WorldWideScience

Sample records for advanced micromachined microphone

  1. Towards a sub 15-dBA optical micromachined microphone.

    Science.gov (United States)

    Kim, Donghwan; Hall, Neal A

    2014-05-01

    Micromachined microphones with grating-based optical-interferometric readout have been demonstrated previously. These microphones are similar in construction to bottom-inlet capacitive microelectromechanical-system (MEMS) microphones, with the exception that optoelectronic emitters and detectors are placed inside the microphone's front or back cavity. A potential advantage of optical microphones in designing for low noise level is the use of highly-perforated microphone backplates to enable low-damping and low thermal-mechanical noise levels. This work presents an experimental study of a microphone diaphragm and backplate designed for optical readout and low thermal-mechanical noise. The backplate is 1 mm × 1 mm and is fabricated in a 2-μm-thick epitaxial silicon layer of a silicon-on-insulator wafer and contains a diffraction grating with 4-μm pitch etched at the center. The presented system has a measured thermal-mechanical noise level equal to 22.6 dBA. Through measurement of the electrostatic frequency response and measured noise spectra, a device model for the microphone system is verified. The model is in-turn used to identify design paths towards MEMS microphones with sub 15-dBA noise floors.

  2. A Micro-Machined Microphone Based on a Combination of Electret and Field-Effect Transistor.

    Science.gov (United States)

    Shin, Kumjae; Jeon, Junsik; West, James Edward; Moon, Wonkyu

    2015-08-18

    Capacitive-type transduction is now widely used in MEMS microphones. However, its sensitivity decreases with reducing size, due to decreasing air gap capacitance. In the present study, we proposed and developed the Electret Gate of Field Effect Transistor (ElGoFET) transduction based on an electret and FET (field-effect-transistor) as a novel mechanism of MEMS microphone transduction. The ElGoFET transduction has the advantage that the sensitivity is dependent on the ratio of capacitance components in the transduction structure. Hence, ElGoFET transduction has high sensitivity even with a smaller air gap capacitance, due to a miniaturization of the transducer. A FET with a floating-gate electrode embedded on a membrane was designed and fabricated and an electret was fabricated by ion implantation with Ga(+) ions. During the assembly process between the FET and the electret, the operating point of the FET was characterized using the static response of the FET induced by the electric field due to the trapped positive charge at the electret. Additionally, we evaluated the microphone performance of the ElGoFET by measuring the acoustic response in air using a semi-anechoic room. The results confirmed that the proposed transduction mechanism has potential for microphone applications.

  3. Micromachined Parts Advance Medicine, Astrophysics, and More

    Science.gov (United States)

    2015-01-01

    In the mid-1990s, Marshall Space Flight Center awarded two SBIR contracts to Potomac Photonics, now based in Baltimore, for the development of computerized workstations capable of mass-producing tiny, intricate, diffractive optical elements. While the company has since discontinued the workstations, those contracts set the stage for Potomac Photonics to be a leader in the micromachining industry, where NASA remains one of its clients.

  4. Advanced technology trend survey of micromachines in Europe; Oshu ni okeru micromachine sentan gijutsu doko chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    In this research survey, the development trend of micromachine technology in Europe was surveyed, development level of micromachine technology of European companies was grasped, and practical application fields of their target were investigated. Technology development level of private companies in Japan`s national projects and practical application fields of Japan`s target were arranged. Trends of micromachine technology development are compared between Japanese companies and European companies. Among micromachine technology development projects in Europe, ``8520 MUST`` is a part of the ESPRIT Project. About 40,000 companies among about 170,000 companies in whole Europe are relating to the MUST Project. The main fields include the manufacturing technology, process control of machines, technology of safety, sensor technology in environmental fields, and automotive technology. The marketing fields of application include the automobile, military technology, home automation, industrial process, medical technology, environmental technology, and games. The results can be compared with the direction of research and development in Japan. 22 figs., 8 tabs.

  5. Advances of focused ion beam in micromachining technology

    Science.gov (United States)

    Zhang, S. J.; Fang, F. Z.; Hu, X. T.

    2007-12-01

    The applications of focused ion beam (FIB) technology in micromachining has advantages over other micromachining technologies, such as high feature resolution, capable markless process, rapid prototyping and adaptive for various materials and geometries. FIB direct-writing techniques are explored for their excellent abilities in micromachining. In addition to FIB technology and its principles for imaging, milling and deposition, a typical FIB system is presented. The key to FIB direct-writing technology is to operate a FIB with a proper beam size, shape, current and energy to remove or add a required amount of material from a pre-defined location in a controlled manner. In this way, high-precision and complicated three-dimensional structures with controlled profiles can be fabricated. Several examples of using milling technique for making high-quality microdevices or high-precision microcomponents for optical and other applications are given. The demonstration of milling a narrow readout gap at an oblique angle on a microaccelerometer shows a FIB's application on a small but accurate post-processing step on a micromechanical device. The diffractive optical element (DOE) with continuous relief and submicron feature size fabricated by FIB milling is also presented to prove high resolution and accurate relief control. Furthermore, FIB milling is used to shape a variety of cutting tools with extremely precise dimensions and complex tool face shapes.

  6. Instrumentation for synchrotron based micromachining at the Center for Advanced Microstructures and Devices (abstract)

    Science.gov (United States)

    Aigeldinger, G.; Goettert, J.; Desta, Y.; Ling, Z. L.; Rupp, L.

    2002-03-01

    The J. Bennett Johnston Sr., Center for Advanced Microstructures and Devices (CAMD) is a synchrotron radiation facility owned by Louisiana State University and operated with financial support from the State of Louisiana (for information how to submit a project proposal go to: http://www.camd.lsu.edu). The centerpiece of CAMD is a 1.3-1.5 GeV electron storage ring. CAMD supports a strong program in x-ray lithography micromachining (XRLM) or LIGA. A total of four beamlines equipped with different scanners is available for exposures. A 2.500 sq. ft class 100 clean room provides basic processing capability for MEMS including optical lithography, thin film deposition, electroplating, and metrology. Three micromachining beamlines are connected to bending magnets. All beamlines are "white light" beamlines, terminated with a beryllium window. The typical source point to scanner distance is 10 m and the horizontal acceptance ranges from 6.5 to 10 mrad. A number of low Z filters can be inserted into the beam adapting the exposure spectrum to the resist thickness. Two beamlines are equipped with commercial scanners from Jenoptik GmbH (for details see Jenoptik's webpage at www.jo-mikrotechnik.com/) and one beamline with a "vacuum" scanner designed in house. The latest model of Jenoptik's DEX02 scanner has been installed at CAMD's XRLM1 beamline in December 2000 and allows advanced exposures using overlay as well as tilt and rotate functions. In addition to these beamlines CAMD has installed a "white light" beamline at its 7 T wiggler source. Preliminary exposure tests in ultrathick samples (1 mm and thicker) have been conducted using an "air scanner." Currently this beamline is dismantled and will be reinstalled together with a PX beamline. In the article further details of the beamlines and scanners as well as some examples of applications of LIGA microstructures fabricated at CAMD will be discussed.

  7. A new type of microphone using flexoelectric barium strontium titnate

    Science.gov (United States)

    Kwon, Seol ryung; Huang, Wenbin; Zhang, Shujun; Yuan, Fuh-Gwo; Jiang, Xiaoning

    2014-03-01

    A flexoelectric bridge-structured microphone using bulk barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was investigated in this study. The flexoelectric microphone was installed in an anechoic box and exposed to the sound pressure emitted from a loud speaker. Charge sensitivity of the flexoelectric microphone was measured and calibrated using a reference microphone. The 1.5 mm×768 μm×50 μm micro-machined bridge-structured flexoelectric microphone has a sensitivity of 0.92 pC/Pa, while its resonance frequency was calculated to be 98.67 kHz. The analytical and experimental results show that the flexoelectric microphone has both high sensitivity and broad bandwidth, indicating that flexoelectric microphones are potential candidates for many applications.

  8. Calibration of High Frequency MEMS Microphones

    Science.gov (United States)

    Shams, Qamar A.; Humphreys, William M.; Bartram, Scott M.; Zuckewar, Allan J.

    2007-01-01

    Understanding and controlling aircraft noise is one of the major research topics of the NASA Fundamental Aeronautics Program. One of the measurement technologies used to acquire noise data is the microphone directional array (DA). Traditional direction array hardware, consisting of commercially available condenser microphones and preamplifiers can be too expensive and their installation in hard-walled wind tunnel test sections too complicated. An emerging micro-machining technology coupled with the latest cutting edge technologies for smaller and faster systems have opened the way for development of MEMS microphones. The MEMS microphone devices are available in the market but suffer from certain important shortcomings. Based on early experiments with array prototypes, it has been found that both the bandwidth and the sound pressure level dynamic range of the microphones should be increased significantly to improve the performance and flexibility of the overall array. Thus, in collaboration with an outside MEMS design vendor, NASA Langley modified commercially available MEMS microphone as shown in Figure 1 to meet the new requirements. Coupled with the design of the enhanced MEMS microphones was the development of a new calibration method for simultaneously obtaining the sensitivity and phase response of the devices over their entire broadband frequency range. Over the years, several methods have been used for microphone calibration. Some of the common methods of microphone calibration are Coupler (Reciprocity, Substitution, and Simultaneous), Pistonphone, Electrostatic actuator, and Free-field calibration (Reciprocity, Substitution, and Simultaneous). Traditionally, electrostatic actuators (EA) have been used to characterize air-condenser microphones for wideband frequency ranges; however, MEMS microphones are not adaptable to the EA method due to their construction and very small diaphragm size. Hence a substitution-based, free-field method was developed to

  9. Fiber Optic Microphone

    Science.gov (United States)

    Cho, Y. C.; George, Thomas; Norvig, Peter (Technical Monitor)

    1999-01-01

    Research into advanced pressure sensors using fiber-optic technology is aimed at developing compact size microphones. Fiber optic sensors are inherently immune to electromagnetic noise, and are very sensitive, light weight, and highly flexible. In FY 98, NASA researchers successfully designed and assembled a prototype fiber-optic microphone. The sensing technique employed was fiber optic Fabry-Perot interferometry. The sensing head is composed of an optical fiber terminated in a miniature ferrule with a thin, silicon-microfabricated diaphragm mounted on it. The optical fiber is a single mode fiber with a core diameter of 8 micron, with the cleaved end positioned 50 micron from the diaphragm surface. The diaphragm is made up of a 0.2 micron thick silicon nitride membrane whose inner surface is metallized with layers of 30 nm titanium, 30 nm platinum, and 0.2 micron gold for efficient reflection. The active sensing area is approximately 1.5 mm in diameter. The measured differential pressure tolerance of this diaphragm is more than 1 bar, yielding a dynamic range of more than 100 dB.

  10. Micro-machined resonator oscillator

    Science.gov (United States)

    Koehler, Dale R.; Sniegowski, Jeffry J.; Bivens, Hugh M.; Wessendorf, Kurt O.

    1994-01-01

    A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

  11. Surface-micromachined magnetic undulator with period length between 10μm and 1 mm for advanced light sources

    Science.gov (United States)

    Harrison, Jere; Joshi, Abhijeet; Lake, Jonathan; Candler, Rob; Musumeci, Pietro

    2012-07-01

    A technological gap exists between the μm-scale wiggling periods achieved using electromagnetic waves of high intensity laser pulses and the mm scale of permanent-magnet and superconducting undulators. In the sub-mm range, surface-micromachined soft-magnetic micro-electro-mechanical system inductors with integrated solenoidal coils have already experimentally demonstrated 100 to 500 mT field amplitude across air gaps as large as 15μm. Simulations indicate that magnetic fields as large as 1.5 T across 50μm inductor gaps are feasible. A simple rearranging of the yoke and pole geometry allows for fabrication of 10+ cm long undulator structures with period lengths between 12.5μm and 1 mm. Such undulators find application both in high average power spontaneous emission sources and, if used in combination with ultrahigh-brightness electron beams, could lead to the realization of low energy compact free-electron lasers. Challenges include electron energy broadening due to wakefields and Joule heating in the electromagnet.

