogenic mechanisms, preoperative assessment, and a strong postoperative maintenance protocol to avoid retrograde peri-implant inflammation.

  8. Cochlear implantation in children and adults in Switzerland

    Brand, Yves; Senn, Pascal; Kompis, Martin; Dillier, Norbert; Allum, John H. J.

    2014-01-01

    The cochlear implant (CI) is one of the most successful neural prostheses developed to date. It offers artificial hearing to individuals with profound sensorineural hearing loss and with insufficient benefit from conventional hearing aids. The first implants available some 30 years ago provided a limited sensation of sound. The benefit for users of these early systems was mostly a facilitation of lip-reading based communication rather than an understanding of speech. Considerable progress has...

  9. Multilayer poly(3,4-ethylenedioxythiophene)-dexamethasone and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate-carbon nanotubes coatings on glassy carbon microelectrode arrays for controlled drug release.

    Castagnola, Elisa; Carli, Stefano; Vomero, Maria; Scarpellini, Alice; Prato, Mirko; Goshi, Noah; Fadiga, Luciano; Kassegne, Sam; Ricci, Davide

    2017-07-13

    The authors present an electrochemically controlled, drug releasing neural interface composed of a glassy carbon (GC) microelectrode array combined with a multilayer poly(3,4-ethylenedioxythiophene) (PEDOT) coating. The system integrates the high stability of the GC electrode substrate, ideal for electrical stimulation and electrochemical detection of neurotransmitters, with the on-demand drug-releasing capabilities of PEDOT-dexamethasone compound, through a mechanically stable interlayer of PEDOT-polystyrene sulfonate (PSS)-carbon nanotubes (CNT). The authors demonstrate that such interlayer improves both the mechanical and electrochemical properties of the neural interface, when compared with a single PEDOT-dexamethasone coating. Moreover, the multilayer coating is able to withstand 10 × 10 6 biphasic pulses and delamination test with negligible change to the impedance spectra. Cross-section scanning electron microscopy images support that the PEDOT-PSS-CNT interlayer significantly improves the adhesion between the GC substrate and PEDOT-dexamethasone coating, showing no discontinuities between the three well-interconnected layers. Furthermore, the multilayer coating has superior electrochemical properties, in terms of impedance and charge transfer capabilities as compared to a single layer of either PEDOT coating or the GC substrate alone. The authors verified the drug releasing capabilities of the PEDOT-dexamethasone layer when integrated into the multilayer interface through repeated stimulation protocols in vitro, and found a pharmacologically relevant release of dexamethasone.

  10. Individual titanium zygomatic implant

    Nekhoroshev, M. V.; Ryabov, K. N.; Avdeev, E. V.

    2018-03-01

    Custom individual implants for the reconstruction of craniofacial defects have gained importance due to better qualitative characteristics over their generic counterparts – plates, which should be bent according to patient needs. The Additive Manufacturing of individual implants allows reducing cost and improving quality of implants. In this paper, the authors describe design of zygomatic implant models based on computed tomography (CT) data. The fabrication of the implants will be carried out with 3D printing by selective laser melting machine SLM 280HL.

  11. Amorphous silicon carbide ultramicroelectrode arrays for neural stimulation and recording

    Deku, Felix; Cohen, Yarden; Joshi-Imre, Alexandra; Kanneganti, Aswini; Gardner, Timothy J.; Cogan, Stuart F.

    2018-02-01

    Objective. Foreign body response to indwelling cortical microelectrodes limits the reliability of neural stimulation and recording, particularly for extended chronic applications in behaving animals. The extent to which this response compromises the chronic stability of neural devices depends on many factors including the materials used in the electrode construction, the size, and geometry of the indwelling structure. Here, we report on the development of microelectrode arrays (MEAs) based on amorphous silicon carbide (a-SiC). Approach. This technology utilizes a-SiC for its chronic stability and employs semiconductor manufacturing processes to create MEAs with small shank dimensions. The a-SiC films were deposited by plasma enhanced chemical vapor deposition and patterned by thin-film photolithographic techniques. To improve stimulation and recording capabilities with small contact areas, we investigated low impedance coatings on the electrode sites. The assembled devices were characterized in phosphate buffered saline for their electrochemical properties. Main results. MEAs utilizing a-SiC as both the primary structural element and encapsulation were fabricated successfully. These a-SiC MEAs had 16 penetrating shanks. Each shank has a cross-sectional area less than 60 µm2 and electrode sites with a geometric surface area varying from 20 to 200 µm2. Electrode coatings of TiN and SIROF reduced 1 kHz electrode impedance to less than 100 kΩ from ~2.8 MΩ for 100 µm2 Au electrode sites and increased the charge injection capacities to values greater than 3 mC cm‑2. Finally, we demonstrated functionality by recording neural activity from basal ganglia nucleus of Zebra Finches and motor cortex of rat. Significance. The a-SiC MEAs provide a significant advancement in the development of microelectrodes that over the years has relied on silicon platforms for device manufacture. These flexible a-SiC MEAs have the potential for decreased tissue damage and reduced

  12. Microelectrode voltammetry of multi-electron transfers complicated by coupled chemical equilibria: a general theory for the extended square scheme.

    Laborda, Eduardo; Gómez-Gil, José María; Molina, Angela

    2017-06-28

    A very general and simple theoretical solution is presented for the current-potential-time response of reversible multi-electron transfer processes complicated by homogeneous chemical equilibria (the so-called extended square scheme). The expressions presented here are applicable regardless of the number of electrons transferred and coupled chemical processes, and they are particularized for a wide variety of microelectrode geometries. The voltammetric response of very different systems presenting multi-electron transfers is considered for the most widely-used techniques (namely, cyclic voltammetry, square wave voltammetry, differential pulse voltammetry and steady state voltammetry), studying the influence of the microelectrode geometry and the number and thermodynamics of the (electro)chemical steps. Most appropriate techniques and procedures for the determination of the 'interaction' between successive transfers are discussed. Special attention is paid to those situations where homogeneous chemical processes, such as protonation, complexation or ion association, affect the electrochemical behaviour of the system by different stabilization of the oxidation states.

  13. Fabrication and surface-modification of implantable microprobes for neuroscience studies

    Cao, H; Nguyen, C M; Chiao, J C

    2012-01-01

    In this work implantable micro-probes for central nervous system (CNS) studies were developed on silicon and polyimide substrates. The probes which contained micro-electrode arrays with different surface modifications were designed for implantation in the CNS. The electrode surfaces were modified with nano-scale structures that could greatly increase the active surface area in order to enhance the electrochemical current outputs while maintaining micro-scale dimensions of the electrodes and probes. The electrodes were made of gold or platinum, and designed with different sizes. The silicon probes were modified by silicon nanowires fabricated with the vapor–liquid–solid mechanism at high temperatures. With polyimide substrates, the nanostructure modification was carried out by applying concentrated gold or silver colloid solutions onto the micro-electrodes at room temperature. The surfaces of electrodes before and after modification were observed by scanning electron microscopy. The silicon nanowire-modified surface was characterized by cyclic voltammetry. Experiments were carried out to investigate the improvement in sensing performance. The modified electrodes were tested with H 2 O 2 , electrochemical L-glutamate and dopamine. Comparisons between electrodes with and without nanostructure modification were conducted showing that the modifications have enhanced the signal outputs of the electrochemical neurotransmitter sensors

  14. Fabrication and surface-modification of implantable microprobes for neuroscience studies

    Cao, H.; Nguyen, C. M.; Chiao, J. C.

    2012-06-01

    In this work implantable micro-probes for central nervous system (CNS) studies were developed on silicon and polyimide substrates. The probes which contained micro-electrode arrays with different surface modifications were designed for implantation in the CNS. The electrode surfaces were modified with nano-scale structures that could greatly increase the active surface area in order to enhance the electrochemical current outputs while maintaining micro-scale dimensions of the electrodes and probes. The electrodes were made of gold or platinum, and designed with different sizes. The silicon probes were modified by silicon nanowires fabricated with the vapor-liquid-solid mechanism at high temperatures. With polyimide substrates, the nanostructure modification was carried out by applying concentrated gold or silver colloid solutions onto the micro-electrodes at room temperature. The surfaces of electrodes before and after modification were observed by scanning electron microscopy. The silicon nanowire-modified surface was characterized by cyclic voltammetry. Experiments were carried out to investigate the improvement in sensing performance. The modified electrodes were tested with H2O2, electrochemical L-glutamate and dopamine. Comparisons between electrodes with and without nanostructure modification were conducted showing that the modifications have enhanced the signal outputs of the electrochemical neurotransmitter sensors.

  15. In vivo pH monitoring using boron doped diamond microelectrode and silver needles: Application to stomach disorder diagnosis

    Fierro, St?phane; Seishima, Ryo; Nagano, Osamu; Saya, Hideyuki; Einaga, Yasuaki

    2013-01-01

    This study presents the in vivo electrochemical monitoring of pH using boron doped diamond (BDD) microelectrode and silver needles for potential application in medical diagnosis. Accurate calibration curve for pH determination were obtained through in vitro electrochemical measurements. The increase induced in stomach pH by treatment with pantoprazole was used to demonstrate that it is possible to monitor the pH in vivo using the simple and noninvasive system proposed herein. Using the result...

  16. Effect of island shape on dielectrophoretic assembly of metal nanoparticle chains in a conductive-island-based microelectrode system

    Ding, Haitao; Shao, Jinyou; Ding, Yucheng; Liu, Weiyu; Li, Xiangming; Tian, Hongmiao; Zhou, Yaopei

    2015-01-01

    Highlights: • Conductive island shape influences the dynamic process occurring in DEP assembly of 10 nm gold nanoparticles in a conductive-island-based microelectrode system. • The DEP-assembled nanoparticle wires form a straighter conduction path with the increase in the geometric angle of conductive island tip. • The different island shapes distort the DEP force distribution and increase the local electrothermally induced fluid flow to different extents, which is important for the morphology and electrical conductance quality of the DEP-assembled metal nanoparticle chains. - Abstract: The electrical conduction quality of an electric circuit connection formed by dielectrophoretic (DEP)-assembled metal nanoparticle wires between small conductive elements plays a significant role in electronic devices. One of the major challenges for improving the electrical conductance of nanowires is optimizing their geometric morphology. So far, the electrical conduction quality has been enhanced by optimizing the AC frequency and conductivity of nanoparticle suspensions. Herein, the effect of the conductive island shapes on the dynamic process occurring in a DEP assembly of 10 nm gold nanoparticles was investigated in a conductive-island-based microelectrode system. The nanoparticle wires between the microelectrodes were assembled in situ from colloidal suspensions. The wires were grown in a much straighter route by increasing the geometric angle of the conductive-island tip. To validate the experiments, the effects of mutual DEP interactions and electrothermally induced fluid flow on the dynamic behavior of particle motion for different island geometric configurations in the conductive-island-based microelectrode system were determined by numerical simulations. The simulation results are consistent with those of experiments. This indicates that different conductive island shapes change the distribution of DEP force and increase the electrothermally induced fluid flow to

  17. Magnetron sputtered diamond-like carbon microelectrodes for on-chip measurement of quantal catecholamine release from cells

    Gao, Yuanfang; Chen, Xiaohui; Gupta, Sanju; Gillis, Kevin D.; Gangopadhyay, Shubhra

    2008-01-01

    Carbon electrodes are widely used in electrochemistry due to their low cost, wide potential window, and low and stable background noise. Carbon-fiber electrodes (CFE) are commonly used to electrochemically measure “quantal” catecholamine release via exocytosis from individual cells, but it is difficult to integrate CFEs into lab-on-a-chip devices. Here we report the development of nitrogen doped diamond-like carbon (DLC:N) microelectrodes on a chip to monitor quantal release of catecholamines...

  18. O2 Plasma Etching and Antistatic Gun Surface Modifications for CNT Yarn Microelectrode Improve Sensitivity and Antifouling Properties.

    Yang, Cheng; Wang, Ying; Jacobs, Christopher B; Ivanov, Ilia N; Venton, B Jill

    2017-05-16

    Carbon nanotube (CNT) based microelectrodes exhibit rapid and selective detection of neurotransmitters. While different fabrication strategies and geometries of CNT microelectrodes have been characterized, relatively little research has investigated ways to selectively enhance their electrochemical properties. In this work, we introduce two simple, reproducible, low-cost, and efficient surface modification methods for carbon nanotube yarn microelectrodes (CNTYMEs): O 2 plasma etching and antistatic gun treatment. O 2 plasma etching was performed by a microwave plasma system with oxygen gas flow and the optimized time for treatment was 1 min. The antistatic gun treatment flows ions by the electrode surface; two triggers of the antistatic gun was the optimized number on the CNTYME surface. Current for dopamine at CNTYMEs increased 3-fold after O 2 plasma etching and 4-fold after antistatic gun treatment. When the two treatments were combined, the current increased 12-fold, showing the two effects are due to independent mechanisms that tune the surface properties. O 2 plasma etching increased the sensitivity due to increased surface oxygen content but did not affect surface roughness while the antistatic gun treatment increased surface roughness but not oxygen content. The effect of tissue fouling on CNT yarns was studied for the first time, and the relatively hydrophilic surface after O 2 plasma etching provided better resistance to fouling than unmodified or antistatic gun treated CNTYMEs. Overall, O 2 plasma etching and antistatic gun treatment improve the sensitivity of CNTYMEs by different mechanisms, providing the possibility to tune the CNTYME surface and enhance sensitivity.

  19. Influence of droplet coverage on the electrochemical response of planar microelectrodes and potential solving strategies based on nesting concept

    Yue Yu

    2016-08-01

    Full Text Available Recently, biosensors have been widely used for the detection of bacteria, viruses and other toxins. Electrodes, as commonly used transducers, are a vital part of electrochemical biosensors. The coverage of the droplets can change significantly based on the hydrophobicity of the microelectrode surface materials. In the present research, screen-printed interdigitated microelectrodes (SPIMs, as one type of planar microelectrode, were applied to investigate the influence of droplet coverage on electrochemical response. Furthermore, three dimensional (3D printing technology was employed to print smart devices with different diameters based on the nesting concept. Theoretical explanations were proposed to elucidate the influence of the droplet coverage on the electrochemical response. 3D-printed ring devices were used to incubate the SPIMs and the analytical performances of the SPIMs were tested. According to the results obtained, our device successfully improved the stability of the signal responses and eliminated irregular signal changes to a large extent. Our proposed method based on the nesting concept provides a promising method for the fabrication of stable electrochemical biosensors. We also introduced two types of electrode bases to improve the signal stability.

  20. Nanostructured gold microelectrodes for SERS and EIS measurements by incorporating ZnO nanorod growth with electroplating

    Zong, Xianli; Zhu, Rong; Guo, Xiaoliang

    2015-01-01

    In this paper, a fine gold nanostructure synthesized on selective planar microelectrodes in micro-chip is realized by using an advanced hybrid fabrication approach incorporating growth of nanorods (NRs) with gold electroplating. By this developed nanostructure, integration of in-situ surface-enhanced Raman spectroscopy (SERS) detection with electrochemical impedance spectroscopy (EIS) measurement for label-free, nondestructive, real-time and rapid monitoring on a single cell has been achieved. Moreover, parameters of Au nanostructures such as size of nanoholes/nanogaps can be controllably adjusted in the fabrication. We have demonstrated a SERS enhancement factor of up to ~2.24 × 106 and double-layer impedance decrease ratio of 90% ~ 95% at low frequency range below 200 kHz by using nanostructured microelectrodes. SERS detection and in-situ EIS measurement of a trapped single cell by using planar microelectrodes are realized to demonstrate the compatibility, multi-functions, high-sensitivity and simplicity of the micro-chip system. This dual function platform integrating SERS and EIS is of great significance in biological, biochemical and biomedical applications. PMID:26558325

  1. The Polypyrrole/Multiwalled Carbon Nanotube Modified Au Microelectrode for Sensitive Electrochemical Detection of Trace Levels of Pb2+

    Xuxing Zhu

    2017-03-01

    Full Text Available The sensitive detection of trace levels of heavy metal ions such as Pb2+ is of significant importance due to the health hazard they pose. In this paper, we present a polypyrrole (PPy/multiwalled carbon nanotube (MWCNT-modified Au microelectrode. The PPy/MWCNT composite film was electrochemically deposited on the microelectrode by cyclic voltammetry (CV. The composite film was investigated by scanning electron microscope (SEM, CV, and electrochemical impedance spectroscopy (EIS, and the results show that this film presents a uniformly distributed and web-like entangled structure and good conductivity. Differential pulse stripping voltammetry (DPSV was applied to determine trace levels of Pb2+. Experimental conditions including accumulation time and deposition potential were optimized. In optimal conditions, the PPy/MWCNT-modified microelectrode performed sensitive detection of Pb2+ within a concentration range from 1 to 100 μg·L−1, and the limit of detection was 0.65 μg·L−1 at the signal-to-noise ratio of three.

  2. Magnesium microelectrode corrosion product transport modelling in relation to chloride induced pitting

    Burrows, R.; Cook, A.; Stevens, N.P.C.

    2012-09-01

    The high magnesium alloy Magnox is used as a fuel clad for the UK gas cooled, graphite moderated reactors of the same name. The fuel is metallic uranium (typically natural enrichment), so a low neutron absorption cross-section clad is required. Following discharge from reactor, spent fuel is stored in water, which acts as an effective heat transfer medium and biological shield. The chemistry of these ponds is carefully controlled to ensure that the Magnox clad remains in a passive state. This is primarily through the maintenance of a high pH and very low anion concentration. Of particular concern is the presence of chloride ions as even very low levels may allow localised corrosion to initiate. Although extensive work has been undertaken historically considering the behaviour of Magnox clad and the acceptable storage envelopes, the challenges of ageing plant and aspirations for accelerated decommissioning give value to further understanding of the corrosion mechanisms of this material. Recently, electrochemical techniques have been employed to characterise performance in a variety of chemistries and microelectrodes have been produced which have shown characteristics of salt film corrosion at moderate chloride concentrations under polarisation. A characteristic of the electrochemical response observed during the mass transport limited (potential independent) salt film regime has been periodic transients which correspond to emission of microscopic hydrogen bubbles from the microelectrode cavity. A simple finite element multi-physics model has been employed to assist in understanding the dominant processes of corrosion product transport away from a magnesium electrode surface which is dissolving under a salt film and this shows that characteristic transients observed in electrochemical tests may be simulated with reasonable agreement by consideration of convection from laminar flow around hydrogen micro-bubbles in the pit cavity combined with aqueous diffusion in the

  3. A wirelessly powered microspectrometer for neural probe-pin device

    Choi, Sang H.; Kim, Min H.; Song, Kyo D.; Yoon, Hargsoon; Lee, Uhn

    2015-12-01

    Treatment of neurological anomalies, whether done invasively or not, places stringent demands on device functionality and size. We have developed a micro-spectrometer for use as an implantable neural probe to monitor neuro-chemistry in synapses. The micro-spectrometer, based on a NASA-invented miniature Fresnel grating, is capable of differentiating the emission spectra from various brain tissues. The micro-spectrometer meets the size requirements, and is able to probe the neuro-chemistry and suppression voltage typically associated with a neural anomaly. This neural probe-pin device (PPD) is equipped with wireless power technology (WPT) to enable operation in a continuous manner without requiring an implanted battery. The implanted neural PPD, together with a neural electronics interface and WPT, enable real-time measurement and control/feedback for remediation of neural anomalies. The design and performance of the combined PPD/WPT device for monitoring dopamine in a rat brain will be presented to demonstrate the current level of development. Future work on this device will involve the addition of an embedded expert system capable of performing semi-autonomous management of neural functions through a routine of sensing, processing, and control.

  4. Interdigitated microelectrode based impedance biosensor for detection of salmonella enteritidis in food samples

    Kim, G; Morgan, M; Hahm, B K; Bhunia, A; Mun, J H; Om, A S

    2008-01-01

    Salmonella enteritidis outbreaks continue to occur, and S. enteritidis-related outbreaks from various food sources have increased public awareness of this pathogen. Conventional methods for pathogens detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Recently developed biosensors have shown great potential for the rapid detection of foodborne pathogens. To develop the biosensor, an interdigitated microelectrode (IME) was fabricated by using semiconductor fabrication process. Anti-Salmonella antibodies were immobilized based on avidin-biotin binding on the surface of the IME to form an active sensing layer. To increase the sensitivity of the sensor, three types of sensors that have different electrode gap sizes (2 μm, 5 μm, 10 μm) were fabricated and tested. The impedimetric biosensor could detect 10 3 CFU/mL of Salmonella in pork meat extract with an incubation time of 5 minutes. This method may provide a simple, rapid and sensitive method to detect foodborne pathogens

  5. Application of active electrode compensation to perform continuous voltage-clamp recordings with sharp microelectrodes.

    Gómez-González, J F; Destexhe, A; Bal, T

    2014-10-01

    Electrophysiological recordings of single neurons in brain tissues are very common in neuroscience. Glass microelectrodes filled with an electrolyte are used to impale the cell membrane in order to record the membrane potential or to inject current. Their high resistance induces a high voltage drop when passing current and it is essential to correct the voltage measurements. In particular, for voltage clamping, the traditional alternatives are two-electrode voltage-clamp technique or discontinuous single electrode voltage-clamp (dSEVC). Nevertheless, it is generally difficult to impale two electrodes in a same neuron and the switching frequency is limited to low frequencies in the case of dSEVC. We present a novel fully computer-implemented alternative to perform continuous voltage-clamp recordings with a single sharp-electrode. To reach such voltage-clamp recordings, we combine an active electrode compensation algorithm (AEC) with a digital controller (AECVC). We applied two types of control-systems: a linear controller (proportional plus integrative controller) and a model-based controller (optimal control). We compared the performance of the two methods to dSEVC using a dynamic model cell and experiments in brain slices. The AECVC method provides an entirely digital method to perform continuous recording and smooth switching between voltage-clamp, current clamp or dynamic-clamp configurations without introducing artifacts.

  6. An iridium oxide microelectrode for monitoring acute local pH changes of endothelial cells.

    Ng, Shu Rui; O'Hare, Danny

    2015-06-21

    pH sensors were fabricated by anodically electrodepositing iridium oxide films (AEIROFs) onto microelectrodes on chips and coated with poly(ethyleneimine) (PEI) for mechanical stability. These demonstrate super-Nernstian response to pH from pH 4.0 to 7.7 in chloride-free phosphate buffer. The surface of the chip was coated with fibronectin for the attachment of porcine aortic endothelial cells (PAECs). The working capability of the pH sensor for monitoring acute local pH changes was investigated by stimulating the PAECs with thrombin. Our results show that thrombin induced acute extracellular acidification of PAECs and dissolution of fibronectin, causing the local pH to decrease. The use of PD98059, a mitogen-activated protein kinase (MAPK) inhibitor, reduced extracellular acidification and an increase in local pH was observed. This study shows that our pH sensors can facilitate the investigation of acute cellular responses to stimulation by monitoring the real-time, local pH changes of cells attached to the sensors.

  7. Rapid Detection Technology for Pesticides Residues Based on Microelectrodes Impedance Immunosensor

    Wen Ping Zhao

    2014-09-01

    Full Text Available Compared with conventional methods, electrochemical immunosensors have many advantages, such as low cost, high sensitivity, and rapid detection, and has certain prospects for realizing real-time-monitoring. In this paper, a design of portable pesticide residues detection instrument was presented based on an electrochemical impedance immunosensor. Firstly, we studied on an impedance immunosensor based on interdigitated array microelectrode (IDAM coupled with magnetic nanobeads-antibody conjugates (MNAC for the pesticide detection. Magnetic nanobeads (diameter 150 nm coated with anti-carbofuran antibodies were used for further amplification of the binding reaction between antibody and hapten (carbofuran. Secondly, in order to develop a portable pesticide residue apparatus, we designed the impedance detection electric circuit. Main work included designing and constructing of the system circuit, designing and debugging of the system software and so on. Thirdly, the apparatus was used for the standard pesticides solutions testing combined with immunosensor to test the reliability and stability. The pesticide added standard recovery was more than 70 % and the impedance test error was less than 5 %. The results showed that the proposed instrument had a good consistence compared with the traditional analytical methods. Thus, it would be a promising rapid detection instrument for pesticide residues in agricultural products.

  8. ZnO crystal growth on microelectrode by electrochemical deposition method

    Kondo, Y; Ashida, A; Nouzu, N; Fujimura, N

    2011-01-01

    Zinc Oxide crystals were grown by constant potential electrochemical deposition method on the substrate with the Pt working electrode which consists of Pt film with large area and μm-sized line and space structured area. In case of depositions with cathodic potential of -0.3V, ZnO crystal is not observed on the micro electrode, but observed on the electrode with large area (0.2 cm 2 ). By using electrolyte with higher pH, ZnO crystal grows on both areas. In case of lower pH, ZnO crystal does not grow on either. From these results, the pH range for growth of ZnO on the microelectrode seems to be higher than that on the electrode with large area. And, it is expected that the pH just on the surface of μm-sized electrode is lower than that in the bulk of electrolyte. Based on these results, it can be concluded that control of the pH in vicinity of the surface is very important to ECD method for micro- and nano-scaled devices.

  9. A microelectrode array electrodeposited with reduced graphene oxide and Pt nanoparticles for norepinephrine and electrophysiological recordings

    Wang, Li; Song, Yilin; Zhang, Yu; Xu, Shengwei; Xu, Huiren; Wang, Mixia; Wang, Yang; Cai, Xinxia

    2017-11-01

    Norepinephrine (NE), a common neurotransmitter released by locus coeruleus neurons, plays an essential role in the communication mechanism of the mammalian nervous system. In this work, a microelectrode array (MEA) was fabricated by micro-electromechanical system (MEMS) technology to provide a rapid, sensitive and reliable method for the direct determination in NE dynamic secretion. To improve the electrical performance, the MEA was electrodeposited with the reduced graphene oxide and Pt nanoparticles (rGOPNps). rGOPNps-MEA was investigated using scanning electron microscopy, atomic force microscopy and electrochemical impedance spectroscopy, differential pulse voltammetry exhibited remarkably electrocatalytic properties towards NE. Calibration results showed a sensitivity of 1.03 nA µM-1 to NE with a detection limit of 0.08 µM. In Particular, the MEA was successfully used for measuring dynamic extracellular NE secretion from the locus coeruleus brain slice, as well as monitoring spike firing from the hippocampal brain slice. This fabricated device has potential in studies of spatially resolved delivery of trace neurochemicals and electrophysiological activities of a variety of biological tissues in vitro.