  12. Ultra Stable, Industrial Green Tailored Pulse Fiber Laser with Diffraction-limited Beam Quality for Advanced Micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Deladurantaye, P; Roy, V; Desbiens, L; Drolet, M; Taillon, Y; Galarneau, P, E-mail: pascal.deladurantaye@ino.ca [INO, 2740 rue Einstein, Quebec City, QC, G1P 4S4 (Canada)

    2011-02-01

    We report on a novel pulsed fiber laser platform providing pulse shaping agility at high repetition rates and at a wavelength of 532 nm. The oscillator is based on the direct modulation of a seed laser diode followed by a chain of fiber amplifiers. Advanced Large Mode Area (LMA) fiber designs as well as proprietary techniques to mitigate non-linear effects enable output energy per pulse up to 100 {mu}J at 1064 nm with diffraction-limited beam quality and narrow line widths suitable for efficient frequency conversion. Ultra stable pulses with tailored pulse shapes were demonstrated in the green region of the spectrum at repetition rates higher than 200 kHz. Pulse durations between 2.5 ns and 640 ns are available, as well as pulse to pulse dynamic shape selection at repetition rates up to 1 MHz. The pulse energy stability at 532 nm is better than {+-} 1.5%, 3{sigma}, over 10 000 pulses. Excellent beam characteristics were obtained. The M{sup 2} parameter is lower than 1.05, the beam waist astigmatism and beam waist asymmetry are below 10% and below 8% respectively, with high stability over time. We foresee that the small spot size, high repetition rate and pulse tailoring capability of this platform will provide advantages to practitioners who are developing novel, advanced processes in many industrially important applications.

  13. Micro-machining.

    Science.gov (United States)

    Brinksmeier, Ekkard; Preuss, Werner

    2012-08-28

    Manipulating bulk material at the atomic level is considered to be the domain of physics, chemistry and nanotechnology. However, precision engineering, especially micro-machining, has become a powerful tool for controlling the surface properties and sub-surface integrity of the optical, electronic and mechanical functional parts in a regime where continuum mechanics is left behind and the quantum nature of matter comes into play. The surprising subtlety of micro-machining results from the extraordinary precision of tools, machines and controls expanding into the nanometre range-a hundred times more precise than the wavelength of light. In this paper, we will outline the development of precision engineering, highlight modern achievements of ultra-precision machining and discuss the necessity of a deeper physical understanding of micro-machining.

  14. Micromachined Artificial Haircell

    Science.gov (United States)

    Liu, Chang (Inventor); Engel, Jonathan (Inventor); Chen, Nannan (Inventor); Chen, Jack (Inventor)

    2010-01-01

    A micromachined artificial sensor comprises a support coupled to and movable with respect to a substrate. A polymer, high-aspect ratio cilia-like structure is disposed on and extends out-of-plane from the support. A strain detector is disposed with respect to the support to detect movement of the support.

  15. Micromachined Fluid Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Shiqiang Liu

    2017-02-01

    Full Text Available Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri-axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern.

  16. Review of micromachining of ceramics by etching

    Institute of Scientific and Technical Information of China (English)

    H.T.TING; K.A.ABOU-EL-HOSSEIN; H.B.CHUA

    2009-01-01

    In the last two decades, there has been an enormous surge in interest in ceramic materials and, as a result, there have been significant advances in their development and applications. Their inherent properties, such as capability of operating at temperatures far above metals, high level of hardness and toughness, low coefficient of thermal expansion and high thermal conductivity rendered ceramics to be one of the leading engineering materials. Many research works have been conducted in the past few years on machining of advanced ceramics using different processing methods in order to obtain a better surface roughness, higher material removal rate and improved tool life. Micromachining using chemical etching is one of those methods that do not involve the problem of tool life and direct tool-work piece contact. However, only a few research works have been done on micromachining of ceramics using chemical etching. Hence, study of chemical machining of advanced ceramics is still needed as the process has found wide application in the industry because of its relative low operating costs. In this work, we summarize the recent progresses in machining of different types of advanced ceramics, material processing methods such as wet etching and dry etching, and finally the prospects for control of material removal rate and surface quality in the process of ceramic micromachining.

  17. Micromachined Amperometric Nitrate Sensor

    OpenAIRE

    Dohyun Kim; Ira Goldberg; Jack Judy

    2003-01-01

    A nitrate-sensing system that consists of a micromachined sensor substrate, nitrate-permeable membrane, integrated microfluidic channels, and standard fluidic connectors has been designed, fabricated, assembled, and tested. Our microsensor was designed for in-situ monitoring of nitrate concentrations in ground water. A silver electrode was patterned for amperometric nitrate detection. An electrochemically oxidized silver electrode was used as a reference electrode. Microfluidic channels were ...

  18. Micromachined Precision Inertial Instruments

    Science.gov (United States)

    2003-11-01

    and vacuum packaging techniques to achieve degree-per-hour inertial micro-gyroscopes. A single-wafer, all-silicon, high aspect-ratio p...Although vacuum packaging substantially reduces the mechanical noise of a surface micromachined accelerometer and lowers the output noise floor...it is desirable to operate sensors in atmosphere since vacuum packaging is not cost effective [15]. Figure 10: Performance improvements for In

  19. An analytical-numerical method for determining the mechanical response of a condenser microphone

    Science.gov (United States)

    Homentcovschi, Dorel; Miles, Ronald N.

    2011-01-01

    The paper is based on determining the reaction pressure on the diaphragm of a condenser microphone by integrating numerically the frequency domain Stokes system describing the velocity and the pressure in the air domain beneath the diaphragm. Afterwards, the membrane displacement can be obtained analytically or numerically. The method is general and can be applied to any geometry of the backplate holes, slits, and backchamber. As examples, the method is applied to the Bruel & Kjaer (B&K) 4134 1/2-inch microphone determining the mechanical sensitivity and the mechano-thermal noise for a domain of frequencies and also the displacement field of the membrane for two specified frequencies. These elements compare well with the measured values published in the literature. Also a new design, completely micromachined (including the backvolume) of the B&K micro-electro-mechanical systems (MEM) 1/4-inch measurement microphone is proposed. It is shown that its mechanical performances are very similar to those of the B&K MEMS measurement microphone. PMID:22225026

  20. Two-Microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Wang, DeLiang; Larsen, Jan

    2008-01-01

    Separation of speech mixtures, often referred to as the cocktail party problem, has been studied for decades. In many source separation tasks, the separation method is limited by the assumption of at least as many sensors as sources. Further, many methods require that the number of signals within...... the recorded mixtures be known in advance. In many real-world applications, these limitations are too restrictive. We propose a novel method for underdetermined blind source separation using an instantaneous mixing model which assumes closely spaced microphones. Two source separation techniques have been...... combined, independent component analysis (ICA) and binary time–frequency (T–F) masking. By estimating binary masks from the outputs of an ICA algorithm, it is possible in an iterative way to extract basis speech signals from a convolutive mixture. The basis signals are afterwards improved by grouping...

  1. Trends in laser micromachining

    Science.gov (United States)

    Gaebler, Frank; van Nunen, Joris; Held, Andrew

    2016-03-01

    Laser Micromachining is well established in industry. Depending on the application lasers with pulse length from μseconds to femtoseconds and wavelengths from 1064nm and its harmonics up to 5μm or 10.6μm are used. Ultrafast laser machining using pulses with pico or femtosecond duration pulses is gaining traction, as it offers very precise processing of materials with low thermal impact. Large-scale industrial ultrafast laser applications show that the market can be divided into various sub segments. One set of applications demand low power around 10W, compact footprint and are extremely sensitive to the laser price whilst still demanding 10ps or shorter laser pulses. A second set of applications are very power hungry and only become economically feasible for large scale deployments at power levels in the 100+W class. There is also a growing demand for applications requiring fs-laser pulses. In our presentation we would like to describe these sub segments by using selected applications from the automotive and electronics industry e.g. drilling of gas/diesel injection nozzles, dicing of LED substrates. We close the presentation with an outlook to micromachining applications e.g. glass cutting and foil processing with unique new CO lasers emitting 5μm laser wavelength.

  2. Standoff photoacoustic detections with high-sensitivity microphones and acoustic arrays

    Science.gov (United States)

    Choa, Fow-Sen; Wang, Chen-Chia; Khurgin, Jacob; Samuels, Alan; Trivedi, Sudhir; Gupta, Deepa

    2016-05-01

    Standoff detection of dangerous chemicals like explosives, nerve gases, and harmful aerosols has continuously been an important subject due to the serious concern about terrorist threats to both overseas and homeland lives and facility. Compared with other currently available standoff optical detection techniques, like Raman, photo-thermal, laser induced breakdown spectroscopy,...etc., photoacoustic (PA) sensing has the advantages of background free and very high detection sensitivity, no need of back reflection surfaces, and 1/R instead of 1/R2 signal decay distance dependence. Furthermore, there is still a great room for PA sensitivity improvement by using different PA techniques, including lockin amplifier, employing new microphones, and microphone array techniques. Recently, we have demonstrated standoff PA detection of isopropanol vapor, solid phase TNT and RDX at a standoff distance. To further calibrate the detection sensitivity, we use nerve gas simulants that were generated and calibrated by a commercial vapor generator. For field operations, array of microphones and microphone-reflector pairs can be utilized to achieve noise rejection and signal enhancement. We have experimentally demonstrated signal enhancement and noise reduction using an array of 4 microphone/4 reflector system as well as an array of 16-microphone/1 reflector. In this work we will review and compare different standoff techniques and discuss the advantages of using different photoacoustic techniques. We will also discuss new advancement of using new types of microphone and the performance comparison of using different structure of microphone arrays and combining lock-in amplifier with acoustic arrays. Demonstration of out-door real-time operations with high power mid-IR laser and microphone array will be presented.

  3. Microphone Phenomena Observed with EFL Students.

    Science.gov (United States)

    Wilcox, Wilma B.

    This study investigated changes in the speech patterns of Japanese college students in an intensive English language course when using a microphone, focusing in part on possible links to "karaoke" activities common in Japan, in which participants sing along with music using a microphone. The researcher first observed several karaoke…

  4. Micromachining using femtosecond lasers

    Science.gov (United States)

    Toenshoff, Hans K.; Ostendorf, Andreas; Nolte, Stefan; Korte, Frank; Bauer, Thorsten

    2000-11-01

    Femtosecond laser systems have been proved to be effective tools for high precision micro-machining. Almost all solid materials can be processed with high precision. The dependence on material properties like thermal conductivity, transparency, heat- or shock sensitivity is strongly reduced and no significant influence on the remaining bulk material is observed after ablation using femtosecond laser pulses. In contrast to conventional laser processing, where the achievable precision is reduced due to a formed liquid phase causing burr formation, the achievable precision using femtosecond pulses is only limited by the diffraction of the used optics. Potential applications of this technique, aincluding the structuring of biodegradable polymers for cardiovascular implants, so-called stents, as well as high precision machining of transparent materials are presented.

  5. Micromachining with Nanostructured Cutting Tools

    CERN Document Server

    Jackson, Mark J

    2013-01-01

    The purpose of the brief is to explain how nanostructured tools can be used to machine materials at the microscale.  The aims of the brief are to explain to readers how to apply nanostructured tools to micromachining applications. This book describes the application of nanostructured tools to machining engineering materials and includes methods for calculating basic features of micromachining. It explains the nature of contact between tools and work pieces to build a solid understanding of how nanostructured tools are made.

  6. Theory and applications of spherical microphone array processing

    CERN Document Server

    Jarrett, Daniel P; Naylor, Patrick A

    2017-01-01

    This book presents the signal processing algorithms that have been developed to process the signals acquired by a spherical microphone array. Spherical microphone arrays can be used to capture the sound field in three dimensions and have received significant interest from researchers and audio engineers. Algorithms for spherical array processing are different to corresponding algorithms already known in the literature of linear and planar arrays because the spherical geometry can be exploited to great beneficial effect. The authors aim to advance the field of spherical array processing by helping those new to the field to study it efficiently and from a single source, as well as by offering a way for more experienced researchers and engineers to consolidate their understanding, adding either or both of breadth and depth. The level of the presentation corresponds to graduate studies at MSc and PhD level. This book begins with a presentation of some of the essential mathematical and physical theory relevant to ...

  7. Mapping Speech Spectra from Throat Microphone to Close-Speaking Microphone: A Neural Network Approach

    Directory of Open Access Journals (Sweden)

    B. Yegnanarayana

    2007-01-01

    Full Text Available Speech recorded from a throat microphone is robust to the surrounding noise, but sounds unnatural unlike the speech recorded from a close-speaking microphone. This paper addresses the issue of improving the perceptual quality of the throat microphone speech by mapping the speech spectra from the throat microphone to the close-speaking microphone. A neural network model is used to capture the speaker-dependent functional relationship between the feature vectors (cepstral coefficients of the two speech signals. A method is proposed to ensure the stability of the all-pole synthesis filter. Objective evaluations indicate the effectiveness of the proposed mapping scheme. The advantage of this method is that the model gives a smooth estimate of the spectra of the close-speaking microphone speech. No distortions are perceived in the reconstructed speech. This mapping technique is also used for bandwidth extension of telephone speech.