  10. Amperometric Self-Referencing Ceramic Based Microelectrode Arrays for D-Serine Detection.

    Campos-Beltrán, Diana; Konradsson-Geuken, Åsa; Quintero, Jorge E; Marshall, Lisa

    2018-03-06

    D-serine is the major D-amino acid in the mammalian central nervous system. As the dominant co-agonist of the endogenous synaptic NMDA receptor, D-serine plays a role in synaptic plasticity, learning, and memory. Alterations in D-serine are linked to neuropsychiatric disorders including schizophrenia. Thus, it is of increasing interest to monitor the concentration of D-serine in vivo as a relevant player in dynamic neuron-glia network activity. Here we present a procedure for amperometric detection of D-serine with self-referencing ceramic-based microelectrode arrays (MEAs) coated with D-amino acid oxidase from the yeast Rhodotorula gracilis (RgDAAO). We demonstrate in vitro D-serine recordings with a mean sensitivity of 8.61 ± 0.83 pA/µM to D-serine, a limit of detection (LOD) of 0.17 ± 0.01 µM, and a selectivity ratio of 80:1 or greater for D-serine over ascorbic acid (mean ± SEM; n = 12) that can be used for freely moving studies.

  11. Depth-time interpolation of feature trends extracted from mobile microelectrode data with kernel functions.

    Wong, Stephen; Hargreaves, Eric L; Baltuch, Gordon H; Jaggi, Jurg L; Danish, Shabbar F

    2012-01-01

    Microelectrode recording (MER) is necessary for precision localization of target structures such as the subthalamic nucleus during deep brain stimulation (DBS) surgery. Attempts to automate this process have produced quantitative temporal trends (feature activity vs. time) extracted from mobile MER data. Our goal was to evaluate computational methods of generating spatial profiles (feature activity vs. depth) from temporal trends that would decouple automated MER localization from the clinical procedure and enhance functional localization in DBS surgery. We evaluated two methods of interpolation (standard vs. kernel) that generated spatial profiles from temporal trends. We compared interpolated spatial profiles to true spatial profiles that were calculated with depth windows, using correlation coefficient analysis. Excellent approximation of true spatial profiles is achieved by interpolation. Kernel-interpolated spatial profiles produced superior correlation coefficient values at optimal kernel widths (r = 0.932-0.940) compared to standard interpolation (r = 0.891). The choice of kernel function and kernel width resulted in trade-offs in smoothing and resolution. Interpolation of feature activity to create spatial profiles from temporal trends is accurate and can standardize and facilitate MER functional localization of subcortical structures. The methods are computationally efficient, enhancing localization without imposing additional constraints on the MER clinical procedure during DBS surgery. Copyright © 2012 S. Karger AG, Basel.

  12. Boron-doped nanocrystalline diamond microelectrode arrays monitor cardiac action potentials.

    Maybeck, Vanessa; Edgington, Robert; Bongrain, Alexandre; Welch, Joseph O; Scorsone, Emanuel; Bergonzo, Philippe; Jackman, Richard B; Offenhäusser, Andreas

    2014-02-01

    The expansion of diamond-based electronics in the area of biological interfacing has not been as thoroughly explored as applications in electrochemical sensing. However, the biocompatibility of diamond, large safe electrochemical window, stability, and tunable electronic properties provide opportunities to develop new devices for interfacing with electrogenic cells. Here, the fabrication of microelectrode arrays (MEAs) with boron-doped nanocrystalline diamond (BNCD) electrodes and their interfacing with cardiomyocyte-like HL-1 cells to detect cardiac action potentials are presented. A nonreductive means of structuring doped and undoped diamond on the same substrate is shown. The resulting BNCD electrodes show high stability under mechanical stress generated by the cells. It is shown that by fabricating the entire surface of the MEA with NCD, in patterns of conductive doped, and isolating undoped regions, signal detection may be improved up to four-fold over BNCD electrodes passivated with traditional isolators. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Porous-microelectrode study on Pt/C catalysts for methanol electrooxidation

    Umeda, Minoru; Kokubo, Mitsuhiro; Mohamedi, Mohamed; Uchida, Isamu

    2003-01-01

    We have developed a porous-microelectrode (PME) to investigate the electroactivity of catalyst particles for proton exchange membrane fuel cells. The cavity at the tip of the PME was filled with Pt/C catalysts prepared by impregnation method. Cyclic voltammograms (CVs) recorded in 1 N H 2 SO 4 aqueous solution revealed that the active area of the stacked catalysts exist not only at the surface but also inside of the stack. For methanol electrooxidation, 30 wt.% Pt/C exhibited the highest electroactivity, whereas the 50 wt.% Pt/C showed extremely small current. The small current is considered as a result of a small active-surface area. Methanol oxidation peak potential shifted toward cathodic direction as Pt-loading decreased, which agrees well with the Pt-oxide formation potential. The activation energy for methanol oxidation was assessed to be 44±3 kJ mol -1 for all Pt/C catalysts and Pt-disc electrode

  14. Te/Pt nanonetwork modified carbon fiber microelectrodes for methanol oxidation

    Tsai, Hsiang-Yu; Shih, Zih-Yu; Lin, Zong-Hong; Chang, Huan-Tsung

    2013-01-01

    Te/Pt nanonetwork-decorated carbon fiber microelectrodes (CFMEs) have been fabricated and employed as anodic catalysts in a direct methanol fuel cell (DMFC). Te nanowires were prepared from tellurite ions (TeO 3 2− ) through a seed-mediated growth process and were deposited onto CFMEs to form three-dimensional Te nanonetworks. The Te nanonetworks then acted as a framework and reducing agent to reduce PtCl 6 2− ions to form Te/Pt through a galvanic replacement reaction, leading to the formation of Te/PtCFMEs. By controlling the reaction time, the amount of Pt and morphology of Te/Pt nanonetworks were controlled, leading to various degrees of electrocatalytic activity. The Te/PtCFMEs provide a high electrochemical active surface area (129.2 m 2 g −1 ), good catalytic activity (1.2 A mg −1 ), high current density (20.0 mA cm −2 ), long durability, and tolerance toward the poisoning species for methanol oxidation in 0.5 M sulfuric acid containing 1 M methanol. We have further demonstrated an enhanced current density by separately using 3 and 5 Te/PtCFMEs. Our results show that the low-cost, stable, and effective Te/PtCFMEs have great potential in the fabrication of cost-effective fuel cells. (paper)

  15. Wearable Multi-Channel Microelectrode Membranes for Elucidating Electrophysiological Phenotypes of Injured Myocardium

    Cao, Hung; Yu, Fei; Zhao, Yu; Zhang, Xiaoxiao; Tai, Joyce; Lee, Juhyun; Darehzereshki, Ali; Bersohn, Malcolm; Lien, Ching-Ling; Chi, Neil C.; Tai, Yu-Chong; Hsiai, Tzung K.

    2014-01-01

    Understanding the regenerative capacity of small vertebrate models has provided new insights into the plasticity of injured myocardium. Here, we demonstrated the application of flexible microelectrode arrays (MEAs) in elucidating electrophysiological phenotypes of zebrafish and neonatal mouse models of heart regeneration. The 4-electrode MEA membranes were designed to detect electrical signals in the aquatic environment. They were micro-fabricated to adhere to the non-planar body surface of zebrafish and neonatal mice. The acquired signals were processed to display electrocardiogram (ECG) with high signal-to-noise-ratios, and were validated via the use of conventional micro-needle electrodes. The 4-channel MEA provided signal stability and spatial resolution, revealing the site-specific electrical injury currents such as ST-depression in response to ventricular cryo-injury. Thus, our polymer-based and wearable MEA membranes provided electrophysiological insights in long-term conduction phenotypes for small vertebral models of heart injury and regeneration with a translational implication for monitoring cardiac patients. PMID:24945366

  16. Interdigitated microelectrode based impedance biosensor for detection of salmonella enteritidis in food samples

    Kim, G [National Institute of Agricultural Engineering, 249 Seodun-dong, Suwon, Republic of Korea, 441-100 (Korea, Republic of); Morgan, M; Hahm, B K; Bhunia, A [Department of Food Science, Purdue University, West Lafayette, IN 47907 (United States); Mun, J H; Om, A S [Department of Food and Nutrient, Hanyang University, 17 Haengdang-dong, Seoul, Republic of Korea, 133-791 (Korea, Republic of)], E-mail: giyoungkim@rda.go.kr

    2008-03-15

    Salmonella enteritidis outbreaks continue to occur, and S. enteritidis-related outbreaks from various food sources have increased public awareness of this pathogen. Conventional methods for pathogens detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Recently developed biosensors have shown great potential for the rapid detection of foodborne pathogens. To develop the biosensor, an interdigitated microelectrode (IME) was fabricated by using semiconductor fabrication process. Anti-Salmonella antibodies were immobilized based on avidin-biotin binding on the surface of the IME to form an active sensing layer. To increase the sensitivity of the sensor, three types of sensors that have different electrode gap sizes (2 {mu}m, 5 {mu}m, 10 {mu}m) were fabricated and tested. The impedimetric biosensor could detect 10{sup 3} CFU/mL of Salmonella in pork meat extract with an incubation time of 5 minutes. This method may provide a simple, rapid and sensitive method to detect foodborne pathogens.

  17. Highly sensitive three-dimensional interdigitated microelectrode for microparticle detection using electrical impedance spectroscopy

    Chang, Fu-Yu; Chen, Ming-Kun; Jang, Ling-Sheng; Wang, Min-Haw

    2016-01-01

    Cell impedance analysis is widely used for monitoring biological and medical reactions. In this study, a highly sensitive three-dimensional (3D) interdigitated microelectrode (IME) with a high aspect ratio on a polyimide (PI) flexible substrate was fabricated for microparticle detection (e.g. cell quantity detection) using electroforming and lithography technology. 3D finite element simulations were performed to compare the performance of the 3D IME (in terms of sensitivity and signal-to-noise ratio) to that of a planar IME for particles in the sensing area. Various quantities of particles were captured in Dulbecco’s modified Eagle medium and their impedances were measured. With the 3D IME, the particles were arranged in the gap, not on the electrode, avoiding the noise due to particle position. For the maximum particle quantities, the results show that the 3D IME has at least 5-fold higher sensitivity than that of the planar IME. The trends of impedance magnitude and phase due to particle quantity were verified using the equivalent circuit model. The impedance (1269 Ω) of 69 particles was used to estimate the particle quantity (68 particles) with 98.6% accuracy using a parabolic regression curve at 500 kHz. (paper)

  18. Bioelectronic tongue of taste buds on microelectrode array for salt sensing.

    Liu, Qingjun; Zhang, Fenni; Zhang, Diming; Hu, Ning; Wang, Hua; Hsia, K Jimmy; Wang, Ping

    2013-02-15

    Taste has received great attention for its potential applications. In this work, we combine the biological tissue with micro-chips to establish a novel bioelectronic tongue system for salt taste detection. Before experiment, we established a computational model of action potential in salt taste receptor cell, simulating the responsive results to natural salt stimuli of NaCl solution with various concentrations. Then 36-channel microelectrode arrays (MEA) with the diameter of 30 μm were fabricated on the glass substrate, and taste epithelium was stripped from rat and fixed on MEA. When stimulated by the salt stimuli, electrophysiological activities of taste receptor cells in taste buds were measured through a multi-channel recording system. Both simulation and experiment results showed a dose-dependent increase in NaCl-induced potentials of taste receptor cells, which indicated good applications in salt measurements. The multi-channel analysis demonstrated that different groups of MEA channels were activated during stimulations, indicating non-overlapping populations of receptor cells in taste buds involved in salt taste perception. The study provides an effective and reliable biosensor platform to help recognize and distinguish salt taste components. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Neural Networks

    Schwindling Jerome

    2010-04-01

    Full Text Available This course presents an overview of the concepts of the neural networks and their aplication in the framework of High energy physics analyses. After a brief introduction on the concept of neural networks, the concept is explained in the frame of neuro-biology, introducing the concept of multi-layer perceptron, learning and their use as data classifer. The concept is then presented in a second part using in more details the mathematical approach focussing on typical use cases faced in particle physics. Finally, the last part presents the best way to use such statistical tools in view of event classifers, putting the emphasis on the setup of the multi-layer perceptron. The full article (15 p. corresponding to this lecture is written in french and is provided in the proceedings of the book SOS 2008.

  20. Stimulation and recording electrodes for neural prostheses

    Pour Aryan, Naser; Rothermel, Albrecht

    2015-01-01

    This book provides readers with basic principles of the electrochemistry of the electrodes used in modern, implantable neural prostheses. The authors discuss the boundaries and conditions in which the electrodes continue to function properly for long time spans, which are required when designing neural stimulator devices for long-term in vivo applications. Two kinds of electrode materials, titanium nitride and iridium are discussed extensively, both qualitatively and quantitatively. The influence of the counter electrode on the safety margins and electrode lifetime in a two electrode system is explained. Electrode modeling is handled in a final chapter.

  1. Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

    Gordon, K A; Papsin, B C; Harrison, R V

    2007-08-01

    The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.

  2. Implantable Medical Devices

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Implantable Medical Devices Updated:Sep 16,2016 For Rhythm Control ... a Heart Attack Introduction Medications Surgical Procedures Implantable Medical Devices • Life After a Heart Attack • Heart Attack ...

  3. Intercavitary implants dosage calculation

    Rehder, B.P.

    The use of spacial geometry peculiar to each treatment for the attainment of intercavitary and intersticial implants dosage calculation is presented. The study is made in patients with intercavitary implants by applying a modified Manchester technique [pt

  4. Implantable electronic medical devices

    Fitzpatrick, Dennis

    2014-01-01

    Implantable Electronic Medical Devices provides a thorough review of the application of implantable devices, illustrating the techniques currently being used together with overviews of the latest commercially available medical devices. This book provides an overview of the design of medical devices and is a reference on existing medical devices. The book groups devices with similar functionality into distinct chapters, looking at the latest design ideas and techniques in each area, including retinal implants, glucose biosensors, cochlear implants, pacemakers, electrical stimulation t

  5. Wireless microsensor network solutions for neurological implantable devices

    Abraham, Jose K.; Whitchurch, Ashwin; Varadan, Vijay K.

    2005-05-01

    The design and development of wireless mocrosensor network systems for the treatment of many degenerative as well as traumatic neurological disorders is presented in this paper. Due to the advances in micro and nano sensors and wireless systems, the biomedical sensors have the potential to revolutionize many areas in healthcare systems. The integration of nanodevices with neurons that are in communication with smart microsensor systems has great potential in the treatment of many neurodegenerative brain disorders. It is well established that patients suffering from either Parkinson"s disease (PD) or Epilepsy have benefited from the advantages of implantable devices in the neural pathways of the brain to alter the undesired signals thus restoring proper function. In addition, implantable devices have successfully blocked pain signals and controlled various pelvic muscles in patients with urinary and fecal incontinence. Even though the existing technology has made a tremendous impact on controlling the deleterious effects of disease, it is still in its infancy. This paper presents solutions of many problems of today's implantable and neural-electronic interface devices by combining nanowires and microelectronics with BioMEMS and applying them at cellular level for the development of a total wireless feedback control system. The only device that will actually be implanted in this research is the electrodes. All necessary controllers will be housed in accessories that are outside the body that communicate with the implanted electrodes through tiny inductively-coupled antennas. A Parkinson disease patient can just wear a hat-system close to the implantable neural probe so that the patient is free to move around, while the sensors continually monitor, record, transmit all vital information to health care specialist. In the event of a problem, the system provides an early warning to the patient while they are still mobile thus providing them the opportunity to react and

  6. Spontaneous and Evoked Activity from Murine Ventral Horn Cultures on Microelectrode Arrays

    Bryan J. Black

    2017-09-01

    Full Text Available Motor neurons are the site of action for several neurological disorders and paralytic toxins, with cell bodies located in the ventral horn (VH of the spinal cord along with interneurons and support cells. Microelectrode arrays (MEAs have emerged as a high content assay platform for mechanistic studies and drug discovery. Here, we explored the spontaneous and evoked electrical activity of VH cultures derived from embryonic mouse spinal cord on multi-well plates of MEAs. Primary VH cultures from embryonic day 15–16 mice were characterized by expression of choline acetyltransferase (ChAT by immunocytochemistry. Well resolved, all-or-nothing spontaneous spikes with profiles consistent with extracellular action potentials were observed after 3 days in vitro, persisting with consistent firing rates until at least day in vitro 19. The majority of the spontaneous activity consisted of tonic firing interspersed with coordinated bursting across the network. After 5 days in vitro, spike activity was readily evoked by voltage pulses where a minimum amplitude and duration required for excitation was 300 mV and 100 μs/phase, respectively. We characterized the sensitivity of spontaneous and evoked activity to a host of pharmacological agents including AP5, CNQX, strychnine, ω-agatoxin IVA, and botulinum neurotoxin serotype A (BoNT/A. These experiments revealed sensitivity of the cultured VH to both agonist and antagonist compounds in a manner consistent with mature tissue derived from slices. In the case of BoNT/A, we also demonstrated intoxication persistence over an 18-day period, followed by partial intoxication recovery induced by N- and P/Q-type calcium channel agonist GV-58. In total, our findings suggest that VH cultures on multi-well MEA plates may represent a moderate throughput, high content assay for performing mechanistic studies and for screening potential therapeutics pertaining to paralytic toxins and neurological disorders.

  7. Multivariate regression methods for estimating velocity of ictal discharges from human microelectrode recordings

    Liou, Jyun-you; Smith, Elliot H.; Bateman, Lisa M.; McKhann, Guy M., II; Goodman, Robert R.; Greger, Bradley; Davis, Tyler S.; Kellis, Spencer S.; House, Paul A.; Schevon, Catherine A.

    2017-08-01

    Objective. Epileptiform discharges, an electrophysiological hallmark of seizures, can propagate across cortical tissue in a manner similar to traveling waves. Recent work has focused attention on the origination and propagation patterns of these discharges, yielding important clues to their source location and mechanism of travel. However, systematic studies of methods for measuring propagation are lacking. Approach. We analyzed epileptiform discharges in microelectrode array recordings of human seizures. The array records multiunit activity and local field potentials at 400 micron spatial resolution, from a small cortical site free of obstructions. We evaluated several computationally efficient statistical methods for calculating traveling wave velocity, benchmarking them to analyses of associated neuronal burst firing. Main results. Over 90% of discharges met statistical criteria for propagation across the sampled cortical territory. Detection rate, direction and speed estimates derived from a multiunit estimator were compared to four field potential-based estimators: negative peak, maximum descent, high gamma power, and cross-correlation. Interestingly, the methods that were computationally simplest and most efficient (negative peak and maximal descent) offer non-inferior results in predicting neuronal traveling wave velocities compared to the other two, more complex methods. Moreover, the negative peak and maximal descent methods proved to be more robust against reduced spatial sampling challenges. Using least absolute deviation in place of least squares error minimized the impact of outliers, and reduced the discrepancies between local field potential-based and multiunit estimators. Significance. Our findings suggest that ictal epileptiform discharges typically take the form of exceptionally strong, rapidly traveling waves, with propagation detectable across millimeter distances. The sequential activation of neurons in space can be inferred from clinically

  8. Trends in cochlear implants.

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management.

  9. Benefits and Risks of Cochlear Implants

    ... and Medical Procedures Implants and Prosthetics Cochlear Implants Benefits and Risks of Cochlear Implants Share Tweet Linkedin ... the Use of Cochlear Implants What are the Benefits of Cochlear Implants? For people with implants: Hearing ...

  10. Evaluating cochlear implant trauma to the scala vestibuli.

    Adunka, O; Kiefer, J; Unkelbach, M H; Radeloff, A; Gstoettner, W

    2005-04-01

    Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. Human temporal bone study with histological and radiological evaluation. Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. Cochlear trauma and intracochlear positions. All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing.

  11. Characterization of Early Cortical Neural Network ...

    We examined the development of neural network activity using microelectrode array (MEA) recordings made in multi-well MEA plates (mwMEAs) over the first 12 days in vitro (DIV). In primary cortical cultures made from postnatal rats, action potential spiking activity was essentially absent on DIV 2 and developed rapidly between DIV 5 and 12. Spiking activity was primarily sporadic and unorganized at early DIV, and became progressively more organized with time in culture, with bursting parameters, synchrony and network bursting increasing between DIV 5 and 12. We selected 12 features to describe network activity and principal components analysis using these features demonstrated a general segregation of data by age at both the well and plate levels. Using a combination of random forest classifiers and Support Vector Machines, we demonstrated that 4 features (CV of within burst ISI, CV of IBI, network spike rate and burst rate) were sufficient to predict the age (either DIV 5, 7, 9 or 12) of each well recording with >65% accuracy. When restricting the classification problem to a binary decision, we found that classification improved dramatically, e.g. 95% accuracy for discriminating DIV 5 vs DIV 12 wells. Further, we present a novel resampling approach to determine the number of wells that might be needed for conducting comparisons of different treatments using mwMEA plates. Overall, these results demonstrate that network development on mwMEA plates is similar to

  12. New Criteria of Indication and Selection of Patients to Cochlear Implant

    André L. L. Sampaio

    2011-01-01

    Full Text Available Numerous changes continue to occur in cochlear implant candidacy. In general, these have been accompanied by concomitant and satisfactory changes in surgical techniques. Together, this has advanced the utility and safety of cochlear implantation. Most devices are now approved for use in patients with severe to profound unilateral hearing loss rather then the prior requirement of a bilateral profound loss. Furthermore, studies have begun utilizing short electrode arrays for shallow insertion in patients with considerable low-frequency residual hearing. This technique will allow the recipient to continue to use acoustically amplified hearing for the low frequencies simultaneously with a cochlear implant for the high frequencies. The advances in design of, and indications for, cochlear implants have been matched by improvements in surgical techniques and decrease in complications. The resulting improvements in safety and efficacy have further encouraged the use of these devices. This paper will review the new concepts in the candidacy of cochlear implant. Medline data base was used to search articles dealing with the following topics: cochlear implant in younger children, cochlear implant and hearing preservation, cochlear implant for unilateral deafness and tinnitus, genetic hearing loss and cochlear implant, bilateral cochlear implant, neuropathy and cochlear implant and neural plasticity, and the selection of patients for cochlear implant.

  13. Importance of Thickness in Human Cardiomyocyte Network for Effective Electrophysiological Stimulation Using On-Chip Extracellular Microelectrodes

    Hamada, Tomoyo; Nomura, Fumimasa; Kaneko, Tomoyuki; Yasuda, Kenji

    2012-06-01

    We have developed a three-dimensionally controlled in vitro human cardiomyocyte network assay for the measurements of drug-induced conductivity changes and the appearance of fatal arrhythmia such as ventricular tachycardia/fibrillation for more precise in vitro predictive cardiotoxicity. To construct an artificial conductance propagation model of a human cardiomyocyte network, first, we examined the cell concentration dependence of the cell network heights and found the existence of a height limit of cell networks, which was double-layer height, whereas the cardiomyocytes were effectively and homogeneously cultivated within the microchamber maintaining their spatial distribution constant and their electrophysiological conductance and propagation were successfully recorded using a microelectrode array set on the bottom of the microchamber. The pacing ability of a cardiomyocyte's electrophysiological response has been evaluated using microelectrode extracellular stimulation, and the stimulation for pacing also successfully regulated the beating frequencies of two-layered cardiomyocyte networks, whereas monolayered cardiomyocyte networks were hardly stimulated by the external electrodes using the two-layered cardiomyocyte stimulation condition. The stability of the lined-up shape of human cardiomyocytes within the rectangularly arranged agarose microchambers was limited for a two-layered cardiomyocyte network because their stronger force generation shrunk those cells after peeling off the substrate. The results indicate the importance of fabrication technology of thickness control of cellular networks for effective extracellular stimulation and the potential concerning thick cardiomyocyte networks for long-term cultivation.

  14. A feasibility study of multi-site,intracellular recordings from mammalian neurons by extracellular gold mushroom-shaped microelectrodes.

    Ojovan, Silviya M; Rabieh, Noha; Shmoel, Nava; Erez, Hadas; Maydan, Eilon; Cohen, Ariel; Spira, Micha E

    2015-09-14

    The development of multi-electrode array platforms for large scale recording of neurons is at the forefront of neuro-engineering research efforts. Recently we demonstrated, at the proof-of-concept level, a breakthrough neuron-microelectrode interface in which cultured Aplysia neurons tightly engulf gold mushroom-shaped microelectrodes (gMμEs). While maintaining their extracellular position, the gMμEs record synaptic- and action-potentials with characteristic features of intracellular recordings. Here we examined the feasibility of using gMμEs for intracellular recordings from mammalian neurons. To that end we experimentally examined the innate size limits of cultured rat hippocampal neurons to engulf gMμEs and measured the width of the "extracellular" cleft formed between the neurons and the gold surface. Using the experimental results we next analyzed the expected range of gMμEs-neuron electrical coupling coefficients. We estimated that sufficient electrical coupling levels to record attenuated synaptic- and action-potentials can be reached using the gMμE-neuron configuration. The definition of the engulfment limits of the gMμEs caps diameter at ≤2-2.5 μm and the estimated electrical coupling coefficients from the simulations pave the way for rational development and application of the gMμE based concept for in-cell recordings from mammalian neurons.

  15. In situ 2D maps of pH shifts across brass–lead galvanic joints using microelectrodes

    Ma, Xiangmeng; Lee, Woo Hyoung; Lytle, Darren A

    2017-01-01

    Galvanic corrosion in drinking water distribution systems, such as conditions following partial lead service line replacement, can be a significant source of lead in tap water. The objective of this work was to measure the pH directly near metal surfaces using a novel experimental tool in order to understand the water chemistry at a lead-containing galvanic couple in drinking water. Specifically, pH microprofiles in the proximity of corroding metal surfaces were measured using a microelectrode to construct detailed in situ 2D spatial maps of the pH across a galvanic couple at 100 µ m above the metal’s surface under flowing and stagnation conditions. The opposite pH trend was directly observed across the galvanic couple under flow and stagnation conditions. Water stagnation resulted in a pH at the anode (leaded solder) of 1.5 pH units lower than the bulk water pH (9.0) and as much as 2.5 pH units lower than the cathode (brass). These conditions can enhance lead release at the anode, which reflects different anodic–cathodic relationships of coupled metals primarily controlled by water flow. Most importantly, this work has demonstrated the ability to make real pH measurement at the surface of corroding metals using a novel microelectrode approach. (paper)

  16. Creation of defined single cell resolution neuronal circuits on microelectrode arrays

    Pirlo, Russell Kirk

    2009-12-01

    The way cell-cell organization of neuronal networks influences activity and facilitates function is not well understood. Microelectrode arrays (MEAs) and advancing cell patterning technologies have enabled access to and control of in vitro neuronal networks spawning much new research in neuroscience and neuroengineering. We propose that small, simple networks of neurons with defined circuitry may serve as valuable research models where every connection can be analyzed, controlled and manipulated. Towards the goal of creating such neuronal networks we have applied microfabricated elastomeric membranes, surface modification and our unique laser cell patterning system to create defined neuronal circuits with single-cell precision on MEAs. Definition of synaptic connectivity was imposed by the 3D physical constraints of polydimethylsiloxane elastomeric membranes. The membranes had 20mum clear-through holes and 2-3mum deep channels which when applied to the surface of the MEA formed microwells to confine neurons to electrodes connected via shallow tunnels to direct neurite outgrowth. Tapering and turning of channels was used to influence neurite polarity. Biocompatibility of the membranes was increased by vacuum baking, oligomer extraction, and autoclaving. Membranes were bound to the MEA by oxygen plasma treatment and heated pressure. The MEA/membrane surface was treated with oxygen plasma, poly-D-lysine and laminin to improve neuron attachment, survival and neurite outgrowth. Prior to cell patterning the outer edge of culture area was seeded with 5x10 5 cells per cm and incubated for 2 days. Single embryonic day 7 chick forebrain neurons were then patterned into the microwells and onto the electrodes using our laser cell patterning system. Patterned neurons successfully attached to and were confined to the electrodes. Neurites extended through the interconnecting channels and connected with adjacent neurons. These results demonstrate that neuronal circuits can be

  17. Neurotoxicity screening of (illicit) drugs using novel methods for analysis of microelectrode array (MEA) recordings.

    Hondebrink, L; Verboven, A H A; Drega, W S; Schmeink, S; de Groot, M W G D M; van Kleef, R G D M; Wijnolts, F M J; de Groot, A; Meulenbelt, J; Westerink, R H S

    2016-07-01

    Annual prevalence of the use of common illicit drugs and new psychoactive substances (NPS) is high, despite the often limited knowledge on the health risks of these substances. Recently, cortical cultures grown on multi-well microelectrode arrays (mwMEAs) have been used for neurotoxicity screening of chemicals, pharmaceuticals, and toxins with a high sensitivity and specificity. However, the use of mwMEAs to investigate the effects of illicit drugs on neuronal activity is largely unexplored. We therefore first characterised the cortical cultures using immunocytochemistry and show the presence of astrocytes, glutamatergic and GABAergic neurons. Neuronal activity is concentration-dependently affected following exposure to six neurotransmitters (glutamate, GABA, serotonin, dopamine, acetylcholine and nicotine). Most neurotransmitters inhibit neuronal activity, although glutamate and acetylcholine transiently increase activity at specific concentrations. These transient effects are not detected when activity is determined during the entire 30min exposure window, potentially resulting in false-negative results. As expected, exposure to the GABAA-receptor antagonist bicuculline increases neuronal activity. Exposure to a positive allosteric modulator of the GABAA-receptor (diazepam) or to glutamate receptor antagonists (CNQX and MK-801) reduces neuronal activity. Further, we demonstrate that exposure to common drugs (3,4-methylenedioxymethamphetamine (MDMA) and amphetamine) and NPS (1-(3-chlorophenyl)piperazine (mCPP), 4-fluoroamphetamine (4-FA) and methoxetamine (MXE)) decreases neuronal activity. MXE most potently inhibits neuronal activity with an IC50 of 0.5μM, whereas 4-FA is least potent with an IC50 of 113μM. Our data demonstrate the importance of analysing neuronal activity within different time windows during exposure to prevent false-negative results. We also show that cortical cultures grown on mwMEAs can successfully be applied to investigate the effects of

  18. Optical effects of ion implantation

    Townsend, P.D.

    1987-01-01

    The review concerns the effects of ion implantation that specifically relate to the optical properties of insulators. Topics which are reviewed include: ion implantation, ion range and damage distributions, colour centre production by ion implantation, high dose ion implantation, and applications for integrated optics. Numerous examples are presented of both diagnostic and industrial examples of ion implantation effects in insulators. (U.K.)

  19. Ion implantation in semiconductors

    Gusev, V.; Gusevova, M.

    1980-01-01

    The historical development is described of the method of ion implantation, the physical research of the method, its technological solution and practical uses. The method is universally applicable, allows the implantation of arbitrary atoms to an arbitrary material, ensures high purity of the doping element. It is linked with sample processing at low temperatures. In implantation it is possible to independently change the dose and energy of the ions thereby affecting the spatial distribution of the ions. (M.S.)

  20. Ion implantation in semiconductors

    Gusev, V; Gusevova, M

    1980-06-01

    The historical development of the method of ion implantation, the physical research of the method, its technological solution and practical uses is described. The method is universally applicable, allows the implantation of arbitrary atoms to an arbitrary material and ensures high purity of the doping element. It is linked with sample processing at low temperatures. In implantation it is possible to independently change the dose and energy of the ions thereby affecting the spatial distribution of the ions.

  1. Trends in Cochlear Implants

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic as...

  2. Audiological outcomes of cochlear implantation in Waardenburg Syndrome

    Magalhães, Ana Tereza de Matos

    2014-01-01

    Full Text Available Introduction: The most relevant clinical symptom in Waardenburg syndrome is profound bilateral sensorioneural hearing loss. Aim: To characterize and describe hearing outcomes after cochlear implantation in patients with Waardenburg syndrome to improve preoperative expectations. Method: This was an observational and retrospective study of a series of cases. Children who were diagnosed with Waardenburg syndrome and who received a multichannel cochlear implant between March 1999 and July 2012 were included in the study. Intraoperative neural response telemetry, hearing evaluation, speech perception, and speech production data before and after surgery were assessed. Results: During this period, 806 patients received a cochlear implant and 10 of these (1.2% were diagnosed with Waardenburg syndrome. Eight of the children received a Nucleus 24® implant and 1 child and 1 adult received a DigiSonic SP implant. The mean age at implantation was 44 months among the children. The average duration of use of a cochlear implant at the time of the study was 43 months. Intraoperative neural responses were present in all cases. Patients who could use the speech processor effectively had a pure tone average of 31 dB in free-field conditions. In addition, the MUSS and MAIS questionnaires revealed improvements in speech perception and production. Four patients did not have a good outcome, which might have been associated with ineffective use of the speech processor. Conclusion: Despite the heterogeneity of the group, patients with Waardenburg syndrome who received cochlear implants were found to have hearing thresholds that allowed access to speech sounds. However, patients who received early intervention and rehabilitation showed better evolution of auditory perception.

  3. Audiological outcomes of cochlear implantation in Waardenburg Syndrome.

    Magalhães, Ana Tereza de Matos; Samuel, Paola Angélica; Goffi-Gomez, Maria Valeria Schimdt; Tsuji, Robinson Koji; Brito, Rubens; Bento, Ricardo Ferreira

    2013-07-01

     The most relevant clinical symptom in Waardenburg syndrome is profound bilateral sensorioneural hearing loss.  To characterize and describe hearing outcomes after cochlear implantation in patients with Waardenburg syndrome to improve preoperative expectations.  This was an observational and retrospective study of a series of cases. Children who were diagnosed with Waardenburg syndrome and who received a multichannel cochlear implant between March 1999 and July 2012 were included in the study. Intraoperative neural response telemetry, hearing evaluation, speech perception, and speech production data before and after surgery were assessed.  During this period, 806 patients received a cochlear implant and 10 of these (1.2%) were diagnosed with Waardenburg syndrome. Eight of the children received a Nucleus 24(®) implant and 1 child and 1 adult received a DigiSonic SP implant. The mean age at implantation was 44 months among the children. The average duration of use of a cochlear implant at the time of the study was 43 months. Intraoperative neural responses were present in all cases. Patients who could use the speech processor effectively had a pure tone average of 31 dB in free-field conditions. In addition, the MUSS and MAIS questionnaires revealed improvements in speech perception and production. Four patients did not have a good outcome, which might have been associated with ineffective use of the speech processor.  Despite the heterogeneity of the group, patients with Waardenburg syndrome who received cochlear implants were found to have hearing thresholds that allowed access to speech sounds. However, patients who received early intervention and rehabilitation showed better evolution of auditory perception.

  4. Ion implantation technology

    Downey, DF; Jones, KS; Ryding, G

    1993-01-01

    Ion implantation technology has made a major contribution to the dramatic advances in integrated circuit technology since the early 1970's. The ever-present need for accurate models in ion implanted species will become absolutely vital in the future due to shrinking feature sizes. Successful wide application of ion implantation, as well as exploitation of newly identified opportunities, will require the development of comprehensive implant models. The 141 papers (including 24 invited papers) in this volume address the most recent developments in this field. New structures and possible approach

  5. High energy ion implantation

    Ziegler, J.F.

    1985-01-01

    High energy ion implantation offers the oppertunity for unique structures in semiconductor processing. The unusual physical properties of such implantations are discussed as well as the special problems in masking and damage annealing. A review is made of proposed circuit structures which involve deep implantation. Examples are: deep buried bipolar collectors fabricated without epitaxy, barrier layers to reduce FET memory sensitivity to soft-fails, CMOS isolation well structures, MeV implantation for customization and correction of completed circuits, and graded reach-throughs to deep active device components. (orig.)

  6. [Silastic implant and synovitis].

    Sennwald, G

    1989-07-22

    The silastic implant based on siloxane polymere induces granulomatous synovitis in certain predisposed individuals, a reaction which may continue even after removal of the implant. This is also true of a prosthesis of the trapezium in two of our patients, though to a lesser degree. This is probably the reason why the problem has not yet been widely recognized. The hypothesis is put forward that an enzymatic predisposition may allow chemical degradation of the fragmented silastic implant into a toxic component responsible for the pathologic condition. The slow progression of the lesions is a challenge for the future and puts in question the further use of silastic implants.

  7. Cochlear implant magnet retrofit.

    Cohen, N L; Breda, S D; Hoffman, R A

    1988-06-01

    An implantable magnet is now available for patients who have received the standard Nucleus 22-channel cochlear implant and who are not able to wear the headband satisfactorily. This magnet is attached in piggy-back fashion to the previously implanted receiver/stimulator by means of a brief operation under local anesthesia. Two patients have received this magnet retrofit, and are now wearing the headset with greater comfort and satisfaction. It is felt that the availability of this magnet will increase patient compliance in regard to hours of implant usage.

  8. Spatial channel interactions in cochlear implants

    Tang, Qing; Benítez, Raul; Zeng, Fan-Gang

    2011-08-01

    The modern multi-channel cochlear implant is widely considered to be the most successful neural prosthesis owing to its ability to restore partial hearing to post-lingually deafened adults and to allow essentially normal language development in pre-lingually deafened children. However, the implant performance varies greatly in individuals and is still limited in background noise, tonal language understanding, and music perception. One main cause for the individual variability and the limited performance in cochlear implants is spatial channel interaction from the stimulating electrodes to the auditory nerve and brain. Here we systematically examined spatial channel interactions at the physical, physiological, and perceptual levels in the same five modern cochlear implant subjects. The physical interaction was examined using an electric field imaging technique, which measured the voltage distribution as a function of the electrode position in the cochlea in response to the stimulation of a single electrode. The physiological interaction was examined by recording electrically evoked compound action potentials as a function of the electrode position in response to the stimulation of the same single electrode position. The perceptual interactions were characterized by changes in detection threshold as well as loudness summation in response to in-phase or out-of-phase dual-electrode stimulation. To minimize potentially confounding effects of temporal factors on spatial channel interactions, stimulus rates were limited to 100 Hz or less in all measurements. Several quantitative channel interaction indexes were developed to define and compare the width, slope and symmetry of the spatial excitation patterns derived from these physical, physiological and perceptual measures. The electric field imaging data revealed a broad but uniformly asymmetrical intracochlear electric field pattern, with the apical side producing a wider half-width and shallower slope than the basal

  9. Efficient universal computing architectures for decoding neural activity.

    Benjamin I Rapoport

    Full Text Available The ability to decode neural activity into meaningful control signals for prosthetic devices is critical to the development of clinically useful brain- machine interfaces (BMIs. Such systems require input from tens to hundreds of brain-implanted recording electrodes in order to deliver robust and accurate performance; in serving that primary function they should also minimize power dissipation in order to avoid damaging neural tissue; and they should transmit data wirelessly in order to minimize the risk of infection associated with chronic, transcutaneous implants. Electronic architectures for brain- machine interfaces must therefore minimize size and power consumption, while maximizing the ability to compress data to be transmitted over limited-bandwidth wireless channels. Here we present a system of extremely low computational complexity, designed for real-time decoding of neural signals, and suited for highly scalable implantable systems. Our programmable architecture is an explicit implementation of a universal computing machine emulating the dynamics of a network of integrate-and-fire neurons; it requires no arithmetic operations except for counting, and decodes neural signals using only computationally inexpensive logic operations. The simplicity of this architecture does not compromise its ability to compress raw neural data by factors greater than [Formula: see text]. We describe a set of decoding algorithms based on this computational architecture, one designed to operate within an implanted system, minimizing its power consumption and data transmission bandwidth; and a complementary set of algorithms for learning, programming the decoder, and postprocessing the decoded output, designed to operate in an external, nonimplanted unit. The implementation of the implantable portion is estimated to require fewer than 5000 operations per second. A proof-of-concept, 32-channel field-programmable gate array (FPGA implementation of this portion

  10. Percutaneous and skeletal biocarbon implants

    Mooney, V.

    1977-01-01

    Review of carbon implants developed by NASA discussed four different types of implants and subsequent improvements. Improvements could be of specific interest to rehabilitation centers and similar organizations.

  11. Degradable Implantate: Entwicklungsbeispiele

    Ruffieux, Kurt; Wintermantel, Erich

    Resorbierbare Implantate werden seit mehreren Jahrzehnten in der Implantologie eingesetzt. Bekannt wurden diese Biomaterialien mit dem Aufkommen von sich selbst auflösenden Nahtfäden auf der Basis von synthetisch hergestellten Polylactiden und Polyglycoliden in den 70er Jahren. In einem nächsten Schritt wurden Implantate wie Platten und Schrauben zur Gewebefixation aus den gleichen Biomaterialien hergestellt.

  12. Risks of Breast Implants

    ... have a risk of developing a type of cancer called breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) in the breast tissue surrounding the implant. BIA-ALCL is not breast cancer. Women diagnosed with BIA-ALCL may need to ...

  13. Ion implantation of metals

    Dearnaley, G.

    1976-01-01

    In this part of the paper descriptions are given of the effects of ion implantation on (a) friction and wear in metals; and (b) corrosion of metals. In the study of corrosion, ion implantation can be used either to introduce a constituent that is known to convey corrosion resistance, or more generally to examine the parameters which control corrosion. (U.K.)

  14. Ion implantation into diamond

    Sato, Susumu

    1994-01-01

    The graphitization and the change to amorphous state of diamond surface layer by ion implantation and its characteristics are reported. In the diamond surface, into which more than 10 16 ions/cm 2 was implanted, the diamond crystals are broken, and the structure changes to other carbon structure such as amorphous state or graphite. Accompanying this change of structure, the electric conductivity of the implanted layer shows two discontinuous values due to high resistance and low resistance. This control of structure can be done by the temperature of the base during the ion implantation into diamond. Also it is referred to that by the base temperature during implantation, the mutual change of the structure between amorphous state and graphite can be controlled. The change of the electric resistance and the optical characteristics by the ion implantation into diamond surface, the structural analysis by Raman spectroscopy, and the control of the structure of the implanted layer by the base temperature during implantation are reported. (K.I.)

  15. Number of implants for mandibular implant overdentures: a systematic review

    Lee, Jeong-Yol; Kim, Ha-Young; Bryant, S. Ross

    2012-01-01

    PURPOSE The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants. PMID:23236572

  16. Ion implantation into iron

    Iwaki, Masaya

    1978-01-01

    The distribution of implanted ions in iron, the friction characteristics and the corrosion of iron were studied. The distribution of Ni or Cr ions implanted into mild steel was measured. The accelerated voltage was 150 keV, and the beam current density was about 2 microampere/cm 2 . The measurement was made with an ion microanalyzer. The measured distribution was compared with that of LSS theory. Deep invasion of Ni was seen in the measured distribution. The distribution of Cr ions was different from the distribution calculated by the LSS theory. The relative friction coefficient of mild steel varied according to the dose of implanted Cu or N ions, and to the accelerating voltage. Formation of compound metals on the surfaces of metals by ion-implantation was investigated for the purpose to prevent the corrosion of metals. The resistance of mild steel in which Ni ions were implanted was larger than that of mild steel without any treatment. (Kato, T.)

  17. [Cochlear implant in children: rational, indications and cost/efficacy].

    Martini, A; Bovo, R; Trevisi, P; Forli, F; Berrettini, S

    2013-06-01

    A cochlear implant (CI) is a partially implanted electronic device that can help to provide a sense of sound and support speech to severely to profoundly hearing impaired patients. It is constituted by an external portion, that usually sits behind the ear and an internal portion surgically placed under the skin. The external components include a microphone connected to a speech processor that selects and arranges sounds pucked up by the microphone. This is connected to a transmitter coil, worn on the side of the head, which transmits data to an internal receiver coil placed under the skin. The received data are delivered to an array of electrodes that are surgically implanted within the cochlea. The primary neural targets of the electrodes are the spiral ganglion cells which innervate fibers of the auditory nerve. When the electrodes are activated by the signal, they send a current along the auditory nerve and auditory pathways to the auditory cortex. Children and adults who are profoundly or severely hearing impaired can be fitted with cochlear implants. According to the Food and Drug Administration, approximately 188,000 people worldwide have received implants. In Italy it is extimated that there are about 6-7000 implanted patients, with an average of 700 CI surgeries per year. Cochlear implantation, followed by intensive postimplantation speech therapy, can help young children to acquire speech, language, and social skills. Early implantation provides exposure to sounds that can be helpful during the critical period when children learn speech and language skills. In 2000, the Food and Drug Administration lowered the age of eligibility to 12 months for one type of CI. With regard to the results after cochlear implantation in relation to early implantation, better linguistic results are reported in children implanted before 12 months of life, even if no sufficient data exist regarding the relation between this advantage and the duration of implant use and how long

  18. A Microelectrode Array with Reproducible Performance Shows Loss of Consistency Following Functionalization with a Self-Assembled 6-Mercapto-1-hexanol Layer

    Damion K. Corrigan

    2018-06-01

    Full Text Available For analytical applications involving label-free biosensors and multiple measurements, i.e., across an electrode array, it is essential to develop complete sensor systems capable of functionalization and of producing highly consistent responses. To achieve this, a multi-microelectrode device bearing twenty-four equivalent 50 µm diameter Pt disc microelectrodes was designed in an integrated 3-electrode system configuration and then fabricated. Cyclic voltammetry and electrochemical impedance spectroscopy were used for initial electrochemical characterization of the individual working electrodes. These confirmed the expected consistency of performance with a high degree of measurement reproducibility for each microelectrode across the array. With the aim of assessing the potential for production of an enhanced multi-electrode sensor for biomedical use, the working electrodes were then functionalized with 6-mercapto-1-hexanol (MCH. This is a well-known and commonly employed surface modification process, which involves the same principles of thiol attachment chemistry and self-assembled monolayer (SAM formation commonly employed in the functionalization of electrodes and the formation of biosensors. Following this SAM formation, the reproducibility of the observed electrochemical signal between electrodes was seen to decrease markedly, compromising the ability to achieve consistent analytical measurements from the sensor array following this relatively simple and well-established surface modification. To successfully and consistently functionalize the sensors, it was necessary to dilute the constituent molecules by a factor of ten thousand to support adequate SAM formation on microelectrodes. The use of this multi-electrode device therefore demonstrates in a high throughput manner irreproducibility in the SAM formation process at the higher concentration, even though these electrodes are apparently functionalized simultaneously in the same film

  19. Conducting polymer coated neural recording electrodes

    Harris, Alexander R.; Morgan, Simeon J.; Chen, Jun; Kapsa, Robert M. I.; Wallace, Gordon G.; Paolini, Antonio G.

    2013-02-01

    Objective. Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Approach. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. Main results. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. Significance. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during

  20. Influence of Palatal Coverage and Implant Distribution on Implant Strain in Maxillary Implant Overdentures.

    Takahashi, Toshihito; Gonda, Tomoya; Mizuno, Yoko; Fujinami, Yozo; Maeda, Yoshinobu

    2016-01-01

    Maxillary implant overdentures are often used in clinical practice. However, there is no agreement or established guidelines regarding prosthetic design or optimal implant placement configuration. The purpose of this study was to examine the influence of palatal coverage and implant number and distribution in relation to impact strain under maxillary implant overdentures. A maxillary edentulous model with implants and experimental overdentures with and without palatal coverage was fabricated. Four strain gauges were attached to each implant, and they were positioned in the anterior, premolar, and molar areas. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the implant strains were compared using one-way analysis of variance (P = .05). The palatolabial strain was much higher on anterior implants than on other implants in both denture types. Although there was no significant difference between the strain under dentures with and without palatal coverage, palateless dentures tended to result in higher implant strain than dentures with palatal coverage. Dentures supported by only two implants registered higher strain than those supported by four or six implants. Implants under palateless dentures registered higher strain than those under dentures with palatal coverage. Anterior implants exhibited higher palatolabial strain than other implants regardless of palatal coverage and implant configuration; it is therefore recommended that maxillary implant overdentures should be supported by six implants with support extending to the distal end of the arch.

  1. In vivo pH monitoring using boron doped diamond microelectrode and silver needles: Application to stomach disorder diagnosis

    Fierro, Stéphane; Seishima, Ryo; Nagano, Osamu; Saya, Hideyuki; Einaga, Yasuaki

    2013-11-01

    This study presents the in vivo electrochemical monitoring of pH using boron doped diamond (BDD) microelectrode and silver needles for potential application in medical diagnosis. Accurate calibration curve for pH determination were obtained through in vitro electrochemical measurements. The increase induced in stomach pH by treatment with pantoprazole was used to demonstrate that it is possible to monitor the pH in vivo using the simple and noninvasive system proposed herein. Using the results of the in vivo and in vitro experiments, a quantitative analysis of the increase in stomach pH is also presented. It is proposed that the catheter-free pH monitoring system presented in this study could be potentially employed in any biological environment.

  2. Noninvasive microelectrode ion flux estimation technique (MIFE) for the study of the regulation of root membrane transport by cyclic nucleotides

    Ordoñ ez, Natalia Maria; Shabala, Lana; Gehring, Christoph A; Shabala, Sergey Nikolayevich

    2013-01-01

    Changes in ion permeability and subsequently intracellular ion concentrations play a crucial role in intracellular and intercellular communication and, as such, confer a broad array of developmental and adaptive responses in plants. These changes are mediated by the activity of plasma-membrane based transport proteins many of which are controlled by cyclic nucleotides and/or other signaling molecules. The MIFE technique for noninvasive microelectrode ion flux measuring allows concurrent quantification of net fluxes of several ions with high spatial (μm range) and temporal (ca. 5 s) resolution, making it a powerful tool to study various aspects of downstream signaling events in plant cells. This chapter details basic protocols enabling the application of the MIFE technique to study regulation of root membrane transport in general and cyclic nucleotide mediated transport in particular. © Springer Science+Business Media New York 2013.

  3. Rapid capacitive detection of femtomolar levels of bisphenol A using an aptamer-modified disposable microelectrode array

    Cui, Haochen; Wu, Jayne; Eda, Shigetoshi; Chen, Jiangang; Chen, Wei; Zheng, Lei

    2015-01-01

    A label-free and single-step method is reported for rapid and highly sensitive detection of bisphenol A (BPA) in aqueous samples. It utilizes an aptamer acting as a probe molecule immobilized on a commercially available array of interdigitated aluminum microelectrodes. BPA was quantified by measuring the interfacial capacitance change rate caused by the specific binding between bisphenol A and the immobilized aptamer. The AC signal also induces an AC electrokinetic effect to generate microfluidic motion for enhanced binding. The capacitive aptasensor achieves a limit of detection as low as 10 fM(2.8 fg ⋅ mL −1 ) with a 20 s response time. The method is inexpensive, highly sensitive, rapid and therefore provides a promising technology for on-site detection of BPA in food and water samples. (author)

  4. Multiple single-unit long-term tracking on organotypic hippocampal slices using high-density microelectrode arrays

    Wei Gong

    2016-11-01

    Full Text Available A novel system to cultivate and record from organotypic brain slices directly on high-density microelectrode arrays (HD-MEA was developed. This system allows for continuous recording of electrical activity of specific individual neurons at high spatial resolution while monitoring at the same time, neuronal network activity. For the first time, the electrical activity patterns of single neurons and the corresponding neuronal network in an organotypic hippocampal slice culture were studied during several consecutive weeks at daily intervals. An unsupervised iterative spike-sorting algorithm, based on PCA and k-means clustering, was developed to assign the activities to the single units. Spike-triggered average extracellular waveforms of an action potential recorded across neighboring electrodes, termed ‘footprints’ of single-units were generated and tracked over weeks. The developed system offers the potential to study chronic impacts of drugs or genetic modifications on individual neurons in slice preparations over extended times.

  5. Noninvasive microelectrode ion flux estimation technique (MIFE) for the study of the regulation of root membrane transport by cyclic nucleotides

    Ordoñez, Natalia Maria

    2013-09-03

    Changes in ion permeability and subsequently intracellular ion concentrations play a crucial role in intracellular and intercellular communication and, as such, confer a broad array of developmental and adaptive responses in plants. These changes are mediated by the activity of plasma-membrane based transport proteins many of which are controlled by cyclic nucleotides and/or other signaling molecules. The MIFE technique for noninvasive microelectrode ion flux measuring allows concurrent quantification of net fluxes of several ions with high spatial (μm range) and temporal (ca. 5 s) resolution, making it a powerful tool to study various aspects of downstream signaling events in plant cells. This chapter details basic protocols enabling the application of the MIFE technique to study regulation of root membrane transport in general and cyclic nucleotide mediated transport in particular. © Springer Science+Business Media New York 2013.