  8. Materials Issues for Micromachines Development - ASCI Program Plan

    Energy Technology Data Exchange (ETDEWEB)

    FANG,HUEI ELIOT; BATTAILE,CORBETT C.; BENAVIDES,GILBERT L.; ENSZ,MARK T.; BUCHHEIT,THOMAS E.; LAVAN,DAVID A.; CHEN,ER-PING; CHRISTENSON,TODD R.; DE BOER,MAARTEN P.; MILLER,SAMUEL L.; DUGGER,MICHAEL T.; PRASAD,SOMURI V.; REEDY JR.,EARL DAVID; THOMPSON,AIDAN P.; WONG,CHUNGNIN C.; YANG,PIN

    2000-05-01

    This report summarizes materials issues associated with advanced micromachines development at Sandia. The intent of this report is to provide a perspective on the scope of the issues and suggest future technical directions, with a focus on computational materials science. Materials issues in surface micromachining (SMM), Lithographic-Galvanoformung-Abformung (LIGA: lithography, electrodeposition, and molding), and meso-machining technologies were identified. Each individual issue was assessed in four categories: degree of basic understanding; amount of existing experimental data capability of existing models; and, based on the perspective of component developers, the importance of the issue to be resolved. Three broad requirements for micromachines emerged from this process. They are: (1) tribological behavior, including stiction, friction, wear, and the use of surface treatments to control these, (2) mechanical behavior at microscale, including elasticity, plasticity, and the effect of microstructural features on mechanical strength, and (3) degradation of tribological and mechanical properties in normal (including aging), abnormal and hostile environments. Resolving all the identified critical issues requires a significant cooperative and complementary effort between computational and experimental programs. The breadth of this work is greater than any single program is likely to support. This report should serve as a guide to plan micromachines development at Sandia.

  9. Extending a context model for microphone forensics

    Science.gov (United States)

    Kraetzer, Christian; Qian, Kun; Dittmann, Jana

    2012-03-01

    In this paper, we extend an existing context model for statistical pattern recognition based microphone forensics by: first, generating a generalized model for this process and second, using this general model to construct a complex new application scenario model for microphone forensic investigations on the detection of playback recordings (a.k.a. replays, re-recordings, double-recordings). Thereby, we build the theoretical basis for answering the question whether an audio recording was made to record a playback or natural sound. The results of our investigations on the research question of playback detection imply that it is possible with our approach on our evaluation set of six microphones. If the recorded sound is not modified prior to playback, we achieve in our tests 89.00% positive indications on the correct two microphones involved. If the sound is post-processed (here, by normalization) this figure decreases (in our normalization example to 36.00%, while another 50.67% of the tests still indicate two microphones, of which one has actually not been involved in the recording and playback recording process).

  10. Laser Micromachining of Glass, Silicon, and Ceramics

    Directory of Open Access Journals (Sweden)

    L. Rihakova

    2015-01-01

    Full Text Available A brief review is focused on laser micromachining of materials. Micromachining of materials is highly widespread method used in many industries, including semiconductors, electronic, medical, and automotive industries, communication, and aerospace. This method is a promising tool for material processing with micron and submicron resolution. In this paper micromachining of glass, silicon, and ceramics is considered. Interaction of these materials with laser radiation and recent research held on laser material treatment is provided.

  11. Laser Micromachining of Glass, Silicon, and Ceramics

    OpenAIRE

    Rihakova, L.; Chmelickova, H.

    2015-01-01

    A brief review is focused on laser micromachining of materials. Micromachining of materials is highly widespread method used in many industries, including semiconductors, electronic, medical, and automotive industries, communication, and aerospace. This method is a promising tool for material processing with micron and submicron resolution. In this paper micromachining of glass, silicon, and ceramics is considered. Interaction of these materials with laser radiation and recent research held o...

  12. Optimization of Microphone Locations for Acoustic Liner Impedance Eduction

    Science.gov (United States)

    Jones, M. G.; Watson, W. R.; June, J. C.

    2015-01-01

    Two impedance eduction methods are explored for use with data acquired in the NASA Langley Grazing Flow Impedance Tube. The first is an indirect method based on the convected Helmholtz equation, and the second is a direct method based on the Kumaresan and Tufts algorithm. Synthesized no-flow data, with random jitter to represent measurement error, are used to evaluate a number of possible microphone locations. Statistical approaches are used to evaluate the suitability of each set of microphone locations. Given the computational resources required, small sample statistics are employed for the indirect method. Since the direct method is much less computationally intensive, a Monte Carlo approach is employed to gather its statistics. A comparison of results achieved with full and reduced sets of microphone locations is used to determine which sets of microphone locations are acceptable. For the indirect method, each array that includes microphones in all three regions (upstream and downstream hard wall sections, and liner test section) provides acceptable results, even when as few as eight microphones are employed. The best arrays employ microphones well away from the leading and trailing edges of the liner. The direct method is constrained to use microphones opposite the liner. Although a number of arrays are acceptable, the optimum set employs 14 microphones positioned well away from the leading and trailing edges of the liner. The selected sets of microphone locations are also evaluated with data measured for ceramic tubular and perforate-over-honeycomb liners at three flow conditions (Mach 0.0, 0.3, and 0.5). They compare favorably with results attained using all 53 microphone locations. Although different optimum microphone locations are selected for the two impedance eduction methods, there is significant overlap. Thus, the union of these two microphone arrays is preferred, as it supports usage of both methods. This array contains 3 microphones in the upstream

  13. Micromachined magnetohydrodynamic actuators and sensors

    Science.gov (United States)

    Lee, Abraham P.; Lemoff, Asuncion V.

    2000-01-01

    A magnetohydrodynamic (MHD) micropump and microsensor which utilizes micromachining to integrate the electrodes with microchannels and includes a magnet for producing magnetic fields perpendicular to both the electrical current direction and the fluid flow direction. The magnet can also be micromachined and integrated with the micropump using existing technology. The MHD micropump, for example, can generate continuous, reversible flow, with readily controllable flow rates. The flow can be reversed by either reversing the electrical current flow or reversing the magnetic field. By mismatching the electrodes, a swirling vortex flow can be generated for potential mixing applications. No moving parts are necessary and the dead volume is minimal. The micropumps can be placed at any position in a fluidic circuit and a combination of micropumps can generate fluidic plugs and valves.

  14. Review of polymer MEMS micromachining

    Science.gov (United States)

    Kim, Brian J.; Meng, Ellis

    2016-01-01

    The development of polymer micromachining technologies that complement traditional silicon approaches has enabled the broadening of microelectromechanical systems (MEMS) applications. Polymeric materials feature a diverse set of properties not present in traditional microfabrication materials. The investigation and development of these materials have opened the door to alternative and potentially more cost effective manufacturing options to produce highly flexible structures and substrates with tailorable bulk and surface properties. As a broad review of the progress of polymers within MEMS, major and recent developments in polymer micromachining are presented here, including deposition, removal, and release techniques for three widely used MEMS polymer materials, namely SU-8, polyimide, and Parylene C. The application of these techniques to create devices having flexible substrates and novel polymer structural elements for biomedical MEMS (bioMEMS) is also reviewed.

  15. Distance effects in electrochemical micromachining

    Science.gov (United States)

    Xu, Lizhong; Pan, Yue; Zhao, Chuanjun

    2016-09-01

    Considering exponential dependence of currents on double-layer voltage and the feedback effect of the electrolyte resistance, a distance effect in electrochemical micromachining is found, namely that both time constant and double-layer voltage depend on the separation of electrodes. The double-layer voltage is the real voltage used in processing. Under DC voltage, the apparent voltages between two electrodes are constant for different separations, but the real voltages change with the separations. Small separations exert substantial effects on the real voltages. Accordingly, a DC-voltage small-separation electrochemical micromachining technique was proposed. The double-layer voltage drops sharply as the small separation increases. Thus, the electrochemical reactions are confined to electrode regions in very close proximity even under DC voltage. The machining precision can be significantly enhanced by reducing the voltage and separation between electrodes. With this technique, the machining of conducting materials with submicrometre precision was achieved.

  16. Distance effects in electrochemical micromachining

    OpenAIRE

    2016-01-01

    Considering exponential dependence of currents on double-layer voltage and the feedback effect of the electrolyte resistance, a distance effect in electrochemical micromachining is found, namely that both time constant and double-layer voltage depend on the separation of electrodes. The double-layer voltage is the real voltage used in processing. Under DC voltage, the apparent voltages between two electrodes are constant for different separations, but the real voltages change with the separat...

  17. Circular microphone array for multi channel audio recording

    NARCIS (Netherlands)

    Hulsebos, E.M.; De Vries, D.; Boone, M.M.; Schuurmans, T.J.G.

    2004-01-01

    An audio system has a circular microphone array with a number of microphones arranged on a circle for receiving a sound field. A digital signal processor is provided for processing output signals from these microphones. To establish well controlled and sharp directivity patterns the audio system per

  18. PECVD silicon nitride diaphragms for condenser microphones

    NARCIS (Netherlands)

    Scheeper, P.R.; Voorthuyzen, J.A.; Bergveld, P.

    1991-01-01

    The application of plasma-enhanced chemical vapour deposited (PECVD) silicon nitride as a diaphragm material for condenser microphones has been investigated. By means of adjusting the SiH4/NH3 gas-flow composition, silicon-rich silicon nitride films have been obtained with a relatively low tensile s

  19. Compressive sensing with a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Xenaki, Angeliki

    2016-01-01

    A wave expansion method is proposed in this work, based on measurements with a spherical microphone array, and formulated in the framework provided by Compressive Sensing. The method promotes sparse solutions via ‘1-norm minimization, so that the measured data are represented by few basis functions...

  20. Two-microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    2006-01-01

    Matlab source code for underdetermined separation of instaneous speech mixtures. The algorithm is described in [1] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: ''Two-microphone Separation of Speech Mixtures,'' 2006, submitted for journal publoication. See also, [2] Michael...

  1. Hearing aid comprising an array of microphones

    NARCIS (Netherlands)

    Boone, M.M.; Berkhout, A.J.; Merks, I.L.D.M.

    1999-01-01

    Hearing aid for improving the hearing ability of the hard of hearing, comprising an array of microphones, the electrical output signals of which are fed to at least one transmission path belonging to an ear. Means are provided for deriving two array output signals from the output signals of the micr

  2. The acoustic center of laboratory standard microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2006-01-01

    center from the inverse distance law is analyzed. Experimental values of the acoustic center of laboratory standard microphones are presented, and numerical results obtained using the boundary element method supplement the experimental data. Estimated uncertainties are also presented. The results...... reported confirm values previously defined in an international standard and extend the frequency range....

  3. APPLICATION OF MICROPHONE ARRAYS FOR DISTANT SPEECH CAPTURE

    Directory of Open Access Journals (Sweden)

    M. B. Stolbov

    2015-07-01

    Full Text Available Application of microphone arrays and beamforming techniques for speech information collection has significant advantages compared to systems operating with a single microphone. This paper presents a brief overview of microphone array systems for collecting distant speech information. The paper is based on an analysis of publications on the use of microphone arrays for speech information collection tasks, as well as on the author’s experience in the development and practical application of planar microphone arrays. The paper describes the main stages of the development of systems for remote capture of audio information. It provides a review of the main applications of microphone arrays, the basic types of microphone arrays and their features. The bulk of the paper deals with planar microphone arrays. We analyze the work of microphone arrays in different acoustic environments. The paper contains the basic equations for calculating the parameters of equidistant planar microphone arrays. Some methods of designing non-equidistant arrays are also mentioned (a list of references is included. We also provide a list of basic digital signal processing algorithms for planar microphone arrays, as well as a list of references on processing algorithms in the frequency domain. The paper includes a list of foreign companies offering systems based on microphone arrays for a wide range of tasks associated with the processing of speech and audio signals. We describe some state-of-the-art speech information collection systems based on microphone arrays. Some promising directions for the development of speech information collection systems using microphone arrays are described in conclusion. The material of the review is usable in designing of microphone arrays for specific practical applications.

  4. Micro-machined calorimetric biosensors

    Science.gov (United States)

    Doktycz, Mitchel J.; Britton, Jr., Charles L.; Smith, Stephen F.; Oden, Patrick I.; Bryan, William L.; Moore, James A.; Thundat, Thomas G.; Warmack, Robert J.

    2002-01-01

    A method and apparatus are provided for detecting and monitoring micro-volumetric enthalpic changes caused by molecular reactions. Micro-machining techniques are used to create very small thermally isolated masses incorporating temperature-sensitive circuitry. The thermally isolated masses are provided with a molecular layer or coating, and the temperature-sensitive circuitry provides an indication when the molecules of the coating are involved in an enthalpic reaction. The thermally isolated masses may be provided singly or in arrays and, in the latter case, the molecular coatings may differ to provide qualitative and/or quantitative assays of a substance.

  5. Microphonics in biopotential measurements with capacitive electrodes.

    Science.gov (United States)

    Luna-Lozano, Pablo S; Pallas-Areny, Ramon

    2010-01-01

    Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity.

  6. Passive wireless MEMS microphones for biomedical applications.

    Science.gov (United States)

    Sezen, A S; Sivaramakrishnan, S; Hur, S; Rajamani, R; Robbins, W; Nelson, B J

    2005-11-01

    This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, battery-less SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their utilization as disposable sensors. A pulse modulated surface acoustic wave interdigital transducer (SAW-IDT) based sensing strategy has been formulated. The sensing strategy relies on detecting the ac component of the acoustic pressure signal only and does not require calibration. The proposed sensing strategy has been successfully implemented on an in-house fabricated SAW-IDT sensor and a variable capacitor which mimics the impedance change of a capacitive microphone. Wireless telemetry distances of up to 5 centimeters have been achieved. A silicon MEMS microphone which will be used with the SAW-IDT device is being microfabricated and tested. The complete passive wireless sensor package will include the MEMS microphone wire-bonded on the SAW substrate and interrogated through an on-board antenna. This work on acoustic sensors breaks new ground by introducing high frequency (i.e., audio frequencies) sensor measurement utilizing SAW-IDT sensors. The developed sensors can be used for wireless monitoring of body sounds in a number of different applications, including monitoring breathing sounds in apnea patients, monitoring chest sounds after cardiac surgery, and for feedback sensing in compression (HFCC) vests used for respiratory ventilation. Another promising application is monitoring chest sounds in neonatal care units where the miniature sensors will minimize discomfort for the newborns.

  7. Microphone Clustering and BP Network based Acoustic Source Localization in Distributed Microphone Arrays

    Directory of Open Access Journals (Sweden)

    CHEN, Z.

    2013-11-01

    Full Text Available A microphone clustering and back propagation (BP neural network based acoustic source localization method using distributed microphone arrays in an intelligent meeting room is proposed. In the proposed method, a novel clustering algorithm is first used to divide all microphones into several clusters where each one corresponds to a specified BP network. Afterwards, the energy-based cluster selecting scheme is applied to select clusters which are small and close to the source. In each chosen cluster, the time difference of arrival of each microphone pair is estimated, and then all estimated time delays act as input of the corresponding BP network for position estimation. Finally, all estimated positions from the chosen clusters are fused for global position estimation. Only subsets rather than all the microphones are responsible for acoustic source localization, which leads to less computational cost; moreover, the local estimation in each selected cluster can be processed in parallel, which expects to improve the localization speed potentially. Simulation results from comparison with other related localization approaches confirm the validity of the proposed method.

  8. Hydrogel microphones for stealthy underwater listening

    Science.gov (United States)

    Gao, Yang; Song, Jingfeng; Li, Shumin; Elowsky, Christian; Zhou, You; Ducharme, Stephen; Chen, Yong Mei; Zhou, Qin; Tan, Li

    2016-08-01

    Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa-1 or 24 μC N-1 at a bias of 1.0 V) without using any signal amplification tools.

  9. Integrated mold/surface-micromachining process

    Energy Technology Data Exchange (ETDEWEB)

    Barron, C.C.; Fleming, J.G.; Montague, S.; Sniegowski, J.J.; Hetherington, D.L.

    1996-03-01

    We detail a new monolithically integrated silicon mold/surface-micromachining process which makes possible the fabrication of stiff, high-aspect-ratio micromachined structures integrated with finely detailed, compliant structures. An important example, which we use here as our process demonstration vehicle, is that of an accelerometer with a large proof mass and compliant suspension. The proof mass is formed by etching a mold into the silicon substrate, lining the mold with oxide, filling it with mechanical polysilicon, and then planarizing back to the level of the substrate. The resulting molded structure is recessed into the substrate, forming a planar surface ideal for subsequent processing. We then add surface-micromachined springs and sense contacts. The principal advantage of this new monolithically integrated mold/surface-micromachining process is that it decouples the design of the different sections of the device: In the case of a sensitive accelerometer, it allows us to optimize independently the proof mass, which needs to be as large, stiff, and heavy as possible, and the suspension, which needs to be as delicate and compliant as possible. The fact that the high-aspect-ratio section of the device is embedded in the substrate enables the monolithic integration of high-aspect-ratio parts with surface-micromachined mechanical parts, and, in the future, also electronics. We anticipate that such an integrated mold/surface micromachining/electronics process will offer versatile high-aspect-ratio micromachined structures that can be batch-fabricated and monolithically integrated into complex microelectromechanical systems.

  10. Micromachined Thermal Flow Sensors—A Review

    Directory of Open Access Journals (Sweden)

    Jonathan T. W. Kuo

    2012-07-01

    Full Text Available Microfabrication has greatly matured and proliferated in use amongst many disciplines. There has been great interest in micromachined flow sensors due to the benefits of miniaturization: low cost, small device footprint, low power consumption, greater sensitivity, integration with on-chip circuitry, etc. This paper reviews the theory of thermal flow sensing and the different configurations and operation modes available. Material properties relevant to micromachined thermal flow sensing and selection criteria are also presented. Finally, recent applications of micromachined thermal flow sensors are presented. Detailed tables of the reviewed devices are included.

  11. Micromachining process – current situation and challenges

    Directory of Open Access Journals (Sweden)

    Lalakiya Meet Rajeshkumar

    2015-01-01

    Full Text Available The rapid progress in the scientific innovations and the hunt for the renewable energy increases the urge for producing the bio electronic products, solar cells, bio batteries, nano robots, MEMS, blood less surgical tools which can be possible with the aid of the micromachining. This article helps us to understand the evolution and the challenges faced by the micromachining process. Micro machining is an enabling technology that facilitates component miniaturization and improved performance characteristics. Growing demand for less weight, high accuracy, high precision, meagre lead time, reduced batch size, less human interference are the key drivers for the micromachining than the conventional machining process.

  12. Review of laser micromachining in contract manufacturing

    Science.gov (United States)

    Ogura, Glenn; Gu, Bo

    1998-06-01

    This paper explores the wide range of laser micromachining applications used in contract manufacturing. Contract manufacturing is used in several key industries such as microelectronics packaging, semiconductor, data storage, medical devices, communications, peripherals, automobiles and aerospace. Material types includes plastics, metals, ceramics, inorganics and composites. However laser micromachining is just one available technology for micromachining and other methods will be reviewed. Contract manufacturing offers two important glimpses of the future. Firstly prototype work for new applications often beings in contract manufacturing. Secondly, contract manufacturing can be an economic springboard to allow laser systems to be installed in a production environment.

  13. Effect of microphone location in ITE versus BTE hearing aids.

    Science.gov (United States)

    Gartrell, E L; Church, G T

    1990-07-01

    Sound pressure measurements were made at the hearing aid microphones of 20 subjects with their in-the-ear (ITE) hearing aids and a behind-the-ear (BTE) hearing aid to determine the influence of microphone location on hearing aid input. A probe tube microphone was used to measure the difference in dB SPL between the ITE and BTE microphone locations. ITE microphone location resulted in a maximum high frequency advantage of 9.2 dB in the 2500 to 5000 Hz range. However, the frequency location of this maximal advantage varied a great deal between individuals, precluding the use of a standard ITE microphone correction factor for 2cc coupler to functional gain conversions.

  14. Optical micromachines for photonic networks

    Science.gov (United States)

    Katagiri, Yoshitada

    2001-10-01

    The optical micromachines controlling the light in spatial and wavelength domains are based on the micro- optomechatronics which handles small objects in micrometers and covers the fields from monolithic fabrication and control techniques. Their advantageous features include quick response, high mechanical stability, and low driving power because of the small inertia effects. A wide variety of functions such as wavelength tuning and optical path switching has been realized. This paper describes typical applications corresponding to these functions and their possible implementations: optical manipulation for small optical components based on momentum transfer of photons, micro lenses fabricated monolithically on a substrate for optical integration circuits, tunable filters with moving mirrors driven by the electrostatic force fro pulse shaping, and optical switches based on thermo capillary for cross connect or add/drop multiplexing operations in network systems. These applications are useful for next-generation photonic reconfigurable networks.

  15. Soft micromachines with programmable motility and morphology

    Science.gov (United States)

    Huang, Hen-Wei; Sakar, Mahmut Selman; Petruska, Andrew J.; Pané, Salvador; Nelson, Bradley J.

    2016-07-01

    Nature provides a wide range of inspiration for building mobile micromachines that can navigate through confined heterogenous environments and perform minimally invasive environmental and biomedical operations. For example, microstructures fabricated in the form of bacterial or eukaryotic flagella can act as artificial microswimmers. Due to limitations in their design and material properties, these simple micromachines lack multifunctionality, effective addressability and manoeuvrability in complex environments. Here we develop an origami-inspired rapid prototyping process for building self-folding, magnetically powered micromachines with complex body plans, reconfigurable shape and controllable motility. Selective reprogramming of the mechanical design and magnetic anisotropy of body parts dynamically modulates the swimming characteristics of the micromachines. We find that tail and body morphologies together determine swimming efficiency and, unlike for rigid swimmers, the choice of magnetic field can subtly change the motility of soft microswimmers.

  16. Compressive sensing with a spherical microphone array.

    Science.gov (United States)

    Fernandez-Grande, Efren; Xenaki, Angeliki

    2016-02-01

    A wave expansion method is proposed in this work, based on measurements with a spherical microphone array, and formulated in the framework provided by Compressive Sensing. The method promotes sparse solutions via ℓ1-norm minimization, so that the measured data are represented by few basis functions. This results in fine spatial resolution and accuracy. This publication covers the theoretical background of the method, including experimental results that illustrate some of the fundamental differences with the "conventional" least-squares approach. The proposed methodology is relevant for source localization, sound field reconstruction, and sound field analysis.

  17. 77 FR 2087 - Certain Silicon Microphone Packages and Products Containing Same; Institution of Investigation

    Science.gov (United States)

    2012-01-13

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same; Institution of Investigation... importation, and the sale within the United States after importation of certain silicon microphone packages... after importation of certain silicon microphone packages and products containing same that infringe...

  18. 76 FR 78042 - Certain Silicon Microphone Packages and Products Containing Same Receipt of Complaint...

    Science.gov (United States)

    2011-12-15

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same Receipt of Complaint... complaint entitled In Re Certain Silicon Microphone Packages and Products Containing Same, DN 2864; the... importation of certain silicon microphone packages and products containing same. The complaint names...

  19. Directional Microphone Hearing Aids in School Environments: Working toward Optimization

    Science.gov (United States)

    Ricketts, Todd A.; Picou, Erin M.; Galster, Jason

    2017-01-01

    Purpose: The hearing aid microphone setting (omnidirectional or directional) can be selected manually or automatically. This study examined the percentage of time the microphone setting selected using each method was judged to provide the best signalto-noise ratio (SNR) for the talkers of interest in school environments. Method: A total of 26…

  20. New probe microphone for investigating the acoustics of the ear

    DEFF Research Database (Denmark)

    Lauridsen, Ole; Günthersen, Carsten

    1981-01-01

    A new probe microphone employing a soft tube and a compensation network for the tube response is described. Because of the soft tube, this microphone is especially suited for investigating the acoustics of the outer ear and the ear canal, and some such measurements are given....

  1. Preamplifier with ultra low frequency cutoff for infrasonic condenser microphone

    DEFF Research Database (Denmark)

    Kinnerup, Rasmus Trock; Marbjerg, Kresten; Rasmussen, Per

    2012-01-01

    Measuring infrasonic sound sets high requirements on the instruments used. Typically the measurement chain consists of a microphone and a preamplifier. As the input resistance of the preamplifier forms a high pass filter with the capacitance of the microphone in the picofarad range, measuring ult...

  2. Comparison of binaural microphones for externalization of sounds

    DEFF Research Database (Denmark)

    Cubick, Jens; Sánchez Rodríguez, C.; Song, Wookeun;

    2015-01-01

    or with microphones placed inside the ear canals of a person. In this study, binaural room impulse responses (BRIRs) were measured with several commercially available binaural microphones, both placed inside the listeners’ ears (individual BRIR) and on a head and torso simulator (generic BRIR). The degree...