  6. Functional characterization of GABAA receptor-mediated modulation of cortical neuron network activity in microelectrode array recordings

    Bader, Benjamin M; Steder, Anne; Klein, Anders Bue

    2017-01-01

    The numerous γ-aminobutyric acid type A receptor (GABAAR) subtypes are differentially expressed and mediate distinct functions at neuronal level. In this study we have investigated GABAAR-mediated modulation of the spontaneous activity patterns of primary neuronal networks from murine frontal...... of the information extractable from the MEA recordings offers interesting insights into the contributions of various GABAAR subtypes/subgroups to cortical network activity and the putative functional interplay between these receptors in these neurons....... cortex by characterizing the effects induced by a wide selection of pharmacological tools at a plethora of activity parameters in microelectrode array (MEA) recordings. The basic characteristics of the primary cortical neurons used in the recordings were studied in some detail, and the expression levels...

  7. Planar potentiometric sensors based on Au and Ag microelectrodes and conducting polymers for flow-cell analysis

    ToczyIowska, Renata; Pokrop, RafaI; Dybko, Artur; Wroblewski, Wojciech

    2005-01-01

    Back-side contact Au and Ag microelectrodes were used as transducers to construct planar all-solid-state electrodes suitable for flow-through analysis. The microsensors were based on plasticized PVC potassium-selective membranes containing ion-electron conducting polymer-polypyrrole doped with di(2-ethylhexyl) sulfosuccinate. The proposed technique allowed simple construction of microsensors in one step, by membrane solution casting directly on the surface of the planar metallic transducers. The performance of the microsensors based on Au and Ag transducers were determined and compared with planar sensors based on internal electrolyte immobilized in polyHEMA. The addition of the polypyrrole to the membrane composition did not influence on the selectivity, reproducibility and long-term stability of the microsensors but improved their standard potential stability in time in comparison with coated-wire type sensors. Moreover, all-solid-state microsensors based on Au transducers exhibited better signal stability than Ag based sensors

  8. Implants for orthodontic anchorage

    Zheng, Xiaowen; Sun, Yannan; Zhang, Yimei; Cai, Ting; Sun, Feng; Lin, Jiuxiang

    2018-01-01

    Abstract Implantanchorage continues to receive much attention as an important orthodontic anchorage. Since the development of orthodontic implants, the scope of applications has continued to increase. Although multiple reviews detailing implants have been published, no comprehensive evaluations have been performed. Thus, the purpose of this study was to comprehensively evaluate the effects of implants based on data published in review articles. An electronic search of the Cochrane Library, Medline, Embase, Ebsco and Sicencedirect for reviews with “orthodontic” and “systematic review or meta analysis” in the title, abstract, keywords, or full text was performed. A subsequent manual search was then performed to identify reviews concerning orthodontic implants. A manual search of the orthodontic journals American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), European Journal of Orthodontics (EJO), and Angle Othodontist was also performed. Such systematic reviews that evaluated the efficacy and safety of orthodontic implants were used to indicate success rates and molar movements. A total of 23 reviews were included in the analysis. The quality of each review was assessed using a measurement tool for Assessment of Multiple Systematic Reviews (AMSTAR), and the review chosen to summarize outcomes had a quality score of >6. Most reviews were less than moderate quality. Success rates of implants ranged in a broad scope, and movement of the maxillary first molar was superior with implants compared with traditional anchorage. PMID:29595673

  9. Maintenance in dental implants

    Giselle Póvoa Gomes

    2008-01-01

    Full Text Available In implants, maintenance is a decisive factor for obtaining success when implant supported overdentures and dentures are used. The present stud presents, a clinical case of a patient, a 70 year-old white man, with a completely edentulous mandibular alveolar ridge, severe bone resorption with presence of basal bone only, and absence of vestibule. Initially, treatment consisted of the placement of a mandibular overdenture, supported on three implants in the anterior inter-foramen region, as the left implant was transfixed in the basal bone of 2 to 3 millimeters. Eleven years later, another two implants were placed in the anterior area and an immediate load was performed up to the first molars, for the placement of an implant supported fixed. Throughout the entire treatment, meticulous maintenance was carried out, with follow-up for fourteen years, interrupted by the patient’s death. From the third month after the opening the three implants initially placed, the presence of keratinized mucosa, definition of the vestibule, maturation of the alveolar ridge and bone formation in the mento region were observed. It was concluded that good planning, allied to mastery of the technique and adequate maintenance were the prerequisites necessary for obtaining favorable results, success of the present case, and for the patient to have a better quality of life.

  10. Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes

    Hou, Jun; Miao, Lingzhan; Wang, Chao; Wang, Peifang; Ao, Yanhui; Qian, Jin; Dai, Shanshan

    2014-01-01

    Highlights: • Temporal and spatial inhibitory effects of ZnO NPs on biofilms were investigated. • 50 mg/L nano-ZnO inhibited the microbial activities only in biofilm outer layer. • Adsorbed ZnO NPs had no adverse effects on the cell membrane integrity of biofilms. • Dissolution of ZnO NPs to toxic zinc ions was the main mechanism of toxicity. - Abstract: The presence of ZnO NPs in waste streams can negatively affect the efficiency of biological nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. In this study, the temporal and spatial inhibitory effects of ZnO NPs on the O 2 respiration activities of aerobic wastewater biofilms were investigated using an O 2 microelectrode. The resulting time–course microelectrode measurements demonstrated that ZnO NPs inhibited O 2 respiration within 2 h. The spatial distributions of net specific O 2 respiration were determined in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. Scanning electron microscopy (SEM) analysis showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. It was found that the inhibition of O 2 respiration induced by higher concentrations of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissolution of the ZnO NPs

  11. Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes

    Hou, Jun [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China); Miao, Lingzhan, E-mail: mlz1988@126.com [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China); Wang, Chao, E-mail: hhuhjy973@126.com [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China); Wang, Peifang; Ao, Yanhui; Qian, Jin; Dai, Shanshan [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China)

    2014-07-15

    Highlights: • Temporal and spatial inhibitory effects of ZnO NPs on biofilms were investigated. • 50 mg/L nano-ZnO inhibited the microbial activities only in biofilm outer layer. • Adsorbed ZnO NPs had no adverse effects on the cell membrane integrity of biofilms. • Dissolution of ZnO NPs to toxic zinc ions was the main mechanism of toxicity. - Abstract: The presence of ZnO NPs in waste streams can negatively affect the efficiency of biological nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. In this study, the temporal and spatial inhibitory effects of ZnO NPs on the O{sub 2} respiration activities of aerobic wastewater biofilms were investigated using an O{sub 2} microelectrode. The resulting time–course microelectrode measurements demonstrated that ZnO NPs inhibited O{sub 2} respiration within 2 h. The spatial distributions of net specific O{sub 2} respiration were determined in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. Scanning electron microscopy (SEM) analysis showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. It was found that the inhibition of O{sub 2} respiration induced by higher concentrations of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissolution of the ZnO NPs.

  12. Electrostatic Spray Deposition-Based Manganese Oxide Films-From Pseudocapacitive Charge Storage Materials to Three-Dimensional Microelectrode Integrands.

    Agrawal, Richa; Adelowo, Ebenezer; Baboukani, Amin Rabiei; Villegas, Michael Franc; Henriques, Alexandra; Wang, Chunlei

    2017-07-26

    In this study, porous manganese oxide (MnO x ) thin films were synthesized via electrostatic spray deposition (ESD) and evaluated as pseudocapacitive electrode materials in neutral aqueous media. Very interestingly, the gravimetric specific capacitance of the ESD-based electrodes underwent a marked enhancement upon electrochemical cycling, from 72 F∙g -1 to 225 F∙g -1 , with a concomitant improvement in kinetics and conductivity. The change in capacitance and resistivity is attributed to a partial electrochemical phase transformation from the spinel-type hausmannite Mn₃O₄ to the conducting layered birnessite MnO₂. Furthermore, the films were able to retain 88.4% of the maximal capacitance after 1000 cycles. Upon verifying the viability of the manganese oxide films for pseudocapacitive applications, the thin films were integrated onto carbon micro-pillars created via carbon microelectromechanical systems (C-MEMS) for examining their application as potential microelectrode candidates. In a symmetric two-electrode cell setup, the MnO x /C-MEMS microelectrodes were able to deliver specific capacitances as high as 0.055 F∙cm -2 and stack capacitances as high as 7.4 F·cm -3 , with maximal stack energy and power densities of 0.51 mWh·cm -3 and 28.3 mW·cm -3 , respectively. The excellent areal capacitance of the MnO x -MEs is attributed to the pseudocapacitive MnO x as well as the three-dimensional architectural framework provided by the carbon micro-pillars.

  13. Electrostatic Spray Deposition-Based Manganese Oxide Films—From Pseudocapacitive Charge Storage Materials to Three-Dimensional Microelectrode Integrands

    Richa Agrawal

    2017-07-01

    Full Text Available In this study, porous manganese oxide (MnOx thin films were synthesized via electrostatic spray deposition (ESD and evaluated as pseudocapacitive electrode materials in neutral aqueous media. Very interestingly, the gravimetric specific capacitance of the ESD-based electrodes underwent a marked enhancement upon electrochemical cycling, from 72 F∙g−1 to 225 F∙g−1, with a concomitant improvement in kinetics and conductivity. The change in capacitance and resistivity is attributed to a partial electrochemical phase transformation from the spinel-type hausmannite Mn3O4 to the conducting layered birnessite MnO2. Furthermore, the films were able to retain 88.4% of the maximal capacitance after 1000 cycles. Upon verifying the viability of the manganese oxide films for pseudocapacitive applications, the thin films were integrated onto carbon micro-pillars created via carbon microelectromechanical systems (C-MEMS for examining their application as potential microelectrode candidates. In a symmetric two-electrode cell setup, the MnOx/C-MEMS microelectrodes were able to deliver specific capacitances as high as 0.055 F∙cm−2 and stack capacitances as high as 7.4 F·cm−3, with maximal stack energy and power densities of 0.51 mWh·cm−3 and 28.3 mW·cm−3, respectively. The excellent areal capacitance of the MnOx-MEs is attributed to the pseudocapacitive MnOx as well as the three-dimensional architectural framework provided by the carbon micro-pillars.

  14. Modification of anti-bacterial surface properties of textile polymers by vacuum arc ion source implantation

    Nikolaev, A.G.; Yushkov, G.Yu.; Oks, E.M.; Oztarhan, A.; Akpek, A.; Hames-Kocabas, E.; Urkac, E.S.; Brown, I.G.

    2014-01-01

    Highlights: • Ion implantation. • Anti-bacterial properties. • Textile polymer. • Vacuum arc ion source. - Abstract: Ion implantation provides an important technology for the modification of material surface properties. The vacuum arc ion source is a unique instrument for the generation of intense beams of metal ions as well as gaseous ions, including mixed metal–gas beams with controllable metal:gas ion ratio. Here we describe our exploratory work on the application of vacuum arc ion source-generated ion beams for ion implantation into polymer textile materials for modification of their biological cell compatibility surface properties. We have investigated two specific aspects of cell compatibility: (i) enhancement of the antibacterial characteristics (we chose to use Staphylococcus aureus bacteria) of ion implanted polymer textile fabric, and (ii) the “inverse” concern of enhancement of neural cell growth rate (we chose Rat B-35 neuroblastoma cells) on ion implanted polymer textile. The results of both investigations were positive, with implantation-generated antibacterial efficiency factor up to about 90%, fully comparable to alternative conventional (non-implantation) approaches and with some potentially important advantages over the conventional approach; and with enhancement of neural cell growth rate of up to a factor of 3.5 when grown on suitably implanted polymer textile material

  15. Modification of anti-bacterial surface properties of textile polymers by vacuum arc ion source implantation

    Nikolaev, A.G., E-mail: nik@opee.hcei.tsc.ru [High Current Electronics Institute, Siberian Branch of the Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Yushkov, G.Yu.; Oks, E.M. [High Current Electronics Institute, Siberian Branch of the Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Oztarhan, A. [Izmir University, Izmir 35140 (Turkey); Akpek, A.; Hames-Kocabas, E.; Urkac, E.S. [Bioengineering Department, Ege University, Bornova 35100, Izmir (Turkey); Brown, I.G. [Lawrence Berkeley National Laboratory, Berkeley, CA 94708 (United States)

    2014-08-15

    Highlights: • Ion implantation. • Anti-bacterial properties. • Textile polymer. • Vacuum arc ion source. - Abstract: Ion implantation provides an important technology for the modification of material surface properties. The vacuum arc ion source is a unique instrument for the generation of intense beams of metal ions as well as gaseous ions, including mixed metal–gas beams with controllable metal:gas ion ratio. Here we describe our exploratory work on the application of vacuum arc ion source-generated ion beams for ion implantation into polymer textile materials for modification of their biological cell compatibility surface properties. We have investigated two specific aspects of cell compatibility: (i) enhancement of the antibacterial characteristics (we chose to use Staphylococcus aureus bacteria) of ion implanted polymer textile fabric, and (ii) the “inverse” concern of enhancement of neural cell growth rate (we chose Rat B-35 neuroblastoma cells) on ion implanted polymer textile. The results of both investigations were positive, with implantation-generated antibacterial efficiency factor up to about 90%, fully comparable to alternative conventional (non-implantation) approaches and with some potentially important advantages over the conventional approach; and with enhancement of neural cell growth rate of up to a factor of 3.5 when grown on suitably implanted polymer textile material.

  16. Nanotechnology for dental implants.

    Tomsia, Antoni P; Lee, Janice S; Wegst, Ulrike G K; Saiz, Eduardo

    2013-01-01

    With the advent of nanotechnology, an opportunity exists for the engineering of new dental implant materials. Metallic dental implants have been successfully used for decades, but they have shortcomings related to osseointegration and mechanical properties that do not match those of bone. Absent the development of an entirely new class of materials, faster osseointegration of currently available dental implants can be accomplished by various surface modifications. To date, there is no consensus regarding the preferred method(s) of implant surface modification, and further development will be required before the ideal implant surface can be created, let alone become available for clinical use. Current approaches can generally be categorized into three areas: ceramic coatings, surface functionalization, and patterning on the micro- to nanoscale. The distinctions among these are imprecise, as some or all of these approaches can be combined to improve in vivo implant performance. These surface improvements have resulted in durable implants with a high percentage of success and long-term function. Nanotechnology has provided another set of opportunities for the manipulation of implant surfaces in its capacity to mimic the surface topography formed by extracellular matrix components of natural tissue. The possibilities introduced by nanotechnology now permit the tailoring of implant chemistry and structure with an unprecedented degree of control. For the first time, tools are available that can be used to manipulate the physicochemical environment and monitor key cellular events at the molecular level. These new tools and capabilities will result in faster bone formation, reduced healing time, and rapid recovery to function.

  17. Ion implantation for microelectronics

    Dearnaley, G.

    1977-01-01

    Ion implantation has proved to be a versatile and efficient means of producing microelectronic devices. This review summarizes the relevant physics and technology and assesses the advantages of the method. Examples are then given of widely different device structures which have been made by ion implantation. While most of the industrial application has been in silicon, good progress continues to be made in the more difficult field of compound semiconductors. Equipment designed for the industrial ion implantation of microelectronic devices is discussed briefly. (Auth.)

  18. Optimization of dental implantation

    Dol, Aleksandr V.; Ivanov, Dmitriy V.

    2017-02-01

    Modern dentistry can not exist without dental implantation. This work is devoted to study of the "bone-implant" system and to optimization of dental prostheses installation. Modern non-invasive methods such as MRI an 3D-scanning as well as numerical calculations and 3D-prototyping allow to optimize all of stages of dental prosthetics. An integrated approach to the planning of implant surgery can significantly reduce the risk of complications in the first few days after treatment, and throughout the period of operation of the prosthesis.

  19. Morphological neural networks

    Ritter, G.X.; Sussner, P. [Univ. of Florida, Gainesville, FL (United States)

    1996-12-31

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

  20. Neural Tube Defects

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  1. Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants

    Sung June Kim

    2008-09-01

    Full Text Available Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between electrodes and targeting cell layers, which limits site resolution for effective multi-channel stimulation. In this paper, we report a newly designed device with a pillar structure that more effectively interfaces with the target. Electrode arrays were successfully fabricated and safely implanted inside the rabbit eye in suprachoroidal space. Optical Coherence Tomography (OCT showed well-preserved pillar structures of the electrode without damage. Bipolar stimulation was applied through paired sites (6:1 and the neural responses were successfully recorded from several regions in the visual cortex. Electrically evoked cortical potential by the pillar electrode array stimulation were compared to visual evoked potential under full-field light stimulation.

  2. Possible sources of neuroprotection following subretinal silicon chip implantation in RCS rats

    Pardue, Machelle T.; Phillips, Michael J.; Yin, Hang; Fernandes, Alcides; Cheng, Yian; Chow, Alan Y.; Ball, Sherry L.

    2005-03-01

    Current retinal prosthetics are designed to stimulate existing neural circuits in diseased retinas to create a visual signal. However, implantation of retinal prosthetics may create a neurotrophic environment that also leads to improvements in visual function. Possible sources of increased neuroprotective effects on the retina may arise from electrical activity generated by the prosthetic, mechanical injury due to surgical implantation, and/or presence of a chronic foreign body. This study evaluates these three neuroprotective sources by implanting Royal College of Surgeons (RCS) rats, a model of retinitis pigmentosa, with a subretinal implant at an early stage of photoreceptor degeneration. Treatment groups included rats implanted with active and inactive devices, as well as sham-operated. These groups were compared to unoperated controls. Evaluation of retinal function throughout an 18 week post-implantation period demonstrated transient functional improvements in eyes implanted with an inactive device at 6, 12 and 14 weeks post-implantation. However, the number of photoreceptors located directly over or around the implant or sham incision was significantly increased in eyes implanted with an active or inactive device or sham-operated. These results indicate that in the RCS rat localized neuroprotection of photoreceptors from mechanical injury or a chronic foreign body may provide similar results to subretinal electrical stimulation at the current output evaluated here.

  3. Neural tissue-spheres

    Andersen, Rikke K; Johansen, Mathias; Blaabjerg, Morten

    2007-01-01

    By combining new and established protocols we have developed a procedure for isolation and propagation of neural precursor cells from the forebrain subventricular zone (SVZ) of newborn rats. Small tissue blocks of the SVZ were dissected and propagated en bloc as free-floating neural tissue...... content, thus allowing experimental studies of neural precursor cells and their niche...

  4. Cochlear implantation in children and adults in Switzerland.

    Brand, Yves; Senn, Pascal; Kompis, Martin; Dillier, Norbert; Allum, John H J

    2014-02-04

    The cochlear implant (CI) is one of the most successful neural prostheses developed to date. It offers artificial hearing to individuals with profound sensorineural hearing loss and with insufficient benefit from conventional hearing aids. The first implants available some 30 years ago provided a limited sensation of sound. The benefit for users of these early systems was mostly a facilitation of lip-reading based communication rather than an understanding of speech. Considerable progress has been made since then. Modern, multichannel implant systems feature complex speech processing strategies, high stimulation rates and multiple sites of stimulation in the cochlea. Equipped with such a state-of-the-art system, the majority of recipients today can communicate orally without visual cues and can even use the telephone. The impact of CIs on deaf individuals and on the deaf community has thus been exceptional. To date, more than 300,000 patients worldwide have received CIs. In Switzerland, the first implantation was performed in 1977 and, as of 2012, over 2,000 systems have been implanted with a current rate of around 150 CIs per year. The primary purpose of this article is to provide a contemporary overview of cochlear implantation, emphasising the situation in Switzerland.

  5. Breast Reconstruction with Implants

    ... your surgical options and discuss the advantages and disadvantages of implant-based reconstruction, and may show you ... Policy Notice of Privacy Practices Notice of Nondiscrimination Advertising Mayo Clinic is a not-for-profit organization ...

  6. Ion Implantation of Polymers

    Popok, Vladimir

    2012-01-01

    The current paper presents a state-of-the-art review in the field of ion implantation of polymers. Numerous published studies of polymers modified by ion beams are analysed. General aspects of ion stopping, latent track formation and changes of structure and composition of organic materials...... are discussed. Related to that, the effects of radiothermolysis, degassing and carbonisation are considered. Specificity of depth distributions of implanted into polymers impurities is analysed and the case of high-fluence implantation is emphasised. Within rather broad topic of ion bombardment, the focus...... is put on the low-energy implantation of metal ions causing the nucleation and growth of nanoparticles in the shallow polymer layers. Electrical, optical and magnetic properties of metal/polymer composites are under the discussion and the approaches towards practical applications are overviewed....

  7. Precipitation processes in implanted materials

    Borders, J.A.

    1978-01-01

    Ion implantation is a nonequilibrium process. It is possible to implant materials with impurities to concentration levels which exceed the solid solubilities. The return of the system to thermodynamic equilibrium is often accomplished by precipitation of the implanted species or a compound involving atoms of both the host and the implanted species. This may involve long time scales when taking place at room temperature or it may take place during the implantation

  8. An Implanted, Stimulated Muscle Powered Piezoelectric Generator

    Lewandowski, Beth; Gustafson, Kenneth; Kilgore, Kevin

    2007-01-01

    A totally implantable piezoelectric generator system able to harness power from electrically activated muscle could be used to augment the power systems of implanted medical devices, such as neural prostheses, by reducing the number of battery replacement surgeries or by allowing periods of untethered functionality. The features of our generator design are no moving parts and the use of a portion of the generated power for system operation and regulation. A software model of the system has been developed and simulations have been performed to predict the output power as the system parameters were varied within their constraints. Mechanical forces that mimic muscle forces have been experimentally applied to a piezoelectric generator to verify the accuracy of the simulations and to explore losses due to mechanical coupling. Depending on the selection of system parameters, software simulations predict that this generator concept can generate up to approximately 700 W of power, which is greater than the power necessary to drive the generator, conservatively estimated to be 50 W. These results suggest that this concept has the potential to be an implantable, self-replenishing power source and further investigation is underway.

  9. Ion implantation for semiconductors

    Grey-Morgan, T.

    1995-01-01

    Full text: Over the past two decades, thousands of particle accelerators have been used to implant foreign atoms like boron, phosphorus and arsenic into silicon crystal wafers to produce special embedded layers for manufacturing semiconductor devices. Depending on the device required, the atomic species, the depth of implant and doping levels are the main parameters for the implantation process; the selection and parameter control is totally automated. The depth of the implant, usually less than 1 micron, is determined by the ion energy, which can be varied between 2 and 600 keV. The ion beam is extracted from a Freeman or Bernas type ion source and accelerated to 60 keV before mass analysis. For higher beam energies postacceleration is applied up to 200 keV and even higher energies can be achieved by mass selecting multiplycharged ions, but with a corresponding reduction in beam output. Depending on the device to be manufactured, doping levels can range from 10 10 to 10 15 atoms/cm 2 and are controlled by implanter beam currents in the range up to 30mA; continuous process monitoring ensures uniformity across the wafer of better than 1 % . As semiconductor devices get smaller, additional sophistication is required in the design of the implanter. The silicon wafers charge electrically during implantation and this charge must be dissipated continuously to reduce the electrical stress in the device and avoid destructive electrical breakdown. Electron flood guns produce low energy electrons (below 10 electronvolts) to neutralize positive charge buildup and implanter design must ensure minimum contamination by other isotopic species and ensure low internal sputter rates. The pace of technology in the semiconductor industry is such that implanters are being built now for 256 Megabit circuits but which are only likely to be widely available five years from now. Several specialist companies manufacture implanter systems, each costing around US$5 million, depending on the

  10. Embedded System for Prosthetic Control Using Implanted Neuromuscular Interfaces Accessed Via an Osseointegrated Implant.

    Mastinu, Enzo; Doguet, Pascal; Botquin, Yohan; Hakansson, Bo; Ortiz-Catalan, Max

    2017-08-01

    Despite the technological progress in robotics achieved in the last decades, prosthetic limbs still lack functionality, reliability, and comfort. Recently, an implanted neuromusculoskeletal interface built upon osseointegration was developed and tested in humans, namely the Osseointegrated Human-Machine Gateway. Here, we present an embedded system to exploit the advantages of this technology. Our artificial limb controller allows for bioelectric signals acquisition, processing, decoding of motor intent, prosthetic control, and sensory feedback. It includes a neurostimulator to provide direct neural feedback based on sensory information. The system was validated using real-time tasks characterization, power consumption evaluation, and myoelectric pattern recognition performance. Functionality was proven in a first pilot patient from whom results of daily usage were obtained. The system was designed to be reliably used in activities of daily living, as well as a research platform to monitor prosthesis usage and training, machine-learning-based control algorithms, and neural stimulation paradigms.

  11. Neural engineering from advanced biomaterials to 3D fabrication techniques

    Kaplan, David

    2016-01-01

    This book covers the principles of advanced 3D fabrication techniques, stem cells and biomaterials for neural engineering. Renowned contributors cover topics such as neural tissue regeneration, peripheral and central nervous system repair, brain-machine interfaces and in vitro nervous system modeling. Within these areas, focus remains on exciting and emerging technologies such as highly developed neuroprostheses and the communication channels between the brain and prostheses, enabling technologies that are beneficial for development of therapeutic interventions, advanced fabrication techniques such as 3D bioprinting, photolithography, microfluidics, and subtractive fabrication, and the engineering of implantable neural grafts. There is a strong focus on stem cells and 3D bioprinting technologies throughout the book, including working with embryonic, fetal, neonatal, and adult stem cells and a variety of sophisticated 3D bioprinting methods for neural engineering applications. There is also a strong focus on b...

  12. Quantitative ion implantation

    Gries, W.H.

    1976-06-01

    This is a report of the study of the implantation of heavy ions at medium keV-energies into electrically conducting mono-elemental solids, at ion doses too small to cause significant loss of the implanted ions by resputtering. The study has been undertaken to investigate the possibility of accurate portioning of matter in submicrogram quantities, with some specific applications in mind. The problem is extensively investigated both on a theoretical level and in practice. A mathematical model is developed for calculating the loss of implanted ions by resputtering as a function of the implanted ion dose and the sputtering yield. Numerical data are produced therefrom which permit a good order-of-magnitude estimate of the loss for any ion/solid combination in which the ions are heavier than the solid atoms, and for any ion energy from 10 to 300 keV. The implanted ion dose is measured by integration of the ion beam current, and equipment and techniques are described which make possible the accurate integration of an ion current in an electromagnetic isotope separator. The methods are applied to two sample cases, one being a stable isotope, the other a radioisotope. In both cases independent methods are used to show that the implantation is indeed quantitative, as predicted. At the same time the sample cases are used to demonstrate two possible applications for quantitative ion implantation, viz. firstly for the manufacture of calibration standards for instrumental micromethods of elemental trace analysis in metals, and secondly for the determination of the half-lives of long-lived radioisotopes by a specific activity method. It is concluded that the present study has advanced quantitative ion implantation to the state where it can be successfully applied to the solution of problems in other fields

  13. Ion implantation - an introduction

    Townsend, P.D.