  3. Measurement of Supersonic Jet Noise with Optical Wave Microphone System

    Institute of Scientific and Technical Information of China (English)

    Masataka KOSAKA; Kunisato SETO; MD. Tawhidul Islam KHAN; Yoichi NAKAZONO

    2005-01-01

    An optical wave microphone system is a new technique of sound measurement. This technique has been developed as a new plasma diagnostic technique to measure electron density fluctuations in the nuclear fusion research. Because the sound wave is a pressure or a density fluctuation, it is possible for this technique to measure the sound wave, too. The acoustical characteristics of the optical wave microphone system were examined by using a speaker as a first step. Next, feasibility of this device to measure jet noise was examined. It was found that the optical wave microphone system could measure the jet noise as well as a sound from speaker.Hence the optical wave microphone system can be considered one of the devices equivalent to condenser microphone. Because of these reason, this device is very convenient to scan the acoustic filed through jet flow from the inside to the out side and more preferable for not disturbing the observation field.

  4. Demonstration of superconducting micromachined cavities

    Energy Technology Data Exchange (ETDEWEB)

    Brecht, T., E-mail: teresa.brecht@yale.edu; Reagor, M.; Chu, Y.; Pfaff, W.; Wang, C.; Frunzio, L.; Devoret, M. H.; Schoelkopf, R. J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States)

    2015-11-09

    Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics. Within a densely integrated device, they can protect qubits from noise and serve as quantum memory units. Whether constructed by machining bulk pieces of metal or microfabricating wafers, 3D enclosures are typically assembled from two or more parts. The resulting seams potentially dissipate crossing currents and limit performance. In this letter, we present measured quality factors of superconducting cavity resonators of several materials, dimensions, and seam locations. We observe that superconducting indium can be a low-loss RF conductor and form low-loss seams. Leveraging this, we create a superconducting micromachined resonator with indium that has a quality factor of two million, despite a greatly reduced mode volume. Inter-layer coupling to this type of resonator is achieved by an aperture located under a planar transmission line. The described techniques demonstrate a proof-of-principle for multilayer microwave integrated quantum circuits for scalable quantum computing.

  5. Physics-based signal processing algorithms for micromachined cantilever arrays

    Science.gov (United States)

    Candy, James V; Clague, David S; Lee, Christopher L; Rudd, Robert E; Burnham, Alan K; Tringe, Joseph W

    2013-11-19

    A method of using physics-based signal processing algorithms for micromachined cantilever arrays. The methods utilize deflection of a micromachined cantilever that represents the chemical, biological, or physical element being detected. One embodiment of the method comprises the steps of modeling the deflection of the micromachined cantilever producing a deflection model, sensing the deflection of the micromachined cantilever and producing a signal representing the deflection, and comparing the signal representing the deflection with the deflection model.

  6. Integrated micromachined transmission lines and endfire slotline antennas

    Science.gov (United States)

    Gearhart, Steven S.; Willke, Theodore L.; Onggosanusi, Eko N.

    1997-09-01

    An entirely new class of micromachined 3D microwave and millimeter-wave integrated circuits and antennas are being developed at the University of Wisconsin-Madison using a subset o the LIGA micromachining process. The deep x-ray lithography and metal plating portions of the LIGA process are used to precisely form tall metal structures on semiconductor and dielectric substrates. This micromachining process allows metal height to be included as a parameter in the design of integrated circuits, which will permit several important advancements in high frequency waveguiding circuits and integrated antennas. With appropriate thick- metal cross-sectional geometry, transmission line losses and dispersion may both be reduced on a given substrate. Vertical-walled metal structures allow increased control over element-to-element coupling for integrated coupled-line filters and couplers and result in very significant reductions in ohmic loss. It will be demonstrated that the first single-level coupled-line 3dB coupler can be fabricated using the LIGA process. In addition, the mechanical properties of the thick metal structures will be utilized in the fabrication of integrated antennas and transmission lines that are unsupported by a dielectric substrate. The elimination of the substrate beneath antennas reduces losses to substrate modes, and the elimination o the substrate beneath transmission line filters is necessary for extremely high Q integrated filters. This paper will present simulated loss results that demonstrate the advantages of thick metal transmission lines, measured results of a coupled-line bandpass filter, and a recently fabricated thick-metal tapered slotline antenna which extends nearly a centimeter off of the edge of a GaAs wafer.

  7. Virtual Microphones for Multichannel Audio Resynthesis

    Directory of Open Access Journals (Sweden)

    Athanasios Mouchtaris

    2003-09-01

    Full Text Available Multichannel audio offers significant advantages for music reproduction, including the ability to provide better localization and envelopment, as well as reduced imaging distortion. On the other hand, multichannel audio is a demanding media type in terms of transmission requirements. Often, bandwidth limitations prohibit transmission of multiple audio channels. In such cases, an alternative is to transmit only one or two reference channels and recreate the rest of the channels at the receiving end. Here, we propose a system capable of synthesizing the required signals from a smaller set of signals recorded in a particular venue. These synthesized “virtual” microphone signals can be used to produce multichannel recordings that accurately capture the acoustics of that venue. Applications of the proposed system include transmission of multichannel audio over the current Internet infrastructure and, as an extension of the methods proposed here, remastering existing monophonic and stereophonic recordings for multichannel rendering.

  8. Micromachined pressure sensors: Review and recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Eaton, W.P.; Smith, J.H. [Sandia National Labs., Albuquerque, NM (United States). Intelligent Micromachines Dept.

    1997-03-01

    Since the discovery of piezoresistivity in silicon in the mid 1950s, silicon-based pressure sensors have been widely produced. Micromachining technology has greatly benefited from the success of the integrated circuits industry, burrowing materials, processes, and toolsets. Because of this, microelectromechanical systems (MEMS) are now poised to capture large segments of existing sensor markets and to catalyze the development of new markets. Given the emerging importance of MEMS, it is instructive to review the history of micromachined pressure sensors, and to examine new developments in the field. Pressure sensors will be the focus of this paper, starting from metal diaphragm sensors with bonded silicon strain gauges, and moving to present developments of surface-micromachined, optical, resonant, and smart pressure sensors. Considerations for diaphragm design will be discussed in detail, as well as additional considerations for capacitive and piezoresistive devices.

  9. Silicon Micromachining for Terahertz Component Development

    Science.gov (United States)

    Chattopadhyay, Goutam; Reck, Theodore J.; Jung-Kubiak, Cecile; Siles, Jose V.; Lee, Choonsup; Lin, Robert; Mehdi, Imran

    2013-01-01

    Waveguide component technology at terahertz frequencies has come of age in recent years. Essential components such as ortho-mode transducers (OMT), quadrature hybrids, filters, and others for high performance system development were either impossible to build or too difficult to fabricate with traditional machining techniques. With micromachining of silicon wafers coated with sputtered gold it is now possible to fabricate and test these waveguide components. Using a highly optimized Deep Reactive Ion Etching (DRIE) process, we are now able to fabricate silicon micromachined waveguide structures working beyond 1 THz. In this paper, we describe in detail our approach of design, fabrication, and measurement of silicon micromachined waveguide components and report the results of a 1 THz canonical E-plane filter.

  10. Fundamental mechanisms of micromachine reliability

    Energy Technology Data Exchange (ETDEWEB)

    DE BOER,MAARTEN P.; SNIEGOWSKI,JEFFRY J.; KNAPP,JAMES A.; REDMOND,JAMES M.; MICHALSKE,TERRY A.; MAYER,THOMAS K.

    2000-01-01

    Due to extreme surface to volume ratios, adhesion and friction are critical properties for reliability of Microelectromechanical Systems (MEMS), but are not well understood. In this LDRD the authors established test structures, metrology and numerical modeling to conduct studies on adhesion and friction in MEMS. They then concentrated on measuring the effect of environment on MEMS adhesion. Polycrystalline silicon (polysilicon) is the primary material of interest in MEMS because of its integrated circuit process compatibility, low stress, high strength and conformal deposition nature. A plethora of useful micromachined device concepts have been demonstrated using Sandia National Laboratories' sophisticated in-house capabilities. One drawback to polysilicon is that in air the surface oxidizes, is high energy and is hydrophilic (i.e., it wets easily). This can lead to catastrophic failure because surface forces can cause MEMS parts that are brought into contact to adhere rather than perform their intended function. A fundamental concern is how environmental constituents such as water will affect adhesion energies in MEMS. The authors first demonstrated an accurate method to measure adhesion as reported in Chapter 1. In Chapter 2 through 5, they then studied the effect of water on adhesion depending on the surface condition (hydrophilic or hydrophobic). As described in Chapter 2, they find that adhesion energy of hydrophilic MEMS surfaces is high and increases exponentially with relative humidity (RH). Surface roughness is the controlling mechanism for this relationship. Adhesion can be reduced by several orders of magnitude by silane coupling agents applied via solution processing. They decrease the surface energy and render the surface hydrophobic (i.e. does not wet easily). However, only a molecular monolayer coats the surface. In Chapters 3-5 the authors map out the extent to which the monolayer reduces adhesion versus RH. They find that adhesion is

  11. Static pressure and temperature coefficients of working standard microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Cutanda Henriquez, Vicente; Torras Rosell, Antoni

    2016-01-01

    The sensitivity of measurement microphones is affected by changes in the environmental conditions, mainly temperature and static pressure. This rate of change has been the object of previous studies focused on Laboratory Standard microphones. The literature describes frequency dependent values...... for these coefficients which are used for calibration purposes. Working standard microphones are not exempt of these influences. However, manufacturers usually provide a low frequency value of the environmental coefficient. While in some applications the influence of this coefficient may be negligible, in others it may...

  12. Comparison of binaural microphones for externalization of sounds

    DEFF Research Database (Denmark)

    Cubick, Jens; Sánchez Rodríguez, C.; Song, Wookeun

    2015-01-01

    or with microphones placed inside the ear canals of a person. In this study, binaural room impulse responses (BRIRs) were measured with several commercially available binaural microphones, both placed inside the listeners’ ears (individual BRIR) and on a head and torso simulator (generic BRIR). The degree...... of externalization of speech and noise stimuli was tested in a listening experiment with a multi-stimulus test. No influence was found for the stimulus signal, but the externalization scores were found to be lower for 0◦ incidence. With all microphones, relatively high externalization scores were achieved...

  13. Tribological issues of polysilicon surface-micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Sniegowski, J.J.

    1997-12-01

    Polysilicon surface-micromachining is a Micro-Electro-Mechanical Systems (MEMS) manufacturing technology where the infrastructure for manufacturing silicon integrated circuits is used to fabricate micro-miniature mechanical devices. This presentation describes a multi-level mechanical polysilicon surface-micromachining technology and includes a discussion of the issues which affect device manufacture and performance. The multi-level technology was developed and is employed primarily to fabricate microactuated mechanisms. The intricate and complex motion offered by these devices is naturally accompanied by various forms of fraction and wear in addition to the classical stiction phenomena associated with micromechanical device fabrication and usage.

  14. New Technology-Driven Approaches in the Design of Preamplifiers for Condenser Microphones

    DEFF Research Database (Denmark)

    Haas-Christensen, Jelena

    to enhance performance of MEMS microphones. A new enhanced performance microphone chip-scale package (CSP) with two microphone dies and the CMOS amplifier has been assembled being the microphone with several dB higher signal-to-noise-ratio comparing to existing microphone products on the market. Due......The topic of this thesis is the design of CMOS preamplifiers for condenser microphones. Increasingly popular type of condenser microphones are MEMS (micro-electro-mechanical) microphones which pose a stringent requirements to the design of interface electronics among other due to their increased...... noise. Besides that, as MEMS microphones are easy to integrate with CMOS circuitry, CMOS circuit design gains importance because it can contribute to the overall improved performance of the system by introducing extra functionalities. Possible methods of sensing a signal from the microphone...

  15. The development of micromachined gyroscope structure and circuitry technology.

    Science.gov (United States)

    Xia, Dunzhu; Yu, Cheng; Kong, Lun

    2014-01-14

    This review surveys micromachined gyroscope structure and circuitry technology. The principle of micromachined gyroscopes is first introduced. Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated. Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs), piezoelectric vibrating gyroscopes (PVGs), surface acoustic wave (SAW) gyroscopes, bulk acoustic wave (BAW) gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs), magnetically suspended gyroscopes (MSGs), micro fiber optic gyroscopes (MFOGs), micro fluid gyroscopes (MFGs), micro atom gyroscopes (MAGs), and special micromachined gyroscopes. Next, the control electronics of micromachined gyroscopes are analyzed. The control circuits are categorized into typical circuitry and special circuitry technologies. The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies. Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail.

  16. The Development of Micromachined Gyroscope Structure and Circuitry Technology

    Directory of Open Access Journals (Sweden)

    Dunzhu Xia

    2014-01-01

    Full Text Available This review surveys micromachined gyroscope structure and circuitry technology. The principle of micromachined gyroscopes is first introduced. Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated. Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs, piezoelectric vibrating gyroscopes (PVGs, surface acoustic wave (SAW gyroscopes, bulk acoustic wave (BAW gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs, magnetically suspended gyroscopes (MSGs, micro fiber optic gyroscopes (MFOGs, micro fluid gyroscopes (MFGs, micro atom gyroscopes (MAGs, and special micromachined gyroscopes. Next, the control electronics of micromachined gyroscopes are analyzed. The control circuits are categorized into typical circuitry and special circuitry technologies. The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies. Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail.

  17. The Development of Micromachined Gyroscope Structure and Circuitry Technology

    Science.gov (United States)

    Xia, Dunzhu; Yu, Cheng; Kong, Lun

    2014-01-01

    This review surveys micromachined gyroscope structure and circuitry technology. The principle of micromachined gyroscopes is first introduced. Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated. Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs), piezoelectric vibrating gyroscopes (PVGs), surface acoustic wave (SAW) gyroscopes, bulk acoustic wave (BAW) gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs), magnetically suspended gyroscopes (MSGs), micro fiber optic gyroscopes (MFOGs), micro fluid gyroscopes (MFGs), micro atom gyroscopes (MAGs), and special micromachined gyroscopes. Next, the control electronics of micromachined gyroscopes are analyzed. The control circuits are categorized into typical circuitry and special circuitry technologies. The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies. Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail. PMID:24424468

  18. Source Coding for Wireless Distributed Microphones in Reverberant Environments

    DEFF Research Database (Denmark)

    Zahedi, Adel

    2016-01-01

    Modern multimedia systems are more and more shifting toward distributed and networked structures. This includes audio systems, where networks of wireless distributed microphones are replacing the traditional microphone arrays. This allows for flexibility of placement and high spatial diversity....... However, it comes with the price of several challenges, including the limited power and bandwidth resources for wireless transmission of audio recordings. In such a setup, we study the problem of source coding for the compression of the audio recordings before the transmission in order to reduce the power...... consumption and/or transmission bandwidth by reduction in the transmission rates. Source coding for wireless microphones in reverberant environments has several special characteristics which make it more challenging in comparison with regular audio coding. The signals which are acquired by the microphones...

  19. Modelling measurement microphones using BEM with visco-thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller

    2012-01-01

    For many decades, models that can explain the behaviour of measurement condenser microphones have been proposed in the literature. These devices have an apparently simple working principle, a charged capacitor whose charge varies when one of its electrodes, the diaphragm, moves as a result of sound...... waves. However, measurement microphones must be manufactured very carefully due to their sensitivity to small changes of their physical parameters. There are different elements in a microphone, the diaphragm, the gap behind it, a back cavity, a vent for pressure equalization and an external medium. All...... these subsystems form a strongly coupled device that cannot be modelled properly as a superposition of submodels, but rather as a whole. For this reason, the challenge of microphone modelling is still an ongoing area of research. In this work, a newly developed Boundary Element Method implementation that includes...

  20. High Efficiency Micromachining System Applied in Nanolithography

    Science.gov (United States)

    Chen, Xing; Lee, Dong Weon; Choi, Young Soo

    Scanning probe lithography such as direct-writing lithographic processes and nanoscratching techniques based on scanning probe microscopy have presented new micromachining methods for microelectromechanical system (MEMS). In this paper, a micromachining system for thermal scanning probe lithography is introduced, which consists of the cantilever arrays and a big stroke micro XY-stage. A large machining area and high machining speed can be realized by combining arrays of cantilevers possessing sharp tips at their top with the novel micro XY-stage which can obtain big displacements under relatively low driving voltage and in a small size. According to the above configuration, this micromachining system is provided with high throughputs and suitable for industrialization due to its MEMS-based simple fabrication process. The novel micro XY-stage applied in this system is presented in detail including the unique structure and principles, which shows an obvious improvement and distinct advantages in comparison with traditional structures. It is analyzed by mathematical model and then simulated using finite element method (FEM), it is proved to be able to practically serve the micromachining system with high capability.

  1. Biomolecular sensing using surface micromachined silicon plates

    NARCIS (Netherlands)

    Zapata, A.M.; Carlen, E.T.; Kim, E.S.; Hsiao, J.; Traviglia, D.; Weinberg, M.S.; Delapierre, G.; Puers, R.

    2007-01-01

    Micromachined sensors to detect surface stress changes associated with interactions between an immobilized chemically selective receptor and a target analyte are presented. The top isolated sensing surface of a free-standing silicon plate is prepared with a thin Au layer, followed by a covalent atta

  2. Micromachined silicon plates for sensing molecular interactions

    NARCIS (Netherlands)

    Carlen, E.T.; Weinberg, M.S.; Dube, C.E.; Zapata, A.M.; Borenstein, J.T.

    2006-01-01

    A micromachined surface stress sensor based on a thin suspended crystalline silicon circular plate measures differential surface stress changes associated with vapor phase chemisorption of an alkanethiol self-assembled monolayer. The isolated face of the suspended silicon plate serves as the sensing

  3. Analyzing acoustic phenomena with a smartphone microphone

    Science.gov (United States)

    Kuhn, Jochen; Vogt, Patrik

    2013-02-01

    This paper describes how different sound types can be explored using the microphone of a smartphone and a suitable app. Vibrating bodies, such as strings, membranes, or bars, generate air pressure fluctuations in their immediate vicinity, which propagate through the room in the form of sound waves. Depending on the triggering mechanism, it is possible to differentiate between four types of sound waves: tone, sound, noise, and bang. In everyday language, non-experts use the terms "tone" and "sound" synonymously; however, from a physics perspective there are very clear differences between the two terms. This paper presents experiments that enable learners to explore and understand these differences. Tuning forks and musical instruments (e.g., recorders and guitars) can be used as equipment for the experiments. The data are captured using a smartphone equipped with the appropriate app (in this paper we describe the app Audio Kit for iOS systems ). The values captured by the smartphone are displayed in a screen shot and then viewed directly on the smartphone or exported to a computer graphics program for printing.

  4. Micromachined Systems-on-a-Chip: Infrastructure, Technology and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J. J.; Krygowski, T. W.; Miller, S. L.; Montague, S.; Rodgers, M. S.; Schriner, H.; Smith, J. H.; Sniegowski, J. J.

    1998-10-09

    A review is made of the infrastructure, technology and capabilities of Sandia National Laboratories for the development of micromechanical systems that have potential space applications. By incorporating advanced fabrication processes, such as chemical mechanical polishing, and several mechanical polysilicon levels, the range' of rrticromechanical systems that can be fabricated in these technologies is virtually limitless. Representative applications include a micro- engine driven mirror, and a micromachined lock. Using a novel integrated MEM!YCMOS technology, a six degree-of-freedom accelerometer/gyroscope system has been designed by researchers at U.C. Berkeley and fabricated on the same silicon chip as the CMOS control circuits to produce an integrated micro-navigational unit.

  5. On the interference between the two microphones in free-field reciprocity calibration

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2004-01-01

    One of the fundamental assumptions in free-field reciprocity calibration of microphones is that the microphones can be substituted by point sources at the positions where the acoustic centers are located. However, in practice the microphones have finite dimensions and, at the distance and in the ......One of the fundamental assumptions in free-field reciprocity calibration of microphones is that the microphones can be substituted by point sources at the positions where the acoustic centers are located. However, in practice the microphones have finite dimensions and, at the distance...

  6. Model Design of Piezoelectric Micromachined Modal Gyroscope

    Directory of Open Access Journals (Sweden)

    Xiaojun Hu

    2011-01-01

    Full Text Available This paper reports a novel kind of solid-state microgyroscope, which is called piezoelectric micromachined modal gyroscope (PMMG. PMMG has large stiffness and robust resistance to shake and strike because there is no evident mass-spring component in its structure. This work focused on quantitative optimization of the gyroscope, which is still blank for such gyroscope. The modal analysis by the finite element method (FEM was firstly conducted. A set of quantitative indicators were developed to optimize the operation mode. By FEM, the harmonic analysis was conducted to find the way to efficiently actuate the operational mode needed. The optimal configuration of driving electrodes was obtained. At last, the Coriolis analysis was conducted to show the relation between angular velocity and differential output voltage by the Coriolis force under working condition. The results obtained in this paper provide theoretical basis for realizing this novel kind of micromachined gyroscope.

  7. Micromachined Inclinometer Based on Fluid Convection

    CERN Document Server

    Crespy, N; Combette, P; Boyer, P Temple; Giani, A; Foucaran, A

    2008-01-01

    This paper presents a numerical simulation and experimental results of a one-dimensional thermal inclinometer with the cavity filled of gas and liquid. The sensor principle consists of one heating resistor placed between two detectors. When the resistor is electrically powered, it creates a symmetrical temperature profile inside a micromachined silicon cavity. By applying a tilt to the sensor, the profile shifts in the same direction of the sensible axis corresponding to the horizontal one to one. The temperature profile and the sensitivity according to the CO2 gas and mineral oil SAE50 have been studied using numerical resolution of fluid dynamics equations with the computational fluid dynamics (CFD) software package Fluent V6.2. We have shown that the sensitivity of liquid sensors is higher than the gas sensors one. By using micromachined silicon technique, a thermal inclinometer with one pair of detectors placed at 300 um from the heater has been made. Experimental measurements corroborate with the numeric...

  8. Design of an electrochemical micromachining machine

    OpenAIRE

    Spieser, A; Ivanov, A.

    2014-01-01

    Electrochemical micromachining (μECM) is a non-conventional machining process based on the phenomenon of electrolysis. μECM became an attractive area of research due to the fact that this process does not create any defective layer after machining and that there is a growing demand for better surface integrity on different micro applications including microfluidics systems, stress-free drilled holes in automotive and aerospace manufacturing with complex shapes, etc. This work presents the des...

  9. Micromachined Piezoelectric Actuators for Cryogenic Adaptive Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes micromachined single crystal piezoelectric actuator arrays to enable ultra-large stroke, high precision shape control for large aperture,...

  10. On the use of mobile phones and wearable microphones for noise exposure measurements: Calibration and measurement accuracy

    Science.gov (United States)

    Dumoulin, Romain

    Despite the fact that noise-induced hearing loss remains the number one occupational disease in developed countries, individual noise exposure levels are still rarely known and infrequently tracked. Indeed, efforts to standardize noise exposure levels present disadvantages such as costly instrumentation and difficulties associated with on site implementation. Given their advanced technical capabilities and widespread daily usage, mobile phones could be used to measure noise levels and make noise monitoring more accessible. However, the use of mobile phones for measuring noise exposure is currently limited due to the lack of formal procedures for their calibration and challenges regarding the measurement procedure. Our research investigated the calibration of mobile phone-based solutions for measuring noise exposure using a mobile phone's built-in microphones and wearable external microphones. The proposed calibration approach integrated corrections that took into account microphone placement error. The corrections were of two types: frequency-dependent, using a digital filter and noise level-dependent, based on the difference between the C-weighted noise level minus A-weighted noise level of the noise measured by the phone. The electro-acoustical limitations and measurement calibration procedure of the mobile phone were investigated. The study also sought to quantify the effect of noise exposure characteristics on the accuracy of calibrated mobile phone measurements. Measurements were carried out in reverberant and semi-anechoic chambers with several mobiles phone units of the same model, two types of external devices (an earpiece and a headset with an in-line microphone) and an acoustical test fixture (ATF). The proposed calibration approach significantly improved the accuracy of the noise level measurements in diffuse and free fields, with better results in the diffuse field and with ATF positions causing little or no acoustic shadowing. Several sources of errors

  11. Design of Surface micromachined Compliant MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Joe Anthony Bradley

    2002-08-01

    The consideration of compliant mechanisms as Microelectromechanical Systems (MEMS) is the focus of this research endeavor. MEMS are micron to millimeter devices that combine electrical, mechanical, and information processing capabilities on the same device. These MEMS need some mechanical motion or parts that move relative to each other. This relative motion, using multiple parts, is not desired because of the assembly requirement and the friction introduced. Compliant devices limits or eliminates friction and the need for multi-component assembly. Compliant devices improve designs by creating single piece mechanisms. The purpose of this research is to validate surface micromachining as a viable fabrication process for compliant MEMS designs. Specifically, this research has sought to fabricate a micro-compliant gripper and a micro-compliant clamp to illustrate the process. While other researchers have created compliant MEMS, most have used comb-drive actuation methods and bulk micromachining processes. This research focuses on fully-compliant devices that use device flexibility for motion and actuation. Validation of these compliant MEMS is achieved by structural optimization of device design and functional performance testing. This research contributes to the ongoing research in MEMS by evaluating the potential of using surface micromachining as a process for fabricating compliant micro-mechanisms.