    1986-01-01

    Ion implantation is a widely used technique with a literature that covers semiconductor production, surface treatments of steels, corrosion resistance, catalysis and integrated optics. This brief introduction outlines advantages of the technique, some aspects of the underlying physics and examples of current applications. Ion implantation is already an essential part of semiconductor technology while in many other areas it is still in an early stage of development. The future scope of the subject is discussed. (author)

  14. Biocompatibility and characterisation of a candidate microelectrode material for biosensor applications

    Cyster, L.A.

    2001-10-01

    Recent advances in microcircuit technology have enabled the fabrication of Multiple Microelectrode Arrays (MEAs) for investigating the characteristics of networks of neuronal cells either in vivo or in vitro. When producing a MEA materials used must be corrosion resistant, have low electrical impedance and the materials must be biocompatible. Existing MEA's have limited life spans, relatively high impedance values and limited uses. Thus creating a requirement for new MEA technology. TiN thin films have become increasingly useful in a wide variety of applications, due to their nature, which includes chemical stability, high hardness, excellent wear and electrical properties and also biocompatibility. The favourable electrical and biocompatibility characteristics of thin films of TiN make them a possible candidate for use in a MEA. TiN thin films can be deposited by a number of methods including evaporation, ion plating and sputtering. The method of deposition, along with process parameters used can have a marked effect on the characteristics of TiN films, including changes in preferred orientation, hardness and wear and also biocompatibility. TiN thin films were deposited onto glass substrates by pulsed DC reactive sputtering of a Ti target, with Argon and nitrogen gas mixtures and labelled Type I TiN films. Also industrial TIN films deposited by Arc Ion plating were carefully selected for comparison and labelled Type II TiN films. The microstructure, composition, surface chemistry, surface topography and roughness were studied using X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Atomic Force Microscopy (AFM) and Profilometry. Type I TIN films showed a surface topography similar to Zone I and Type II TiN films showed a surface topography similar to Zone 2 of the Movchan and Dernchishin structure zone model for sputtered films. XPS showed that the surface composition of all TiN films was predominantly TiO 2 , TiN and TiN x O y . Significant

  15. Vagal stimulation targets select populations of intrinsic cardiac neurons to control neurally induced atrial fibrillation.

    Salavatian, Siamak; Beaumont, Eric; Longpré, Jean-Philippe; Armour, J Andrew; Vinet, Alain; Jacquemet, Vincent; Shivkumar, Kalyanam; Ardell, Jeffrey L

    2016-11-01

    Mediastinal nerve stimulation (MNS) reproducibly evokes atrial fibrillation (AF) by excessive and heterogeneous activation of intrinsic cardiac (IC) neurons. This study evaluated whether preemptive vagus nerve stimulation (VNS) impacts MNS-induced evoked changes in IC neural network activity to thereby alter susceptibility to AF. IC neuronal activity in the right atrial ganglionated plexus was directly recorded in anesthetized canines (n = 8) using a linear microelectrode array concomitant with right atrial electrical activity in response to: 1) epicardial touch or great vessel occlusion vs. 2) stellate or vagal stimulation. From these stressors, post hoc analysis (based on the Skellam distribution) defined IC neurons so recorded as afferent, efferent, or convergent (afferent and efferent inputs) local circuit neurons (LCN). The capacity of right-sided MNS to modify IC activity in the induction of AF was determined before and after preemptive right (RCV)- vs. left (LCV)-sided VNS (15 Hz, 500 μs; 1.2× bradycardia threshold). Neuronal (n = 89) activity at baseline (0.11 ± 0.29 Hz) increased during MNS-induced AF (0.51 ± 1.30 Hz; P neuronal synchrony increased during neurally induced AF, a local neural network response mitigated by preemptive VNS. These antiarrhythmic effects persisted post-VNS for, on average, 26 min. In conclusion, VNS preferentially targets convergent LCNs and their interactive coherence to mitigate the potential for neurally induced AF. The antiarrhythmic properties imposed by VNS exhibit memory. Copyright © 2016 the American Physiological Society.

  16. Contraceptive implants: current perspectives

    Rowlands S

    2014-09-01

    Full Text Available Sam Rowlands,1,2 Stephen Searle3 1Centre of Postgraduate Medical Research and Education, School of Health and Social Care, Bournemouth University, Bournemouth, United Kingdom; 2Dorset HealthCare, Bournemouth, United Kingdom; 3Sexual Health Services, Chesterfield, United KingdomAbstract: Progestin-only contraceptive implants are a highly cost-effective form of long-acting reversible contraception. They are the most effective reversible contraceptives and are of a similar effectiveness to sterilization. Pregnancies are rare in women using this method of contraception, and those that do occur must be fully investigated, with an ultrasound scan of the arm and serum etonogestrel level if the implant cannot be located. There are very few contraindications to use of implants, and they have an excellent safety profile. Both acceptability and continuation with the method are high. Noncontraceptive benefits include improvements in dysmenorrhea, ovulatory pain, and endometriosis. Problematic bleeding is a relatively common adverse effect that must be covered in preinsertion information-giving and supported adequately if it occurs. Recognized training for both insertion and removal should be undertaken. Care needs to be taken at both insertion and removal to avoid neurovascular injury. Implants should always be palpable; if they are not, noninsertion should be assumed until disproven. Etonogestrel implants are now radiopaque, which aids localization. Anticipated difficult removals should be performed by specially trained experts. Keywords: contraceptive, subdermal implant, etonogestrel, levonorgestrel, progestin-only, long-acting reversible contraception

  17. Anodized dental implant surface

    Sunil Kumar Mishra

    2017-01-01

    Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  18. Plasma source ion implantation

    Conrad, J.R.; Forest, C.

    1986-01-01

    The authors' technique allows the ion implantation to be performed directly within the ion source at higher currents without ion beam extraction and transport. The potential benefits include greatly increased production rates (factors of 10-1000) and the ability to implant non-planar targets without rastering or shadowing. The technique eliminates the ion extractor grid set, beam raster equipment, drift space and target manipulator equipment. The target to be implanted is placed directly within the plasma source and is biased to a large negative potential so that plasma ions gain energy as they accelerate through the potential drop across the sheath that forms at the plasma boundary. Because the sheath surrounds the target on all sides, all surfaces of the target are implanted without the necessity to raster the beam or to rotate the target. The authors have succeeded in implanting nitrogen ions in a silicon target to the depths and concentrations required for surface treatment of materials like stainless steel and titanium alloys. They have performed ESCA measurements of the penetration depth profile of a silicon target that was biased to 30 kV in a nitrogen discharge plasma. Nitrogen ions were implanted to a depth of 700A at a peak concentration of 30% atomic. The measured profile is quite similar to a previously obtained profile in titanium targets with conventional techniques

  19. EDITORIAL: Why we need a new journal in neural engineering

    Durand, Dominique M.

    2004-03-01

    revolutionary change in the quality of life of persons with sensory and/or motor deficits. Microelectrode technology represents the initial step towards this goal and has already improved the quality of life of many patients, as is evident from the success of auditory prostheses. The cost to society of neurological disorders such as stroke, Parkinson's disease, Alzheimer's disease and epilepsy is staggering. Stroke, which is the third leading cause of death in North America, runs up costs of 40 billion to society per year for its treatment. Costs associated with brain disorders are estimated at 285 billion. Breakthroughs in this field will have a significant impact on the market for enabling technologies. The market for neurological medical devices totaled 2 billion in 1999 and is projected to grow at a rate of 20 to 30% in the next ten years, far outpacing the market for cardiac devices. Although we have all recognized the importance of interdisciplinary research (see the NIH Road map at http://nihroadmap.nih.gov/), the fields of neuroscience and engineering have remained compartmentalized. Collaboration is still difficult since the language of these disciplines is different. Moreover, the scientific journals in these fields are also clearly separate. Researchers involved in neural engineering have a choice of publishing their research in either neuroscience-oriented journals such as Journal of Neuroscience, Journal of Neurophysiology and Brain Research or in engineering journals such as IEEE Transactions on Biomedical Engineering, IEEE Transactions on Neural Systems and Rehabilitation and Annals of Biomedical Engineering. There is no journal currently available focusing on the interdisciplinary field of neural engineering. In order to capitalize on the potential of neural engineering to investigate neural function and to solve problems related to neural disorders, it is necessary to break down the traditional barriers between neuroscientists and engineers not just in the

  20. Short dental implants: an emerging concept in implant treatment.

    Al-Hashedi, Ashwaq Ali; Taiyeb Ali, Tara Bai; Yunus, Norsiah

    2014-06-01

    Short implants have been advocated as a treatment option in many clinical situations where the use of conventional implants is limited. This review outlines the effectiveness and clinical outcomes of using short implants as a valid treatment option in the rehabilitation of edentulous atrophic alveolar ridges. Initially, an electronic search was performed on the following databases: Medline, PubMed, Embase, Cochrane Database of Systematic Reviews, and DARE using key words from January 1990 until May 2012. An additional hand search was included for the relevant articles in the following journals: International Journal of Oral and Maxillofacial Implants, Clinical Oral Implants Research, Journal of Clinical Periodontology, International Journal of Periodontics, Journal of Periodontology, and Clinical Implant Dentistry and Related Research. Any relevant papers from the journals' references were hand searched. Articles were included if they provided detailed data on implant length, reported survival rates, mentioned measures for implant failure, were in the English language, involved human subjects, and researched implants inserted in healed atrophic ridges with a follow-up period of at least 1 year after implant-prosthesis loading. Short implants demonstrated a high rate of success in the replacement of missing teeth in especially atrophic alveolar ridges. The advanced technology and improvement of the implant surfaces have encouraged the success of short implants to a comparable level to that of standard implants. However, further randomized controlled clinical trials and prospective studies with longer follow-up periods are needed.

  1. Neural electrical activity and neural network growth.

    Gafarov, F M

    2018-05-01

    The development of central and peripheral neural system depends in part on the emergence of the correct functional connectivity in its input and output pathways. Now it is generally accepted that molecular factors guide neurons to establish a primary scaffold that undergoes activity-dependent refinement for building a fully functional circuit. However, a number of experimental results obtained recently shows that the neuronal electrical activity plays an important role in the establishing of initial interneuronal connections. Nevertheless, these processes are rather difficult to study experimentally, due to the absence of theoretical description and quantitative parameters for estimation of the neuronal activity influence on growth in neural networks. In this work we propose a general framework for a theoretical description of the activity-dependent neural network growth. The theoretical description incorporates a closed-loop growth model in which the neural activity can affect neurite outgrowth, which in turn can affect neural activity. We carried out the detailed quantitative analysis of spatiotemporal activity patterns and studied the relationship between individual cells and the network as a whole to explore the relationship between developing connectivity and activity patterns. The model, developed in this work will allow us to develop new experimental techniques for studying and quantifying the influence of the neuronal activity on growth processes in neural networks and may lead to a novel techniques for constructing large-scale neural networks by self-organization. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Modeling of Auditory Neuron Response Thresholds with Cochlear Implants

    Frederic Venail

    2015-01-01

    Full Text Available The quality of the prosthetic-neural interface is a critical point for cochlear implant efficiency. It depends not only on technical and anatomical factors such as electrode position into the cochlea (depth and scalar placement, electrode impedance, and distance between the electrode and the stimulated auditory neurons, but also on the number of functional auditory neurons. The efficiency of electrical stimulation can be assessed by the measurement of e-CAP in cochlear implant users. In the present study, we modeled the activation of auditory neurons in cochlear implant recipients (nucleus device. The electrical response, measured using auto-NRT (neural responses telemetry algorithm, has been analyzed using multivariate regression with cubic splines in order to take into account the variations of insertion depth of electrodes amongst subjects as well as the other technical and anatomical factors listed above. NRT thresholds depend on the electrode squared impedance (β = −0.11 ± 0.02, P<0.01, the scalar placement of the electrodes (β = −8.50 ± 1.97, P<0.01, and the depth of insertion calculated as the characteristic frequency of auditory neurons (CNF. Distribution of NRT residues according to CNF could provide a proxy of auditory neurons functioning in implanted cochleas.

  3. Identity and conflicts in the ethics of neural implants

    L. E. Echarte; M. García-Valdecasas

    2014-01-01

    El desarrollo de la tecnología neuroprostética está generando importantes problemas teóricos y prácticos relacionados con la identidad personal. En este contexto, la Extended Mind Theory (EMT) es una teoría que da una respuesta a dichos problemas señalando que la mente es coextensa con el mundo, y que como tal, la mente y el mundo se entremezclan hasta forman una única entidad. La EMT también presupone que los estados físicos determina la naturaleza de los estados mentales. En este artículo, ...

  4. Using Arrays of Microelectrodes Implanted in Residual Peripheral Nerves to Provide Dexterous Control of, and Modulated Sensory Feedback from, a Hand Prosthesis

    2016-10-01

    machine interface (Some figures may appear in colour only in the online journal) 1. Introduction The volitional control of movement involves a complex and...enrolment, volunteers underwent a psychosocial evaluation in order to determine if any underlying psychological conditions were present which would

  5. Implantable oxygen microelectrode suitable for medium-term investigations of post-surgical tissue hypoxia and changes in tumor tissue oxygenation produced by radiotherapy

    Burke, T.R.; Johnson, R.J.; Krishnamsetty, C.B.; Sako, K.; Karakousis, C.; Wojtas, F.

    1980-01-01

    Teflon-covered platinum oxygen probes were used to monitor tissue oxygen levels in post-surgical cancer patients and those treated with radiotherapy. Progressive wound healing was usually accompanied by a decrease in tissue pO2. Radiotherapy produced a slight increase in pO2 while hyperthermia effected a significant increase in the oxygen level during 100% oxygen breathing

  6. Neural network segmentation of magnetic resonance images

    Frederick, B.

    1990-01-01

    Neural networks are well adapted to the task of grouping input patterns into subsets which share some similarity. Moreover, once trained, they can generalize their classification rules to classify new data sets. Sets of pixel intensities from magnetic resonance (MR) images provide a natural input to a neural network; by varying imaging parameters, MR images can reflect various independent physical parameters of tissues in their pixel intensities. A neural net can then be trained to classify physically similar tissue types based on sets of pixel intensities resulting from different imaging studies on the same subject. This paper reports that a neural network classifier for image segmentation was implanted on a Sun 4/60, and was tested on the task of classifying tissues of canine head MR images. Four images of a transaxial slice with different imaging sequences were taken as input to the network (three spin-echo images and an inversion recovery image). The training set consisted of 691 representative samples of gray matter, white matter, cerebrospinal fluid, bone, and muscle preclassified by a neuroscientist. The network was trained using a fast backpropagation algorithm to derive the decision criteria to classify any location in the image by its pixel intensities, and the image was subsequently segmented by the classifier

  7. Improving Neural Recording Technology at the Nanoscale

    Ferguson, John Eric

    Neural recording electrodes are widely used to study normal brain function (e.g., learning, memory, and sensation) and abnormal brain function (e.g., epilepsy, addiction, and depression) and to interface with the nervous system for neuroprosthetics. With a deep understanding of the electrode interface at the nanoscale and the use of novel nanofabrication processes, neural recording electrodes can be designed that surpass previous limits and enable new applications. In this thesis, I will discuss three projects. In the first project, we created an ultralow-impedance electrode coating by controlling the nanoscale texture of electrode surfaces. In the second project, we developed a novel nanowire electrode for long-term intracellular recordings. In the third project, we created a means of wirelessly communicating with ultra-miniature, implantable neural recording devices. The techniques developed for these projects offer significant improvements in the quality of neural recordings. They can also open the door to new types of experiments and medical devices, which can lead to a better understanding of the brain and can enable novel and improved tools for clinical applications.

  8. Neural interface methods and apparatus to provide artificial sensory capabilities to a subject

    Buerger, Stephen P.; Olsson, III, Roy H.; Wojciechowski, Kenneth E.; Novick, David K.; Kholwadwala, Deepesh K.

    2017-01-24

    Embodiments of neural interfaces according to the present invention comprise sensor modules for sensing environmental attributes beyond the natural sensory capability of a subject, and communicating the attributes wirelessly to an external (ex-vivo) portable module attached to the subject. The ex-vivo module encodes and communicates the attributes via a transcutaneous inductively coupled link to an internal (in-vivo) module implanted within the subject. The in-vivo module converts the attribute information into electrical neural stimuli that are delivered to a peripheral nerve bundle within the subject, via an implanted electrode. Methods and apparatus according to the invention incorporate implantable batteries to power the in-vivo module allowing for transcutaneous bidirectional communication of low voltage (e.g. on the order of 5 volts) encoded signals as stimuli commands and neural responses, in a robust, low-error rate, communication channel with minimal effects to the subjects' skin.

  9. EDITORIAL: Special issue on optical neural engineering: advances in optical stimulation technology Special issue on optical neural engineering: advances in optical stimulation technology

    Shoham, Shy; Deisseroth, Karl

    2010-08-01

    this technology, which is increasingly being applied for both photo- stimulation and imaging [25, 26]. Finally, the paper by Pikov et al [27] studies the modulatory biophysical effects exerted by low power millimeter waves on neuronal excitability and membrane properties of cortical pyramidal neurons in vitro. These extensive neuro-modulatory effects seem to include a thermal component (related to the photo-thermal effects observed under laser illumination [28]) as well as a more specific effect exerted by these lower frequency (sub-THz) electromagnetic waves. These new contributions augment five previous manuscripts published by the journal on optical stimulation technology, which reported the development of a fiber-based system for in vivo optogenetic cortical stimulation [29], patterned stimulation systems based on computer-generated holography [23] and on arrays of micro-LEDs [30] designed for an optical retina neuroprosthetic [31], and an integrated system for optical stimulation with microelectrode array recording [32]. Without doubt, many more will quickly follow as neural engineers and neuroscientists increasingly tackle the many challenges that this exciting area poses. We can all expect to hear much more in the near future about the biophysics and implementation of photo-physical neural-interaction mechanisms, the design of new optogenetic probes and patterned-stimulation systems (including stand-alone and implantable systems), further integration of electrodes and optical components into electro-optical neurostimulation systems, and rapid progress towards multiple medical applications for alleviating neurological disabilities and improving human health. References [1] Durand D M 2006 What is neural engineering? J. Neural Eng. 4 (4) [2] Niemz M H 2007 Laser-Tissue Interactions: Fundamentals and Applications 3rd edn (Berlin: Springer) [3] Arsonval A D 1891 La fibre musculaire est directement excitable par la lumiere C. R. Soc. Biol. 43 318-20 [4] Arvanitaki A

  10. A Rare Complication of Cochlear Implantation After Magnetic Resonance Imaging: Reversion of the Magnet.

    Öztürk, Erkan; Doruk, Can; Orhan, Kadir Serkan; Çelik, Mehmet; Polat, Beldan; Güldiken, Yahya

    2017-06-01

    Cochlear implants are mechanical devices used for patients with severe sensory-neural hearing loss, which has an inner magnet. It is proven that 1.5 Tesla magnetic resonance imaging (MRI) scanners are safe to use in patients with cochlear implant. In our patient, the authors aim to introduce a rare complication caused after a 1.5 Tesla MRI scanning and the management of this situation; the reversion of the magnet of the implant without displacement and significance of surgery in management.

  11. Preparation of high purity nickel film from industrial effluent by the distribution of charge over microelectrodes using newly designed free electrolytic diffusion approach

    Ahmed, Sheikh Asrar; Qadir, Muhammad Abdul; Zafar, Muhammad Nadeem; Hussain, Ishtiaq; Tufail, Shahid; Rashid, Saima; Shah, Hamid Ali

    2008-01-01

    The present work deals with the development of a newly designed free electrolytic diffusion approach (the distribution of charge over microelectrodes) for the purification of metals and was successfully applied for the purification of nickel from the industrial effluent containing high proportion of nickel. Atomic absorption spectrophotometer (AAS) analyzed the purified nickel deposited on working microelectrodes. The results obtained show that the purity of nickel was enhanced from 95% to 99.9% with traces of copper etc. It was concluded that distribution of charge over the microcathodes at a rate of 50 cycles per second (cps) shows better results for the production of high purity (HP) nickel as compared to 25 cycles per second (cps)

  12. Preparation of high purity nickel film from industrial effluent by the distribution of charge over microelectrodes using newly designed free electrolytic diffusion approach

    Ahmed, Sheikh Asrar; Qadir, Muhammad Abdul [Institute of Chemistry, University of the Punjab, Lahore, 54590 (Pakistan); Zafar, Muhammad Nadeem [Institute of Chemistry, University of the Punjab, Lahore, 54590 (Pakistan)], E-mail: znadeempk@yahoo.com; Hussain, Ishtiaq [Institute of Chemistry, University of the Punjab, Lahore, 54590 (Pakistan); Tufail, Shahid [PCSIR Laboratories Complex, Feroz pur Road, Lahore (Pakistan); Rashid, Saima; Shah, Hamid Ali [Institute of Chemistry, University of the Punjab, Lahore, 54590 (Pakistan)

    2008-09-15

    The present work deals with the development of a newly designed free electrolytic diffusion approach (the distribution of charge over microelectrodes) for the purification of metals and was successfully applied for the purification of nickel from the industrial effluent containing high proportion of nickel. Atomic absorption spectrophotometer (AAS) analyzed the purified nickel deposited on working microelectrodes. The results obtained show that the purity of nickel was enhanced from 95% to 99.9% with traces of copper etc. It was concluded that distribution of charge over the microcathodes at a rate of 50 cycles per second (cps) shows better results for the production of high purity (HP) nickel as compared to 25 cycles per second (cps)

  13. Chaotic diagonal recurrent neural network

    Wang Xing-Yuan; Zhang Yi

    2012-01-01

    We propose a novel neural network based on a diagonal recurrent neural network and chaos, and its structure and learning algorithm are designed. The multilayer feedforward neural network, diagonal recurrent neural network, and chaotic diagonal recurrent neural network are used to approach the cubic symmetry map. The simulation results show that the approximation capability of the chaotic diagonal recurrent neural network is better than the other two neural networks. (interdisciplinary physics and related areas of science and technology)

  14. In vivo characterization of the electrophysiological and astrocytic responses to a silicon neuroprobe implanted in the mouse neocortex.

    Mols, Katrien; Musa, Silke; Nuttin, Bart; Lagae, Liesbet; Bonin, Vincent

    2017-11-15

    Silicon neuroprobes hold great potential for studies of large-scale neural activity and brain computer interfaces, but data on brain response in chronic implants is limited. Here we explored with in vivo cellular imaging the response to multisite silicon probes for neural recordings. We tested a chronic implant for mice consisting of a CMOS-compatible silicon probe rigidly implanted in the cortex under a cranial imaging window. Multiunit recordings of cortical neurons with the implant showed no degradation of electrophysiological signals weeks after implantation (mean spike and noise amplitudes of 186 ± 42 µV pp and 16 ± 3.2 µV rms , respectively, n = 5 mice). Two-photon imaging through the cranial window allowed longitudinal monitoring of fluorescently-labeled astrocytes from the second week post implantation for 8 weeks (n = 3 mice). The imaging showed a local increase in astrocyte-related fluorescence that remained stable from the second to the tenth week post implantation. These results demonstrate that, in a standard electrophysiology protocol in mice, rigidly implanted silicon probes can provide good short to medium term chronic recording performance with a limited astrocyte inflammatory response. The precise factors influencing the response to silicon probe implants remain to be elucidated.

  15. Development of Li+ Selective Microelectrode Using PPy [3,3'-Co(1,2-C2B9H112] as a Solid Contact

    Safae MERZOUK

    2014-05-01

    Full Text Available Planar all solid-contact ion-selective microelectrodes (ASC-µISEs with a conducting polymer (polypyrrole doped with cobaltabis(dicarbollide anion [3,3'-Co(1,2-C2B9H112] as a solid contact layer between the polymeric membrane sensitive to lithium (Li and the gold (Au substrate were prepared and investigated. The N,N-dicyclohexyl-N',N'-diisobutylyl-cis-cyclohexane-1,2- dicarboxamide (ETH 1810 was used as ionophore for Li recognition. The developed microelectrodes show a linear response for Li+ concentration between 6´10-5 M and 1´10-1 M with slope of 53±1 mV per decade and exhibits remarkably enhanced selectivity for Li over other cations. The calibration plots using artificial serum containing three different levels of sodium chloride (NaCl (135, 145 and 155 mM as a background electrolyte were shown a linear response with a slope of 50 mV per decade in the clinical range of interest (0.7-1.5´10-3 M Li+. The developed microelectrodes will be used to determine Li+ concentrations in serum samples of manic-depressive patients under Li treatment.

  16. GABA and Gap Junctions in the Development of Synchronized Activity in Human Pluripotent Stem Cell-Derived Neural Networks

    Meeri Eeva-Liisa Mäkinen

    2018-03-01

    Full Text Available The electrical activity of the brain arises from single neurons communicating with each other. However, how single neurons interact during early development to give rise to neural network activity remains poorly understood. We studied the emergence of synchronous neural activity in human pluripotent stem cell (hPSC-derived neural networks simultaneously on a single-neuron level and network level. The contribution of gamma-aminobutyric acid (GABA and gap junctions to the development of synchronous activity in hPSC-derived neural networks was studied with GABA agonist and antagonist and by blocking gap junctional communication, respectively. We characterized the dynamics of the network-wide synchrony in hPSC-derived neural networks with high spatial resolution (calcium imaging and temporal resolution microelectrode array (MEA. We found that the emergence of synchrony correlates with a decrease in very strong GABA excitation. However, the synchronous network was found to consist of a heterogeneous mixture of synchronously active cells with variable responses to GABA, GABA agonists and gap junction blockers. Furthermore, we show how single-cell distributions give rise to the network effect of GABA, GABA agonists and gap junction blockers. Finally, based on our observations, we suggest that the earliest form of synchronous neuronal activity depends on gap junctions and a decrease in GABA induced depolarization but not on GABAA mediated signaling.