  12. Design of Surface Micromachined Compliant MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Joe Anthony [Iowa State Univ., Ames, IA (United States)

    2002-12-31

    The consideration of compliant mechanisms as Microelectromechanical Systems (MEMS) is the focus of this research endeavor. MEMS are micron to millimeter devices that combine electrical, mechanical, and information processing capabilities on the same device. These MEMS need some mechanical motion or parts that move relative to each other. This relative motion, using multiple parts, is not desired because of the assembly requirement and the friction introduced. Compliant devices limits or eliminates friction and the need for multi-component assembly. Compliant devices improve designs by creating single piece mechanisms. The purpose of this research is to validate surface micromachining as a viable fabrication process for compliant MEMS designs. Specifically, this research has sought to fabricate a micro-compliant gripper and a micro-compliant clamp to illustrate the process. While other researchers have created compliant MEMs, most have used comb-drive actuation methods and bulk micromachining processes. This research focused on fully-compliant devices that use device flexibility for motion and actuation. Validation of these compliant MEMS is achieved by structural optimization of device design and functional performance testing. This research contributes to the ongoing research in MEMS by evaluating the potential of using surface micromachining as a process for fabricating compliant micro-mechanisms.

  13. Design of Surface micromachined Compliant MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Joe Anthony [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The consideration of compliant mechanisms as Microelectromechanical Systems (MEMS) is the focus of this research endeavor. MEMS are micron to millimeter devices that combine electrical, mechanical, and information processing capabilities on the same device. These MEMS need some mechanical motion or parts that move relative to each other. This relative motion, using multiple parts, is not desired because of the assembly requirement and the friction introduced. Compliant devices limits or eliminates friction and the need for multi-component assembly. Compliant devices improve designs by creating single piece mechanisms. The purpose of this research is to validate surface micromachining as a viable fabrication process for compliant MEMS designs. Specifically, this research has sought to fabricate a micro-compliant gripper and a micro-compliant clamp to illustrate the process. While other researchers have created compliant MEMS, most have used comb-drive actuation methods and bulk micromachining processes. This research focuses on fully-compliant devices that use device flexibility for motion and actuation. Validation of these compliant MEMS is achieved by structural optimization of device design and functional performance testing. This research contributes to the ongoing research in MEMS by evaluating the potential of using surface micromachining as a process for fabricating compliant micro-mechanisms.

  14. Improved Open-Microphone Speech Recognition

    Science.gov (United States)

    Abrash, Victor

    2002-01-01

    Many current and future NASA missions make extreme demands on mission personnel both in terms of work load and in performing under difficult environmental conditions. In situations where hands are impeded or needed for other tasks, eyes are busy attending to the environment, or tasks are sufficiently complex that ease of use of the interface becomes critical, spoken natural language dialog systems offer unique input and output modalities that can improve efficiency and safety. They also offer new capabilities that would not otherwise be available. For example, many NASA applications require astronauts to use computers in micro-gravity or while wearing space suits. Under these circumstances, command and control systems that allow users to issue commands or enter data in hands-and eyes-busy situations become critical. Speech recognition technology designed for current commercial applications limits the performance of the open-ended state-of-the-art dialog systems being developed at NASA. For example, today's recognition systems typically listen to user input only during short segments of the dialog, and user input outside of these short time windows is lost. Mistakes detecting the start and end times of user utterances can lead to mistakes in the recognition output, and the dialog system as a whole has no way to recover from this, or any other, recognition error. Systems also often require the user to signal when that user is going to speak, which is impractical in a hands-free environment, or only allow a system-initiated dialog requiring the user to speak immediately following a system prompt. In this project, SRI has developed software to enable speech recognition in a hands-free, open-microphone environment, eliminating the need for a push-to-talk button or other signaling mechanism. The software continuously captures a user's speech and makes it available to one or more recognizers. By constantly monitoring and storing the audio stream, it provides the spoken

  15. Space discriminative function for microphone array robust speech recognition

    Institute of Scientific and Technical Information of China (English)

    Zhao Xianyu; Ou Zhijian; Wang Zuoying

    2005-01-01

    Based on W-disjoint orthogonality of speech mixtures, a space discriminative function was proposed to enumerate and localize competing speakers in the surrounding environments. Then, a Wiener-like post-filterer was developed to adaptively suppress interferences. Experimental results with a hands-free speech recognizer under various SNR and competing speakers settings show that nearly 69% error reduction can be obtained with a two-channel small aperture microphone array against the conventional single microphone baseline system. Comparisons were made against traditional delay-and-sum and Griffiths-Jim adaptive beamforming techniques to further assess the effectiveness of this method.

  16. Chip-size-packaged silicon microphones [for hearing instruments

    DEFF Research Database (Denmark)

    Müllenborn, Matthias; Rombach, Pirmin; Klein, Udo;

    2001-01-01

    The first results of silicon microphones that are completely batch-packaged and integrated with signal conditioning circuitry in a chip stack are discussed. The chip stack is designed to be directly mounted into a system, such as a hearing instrument, without further single-chip handling or wire ...... consumption of about 50 μW in the near future, thereby living up to the tight specifications of microphones for hearing instruments. Other potential applications include mobile phones, headsets, and wearable computers, in which space is constrained....

  17. Small foamed polystyrene shield protects low-frequency microphones from wind noise

    Science.gov (United States)

    Tedrick, R. N.

    1964-01-01

    A foamed polystyrene noise shield for microphones has been designed in teardrop shape to minimize air turbulence. The shield slips on and off the microphone head easily and is very effective in low-frequency sound intensity measurements.

  18. Posture Adjustment of Microphone Based on Image Recognition in Automatic Welding System

    Institute of Scientific and Technical Information of China (English)

    Wang Jin'e; Gao Ping; Huang Haibo; Li Xiangpeng; Zheng Liang; Xu Wenkui; Chen Liguo

    2015-01-01

    As the requirements of production process is getting higher and higher with the reduction of volume ,mi-crophone production automation become an urgent need to improve the production efficiency .The most important part is studied and a precise algorithm of calculating the deviation angle of four types microphones is proposed , based on the feature extraction and visual detection .Pretreatment is performed to achieve the real-time microphone image .Canny edge detection and typical feature extraction are used to distinguish the four types of microphones , categorizing them as type M 1 and type M2 .And Hough transformation is used to extract the image features of mi-crophone .Therefore ,the deviation angle between the posture of microphone and the ideal posture in 2D plane can be achieved .Depending on the angle ,the system drives the motor to adjust posture of the microphone .The final purpose is to realize the high efficiency welding of four different types of microphones .

  19. Size Reduction of Tunable Micromachined Filters for High Speed Operations

    Institute of Scientific and Technical Information of China (English)

    Tomoyuki; Hino; Takeru; Amano; Wiganes; Janto; Fumio; Koyama

    2003-01-01

    The size reduction of tunable micromachined filters is carried out for high-speed wavelength tuning. We fabricated micromachined filters having a miniature structure with an air gap of 300 run and a short cantilever of 45 urn, exhibiting fast response of below 3 us.

  20. Size Reduction of Tunable Micromachined Filters for High Speed Operations

    Institute of Scientific and Technical Information of China (English)

    Tomoyuki Hino; Takeru Amano; Wiganes Janto; Fumio Koyama

    2003-01-01

    The size reduction of tunable micromachined filters is carried out for high-speed wavelength tuning. We fabricated micromachined filters having a miniature structure with an air gap of 300 nm and a short cantilever of 45 μm, exhibiting fast response of below 3 μs.

  1. On experimental determination of the random-incidence response of microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2007-01-01

    The random-incidence sensitivity of a microphone is defined as the ratio of the output voltage to the sound pressure that would exist at the position of the acoustic center of the microphone in the absence of the microphone in a sound field with incident plane waves coming from all directions. Th...

  2. 78 FR 45272 - Certain Silicon Microphone Packages and Products Containing Same Institution of Investigation...

    Science.gov (United States)

    2013-07-26

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same Institution of Investigation... importation, and the sale within the United States after importation of certain silicon microphone packages... importation, or the sale within the United States after importation of certain silicon microphone packages...

  3. 78 FR 38734 - Certain Silicon Microphone Packages and Products Containing Same; Notice of Receipt of Complaint...

    Science.gov (United States)

    2013-06-27

    ... COMMISSION Certain Silicon Microphone Packages and Products Containing Same; Notice of Receipt of Complaint... complaint entitled Certain Silicon Microphone Packages and Products Containing Same, DN 2962; the Commission... importation of certain silicon microphone packages and products containing same. The complaint names...

  4. Friction in surface micromachined microengines

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S.L.; Sniegowski, J.J.; LaVigne, G.; McWhorter, P.J.

    1996-03-01

    Understanding the frictional properties of advanced Micro-Electro- Mechanical Systems (MEMS) is essential in order to develop optimized designs and fabrication processes, as well as to qualify devices for commercial applications. We develop and demonstrate a method to experimentally measure the forces associated with sliding friction of devices rotating on a hub. The method is demonstrated on the rotating output gear of the microengine recently developed at Sandia National Laboratories. In-situ measurements of an engine running at 18300 rpm give a coefficient of friction of 0.5 for radial (normal) forces less than 4 {mu}N. For larger forces the effective coefficient of friction abruptly increases, suggesting a fundamental change in the basic nature of the interaction between the gear and hub. The experimental approach we have developed to measure the frictional forces associated with the microengine is generically applicable to other MEMS devices.

  5. Free-field calibration of measurement microphones at high frequencies

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Torras Rosell, Antoni;

    2011-01-01

    Measurement microphones are typically calibrated in a free field at frequencies up to 50 kHz. This is a sufficiently high frequency for the most of sound measurement applications related with noise assessment. However, other applications such as assessment of the noise emitted by ultrasound clean...

  6. Design and analysis of diaphragms in dynamic microphones

    Directory of Open Access Journals (Sweden)

    Zi-Gui Huang

    2015-07-01

    Full Text Available Most contemporary high-end microphones are dynamic microphones, adopting the most basic electromagnetic transduction principles. This study investigated the diaphragm structures of dynamic microphones. The diaphragms were composed of polyimide material, and the boundary settings required for actual operation were provided using finite element model analysis software. The characteristic frequencies caused by grooving variations on the three-dimensional diaphragm were analyzed for the various groove shapes and number. The groove angles and width variations were examined based on the optimal groove shape selected in the aforementioned analysis, and the effects of these shapes were determined based on the analytical results. Acoustic waves cause thin films to vibrate, forming the working principle behind dynamic microphones. The thin film drives a coil to vibrate in a magnetic field and cuts the line of magnetic force, subsequently producing a voltage on both ends of the coil. This audio-frequency-inducted voltage represents an acoustic wave message. The finite element model analysis software was used to conduct electromagnetic induction simulations; the sound source was fed to the diaphragm to drive the coil. The coil vibrations caused the line of magnetic force to be cut, and the final voltages produced were examined and compared.

  7. A Multifunction Low-Power Preamplifier for MEMS Capacitive Microphones

    DEFF Research Database (Denmark)

    Jawed, Syed Arsalan; Nielsen, Jannik Hammel; Gottardi, Massimo;

    2009-01-01

    A multi-function two-stage chopper-stabilized preamplifier (PAMP) for MEMS capacitive microphones (MCM) is presented. The PAMP integrates digitally controllable gain, high-pass filtering and offset control, adding flexibility to the front-end readout of MCMs. The first stage of the PAMP consists...

  8. Single and multiple microphone noise reduction strategies in cochlear implants.

    Science.gov (United States)

    Kokkinakis, Kostas; Azimi, Behnam; Hu, Yi; Friedland, David R

    2012-06-01

    To restore hearing sensation, cochlear implants deliver electrical pulses to the auditory nerve by relying on sophisticated signal processing algorithms that convert acoustic inputs to electrical stimuli. Although individuals fitted with cochlear implants perform well in quiet, in the presence of background noise, the speech intelligibility of cochlear implant listeners is more susceptible to background noise than that of normal hearing listeners. Traditionally, to increase performance in noise, single-microphone noise reduction strategies have been used. More recently, a number of approaches have suggested that speech intelligibility in noise can be improved further by making use of two or more microphones, instead. Processing strategies based on multiple microphones can better exploit the spatial diversity of speech and noise because such strategies rely mostly on spatial information about the relative position of competing sound sources. In this article, we identify and elucidate the most significant theoretical aspects that underpin single- and multi-microphone noise reduction strategies for cochlear implants. More analytically, we focus on strategies of both types that have been shown to be promising for use in current-generation implant devices. We present data from past and more recent studies, and furthermore we outline the direction that future research in the area of noise reduction for cochlear implants could follow.