  17. GABA and Gap Junctions in the Development of Synchronized Activity in Human Pluripotent Stem Cell-Derived Neural Networks

    Mäkinen, Meeri Eeva-Liisa; Ylä-Outinen, Laura; Narkilahti, Susanna

    2018-01-01

    The electrical activity of the brain arises from single neurons communicating with each other. However, how single neurons interact during early development to give rise to neural network activity remains poorly understood. We studied the emergence of synchronous neural activity in human pluripotent stem cell (hPSC)-derived neural networks simultaneously on a single-neuron level and network level. The contribution of gamma-aminobutyric acid (GABA) and gap junctions to the development of synchronous activity in hPSC-derived neural networks was studied with GABA agonist and antagonist and by blocking gap junctional communication, respectively. We characterized the dynamics of the network-wide synchrony in hPSC-derived neural networks with high spatial resolution (calcium imaging) and temporal resolution microelectrode array (MEA). We found that the emergence of synchrony correlates with a decrease in very strong GABA excitation. However, the synchronous network was found to consist of a heterogeneous mixture of synchronously active cells with variable responses to GABA, GABA agonists and gap junction blockers. Furthermore, we show how single-cell distributions give rise to the network effect of GABA, GABA agonists and gap junction blockers. Finally, based on our observations, we suggest that the earliest form of synchronous neuronal activity depends on gap junctions and a decrease in GABA induced depolarization but not on GABAA mediated signaling. PMID:29559893

  18. Evolvable Neural Software System

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  19. [Bilateral cochlear implants].

    Müller, J

    2017-07-01

    Cochlear implants (CI) are standard for the hearing rehabilitation of severe to profound deafness. Nowadays, if bilaterally indicated, bilateral implantation is usually recommended (in accordance with German guidelines). Bilateral implantation enables better speech discrimination in quiet and in noise, and restores directional and spatial hearing. Children with bilateral CI are able to undergo hearing-based hearing and speech development. Within the scope of their individual possibilities, bilaterally implanted children develop faster than children with unilateral CI and attain, e.g., a larger vocabulary within a certain time interval. Only bilateral implantation allows "binaural hearing," with all the benefits that people with normal hearing profit from, namely: better speech discrimination in quiet and in noise, as well as directional and spatial hearing. Naturally, the developments take time. Binaural CI users benefit from the same effects as normal hearing persons: head shadow effect, squelch effect, and summation and redundancy effects. Sequential CI fitting is not necessarily disadvantageous-both simultaneously and sequentially fitted patients benefit in a similar way. For children, earliest possible fitting and shortest possible interval between the two surgeries seems to positively influence the outcome if bilateral CI are indicated.

  20. Psychological intervention following implantation of an implantable defibrillator

    Pedersen, Susanne S.; van den Broek, Krista C; Sears, Samuel F

    2007-01-01

    The medical benefits of the implantable cardioverter defibrillator (ICD) are unequivocal, but a subgroup of patients experiences emotional difficulties following implantation. For this subgroup, some form of psychological intervention may be warranted. This review provides an overview of current ...

  1. Neural Basis of Empathy and Its Dysfunction in Autism Spectrum Disorders (ASD)

    2014-10-01

    our work tests the idea that empathy derives from the activation of neural circuits that process primary emotions or feelings , such as reward or...ticipated. For all monkeys, a sterile surgery was performed to implant a head- restraint prosthesis (Crist Instruments) using standard techniques11...participated in the study. All animals underwent standard surgical procedures for implanting a head-restraint prosthesis at least 6 mo before the present study

  2. Management of peri-implantitis

    Jayachandran Prathapachandran

    2012-01-01

    Full Text Available Peri-implantitis is a site-specific infectious disease that causes an inflammatory process in soft tissues, and bone loss around an osseointegrated implant in function. The etiology of the implant infection is conditioned by the status of the tissue surrounding the implant, implant design, degree of roughness, external morphology, and excessive mechanical load. The microorganisms most commonly associated with implant failure are spirochetes and mobile forms of Gram-negative anaerobes, unless the origin is the result of simple mechanical overload. Diagnosis is based on changes of color in the gingiva, bleeding and probing depth of peri-implant pockets, suppuration, X-ray, and gradual loss of bone height around the tooth. Treatment will differ depending upon whether it is a case of peri-implant mucositis or peri-implantitis. The management of implant infection should be focused on the control of infection, the detoxification of the implant surface, and regeneration of the alveolar bone. This review article deals with the various treatment options in the management of peri-implantitis. The article also gives a brief description of the etiopathogenesis, clinical features, and diagnosis of peri-implantitis.

  3. Niche-dependent development of functional neuronal networks from embryonic stem cell-derived neural populations

    Siebler Mario

    2009-08-01

    Full Text Available Abstract Background The present work was performed to investigate the ability of two different embryonic stem (ES cell-derived neural precursor populations to generate functional neuronal networks in vitro. The first ES cell-derived neural precursor population was cultivated as free-floating neural aggregates which are known to form a developmental niche comprising different types of neural cells, including neural precursor cells (NPCs, progenitor cells and even further matured cells. This niche provides by itself a variety of different growth factors and extracellular matrix proteins that influence the proliferation and differentiation of neural precursor and progenitor cells. The second population was cultivated adherently in monolayer cultures to control most stringently the extracellular environment. This population comprises highly homogeneous NPCs which are supposed to represent an attractive way to provide well-defined neuronal progeny. However, the ability of these different ES cell-derived immature neural cell populations to generate functional neuronal networks has not been assessed so far. Results While both precursor populations were shown to differentiate into sufficient quantities of mature NeuN+ neurons that also express GABA or vesicular-glutamate-transporter-2 (vGlut2, only aggregate-derived neuronal populations exhibited a synchronously oscillating network activity 2–4 weeks after initiating the differentiation as detected by the microelectrode array technology. Neurons derived from homogeneous NPCs within monolayer cultures did merely show uncorrelated spiking activity even when differentiated for up to 12 weeks. We demonstrated that these neurons exhibited sparsely ramified neurites and an embryonic vGlut2 distribution suggesting an inhibited terminal neuronal maturation. In comparison, neurons derived from heterogeneous populations within neural aggregates appeared as fully mature with a dense neurite network and punctuated

  4. Ion implantation control system

    Gault, R. B.; Keutzer, L. L.

    1985-01-01

    A control system is disclosed for an ion implantation system of the type in which the wafers to be implanted are mounted around the periphery of a disk which rotates and also moves in a radial direction relative to an ion beam to expose successive sections of each wafer to the radiation. The control system senses beam current which passes through one or more apertures in the disk and is collected by a Faraday cup. This current is integrated to obtain a measure of charge which is compared with a calculated value based upon the desired ion dosage and other parameters. The resultant controls the number of incremental steps the rotating disk moves radially to expose the adjacent sections of each wafer. This process is continued usually with two or more traverses until the entire surface of each wafer has been implanted with the proper ion dosage

  5. Implantation for tribological applications

    Leutenecker, R.; Cao-Minh, U.; Overbeck, R.

    1992-08-01

    Empirical results on the strength enhancement of steels by N- and B-implantation should be explained from a materials science point of view. The methods applied were X-ray diffractometry and element depth profiling. The investigations of N-implanted steels focussed on the nitride formation in selected model materials and, with respect to applications, in: X90 CrMoV and S 6-5-2 tool steels, austenite X10 CrNiTi189 as well as in hard chromium plates. Main topic in B-implanted steels were the transformations: crystalline Fe-phase - amorphous Fe-B-phase - crystalline boride phases. The result is an improvement in process control by first an insight into the strength enhancing mechanisms and second in into their generation depending on the materials microstructure and the process parameter. (orig.). 101 figs., 16 tabs., 15 refs [de

  6. Dental implants: A review.

    Guillaume, B

    2016-12-01

    A high number of patients have one or more missing tooth and it is estimated that one in four American subjects over the age of 74 have lost all their natural teeth. Many options exist to replace missing teeth but dental implants have become one of the most used biomaterial to replace one (or more) missing tooth over the last decades. Contemporary dental implants made with titanium have been proven safe and effective in large series of patients. This review considers the main historical facts concerned with dental implants and present the different critical factors that will ensure a good osseo-integration that will ensure a stable prosthesis anchorage. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  7. Tribology of implantation bilayers

    Pivin, J.C.

    1989-01-01

    The mechanical behaviour of implantation films must be analysed in terms of bilayer rheology (laws of mechanical behaviour). Tribology takes into account thermodynamical, chemical and metallurgical parameters to interpret the friction properties of a system as a whole. One can distinguish between alloying effects of ion implantation and structural modifications. Alloying affects the basic properties of the crystal: elasticity, cohesion, mobility of planar defects, and its surface electronic structure, which determines the reactivity with the atmosphere or the friction counterpart (adhesion). Radiation damage and phase changes act more particularly on the modes of gliding and climbing of dislocations, and fracture mechanisms. 105 refs.; 11 figs.; 1 table

  8. [Tinnitus and implants].

    Despreaux, G; Tison, P; Van Den Abbeele, T; Moine, A; Frachet, B

    1990-01-01

    The experience with cochlear implantation at Avicenne hospital prompted us to carry out a retrospective study on tinnitus in a population of operated patients. Improvement or disappearance of the symptoms was noted in all cases. These results, which partly match those found in the literature, are probably produced by rehabilitation inhibiting the "deafferentation" mechanisms in analogy with pain phenomena. In some precise cases, which are described, they led us to proposing implantation even though the main, if not sole, complaint of the patient was tinnitus.

  9. Fast batch injection analysis of H{sub 2}O{sub 2} using an array of Pt-modified gold microelectrodes obtained from split electronic chips

    Pacheco, Bruno D.; Valerio, Jaqueline [Centro de Ciencias e Humanidades - Universidade Presbiteriana Mackenzie, Rua da Consolacao, 896, 01302-907 Sao Paulo, SP (Brazil); Angnes, Lucio [Departamento de Quimica Fundamental, Instituto de Quimica da USP, Av. Prof. Lineu Prestes, 748, 05508-000 Cidade Universitaria, Sao Paulo, SP (Brazil); Pedrotti, Jairo J., E-mail: jpedrotti@mackenzie.br [Centro de Ciencias e Humanidades - Universidade Presbiteriana Mackenzie, Rua da Consolacao, 896, 01302-907 Sao Paulo, SP (Brazil)

    2011-06-24

    Graphical abstract: Highlights: > An array of gold microelectrodes modified with Pt was used for batch injection analysis of H{sub 2}O{sub 2} in rainwater. > The microelectrode array (n = 14) was obtained from electronic chips developed for surface mounted device technology. > The analytical frequency of the method can attain 300 determinations per hour. > The volume-weighted mean concentration of H{sub 2}O{sub 2} in rainwater investigated (n = 25) was 14.2 {mu}mol L{sup -1}. - Abstract: A fast and robust analytical method for amperometric determination of hydrogen peroxide (H{sub 2}O{sub 2}) based on batch injection analysis (BIA) on an array of gold microelectrodes modified with platinum is proposed. The gold microelectrode array (n = 14) was obtained from electronic chips developed for surface mounted device technology (SMD), whose size offers advantages to adapt them in batch cells. The effect of the dispensing rate, volume injected, distance between the platinum microelectrodes and the pipette tip, as well as the volume of solution in the cell on the analytical response were evaluated. The method allows the H{sub 2}O{sub 2} amperometric determination in the concentration range from 0.8 {mu}mol L{sup -1} to 100 {mu}mol L{sup -1}. The analytical frequency can attain 300 determinations per hour and the detection limit was estimated in 0.34 {mu}mol L{sup -1} (3{sigma}). The anodic current peaks obtained after a series of 23 successive injections of 50 {mu}L of 25 {mu}mol L{sup -1} H{sub 2}O{sub 2} showed an RSD < 0.9%. To ensure the good selectivity to detect H{sub 2}O{sub 2}, its determination was performed in a differential mode, with selective destruction of the H{sub 2}O{sub 2} with catalase in 10 mmol L{sup -1} phosphate buffer solution. Practical application of the analytical procedure involved H{sub 2}O{sub 2} determination in rainwater of Sao Paulo City. A comparison of the results obtained by the proposed amperometric method with another one which

  10. A neural flow estimator

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  11. Neural Systems Laboratory

    Federal Laboratory Consortium — As part of the Electrical and Computer Engineering Department and The Institute for System Research, the Neural Systems Laboratory studies the functionality of the...

  12. A high-throughput electrochemical impedance spectroscopy evaluation of bioresponsibility of the titanium microelectrode array integrated with hydroxyapatite and silver

    Zhang Fan; Lin Longxiang; Wang Guowei; Hu Ren; Lin Changjian; Chen Yong

    2012-01-01

    Highlights: ► The EIS of living MG63 cells on the Ti MEA chip with Ag, HA, and Ag–HA was monitored. ► The R cell can be related to the bioresponsibility of the coatings. ► The bioactivity order was evaluated as follows: Ti–Ag–HA > Ti–HA ≈ Ti–Ag > Ti. - Abstract: This paper reports a transparent Ti microelectrode array (MEA) system for a high-throughput evaluation of bioresponsibility using electrochemical impedance spectroscopy (EIS). The MEA chip integrated with hydroxyapatite (HA) and Ag coatings was selectively prepared by electrochemical deposition based on a novel procedure of multichannel current control. The EIS measurement of living MG63 osteosarcoma cells in the integrated MEA chip was conducted, and the result was analyzed using an equivalent circuit corresponding to a titanium oxide film, protein adsorption layer, cell adhesion layer, and medium. It is shown that the bioresponsibility of Ti–Ag–HA on the MEA chip can be improved, compared with the Ti, Ti–HA, and Ti–Ag coatings. The system was further used for real-time EIS monitoring during continuous cell culture for a long period (12 days). The effect of the long-term cell proliferation on the EIS behavior was discussed. This integrated system is valuable to significantly simplify the operation procedures and quickly evaluate the bioresponsibility of biomaterials.

  13. Theoretical and experimental study of the bending influence on the capacitance of interdigitated micro-electrodes patterned on flexible substrates

    Molina-Lopez, F.; Briand, D.; Rooij, N. F. de; Kinkeldei, T.; Tröster, G.

    2013-01-01

    Interdigitated electrodes are common structures in the fields of microelectronics and MEMS. Recent developments in flexible electronics compel an understanding of such structures under bending constraints. In this work, the behavior of interdigitated micro-electrodes when subjected to circular bending has been theoretically and experimentally studied through changes in capacitance. An analytical model has been developed to calculate the expected variation in capacitance of such structures while undergoing outward and inward bending along the direction perpendicular to the electrodes. The model combines conformal mapping techniques to account for the electric field redistribution and fundamental aspects of solid mechanics in order to define the geometrical deformation of the electrodes while bending. To experimentally verify our theoretical predictions, several interdigitated electrode structures with different geometries were fabricated on polymeric substrates by means of photolithography. The samples, placed in a customized bending setup, were bent to controlled radii of curvature while measuring their capacitance. A maximum variation in capacitance of less than 3% was observed at a minimum radius of curvature of 2.5 mm for all the devices tested with very thin electrodes whereas changes of up to 7% were found on stiffer, plated electrodes. Larger or smaller variations would be possible, in theory, by adjusting the geometry of the device. This work establishes a useful predictive tool for the design and evaluation of truly flexible/bendable electronics consisting of interdigitated structures, allowing one to tune the bending influence on the capacitance value through geometrical design

  14. A Multi-Functional Microelectrode Array Featuring 59760 Electrodes, 2048 Electrophysiology Channels, Stimulation, Impedance Measurement and Neurotransmitter Detection Channels.

    Dragas, Jelena; Viswam, Vijay; Shadmani, Amir; Chen, Yihui; Bounik, Raziyeh; Stettler, Alexander; Radivojevic, Milos; Geissler, Sydney; Obien, Marie; Müller, Jan; Hierlemann, Andreas

    2017-06-01

    Biological cells are characterized by highly complex phenomena and processes that are, to a great extent, interdependent. To gain detailed insights, devices designed to study cellular phenomena need to enable tracking and manipulation of multiple cell parameters in parallel; they have to provide high signal quality and high spatiotemporal resolution. To this end, we have developed a CMOS-based microelectrode array system that integrates six measurement and stimulation functions, the largest number to date. Moreover, the system features the largest active electrode array area to date (4.48×2.43 mm 2 ) to accommodate 59,760 electrodes, while its power consumption, noise characteristics, and spatial resolution (13.5 μm electrode pitch) are comparable to the best state-of-the-art devices. The system includes: 2,048 action-potential (AP, bandwidth: 300 Hz to 10 kHz) recording units, 32 local-field-potential (LFP, bandwidth: 1 Hz to 300 Hz) recording units, 32 current recording units, 32 impedance measurement units, and 28 neurotransmitter detection units, in addition to the 16 dual-mode voltage-only or current/voltage-controlled stimulation units. The electrode array architecture is based on a switch matrix, which allows for connecting any measurement/stimulation unit to any electrode in the array and for performing different measurement/stimulation functions in parallel.

  15. Silicon Wafer-Based Platinum Microelectrode Array Biosensor for Near Real-Time Measurement of Glutamate in Vivo

    Nigel T. Maidment

    2008-08-01

    Full Text Available Using Micro-Electro-Mechanical-Systems (MEMS technologies, we have developed silicon wafer-based platinum microelectrode arrays (MEAs modified with glutamate oxidase (GluOx for electroenzymatic detection of glutamate in vivo. These MEAs were designed to have optimal spatial resolution for in vivo recordings. Selective detection of glutamate in the presence of the electroactive interferents, dopamine and ascorbic acid, was attained by deposition of polypyrrole and Nafion. The sensors responded to glutamate with a limit of detection under 1μM and a sub-1-second response time in solution. In addition to extensive in vitro characterization, the utility of these MEA glutamate biosensors was also established in vivo. In the anesthetized rat, these MEA glutamate biosensors were used for detection of cortically-evoked glutamate release in the ventral striatum. The MEA biosensors also were applied to the detection of stress-induced glutamate release in the dorsal striatum of the freely-moving rat.

  16. Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes.

    Chae, Kyu-Jung; Rameshwar, T; Jang, Am; Kim, Sung H; Kim, In S

    2008-09-01

    There is growing interest in the development of more cost-effective and retrofit technologies for the upgrade and expansion of existing wastewater treatment plants with extreme space constraints. A free-floating sponge media (BioCube) process, using a 24 L lab scale reactor, was operated to study the nitrification profiles and microbial community. The COD removal efficiencies were maintained, at an average of 95%, with the mixed liquor suspended solids (MLSS) inside the BioCube sponge media maintained at 12,688 mg/L. The nitrification removal efficiencies were between 92% and 100%, with an average value of 99%. From the results of microelectrode measurements, the ammonium ion concentration was found to rapidly decrease from the surface of the BioCube sponge media to a depth of 2mm due to chemical reactions carried out by ammonia oxidizing bacteria (AOB) species. Multi-fluorescence in situ hybridization (FISH) has been used to investigate the spatial distributions of various microbial activities within reactors. Microbial communities were targeted using different oligonucleotide probes specific to AOB and nitrite oxidizing bacteria (NOB). There were a large number of AOB populations, but these were not uniformly distributed in the biofilm compared to the NOB populations.

  17. Comparative Analysis of Human and Rodent Brain Primary Neuronal Culture Spontaneous Activity Using Micro-Electrode Array Technology.

    Napoli, Alessandro; Obeid, Iyad

    2016-03-01

    Electrical activity in embryonic brain tissue has typically been studied using Micro Electrode Array (MEA) technology to make dozens of simultaneous recordings from dissociated neuronal cultures, brain stem cell progenitors, or brain slices from fetal rodents. Although these rodent neuronal primary culture electrical properties are mostly investigated, it has not been yet established to what extent the electrical characteristics of rodent brain neuronal cultures can be generalized to those of humans. A direct comparison of spontaneous spiking activity between rodent and human primary neurons grown under the same in vitro conditions using MEA technology has never been carried out before and will be described in the present study. Human and rodent dissociated fetal brain neuronal cultures were established in-vitro by culturing on a glass grid of 60 planar microelectrodes neurons under identical conditions. Three different cultures of human neurons were produced from tissue sourced from a single aborted fetus (at 16-18 gestational weeks) and these were compared with seven different cultures of embryonic rat neurons (at 18 gestational days) originally isolated from a single rat. The results show that the human and rodent cultures behaved significantly differently. Whereas the rodent cultures demonstrated robust spontaneous activation and network activity after only 10 days, the human cultures required nearly 40 days to achieve a substantially weaker level of electrical function. These results suggest that rat neuron preparations may yield inferences that do not necessarily transfer to humans. © 2015 Wiley Periodicals, Inc.

  18. Neural stimulators: A guide to imaging and postoperative appearances

    Adams, A.; Shand-Smith, J.; Watkins, L.; McEvoy, A.W.; Elneil, S.; Zrinzo, L.; Davagnanam, I.

    2014-01-01

    Implantable neural stimulators have been developed to aid patients with debilitating neurological conditions that are not amenable to other therapies. The aim of this article is to improve understanding of correct anatomical placement as well as the relevant imaging methods used to assess these devices. Potential complications following their insertion and an overview of the current indications and potential mechanism of action of these devices is provided

  19. Recent advances in dental implants.

    Hong, Do Gia Khang; Oh, Ji-Hyeon

    2017-12-01

    Dental implants are a common treatment for the loss of teeth. This paper summarizes current knowledge on implant surfaces, immediate loading versus conventional loading, short implants, sinus lifting, and custom implants using three-dimensional printing. Most of the implant surface modifications showed good osseointegration results. Regarding biomolecular coatings, which have been recently developed and studied, good results were observed in animal experiments. Immediate loading had similar clinical outcomes compared to conventional loading and can be used as a successful treatment because it has the advantage of reducing treatment times and providing early function and aesthetics. Short implants showed similar clinical outcomes compared to standard implants. A variety of sinus augmentation techniques, grafting materials, and alternative techniques, such as tilted implants, zygomatic implants, and short implants, can be used. With the development of new technologies in three-dimension and computer-aided design/computer-aided manufacturing (CAD/CAM) customized implants can be used as an alternative to conventional implant designs. However, there are limitations due to the lack of long-term studies or clinical studies. A long-term clinical trial and a more predictive study are needed.

  20. Untreated silicone breast implant rupture

    Hölmich, Lisbet R; Vejborg, Ilse M; Conrad, Carsten

    2004-01-01

    Implant rupture is a well-known complication of breast implant surgery that can pass unnoticed by both patient and physician. To date, no prospective study has addressed the possible health implications of silicone breast implant rupture. The aim of the present study was to evaluate whether untre...

  1. Two-stage implant systems.

    Fritz, M E

    1999-06-01

    Since the advent of osseointegration approximately 20 years ago, there has been a great deal of scientific data developed on two-stage integrated implant systems. Although these implants were originally designed primarily for fixed prostheses in the mandibular arch, they have been used in partially dentate patients, in patients needing overdentures, and in single-tooth restorations. In addition, this implant system has been placed in extraction sites, in bone-grafted areas, and in maxillary sinus elevations. Often, the documentation of these procedures has lagged. In addition, most of the reports use survival criteria to describe results, often providing overly optimistic data. It can be said that the literature describes a true adhesion of the epithelium to the implant similar to adhesion to teeth, that two-stage implants appear to have direct contact somewhere between 50% and 70% of the implant surface, that the microbial flora of the two-stage implant system closely resembles that of the natural tooth, and that the microbiology of periodontitis appears to be closely related to peri-implantitis. In evaluations of the data from implant placement in all of the above-noted situations by means of meta-analysis, it appears that there is a strong case that two-stage dental implants are successful, usually showing a confidence interval of over 90%. It also appears that the mandibular implants are more successful than maxillary implants. Studies also show that overdenture therapy is valid, and that single-tooth implants and implants placed in partially dentate mouths have a success rate that is quite good, although not quite as high as in the fully edentulous dentition. It would also appear that the potential causes of failure in the two-stage dental implant systems are peri-implantitis, placement of implants in poor-quality bone, and improper loading of implants. There are now data addressing modifications of the implant surface to alter the percentage of

  2. Neural Networks: Implementations and Applications

    Vonk, E.; Veelenturf, L.P.J.; Jain, L.C.

    1996-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  3. Braided Multi-Electrode Probes (BMEPs) for Neural Interfaces

    Kim, Tae Gyo

    Although clinical use of invasive neural interfaces is very limited, due to safety and reliability concerns, the potential benefits of their use in brain machine interfaces (BMIs) seem promising and so they have been widely used in the research field. Microelectrodes as invasive neural interfaces are the core tool to record neural activities and their failure is a critical issue for BMI systems. Possible sources of this failure are neural tissue motions and their interactions with stiff electrode arrays or probes fixed to the skull. To overcome these tissue motion problems, we have developed novel braided multi-electrode probes (BMEPs). By interweaving ultra-fine wires into a tubular braid structure, we obtained a highly flexible multi-electrode probe. In this thesis we described BMEP designs and how to fabricate BMEPs, and explore experiments to show the advantages of BMEPs through a mechanical compliance comparison and a chronic immunohistological comparison with single 50microm nichrome wires used as a reference electrode type. Results from the mechanical compliance test showed that the bodies of BMEPs have 4 to 21 times higher compliance than the single 50microm wire and the tethers of BMEPs were 6 to 96 times higher compliance, depending on combinations of the wire size (9.6microm or 12.7microm), the wire numbers (12 or 24), and the length of tether (3, 5 or 10 mm). Results from the immunohistological comparison showed that both BMEPs and 50microm wires anchored to the skull caused stronger tissue reactions than unanchored BMEPs and 50microm wires, and 50microm wires caused stronger tissue reactions than BMEPs. In in-vivo tests with BMEPs, we succeeded in chronic recordings from the spinal cord of freely jumping frogs and in acute recordings from the spinal cord of decerebrate rats during air stepping which was evoked by mesencephalic locomotor region (MLR) stimulation. This technology may provide a stable and reliable neural interface to spinal cord

  4. Semiconductor Ion Implanters

    MacKinnon, Barry A.; Ruffell, John P.

    2011-01-01

    In 1953 the Raytheon CK722 transistor was priced at $7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at $6.2 billion! Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing 'only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around $2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  5. Implantable enzyme amperometric biosensors.

    Kotanen, Christian N; Moussy, Francis Gabriel; Carrara, Sandro; Guiseppi-Elie, Anthony

    2012-05-15

    The implantable enzyme amperometric biosensor continues as the dominant in vivo format for the detection, monitoring and reporting of biochemical analytes related to a wide range of pathologies. Widely used in animal studies, there is increasing emphasis on their use in diabetes care and management, the management of trauma-associated hemorrhage and in critical care monitoring by intensivists in the ICU. These frontier opportunities demand continuous indwelling performance for up to several years, well in excess of the currently approved seven days. This review outlines the many challenges to successful deployment of chronically implantable amperometric enzyme biosensors and emphasizes the emerging technological approaches in their continued development. The foreign body response plays a prominent role in implantable biotransducer failure. Topics considering the approaches to mitigate the inflammatory response, use of biomimetic chemistries, nanostructured topographies, drug eluting constructs, and tissue-to-device interface modulus matching are reviewed. Similarly, factors that influence biotransducer performance such as enzyme stability, substrate interference, mediator selection and calibration are reviewed. For the biosensor system, the opportunities and challenges of integration, guided by footprint requirements, the limitations of mixed signal electronics, and power requirements, has produced three systems approaches. The potential is great. However, integration along the multiple length scales needed to address fundamental issues and integration across the diverse disciplines needed to achieve success of these highly integrated systems, continues to be a challenge in the development and deployment of implantable amperometric enzyme biosensor systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. HA-Coated Implant

    Daugaard, Henrik; Søballe, Kjeld; Bechtold, Joan E

    2014-01-01

    of improving the fixation of implants. Of these, hydroxyapatite (HA) is the most widely used and most extensively investigated. HA is highly osseoconductive, and the positive effect is well documented in both basic and long-term clinical research [1–6]. This chapter describes experimental and clinical studies...

  7. Middle ear implants

    K S Gangadhara Somayaji

    2013-01-01

    Full Text Available Hearing loss is becoming more common in the society living in cities with lot of background noise around, and frequent use of gadgets like mobile phones, MP3s, and IPods are adding to the problem. The loss may involve the conductive or perceptive pathway. Majority of the patients with conductive hearing loss will revert back to normal hearing levels with medical and/or surgical treatment. However, in sensorineural hearing loss, many factors are involved in the management. Though traditionally hearing aids in various forms are the most commonly used modality in managing these patients, there are some drawbacks associated with them. Implantable middle ear amplifiers represent the most recent breakthrough in the management of hearing loss. Middle ear implants are surgically implanted electronic devices that aim to correct hearing loss by stimulating the ossicular chain or middle ear. Of late, they are also being used in the management of congenital conductive hearing loss and certain cases of chronic otitis media with residual hearing loss. The article aims to provide general information about the technology, indications and contraindications, selection of candidates, available systems, and advantages of middle ear implants. (MEI

  8. Delayed breast implant reconstruction

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne

    2011-01-01

    the period 1999 to 2006; 239 one-stage procedures and 353 two-stage procedures. The postoperative course through November 2009 was evaluated by cumulative incidence adjusting for competing risks for the selected outcomes; hematoma, infection, seroma, implant rupture, severe capsular contracture (modified...

  9. Remote actuated valve implant

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  10. State-dependent, bidirectional modulation of neural network activity by endocannabinoids.

    Piet, Richard; Garenne, André; Farrugia, Fanny; Le Masson, Gwendal; Marsicano, Giovanni; Chavis, Pascale; Manzoni, Olivier J

    2011-11-16

    The endocannabinoid (eCB) system and the cannabinoid CB1 receptor (CB1R) play key roles in the modulation of brain functions. Although actions of eCBs and CB1Rs are well described at the synaptic level, little is known of their modulation of neural activity at the network level. Using microelectrode arrays, we have examined the role of CB1R activation in the modulation of the electrical activity of rat and mice cortical neural networks in vitro. We find that exogenous activation of CB1Rs expressed on glutamatergic neurons decreases the spontaneous activity of cortical neural networks. Moreover, we observe that the net effect of the CB1R antagonist AM251 inversely correlates with the initial level of activity in the network: blocking CB1Rs increases network activity when basal network activity is low, whereas it depresses spontaneous activity when its initial level is high. Our results reveal a complex role of CB1Rs in shaping spontaneous network activity, and suggest that the outcome of endogenous neuromodulation on network function might be state dependent.

  11. Enhanced biocompatibility of neural probes by integrating microstructures and delivering anti-inflammatory agents via microfluidic channels

    Liu, Bin; Kim, Eric; Meggo, Anika; Gandhi, Sachin; Luo, Hao; Kallakuri, Srinivas; Xu, Yong; Zhang, Jinsheng

    2017-04-01

    Objective. Biocompatibility is a major issue for chronic neural implants, involving inflammatory and wound healing responses of neurons and glial cells. To enhance biocompatibility, we developed silicon-parylene hybrid neural probes with open architecture electrodes, microfluidic channels and a reservoir for drug delivery to suppress tissue responses. Approach. We chronically implanted our neural probes in the rat auditory cortex and investigated (1) whether open architecture electrode reduces inflammatory reaction by measuring glial responses; and (2) whether delivery of antibiotic minocycline reduces inflammatory and tissue reaction. Four weeks after implantation, immunostaining for glial fibrillary acid protein (astrocyte marker) and ionizing calcium-binding adaptor molecule 1 (macrophages/microglia cell marker) were conducted to identify immunoreactive astrocyte and microglial cells, and to determine the extent of astrocytes and microglial cell reaction/activation. A comparison was made between using traditional solid-surface electrodes and newly-designed electrodes with open architecture, as well as between deliveries of minocycline and artificial cerebral-spinal fluid diffused through microfluidic channels. Main results. The new probes with integrated micro-structures induced minimal tissue reaction compared to traditional electrodes at 4 weeks after implantation. Microcycline delivered through integrated microfluidic channels reduced tissue response as indicated by decreased microglial reaction around the neural probes implanted. Significance. The new design will help enhance the long-term stability of the implantable devices.

  12. Estimation of network structure for signal propagations by the analysis of multichannel action potentials in cultured neural networks; Ta channel katsudo den`i kaiseki ni yoru baiyo shinkei kairomonai kofun denpa keiro no suitei

    Konno, N.; Fukami, T.; Shiina, T. [University of Tsukuba, Tsukuba (Japan); Jinbo, Y. [Nippon Telegraph and Telephone Corp., Tokyo (Japan)

    1998-07-01

    We have fabricated a 64 embedded microelectrode-array substrate using semiconductor technology to investigate the biological signal processing in brain by using cultured neural networks of fetal rat neocortex in vitro. We analyzed temporal and spatial neural networks patterns cultured on electrode-array substrate and attempted to examine the network structure constituted by neurons and the propagating patterns of electrical activity induced by the electric stimulus. In the experiments, each microelectrode size was 30 {mu}m squared and 150{mu} m spaced. For stimulation, one of the electrodes was selected and current pulses were applied through an isolated circuit. After the network was cultured in about 50 days, responses of neurons to electric stimulus were monitored extracellularly through 64-channel electrode array. Data recorded at each electrode consist of several spike trains generated by different cells. Therefore, these trains were separated by using wavelet transform and template matching for each electrode. We referred the temporal patterns of generated spikes for each electrode to as `spike sequences`. Next, we compared With the spike sequences among multichannel data and visualized the Cultured neural networks structure by identifying the directions of propagations and cell connections. 15 refs., 9 figs.

  13. Critical Branching Neural Networks

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  14. Consciousness and neural plasticity

    changes or to abandon the strong identity thesis altogether. Were one to pursue a theory according to which consciousness is not an epiphenomenon to brain processes, consciousness may in fact affect its own neural basis. The neural correlate of consciousness is often seen as a stable structure, that is...

  15. Comparison of Classifier Architectures for Online Neural Spike Sorting.

    Saeed, Maryam; Khan, Amir Ali; Kamboh, Awais Mehmood

    2017-04-01

    High-density, intracranial recordings from micro-electrode arrays need to undergo Spike Sorting in order to associate the recorded neuronal spikes to particular neurons. This involves spike detection, feature extraction, and classification. To reduce the data transmission and power requirements, on-chip real-time processing is becoming very popular. However, high computational resources are required for classifiers in on-chip spike-sorters, making scalability a great challenge. In this review paper, we analyze several popular classifiers to propose five new hardware architectures using the off-chip training with on-chip classification approach. These include support vector classification, fuzzy C-means classification, self-organizing maps classification, moving-centroid K-means classification, and Cosine distance classification. The performance of these architectures is analyzed in terms of accuracy and resource requirement. We establish that the neural networks based Self-Organizing Maps classifier offers the most viable solution. A spike sorter based on the Self-Organizing Maps classifier, requires only 7.83% of computational resources of the best-reported spike sorter, hierarchical adaptive means, while offering a 3% better accuracy at 7 dB SNR.

  16. High-Density Stretchable Electrode Grids for Chronic Neural Recording.

    Tybrandt, Klas; Khodagholy, Dion; Dielacher, Bernd; Stauffer, Flurin; Renz, Aline F; Buzsáki, György; Vörös, János

    2018-04-01

    Electrical interfacing with neural tissue is key to advancing diagnosis and therapies for neurological disorders, as well as providing detailed information about neural signals. A challenge for creating long-term stable interfaces between electronics and neural tissue is the huge mechanical mismatch between the systems. So far, materials and fabrication processes have restricted the development of soft electrode grids able to combine high performance, long-term stability, and high electrode density, aspects all essential for neural interfacing. Here, this challenge is addressed by developing a soft, high-density, stretchable electrode grid based on an inert, high-performance composite material comprising gold-coated titanium dioxide nanowires embedded in a silicone matrix. The developed grid can resolve high spatiotemporal neural signals from the surface of the cortex in freely moving rats with stable neural recording quality and preserved electrode signal coherence during 3 months of implantation. Due to its flexible and stretchable nature, it is possible to minimize the size of the craniotomy required for placement, further reducing the level of invasiveness. The material and device technology presented herein have potential for a wide range of emerging biomedical applications. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. A comparison of electrochemically pre-treated and spark-platinized carbon fiber microelectrode. Measurement of 8-oxo-7,8-dihydro-2′-deoxyguanosine in human urine and plasma

    Bartosova, Z.; Riman, D. [Department of Analytical Chemistry, Palacky University, Faculty of Science, 17.listopadu 12, CZ-771 46 Olomouc (Czech Republic); Halouzka, V. [Department of Analytical Chemistry, Palacky University, Faculty of Science, 17.listopadu 12, CZ-771 46 Olomouc (Czech Republic); Department of Physics and Materials Engineering, Faculty of Technology, Tomas Bata University in Zlin, nam. T.G. Masaryka 275, CZ-76001 Zlin (Czech Republic); Vostalova, J.; Simanek, V. [Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, CZ-775 15 Olomouc (Czech Republic); Hrbac, J., E-mail: jhrbac@atlas.cz [Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Jirovsky, D., E-mail: david.jirovsky@upol.cz [Department of Analytical Chemistry, Palacky University, Faculty of Science, 17.listopadu 12, CZ-771 46 Olomouc (Czech Republic)

    2016-09-07

    A novel method of carbon fiber microelectrode activation using spark discharge was demonstrated and compared to conventional electrochemical pretreatment by potential cycling. The spark discharge was performed at 800 V between the microelectrode connected to positive pole of the power supply and platinum counter electrode. Spark discharge led both to trimming of the fiber tip into conical shape and to the modification of carbon fiber microelectrode with platinum, as proven by scanning electron microscopy and electron dispersive X-ray spectroscopy. After the characterization of electrochemical properties using ferricyanide voltammetry, the activated electrodes were used for electrochemical analysis of 8-oxo-7,8-dihydro-2′-deoxyguanosine, an oxidative stress marker. Subnanomolar detection limits (0.55 nmol L{sup −1}) in high-performance liquid chromatography were achieved for spark platinized electrodes incorporated into the flow detection cell. - Highlights: • Novel method of carbon fiber microelectrode activation and platinization using spark discharge. • The activation procedure is efficient, fast and solvent-free. • Modification of the surface and the shape of the carbon fiber microelectrode during the process. • The spark-etched platinized carbon fiber sensors are highly sensitive. • The sensor was successfully applied to HPLC analysis of 8-oxo-7,8-dihydro-2′-deoxyguanosine in plasma and urine.

  18. High-throughput cardiac safety evaluation and multi-parameter arrhythmia profiling of cardiomyocytes using microelectrode arrays

    Gilchrist, Kristin H., E-mail: kgilchrist@rti.org; Lewis, Gregory F.; Gay, Elaine A.; Sellgren, Katelyn L.; Grego, Sonia

    2015-10-15

    Microelectrode arrays (MEAs) recording extracellular field potentials of human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM) provide a rich data set for functional assessment of drug response. The aim of this work is the development of a method for a systematic analysis of arrhythmia using MEAs, with emphasis on the development of six parameters accounting for different types of cardiomyocyte signal irregularities. We describe a software approach to carry out such analysis automatically including generation of a heat map that enables quick visualization of arrhythmic liability of compounds. We also implemented signal processing techniques for reliable extraction of the repolarization peak for field potential duration (FPD) measurement even from recordings with low signal to noise ratios. We measured hiPS-CM's on a 48 well MEA system with 5 minute recordings at multiple time points (0.5, 1, 2 and 4 h) after drug exposure. We evaluated concentration responses for seven compounds with a combination of hERG, QT and clinical proarrhythmia properties: Verapamil, Ranolazine, Flecainide, Amiodarone, Ouabain, Cisapride, and Terfenadine. The predictive utility of MEA parameters as surrogates of these clinical effects were examined. The beat rate and FPD results exhibited good correlations with previous MEA studies in stem cell derived cardiomyocytes and clinical data. The six-parameter arrhythmia assessment exhibited excellent predictive agreement with the known arrhythmogenic potential of the tested compounds, and holds promise as a new method to predict arrhythmic liability. - Highlights: • Six parameters describing arrhythmia were defined and measured for known compounds. • Software for efficient parameter extraction from large MEA data sets was developed. • The proposed cellular parameter set is predictive of clinical drug proarrhythmia.

  19. Facilitated extracellular electron transfer of Shewanella loihica PV-4 by antimony-doped tin oxide nanoparticles as active microelectrodes.

    Zhang, Xiaojian; Liu, Huan; Wang, Jinrong; Ren, Guangyuan; Xie, Beizhen; Liu, Hong; Zhu, Ying; Jiang, Lei

    2015-11-28

    Dissimilatory metal reducing bacteria are capable of extracellular electron transfer (EET) to insoluble metal oxides as external electron acceptors for their anaerobic respiration, which is recognized as an important energy-conversion process in natural and engineered environments, such as in mineral cycling, bioremediation, and microbial fuel/electrolysis cells. However, the low EET efficiency remains one of the major bottlenecks for its practical application. We report firstly that the microbial current generated by Shewanella loihica PV-4 (S. loihica PV-4) could be greatly improved that is up to ca. 115 fold, by adding antimony-doped tin oxide (ATO) nanoparticles in the electrochemical reactor. The results demonstrate that the biocompatible, electrically conductive ATO nanoparticles acted as active microelectrodes could facilitate the formation of a cells/ATO composite biofilm and the reduction of the outer membrane c-type cytochromes (OM c-Cyts) that are beneficial for the electron transfer from cells to electrode. Meanwhile, a synergistic effect between the participation of OM c-Cyts and the accelerated EET mediated by cell-secreted flavins may play an important role for the enhanced current generation in the presence of ATO nanoparticles. Moreover, it is worth noting that the TCA cycle in S. loihica PV-4 cells is activated by adding ATO nanoparticles, even if the potential is poised at +0.2 V, thereby also improving the EET process. The results presented here may provide a simple and effective strategy to boost the EET of S. loihica PV-4 cells, which is conducive to providing potential applications in bioelectrochemical systems.

  20. Bio-electrochemical microelectrode arrays for glutamate and electrophysiology detection in hippocampus of temporal lobe epileptic rats.

    Li, Ziyue; Song, Yilin; Xiao, Guihua; Gao, Fei; Xu, Shengwei; Wang, Mixia; Zhang, Yu; Guo, Fengru; Liu, Jie; Xia, Yang; Cai, Xinxia

    2018-06-01

    Temporal Lobe Epilepsy (TLE) is a chronic neurological disorder, characterized by sudden, repeated and transient central nervous system dysfunction. For better understanding of TLE, bio-nanomodified microelectrode arrays (MEA) are designed, for the achievement of high-quality simultaneous detection of glutamate signals (Glu) and multi-channel electrophysiological signals including action potentials (spikes) and local field potentials (LFPs). The MEA was fabricated by Micro-Electro-Mechanical System fabrication technology and all recording sites were modified with platinum black nano-particles, the average impedance decreased by nearly 90 times. Additionally, glutamate oxidase was also modified for the detection of Glu. The average sensitivity of the electrode in Glu solution was 1.999 ± 0.032 × 10 -2 pA/μM·μm 2 (n = 3) and linearity was R = 0.9986, with a good selectivity of 97.82% for glutamate and effective blocking of other interferents. In the in-vivo experiments, the MEA was subjected in hippocampus to electrophysiology and Glu concentration detection. During seizures, the fire rate of spikes increases, and the interspike interval is concentrated within 30 ms. The amplitude of LFPs increases by 3 times and the power increases. The Glu level (4.22 μM, n = 4) was obviously higher than normal rats (2.24 μM, n = 4). The MEA probe provides an advanced tool for the detection of dual-mode signals in the research of neurological diseases. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. QSpike Tools: a Generic Framework for Parallel Batch Preprocessing of Extracellular Neuronal Signals Recorded by Substrate Microelectrode Arrays

    Mufti eMahmud

    2014-03-01

    Full Text Available Micro-Electrode Arrays (MEAs have emerged as a mature technique to investigate brain (dysfunctions in vivo and in in vitro animal models. Often referred to as smart Petri dishes, MEAs has demonstrated a great potential particularly for medium-throughput studies in vitro, both in academic and pharmaceutical industrial contexts. Enabling rapid comparison of ionic/pharmacological/genetic manipulations with control conditions, MEAs are often employed to screen compounds by monitoring non-invasively the spontaneous and evoked neuronal electrical activity in longitudinal studies, with relatively inexpensive equipment. However, in order to acquire sufficient statistical significance, recordings last up to tens of minutes and generate large amount of raw data (e.g., 60 channels/MEA, 16 bits A/D conversion, 20kHz sampling rate: ~8GB/MEA,h uncompressed. Thus, when the experimental conditions to be tested are numerous, the availability of fast, standardized, and automated signal preprocessing becomes pivotal for any subsequent analysis and data archiving. To this aim, we developed an in-house cloud-computing system, named QSpike Tools, where CPU-intensive operations, required for preprocessing of each recorded channel (e.g., filtering, multi-unit activity detection, spike-sorting, etc., are decomposed and batch-queued to a multi-core architecture or to computer cluster. With the commercial availability of new and inexpensive high-density MEAs, we believe that disseminating QSpike Tools might facilitate its wide adoption and customization, and possibly inspire the creation of community-supported cloud-computing facilities for MEAs users.

  2. QSpike tools: a generic framework for parallel batch preprocessing of extracellular neuronal signals recorded by substrate microelectrode arrays.

    Mahmud, Mufti; Pulizzi, Rocco; Vasilaki, Eleni; Giugliano, Michele

    2014-01-01

    Micro-Electrode Arrays (MEAs) have emerged as a mature technique to investigate brain (dys)functions in vivo and in in vitro animal models. Often referred to as "smart" Petri dishes, MEAs have demonstrated a great potential particularly for medium-throughput studies in vitro, both in academic and pharmaceutical industrial contexts. Enabling rapid comparison of ionic/pharmacological/genetic manipulations with control conditions, MEAs are employed to screen compounds by monitoring non-invasively the spontaneous and evoked neuronal electrical activity in longitudinal studies, with relatively inexpensive equipment. However, in order to acquire sufficient statistical significance, recordings last up to tens of minutes and generate large amount of raw data (e.g., 60 channels/MEA, 16 bits A/D conversion, 20 kHz sampling rate: approximately 8 GB/MEA,h uncompressed). Thus, when the experimental conditions to be tested are numerous, the availability of fast, standardized, and automated signal preprocessing becomes pivotal for any subsequent analysis and data archiving. To this aim, we developed an in-house cloud-computing system, named QSpike Tools, where CPU-intensive operations, required for preprocessing of each recorded channel (e.g., filtering, multi-unit activity detection, spike-sorting, etc.), are decomposed and batch-queued to a multi-core architecture or to a computers cluster. With the commercial availability of new and inexpensive high-density MEAs, we believe that disseminating QSpike Tools might facilitate its wide adoption and customization, and inspire the creation of community-supported cloud-computing facilities for MEAs users.

  3. Efter cochlear implant

    Højen, Anders

    Dit barn har netop fået et cochlear implant. Hvad nu? Skal barnet fokusere udelukkende på at lære talt sprog, eller skal det også lære/fortsætte med tegnsprog eller støttetegn? Det er et vanskeligt spørgsmål, og før valget foretages, er det vigtigt at vurdere hvilke konsekvenser valget har, dels...... for den sproglige udvikling isoleret set, og dels for barnets udvikling ud fra en helhedsbetragtning. Dette indlæg fokuserer på, hvilke forventninger man kan have til cochlear implant-brugeres sproglige udvikling med talt sprog alene, hhv. med to sprog (tale og tegn). Disse forventninger er baseret på...

  4. Delayed breast implant reconstruction

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne

    2012-01-01

    We evaluated the association between radiation therapy and severe capsular contracture or reoperation after 717 delayed breast implant reconstruction procedures (288 1- and 429 2-stage procedures) identified in the prospective database of the Danish Registry for Plastic Surgery of the Breast during...... of radiation therapy was associated with a non-significantly increased risk of reoperation after both 1-stage (HR = 1.4; 95% CI: 0.7-2.5) and 2-stage (HR = 1.6; 95% CI: 0.9-3.1) procedures. Reconstruction failure was highest (13.2%) in the 2-stage procedures with a history of radiation therapy. Breast...... reconstruction approaches other than implants should be seriously considered among women who have received radiation therapy....

  5. Piezosurgery in implant dentistry

    Stübinger, Stefan; Stricker, Andres; Berg, Britt-Isabelle

    2015-01-01

    Piezosurgery, or the use of piezoelectric devices, is being applied increasingly in oral and maxillofacial surgery. The main advantages of this technique are precise and selective cuttings, the avoidance of thermal damage, and the preservation of soft-tissue structures. Through the application of piezoelectric surgery, implant-site preparation, bone grafting, sinus-floor elevation, edentulous ridge splitting or the lateralization of the inferior alveolar nerve are very technically feasible. This clinical overview gives a short summary of the current literature and outlines the advantages and disadvantages of piezoelectric bone surgery in implant dentistry. Overall, piezoelectric surgery is superior to other methods that utilize mechanical instruments. Handling of delicate or compromised hard- and soft-tissue conditions can be performed with less risk for the patient. With respect to current and future innovative surgical concepts, piezoelectric surgery offers a wide range of new possibilities to perform customized and minimally invasive osteotomies. PMID:26635486

  6. Dynamics of neural cryptography.

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  7. Dynamics of neural cryptography

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-01-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible

  8. Dynamics of neural cryptography

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  9. Ion implantation in metals

    Vook, F.L.

    1977-02-01

    The application of ion beams to metals is rapidly emerging as a promising area of research and technology. This report briefly describes some of the recent advances in the modification and study of the basic properties of metals by ion implantation techniques. Most of the research discussed illustrates some of the new and exciting applications of ion beams to metals which are under active investigation at Sandia Laboratories, Albuquerque

  10. The breast implant controversy.

    Cook, R R; Harrison, M C; LeVier, R R

    1994-02-01

    The breast implant issue is a "bad news/good news" story. For many women with implants, the controversy has caused a fair degree of anxiety which may or may not be resolved as further information becomes available. It has also taken its toll on Dow Corning. Whole lines of medical products have been eliminated or are being phase out. The development of new medical applications has been terminated. As a consequence, employees have lost their jobs. What the effect will be on the biomedical industry as a whole remains to be seen (11). While silicones have been an important component in various medical devices, it is likely that other materials can be used as replacements. However, suppliers of non-silicone materials are also reevaluating their role in this market. For example, Du Pont, the nation's largest chemical company, has determined that the unpredictable and excessive costs of doing business with manufacturers of implantable medical devices no longer justifies the unrestricted sale of standard raw materials into this industry. Other companies are quietly following suit. On the up side, it is possible that the research being driven by this controversy will result in a greater understanding of the immunologic implications of xenobiotics, of the importance of nonbiased observations, of the need for ready access to valid data sets, and of the opportunity for valid scientific information to guide legal decisions. Only time will tell.

  11. A sensitive impedance biosensor based on immunomagnetic separation and urease catalysis for rapid detection of Listeria monocytogenes using an immobilization-free interdigitated array microelectrode.

    Chen, Qi; Lin, Jianhan; Gan, Chengqi; Wang, Yuhe; Wang, Dan; Xiong, Yonghua; Lai, Weihua; Li, Yuntao; Wang, Maohua

    2015-12-15

    In this study, we described a novel impedance biosensor combining immunomagnetic separation with urease catalysis for sensitive detection of foodborne bacteria using Listeria monocytogenes as model and an immobilization-free microelectrode as detector. The monoclonal antibodies (MAbs) were immobilized on the surface of the magnetic nanoparticles (MNPs) with the diameter of 180 nm by biotin-streptavidin system for specifically and efficiently separating Listeria cells from sample background. The polyclonal antibodies (PAbs) and the urease were modified onto the surface of the gold nanoparticles (AuNPs) with the diameter of 20 nm and the modified AuNPs were used to react with Listera to form the MNP-MAb-Listeria-PAb-AuNP-urease sandwich complexes. The urease in the complexes could catalyze the hydrolysis of the urea into ammonium carbonate and this led to an increase in the ionic strength of the media, which could be detected by the microelectrode. The magnetic separation efficiencies for L. monocytogenes at the concentrations ranging from 3.0×10(1) to 3.0×10(4) CFU/mL were over 95% for the pure cultures and over 85% for the spiked lettuce samples. The lower detection limit of this biosensor for L. monocytogenes was found to be 300 CFU/mL in both the pure cultures and the spiked lettuce samples. The microelectrode was demonstrated to be reusable for over 50 times with thorough cleaning by deionized water. This biosensor showed its potential to provide a simple, low-cost and sensitive method for rapid screening of foodborne pathogens and could be extended for detection of other biological or chemical targets. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Flexible nanohybrid microelectrode based on carbon fiber wrapped by gold nanoparticles decorated nitrogen doped carbon nanotube arrays: In situ electrochemical detection in live cancer cells.

    Zhang, Yan; Xiao, Jian; Sun, Yimin; Wang, Lu; Dong, Xulin; Ren, Jinghua; He, Wenshan; Xiao, Fei

    2018-02-15

    The rapidly growing demand for in situ real-time monitoring of chemical information in vitro and in vivo has attracted tremendous research efforts into the design and construction of high-performance biosensor devices. Herein, we develop a new type of flexible nanohybrid microelectrode based on carbon fiber wrapped by gold nanoparticles decorated nitrogen-doped carbon nanotube arrays, and explore its practical application in in situ electrochemical detection of cancer biomarker H 2 O 2 secreted from live cancer cells. Our results demonstrate that carbon fiber material with microscale size and fascinating mechanical properties can be used as a robust and flexible microelectrode substrate in the electrochemical biosensor system. And the highly ordered nitrogen-doped carbon nanotube arrays that grown on carbon fiber possess high surface area-to-volume ratio and abundant active sites, which facilitate the loading of high-density and uniformly dispersed gold nanoparticles on it. Benefited from the unique microstructure and excellent electrocatalytic properties of different components in the nanohybrid fiber microelectrode, an effective electrochemical sensing platform based on it has been built up for the sensitive and selective detection of H 2 O 2 , the detection limit is calculated to be 50nM when the signal-to-noise ratio is 3:1, and the linear dynamic range is up to 4.3mM, with a high sensitivity of 142µAcm -2 mM -1 . These good sensing performances, coupled with its intrinsic mechanical flexibility and biocompatibility, allow for its use in in situ real-time tracking H 2 O 2 secreted from breast cancer cell lines MCF-7 and MBA-MD-231, and evaluating the sensitivity of different cancer cells to chemotherapy or radiotherapy treatments, which hold great promise for clinic application in cancer diagnose and management. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Bioluminescence Imaging of Olig2-Neural Stem Cells Reveals Improved Engraftment in a Demyelination Mouse Model

    Sher, Falak; van Dam, Go; Boddeke, Erik; Copray, Sjef

    2009-01-01

    A major issue in the potential application of neural stem cell (NSC)-based cell replacement therapy for demyelinating diseases is the question of the survival, functional behavior, and stability of implanted NSC-derived oligodendrocyte precursor cells (OPCs) over an extended period. To address this

  14. ANT Advanced Neural Tool

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-07-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs.

  15. ANT Advanced Neural Tool

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-01-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs

  16. Cochlear implants in children implanted in Jordan: A parental overview.

    Alkhamra, Rana A

    2015-07-01

    Exploring the perspective of parents on the cochlear implant process in Jordan. Sixty parents of deaf children were surveyed on the information gathering process prior to cochlear implant surgery, and their implant outcome expectations post-surgery. Whether child or parent characteristics may impact parents' post-surgical expectations was explored. Although parents used a variety of information sources when considering a cochlear implant, the ear, nose and throat doctor comprised their major source of information (60%). Parents received a range of information prior to cochlear implant but agreed (93.3%) on the need for a multidisciplinary team approach. Post-surgically, parents' expected major developments in the areas of spoken language (97%), and auditory skills (100%). Receiving education in mainstream schools (92%) was expected too. Parents perceived the cochlear implant decision as the best decision they can make for their child (98.3%). A significant correlation was found between parents contentment with the cochlear implant decision and expecting developments in the area of reading and writing (r=0.7). Child's age at implantation and age at hearing loss diagnosis significantly affected parents' post-implant outcome expectations (pparents agree on the need for a comprehensive multidisciplinary team approach during the different stages of the cochlear implant process. Parents' education about cochlear implants prior to the surgery can affect their post-surgical outcome expectations. The parental perspective presented in this study can help professionals develop better understanding of parents' needs and expectations and henceforth improve their services and support during the different stages of the cochlear implant process. Copyright © 2015. Published by Elsevier Ireland Ltd.

  17. Rapid Voltammetric Measurements at Conducting Polymer Microelectrodes Using Ultralow-Capacitance Poly(3,4-ethylenedioxythiophene):Tosylate

    Meier, Adam R.; Matteucci, Marco; Vreeland, Richard F.

    2016-01-01

    . The adsorption characteristics of dopamine at the polymer electrode were fit to a Langmuir isotherm. The low apparent capacitance and the microlithographic processes for electrode design make PEDOT:tosylate an attractive material for future applications as an implantable biosens9r for FSCV measurements...

  18. Restoration of orbicularis oculi muscle function in rabbits with peripheral facial paralysis via an implantable artificial facial nerve system.

    Sun, Yajing; Jin, Cheng; Li, Keyong; Zhang, Qunfeng; Geng, Liang; Liu, Xundao; Zhang, Yi

    2017-12-01

    The purpose of the present study was to restore orbicularis oculi muscle function using the implantable artificial facial nerve system (IAFNS). The in vivo part of the IAFNS was implanted into 12 rabbits that were facially paralyzed on the right side of the face to restore the function of the orbicularis oculi muscle, which was indicated by closure of the paralyzed eye when the contralateral side was closed. Wireless communication links were established between the in vivo part (the processing chip and microelectrode) and the external part (System Controller program) of the system, which were used to set the working parameters and indicate the working state of the processing chip and microelectrode implanted in the body. A disturbance field strength test of the IAFNS processing chip was performed in a magnetic field dark room to test its electromagnetic radiation safety. Test distances investigated were 0, 1, 3 and 10 m, and levels of radiation intensity were evaluated in the horizontal and vertical planes. Anti-interference experiments were performed to test the stability of the processing chip under the interference of electromagnetic radiation. The fully implanted IAFNS was run for 5 h per day for 30 consecutive days to evaluate the accuracy and precision as well as the long-term stability and effectiveness of wireless communication. The stimulus intensity (range, 0-8 mA) was set every 3 days to confirm the minimum stimulation intensity which could indicate the movement of the paralyzed side was set. Effective stimulation rate was also tested by comparing the number of eye-close movements on both sides. The results of the present study indicated that the IAFNS could rebuild the reflex arc, inducing the experimental rabbits to close the eye of the paralyzed side. The System Controller program was able to reflect the in vivo part of the artificial facial nerve system in real-time and adjust the working pattern, stimulation intensity and frequency, range of wave

  19. Improving osseointegration of dental implants.

    Elias, Carlos Nelson; Meirelles, Luiz

    2010-03-01

    In the beginning of implantology, the procedures adopted for treating patients were performed in two surgical phases with an interval of 3-6 months. Nowadays, it is possible to insert and load a dental implant in the same surgical procedure. This change is due to several factors, such as improvement of surgical technique, modifications of the implant design, increased quality of implant manufacturing, development of the surgical instruments' quality, careful patient screening and adequate treatment of the implant surface. The clinical results show that adequate treatment of surfaces is crucial for reducing healing time and treating at-risk patients. The surface properties of dental implants can be significantly improved at the manufacturing stage, affecting cells' activity during the healing phase that will ultimately determine the host tissue response, a fundamental requirement for clinical success. This review focuses on different types of dental implant surfaces and the influence of surface characteristics on osseointegration.

  20. Hidden neural networks

    Krogh, Anders Stærmose; Riis, Søren Kamaric

    1999-01-01

    A general framework for hybrids of hidden Markov models (HMMs) and neural networks (NNs) called hidden neural networks (HNNs) is described. The article begins by reviewing standard HMMs and estimation by conditional maximum likelihood, which is used by the HNN. In the HNN, the usual HMM probability...... parameters are replaced by the outputs of state-specific neural networks. As opposed to many other hybrids, the HNN is normalized globally and therefore has a valid probabilistic interpretation. All parameters in the HNN are estimated simultaneously according to the discriminative conditional maximum...... likelihood criterion. The HNN can be viewed as an undirected probabilistic independence network (a graphical model), where the neural networks provide a compact representation of the clique functions. An evaluation of the HNN on the task of recognizing broad phoneme classes in the TIMIT database shows clear...

  1. Dextran as a fast resorbable and mechanically stiff coating for flexible neural probes

    Kil, D.; Brancato, L.; Puers, R.

    2017-11-01

    In this paper we report on the use of dextran as a temporary, fast dissolving stiff coating for flexible neural probes. Although polymer-based neural implants offer several advantages, compared to their rigid silicon counterparts, they pose significant challenges during implantation. Due to their extreme flexibility, they have the tendency to buckle under the axial load applied during insertion. The structural stiffness of the implants can be temporarily increased by applying a bioresorbable dextran coating which eases the penetration of neural tissue. For this application three types of dextran with different molecular weights are analysed. The dissolution rate of the coatings is reported as well as the increased bending stiffness resulting from the dextran coating of Parylene C neural probes. Based on these findings the dissolution rate can be linked to parameters such as molecular weight, coating thickness and the surface area exposed to the dissolution medium. The mechanical characterization yields information on how the structural stiffness of neural probes can be tuned by varying the dextran’s molecular weight and coating thickness.

  2. A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

    2015-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  3. Implantable electrode for recording nerve signals in awake animals

    Ninomiya, I.; Yonezawa, Y.; Wilson, M. F.

    1976-01-01

    An implantable electrode assembly consisting of collagen and metallic electrodes was constructed to measure simultaneously neural signals from the intact nerve and bioelectrical noises in awake animals. Mechanical artifacts, due to bodily movement, were negligibly small. The impedance of the collagen electrodes, measured in awake cats 6-7 days after implantation surgery, ranged from 39.8-11.5 k ohms at a frequency range of 20-5 kHz. Aortic nerve activity and renal nerve activity, measured in awake conditions using the collagen electrode, showed grouped activity synchronous with the cardiac cycle. Results indicate that most of the renal nerve activity was from postganglionic sympathetic fibers and was inhibited by the baroceptor reflex in the same cardiac cycle.

  4. Neural networks for aircraft control

    Linse, Dennis

    1990-01-01

    Current research in Artificial Neural Networks indicates that networks offer some potential advantages in adaptation and fault tolerance. This research is directed at determining the possible applicability of neural networks to aircraft control. The first application will be to aircraft trim. Neural network node characteristics, network topology and operation, neural network learning and example histories using neighboring optimal control with a neural net are discussed.

  5. Active Neural Localization

    Chaplot, Devendra Singh; Parisotto, Emilio; Salakhutdinov, Ruslan

    2018-01-01

    Localization is the problem of estimating the location of an autonomous agent from an observation and a map of the environment. Traditional methods of localization, which filter the belief based on the observations, are sub-optimal in the number of steps required, as they do not decide the actions taken by the agent. We propose "Active Neural Localizer", a fully differentiable neural network that learns to localize accurately and efficiently. The proposed model incorporates ideas of tradition...

  6. Neural cryptography with feedback.

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  7. The cochlear implant and possibilities for narrowing the remaining gaps between prosthetic and normal hearing

    Blake S. Wilson

    2017-12-01

    Full Text Available Background: The cochlear implant has become the standard of care for severe or worse losses in hearing and indeed has produced the first substantial restoration of a lost or absent human sense using a medical intervention. However, the devices are not perfect and many efforts to narrow the remaining gaps between prosthetic and normal hearing are underway. Objective: To assess the present status of cochlear implants and to describe possibilities for improving them. Results: The present-day devices work well in quiet conditions for the great majority of users. However, not all users have high levels of speech reception in quiet and nearly all users struggle with speech reception in typically noisy acoustic environments. In addition, perception of sounds more complex than speech, such as most music, is generally poor unless residual hearing at low frequencies can be stimulated acoustically in conjunction with the electrical stimuli provided by the implant. Possibilities for improving the present devices include increasing the spatial specificity of neural excitation by reducing masking effects or with new stimulus modes; prudent pruning of interfering or otherwise detrimental electrodes from the stimulation map; a further relaxation in the criteria for implant candidacy, based on recent evidence from persons with high levels of residual hearing and to allow many more people to benefit from cochlear implants; and “top down” or “brain centric” approaches to implant designs and applications. Conclusions: Progress in the development of the cochlear implant and related treatments has been remarkable but room remains for improvements. The future looks bright as there are multiple promising possibilities for improvements and many talented teams are pursuing them. Keywords: Auditory prosthesis, Cochlear implant, Cochlear prosthesis, Deafness, Neural prosthesis

  8. Immediate Direct-To-Implant Breast Reconstruction Using Anatomical Implants

    Sung-Eun Kim

    2014-09-01

    Full Text Available BackgroundIn 2012, a new anatomic breast implant of form-stable silicone gel was introduced onto the Korean market. The intended use of this implant is in the area of aesthetic breast surgery, and many reports are promising. Thus far, however, there have been no reports on the use of this implant for breast reconstruction in Korea. We used this breast implant in breast reconstruction surgery and report our early experience.MethodsFrom November 2012 to April 2013, the Natrelle Style 410 form-stable anatomically shaped cohesive silicone gel-filled breast implant was used in 31 breasts of 30 patients for implant breast reconstruction with an acellular dermal matrix. Patients were treated with skin-sparing mastectomies followed by immediate breast reconstruction.ResultsThe mean breast resection volume was 240 mL (range, 83-540 mL. The mean size of the breast implants was 217 mL (range, 125-395 mL. Breast shape outcomes were considered acceptable. Infection and skin thinning occurred in one patient each, and hematoma and seroma did not occur. Three cases of wound dehiscence occurred, one requiring surgical intervention, while the others healed with conservative treatment in one month. Rippling did not occur. So far, complications such as capsular contracture and malrotation of breast implant have not yet arisen.ConclusionsBy using anatomic breast implants in breast reconstruction, we achieved satisfactory results with aesthetics better than those obtained with round breast implants. Therefore, we concluded that the anatomical implant is suitable for breast reconstruction.

  9. Chitosan derived co-spheroids of neural stem cells and mesenchymal stem cells for neural regeneration.

    Han, Hao-Wei; Hsu, Shan-Hui

    2017-10-01

    Chitosan has been considered as candidate biomaterials for neural applications. The effective treatment of neurodegeneration or injury to the central nervous system (CNS) is still in lack nowadays. Adult neural stem cells (NSCs) represents a promising cell source to treat the CNS diseases but they are limited in number. Here, we developed the core-shell spheroids of NSCs (shell) and mesenchymal stem cells (MSCs, core) by co-culturing cells on the chitosan surface. The NSCs in chitosan derived co-spheroids displayed a higher survival rate than those in NSC homo-spheroids. The direct interaction of NSCs with MSCs in the co-spheroids increased the Notch activity and differentiation tendency of NSCs. Meanwhile, the differentiation potential of MSCs in chitosan derived co-spheroids was significantly enhanced toward neural lineages. Furthermore, NSC homo-spheroids and NSC/MSC co-spheroids derived on chitosan were evaluated for their in vivo efficacy by the embryonic and adult zebrafish brain injury models. The locomotion activity of zebrafish receiving chitosan derived NSC homo-spheroids or NSC/MSC co-spheroids was partially rescued in both models. Meanwhile, the higher survival rate was observed in the group of adult zebrafish implanted with chitosan derived NSC/MSC co-spheroids as compared to NSC homo-spheroids. These evidences indicate that chitosan may provide an extracellular matrix-like environment to drive the interaction and the morphological assembly between NSCs and MSCs and promote their neural differentiation capacities, which can be used for neural regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Dental implants in growing children

    S K Mishra

    2013-01-01

    Full Text Available The replacement of teeth by implants is usually restricted to patients with completed craniofacial growth. The aim of this literature review is to discuss the use of dental implants in normal growing patients and in patients with ectodermal dysplasia and the influence of maxillary and mandibular skeletal and dental growth on the stability of those implants. It is recommended that while deciding the optimal individual time point of implant insertion, the status of skeletal growth, the degree of hypodontia, and extension of related psychological stress should be taken into account, in addition to the status of existing dentition and dental compliance of a pediatric patient.

  11. Printing of Titanium implant prototype

    Wiria, Florencia Edith; Shyan, John Yong Ming; Lim, Poon Nian; Wen, Francis Goh Chung; Yeo, Jin Fei; Cao, Tong

    2010-01-01

    Dental implant plays an important role as a conduit of force and stress to flow from the tooth to the related bone. In the load sharing between an implant and its related bone, the amount of stress carried by each of them directly related to their stiffness or modulus. Hence, it is a crucial issue for the implant to have matching mechanical properties, in particular modulus, between the implant and its related bone. Titanium is a metallic material that has good biocompatibility and corrosion resistance. Whilst the modulus of the bulk material is still higher than that of bone, it is the lowest among all other commonly used metallic implant materials, such as stainless steel or cobalt alloy. Hence it is potential to further reduce the modulus of pure Titanium by engineering its processing method to obtain porous structure. In this project, porous Titanium implant prototype is fabricated using 3-dimensional printing. This technique allows the flexibility of design customization, which is beneficial for implant fabrication as tailoring of implant size and shape helps to ensure the implant would fit nicely to the patient. The fabricated Titanium prototype had a modulus of 4.8-13.2 GPa, which is in the range of natural bone modulus. The compressive strength achieved was between 167 to 455 MPa. Subsequent cell culture study indicated that the porous Titanium prototype had good biocompatibility and is suitable for bone cell attachment and proliferation.

  12. Cochlear implantation in Mondini dysplasia.

    Daneshi, Ahmad; Hassanzadeh, Saeid; Abasalipour, Parvaneh; Emamdjomeh, Hessamaddin; Farhadi, Mohammad

    2003-01-01

    The use of cochlear implantation to treat patients with inner ear malformations such as Mondini dysplasia has been increasingly successful. Until now, conventional hearing aids in these patients have not performed well. Consequently, the hearing problem for patients with this condition has been somewhat improved with the use of cochlear implants. Various results of cochlear implantation have been reported in these patients so far. This is a report of 5 patients with Mondini malformation who have undergone cochlear implant surgery. Copyright 2003 S. Karger AG, Basel

  13. Implant-retained maxillary overdentures.

    Eckert, Steven E; Carr, Alan B

    2004-07-01

    Overdentures supported by osseointegrated implants overcome many of the complications observed with overdentures supported by natural teeth. Dental implants are free of biologic consequences associated with natural teeth, such as dental caries and periodontal disease. Bone undercuts adjacent to implants do not mimic those found adjacent to natural tooth roots. Implants are used to provide predictable retention, support, and stability for overdenture prostheses. When lip or facial support is required, the overdenture is the treatment of choice. Likewise the overdenture may improve phonetic deficiencies associated with alveolar bone loss.

  14. Cochlear implants in Waardenburg syndrome.

    Cullen, Robert D; Zdanski, Carlton; Roush, Patricia; Brown, Carolyn; Teagle, Holly; Pillsbury, Harold C; Buchman, Craig

    2006-07-01

    Waardenburg syndrome is an autosomal-dominant syndrome characterized by dystopia canthorum, hyperplasia of the eyebrows, heterochromia irides, a white forelock, and sensorineural hearing loss in 20% to 55% of patients. This patient population accounts for approximately 2% of congenitally deaf children. The purpose of this retrospective case review was to describe the outcomes for those children with Waardenburg syndrome who have undergone cochlear implantation. Pediatric cochlear implant recipients with documented evidence of Waardenburg syndrome underwent retrospective case review. All patients received their cochlear implants at the study institution followed by outpatient auditory habilitation. Charts were reviewed for etiology and duration of deafness, age at time of cochlear implantation, perioperative complications, duration of use, and performance outcomes. Results of standard tests batteries for speech perception and production administered as a part of the patients' auditory habilitation were reviewed. Seven patients with Waardenburg syndrome and cochlear implants were identified. The average age at implantation was 37 months (range, 18-64 months) and the average duration of use was 69 months (range, 12-143 months). All of these patients are active users of their devices and perform very well after implantation. There were no major complications in this small group of patients. Children with congenital sensorineural hearing loss without other comorbidities (e.g., developmental delay, inner ear malformations) perform well when they receive cochlear implantation and auditory habilitation. Patients with Waardenburg syndrome can be expected to have above-average performance after cochlear implantation.

  15. Age at implantation and auditory memory in cochlear implanted children.

    Mikic, B; Miric, D; Nikolic-Mikic, M; Ostojic, S; Asanovic, M

    2014-05-01

    Early cochlear implantation, before the age of 3 years, provides the best outcome regarding listening, speech, cognition an memory due to maximal central nervous system plasticity. Intensive postoperative training improves not only auditory performance and language, but affects auditory memory as well. The aim of this study was to discover if the age at implantation affects auditory memory function in cochlear implanted children. A total of 50 cochlear implanted children aged 4 to 8 years were enrolled in this study: early implanted (1-3y) n = 27 and late implanted (4-6y) n = 23. Two types of memory tests were used: Immediate Verbal Memory Test and Forward and Backward Digit Span Test. Early implanted children performed better on both verbal and numeric tasks of auditory memory. The difference was statistically significant, especially on the complex tasks. Early cochlear implantation, before the age of 3 years, significantly improve auditory memory and contribute to better cognitive and education outcomes.

  16. Neurofeedback Control in Parkinsonian Patients Using Electrocorticography Signals Accessed Wirelessly With a Chronic, Fully Implanted Device.

    Khanna, Preeya; Swann, Nicole C; de Hemptinne, Coralie; Miocinovic, Svjetlana; Miller, Andrew; Starr, Philip A; Carmena, Jose M

    2017-10-01

    Parkinson's disease (PD) is characterized by motor symptoms such as rigidity and bradykinesia that prevent normal movement. Beta band oscillations (13-30 Hz) in neural local field potentials (LFPs) have been associated with these motor symptoms. Here, three PD patients implanted with a therapeutic deep brain neural stimulator that can also record and wirelessly stream neural data played a neurofeedback game where they modulated their beta band power from sensorimotor cortical areas. Patients' beta band power was streamed in real-time to update the position of a cursor that they tried to drive into a cued target. After playing the game for 1-2 hours each, all three patients exhibited above chance-level performance regardless of subcortical stimulation levels. This study, for the first time, demonstrates using an invasive neural recording system for at-home neurofeedback training. Future work will investigate chronic neurofeedback training as a potentially therapeutic tool for patients with neurological disorders.

  17. Cochlear implants and spoken language processing abilities: review and assessment of the literature.

    Peterson, Nathaniel R; Pisoni, David B; Miyamoto, Richard T

    2010-01-01

    Cochlear implants (CIs) process sounds electronically and then transmit electric stimulation to the cochlea of individuals with sensorineural deafness, restoring some sensation of auditory perception. Many congenitally deaf CI recipients achieve a high degree of accuracy in speech perception and develop near-normal language skills. Post-lingually deafened implant recipients often regain the ability to understand and use spoken language with or without the aid of visual input (i.e. lip reading). However, there is wide variation in individual outcomes following cochlear implantation, and some CI recipients never develop useable speech and oral language skills. The causes of this enormous variation in outcomes are only partly understood at the present time. The variables most strongly associated with language outcomes are age at implantation and mode of communication in rehabilitation. Thus, some of the more important factors determining success of cochlear implantation are broadly related to neural plasticity that appears to be transiently present in deaf individuals. In this article we review the expected outcomes of cochlear implantation, potential predictors of those outcomes, the basic science regarding critical and sensitive periods, and several new research directions in the field of cochlear implantation.

  18. Conductive component after cochlear implantation in patients with residual hearing conservation.

    Chole, Richard A; Hullar, Timothy E; Potts, Lisa G

    2014-12-01

    Changes in auditory thresholds following cochlear implantation are generally assumed to be due to damage to neural elements. Theoretical studies have suggested that placement of a cochlear implant can cause a conductive hearing loss. Identification of a conductive component following cochlear implantation could guide improvements in surgical techniques or device designs. The purpose of this study is to characterize new-onset conductive hearing losses after cochlear implantation. In a prospective study, air- and bone-conduction audiometric testing were completed on cochlear implant recipients. An air-bone gap equal to or greater than 15 dB HL at 2 frequencies determined the presence of a conductive component. Of the 32 patients with preoperative bone-conduction hearing, 4 patients had a new-onset conductive component resulting in a mixed hearing loss, with air-conduction thresholds ranging from moderate to profound and an average air-bone gap of 30 dB HL. One had been implanted through the round window, 2 had an extended round window, and 1 had a separate cochleostomy. Loss of residual hearing following cochlear implantation may be due in part to a conductive component. Identifying the mechanism for this conductive component may help minimize hearing loss. Postoperative hearing evaluation should measure both air- and bone-conduction thresholds.

  19. Fabrication of a 3D micro/nano dual-scale carbon array and its demonstration as the microelectrodes for supercapacitors

    Jiang, Shulan; Shi, Tielin; Gao, Yang; Long, Hu; Xi, Shuang; Tang, Zirong

    2014-04-01

    An easily accessible method is proposed for the fabrication of a 3D micro/nano dual-scale carbon array with a large surface area. The process mainly consists of three critical steps. Firstly, a hemispherical photoresist micro-array was obtained by the cost-effective nanoimprint lithography process. Then the micro-array was transformed into hierarchical structures with longitudinal nanowires on the microstructure surface by oxygen plasma etching. Finally, the micro/nano dual-scale carbon array was fabricated by carbonizing these hierarchical photoresist structures. It has also been demonstrated that the micro/nano dual-scale carbon array can be used as the microelectrodes for supercapacitors by the electrodeposition of a manganese dioxide (MnO2) film onto the hierarchical carbon structures with greatly enhanced electrochemical performance. The specific gravimetric capacitance of the deposited micro/nano dual-scale microelectrodes is estimated to be 337 F g-1 at the scan rate of 5 mV s-1. This proposed approach of fabricating a micro/nano dual-scale carbon array provides a facile way in large-scale microstructures’ manufacturing for a wide variety of applications, including sensors and on-chip energy storage devices.

  20. Rapid Detection of Ascorbic Acid Based on a Dual-Electrode Sensor System Using a Powder Microelectrode Embedded with Carboxyl Multi-Walled Carbon Nanotubes.

    He, Bao-Shan; Zhang, Jun-Xia

    2017-07-02

    In this paper, carboxyl groups were introduced by liquid oxidation methods onto multi-walled carbon nanotubes (MWCNTs) to improve the MWCNTs' electrocatalytic properties. A platinum wire microelectrode (ME) was corroded using aqua regia and subsequently embedded with MWCNTs to achieve more active sites, producing a so-called powder microelectrode (PME). Compared with conventional MEs, the PME has a larger specific surface area and more active sites. When PME was used to detect ascorbic acid (AA), the AA oxidation potential shifted negatively and current peak was visibly increased. The calibration curve obtained for AA was in a range of 5.00 × 10 -6 ~9.50 × 10 -4 mol·L -1 : I pa (μA) = 3.259 × 10 -2 + 1.801 × 10² C (mol·L -1 ) under the optimum testing conditions. Moreover, the detection and quantitation limits were confirmed at 4.89 × 10 -7 mol·L -1 and 1.63 × 10 -7 mol·L -1 , respectively. When the fabricated PME was practically applied to detect AA, it was shown a recovery rate of 94~107% with relative standard deviation (RSD) <5%. The proposed strategy thus offers a promising, rapid, selective and low-cost approach to effective analysis of AA.