  9. Predicting hearing aid microphone preference in everyday listening.

    Science.gov (United States)

    Walden, Brian E; Surr, Rauna K; Cord, Mary T; Dyrlund, Ole

    2004-05-01

    Seventeen hearing-impaired adults were fit with omnidirectional/directional hearing aids, which they wore during a four-week trial. For each listening situation encountered in daily living during a total of seven days, participants selected the preferred microphone mode and described the listening situation in terms of five environmental variables, using a paper and pencil form. Results indicated that hearing-impaired adults typically spend the majority of their active listening time in situations with background noise present and surrounding the listener, and the signal source located in front and relatively near. Microphone preferences were fairly evenly distributed across listening situations but differed depending on the characteristics of the listening environment. The omnidirectional mode tended to be preferred in relatively quiet listening situations or, in the presence of background noise, when the signal source was relatively far away. The directional mode tended to be preferred when background noise was present and the signal source was located in front of and relatively near the listener. Results suggest that knowing only signal location and distance and whether background noise is present or absent, omnidirectional/directional hearing aids can be set in the preferred mode in most everyday listening situations. These findings have relevance for counseling patients when to set manually switchable omnidirectional/directional hearing aids in each microphone mode, as well as for the development of automatic algorithms for selecting omnidirectional versus directional microphone processing.

  10. The static pressure and temperature coefficients of laboratory standard microphones

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1999-01-01

    The sensitivity of condenser measurement microphones depends on the environmental conditions due to the changes in the acoustic properties of the air enclosed between diaphragm and backelectrode and in the cavity behind the backelectrode. A theoretical investigation has been performed based on an...

  11. Static pressure and temperature coefficients of laboratory standard microphones

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1996-01-01

    The sensitivity of condenser measurement microphones depends on the environmental conditions due to the changes in the acoustic properties of the enclosed air between diaphragm and back-electrode and in the cavity behind the backelectrode. A theoretical investigation has been performed based on a...

  12. Micromachined permanent magnets and their MEMS applications

    Science.gov (United States)

    Cho, Hyoung Jin

    2002-01-01

    In this research, new micromachined permanent magnets have been proposed, developed and characterized for MEMS applications. In realizing micromachined permanent magnets, a new electroplating technique using external magnetic field and a bumper filling technique using a photolithographically defined mold with resin bonded magnetic particles have been developed. The newly developed micromachining techniques allow thick film-type permanent magnet components to be integrated to magnetic MEMS devices with dimensional control and alignment. Permanent magnet arrays with the dimensions ranging from 30 mum to 200 mum have been developed with an energy density up to 2.7 kJ/m3 in precisely defined forms in the micro scale. For the applications of the permanent magnets developed in this work, three novel magnetic MEMS devices such as a bi-directional magnetic actuator, a magnetically driven optical scanner, and a magnetic cell separator have been successfully realized. After design and modeling, each device has been fabricated and fully characterized. The bi-directional actuator with the electroplated permanent magnet array has achieved bi-directional motion clearly and shown good agreement with the analytical and simulated models. The optical scanner has shown linear bi-directional response under static actuation and stable bi-directional scanning performance under dynamic actuation. As a potential BioMEMS application of the developed permanent magnet, the prototype magnetic cell separator using the electroplated permanent magnet strip array has been proposed and demonstrated for magnetic bead patterning. In conclusion, new thick film-type, electroplated CoNiMnP and epoxy resin bonded Sr-ferrite permanent magnets have been developed and characterized, and then, three new magnetic MEMS devices using the permanent magnets such as a bi-directional magnetic actuator, an optical scanner and a magnetic cell separator have been realized in this research. The new micromachined

  13. Active micromachines: Microfluidics powered by mesoscale turbulence

    CERN Document Server

    Thampi, Sumesh P; Shendruk, Tyler N; Golestanian, Ramin; Yeomans, Julia M

    2016-01-01

    Dense active matter, from bacterial suspensions and microtubule bundles driven by motor proteins to cellular monolayers and synthetic Janus particles, is characterised by mesoscale turbulence, the emergence of chaotic flow structures. By immersing an ordered array of symmetric rotors in an active fluid, we introduce a microfluidic system that exploits spontaneous symmetry breaking in mesoscale turbulence to generate work. The lattice of rotors self-organises into a spin-state where neighbouring discs continuously rotate in permanent alternating directions due to combined hydrodynamic and elastic effects. Our virtual prototype demonstrates a new research direction for the design of micromachines powered by the nematohydrodynamic properties of active turbulence.

  14. Optical network of silicon micromachined sensors

    Science.gov (United States)

    Wilson, Mark L.; Burns, David W.; Zook, J. David

    1996-03-01

    The Honeywell Technology Center, in collaboration with the University of Wisconsin and the Mobil Corporation, and under funding from this ARPA sponsored program, are developing a new type of `hybrid' micromachined silicon/fiber optic sensor that utilizes the best attributes of each technology. Fiber optics provide a noise free method to read out the sensor without electrical power required at the measurement point. Micromachined silicon sensor techniques provide a method to design many different types of sensors such as temperature, pressure, acceleration, or magnetic field strength and report the sensor data using FDM methods. Our polysilicon resonant microbeam structures have a built in Fabry-Perot interferometer that offers significant advantages over other configurations described in the literature. Because the interferometer is an integral part of the structure, the placement of the fiber becomes non- critical, and packaging issues become considerably simpler. The interferometer spacing are determined by the thin-film fabrication processes and therefore can be extremely well controlled. The main advantage, however, is the integral vacuum cavity that ensures high Q values. Testing results have demonstrated relaxed alignment tolerances in packaging these devices, with an excellent Signal to Noise Ratio. Networks of 16 or more sensors are currently being developed. STORM (Strain Transduction by Optomechanical Resonant Microbeams) sensors can also provide functionality and self calibration information which can be used to improve the overall system reliability. Details of the sensor and network design, as well as test results, are presented.

  15. Source Coding for Wireless Distributed Microphones in Reverberant Environments

    DEFF Research Database (Denmark)

    Zahedi, Adel

    2016-01-01

    Modern multimedia systems are more and more shifting toward distributed and networked structures. This includes audio systems, where networks of wireless distributed microphones are replacing the traditional microphone arrays. This allows for flexibility of placement and high spatial diversity......'s recording. This means that ignoring this correlation will be a waste of the scarce power and bandwidth resources. In this thesis, we study both information-theoretic and audio coding aspects of the coding problem in the above-mentioned framework. We formulate rate-distortion problems which take into account...... on the performance of the audio coding system. We derive explicit formulas for the rate-distortion functions, and design coding schemes that asymptotically achieve the performance bounds. We justify the Gaussianity assumption by showing that the results will still be relevant for non-Gaussian sources including audio...

  16. A self-steering close-talking microphone array

    Institute of Scientific and Technical Information of China (English)

    PENG Ke; YANG Xinfeng; XU Boling

    2005-01-01

    For communication in extremely noisy environments, close-talking microphone arrays are useful. Differential microphone array systems possessing excellent nearfield directivity and strong farfield-noise reduction capability are very suitable for close-talking situations. In order to improve the focusing effect at the desired bearing in the nearfield, we propose a novel self-steering system of closetalking arrays with the first-order differential sub-arrays in this paper. Calculations of directivity patterns and directivity factors show that when a kind of optimized beamforming technique is adopted even small arrays with a focusing configuration will exhibit a satisfactory nearfield directivity which is electronically steerable within a specific range. The superiority of the proposed array system is verified by experiments with real acoustic data.

  17. Reconstruction of sound fields with a spherical microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Walton, Tim

    2014-01-01

    Spherical microphone arrays are very well suited for sound field measurements in enclosures or interior spaces, and generally in acoustic environments where sound waves impinge on the array from multiple directions. Because of their directional properties, they make it possible to resolve sound...... waves traveling in any direction. In particular, rigid sphere microphone arrays are robust, and have the favorable property that the scattering introduced by the array can be compensated for - making the array virtually transparent. This study examines a recently proposed sound field reconstruction...... method based on a point source expansion, i.e. equivalent source method, using a rigid spherical array. The study examines the capability of the method to distinguish between sound waves arriving from different directions (i.e., as a sound field separation method). This is representative of the potential...

  18. Audio Sensing Aid based Wireless Microphone Emulation Attacks Detection

    Directory of Open Access Journals (Sweden)

    Wang Shan-shan

    2013-10-01

    Full Text Available The wireless microphone network is an important PU network for CRN, but there is no effective technology to solve the problem of microphone evaluation attacks. Therefore, this paper propose ASA algorithm, which utilizes three devices to detect MUs, and they are loudspeaker audio sensor (LAS, environment audio sensor (EAS, and radio frequency fingerprint detector (RFFD. LASs are installed near loudspeakers, which have two main effects: One is to sense loudspeakers’ output, and the other is to broadcast warning information to all SUs through the common control channel when detecting valid output. EASs are pocket voice captures provided to SU, and utilized to sense loudspeaker sound at SU’s location. Utilizing EASs and energy detections in SU can detect primary user emulation attack (PUEA fast. But to acquire the information of attacked channels, we need explore RFFDs to analyze the features of PU transmitters. The results show that the proposed algorithm can detect PUEA well.    

  19. Factors affecting the performance of large-aperture microphone arrays.

    Science.gov (United States)

    Silverman, Harvey F; Patterson, William R; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m x 8 m x 3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  20. Factors affecting the performance of large-aperture microphone arrays

    Science.gov (United States)

    Silverman, Harvey F.; Patterson, William R.; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  1. Microphone Array Speaker Localizers Using Spatial-Temporal Information

    Directory of Open Access Journals (Sweden)

    Dvorkind Tsvi Gregory

    2006-01-01

    Full Text Available A dual-step approach for speaker localization based on a microphone array is addressed in this paper. In the first stage, which is not the main concern of this paper, the time difference between arrivals of the speech signal at each pair of microphones is estimated. These readings are combined in the second stage to obtain the source location. In this paper, we focus on the second stage of the localization task. In this contribution, we propose to exploit the speaker's smooth trajectory for improving the current position estimate. Three localization schemes, which use the temporal information, are presented. The first is a recursive form of the Gauss method. The other two are extensions of the Kalman filter to the nonlinear problem at hand, namely, the extended Kalman filter and the unscented Kalman filter. These methods are compared with other algorithms, which do not make use of the temporal information. An extensive experimental study demonstrates the advantage of using the spatial-temporal methods. To gain some insight on the obtainable performance of the localization algorithm, an approximate analytical evaluation, verified by an experimental study, is conducted. This study shows that in common TDOA-based localization scenarios—where the microphone array has small interelement spread relative to the source position—the elevation and azimuth angles can be accurately estimated, whereas the Cartesian coordinates as well as the range are poorly estimated.

  2. Noise Reduction with Microphone Arrays for Speaker Identification

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Z

    2011-12-22

    Reducing acoustic noise in audio recordings is an ongoing problem that plagues many applications. This noise is hard to reduce because of interfering sources and non-stationary behavior of the overall background noise. Many single channel noise reduction algorithms exist but are limited in that the more the noise is reduced; the more the signal of interest is distorted due to the fact that the signal and noise overlap in frequency. Specifically acoustic background noise causes problems in the area of speaker identification. Recording a speaker in the presence of acoustic noise ultimately limits the performance and confidence of speaker identification algorithms. In situations where it is impossible to control the environment where the speech sample is taken, noise reduction filtering algorithms need to be developed to clean the recorded speech of background noise. Because single channel noise reduction algorithms would distort the speech signal, the overall challenge of this project was to see if spatial information provided by microphone arrays could be exploited to aid in speaker identification. The goals are: (1) Test the feasibility of using microphone arrays to reduce background noise in speech recordings; (2) Characterize and compare different multichannel noise reduction algorithms; (3) Provide recommendations for using these multichannel algorithms; and (4) Ultimately answer the question - Can the use of microphone arrays aid in speaker identification?

  3. Micromachined dual input axis rate gyroscope

    Science.gov (United States)

    Juneau, Thor Nelson

    The need for inexpensive yet reliable angular rate sensors in fields ranging from automotive to consumer electronics has motivated prolific micromachined rate gyroscope research. The vast majority of research has focused on single input axis rate gyroscopes based upon either translational resonance, such as tuning forks, or structural mode resonance, such as vibrating rings. However, this work presents a novel, contrasting approach based on angular resonance of a rotating rigid rotor suspended by torsional springs. The inherent symmetry of the circular design allows angular rate measurement about two axes simultaneously, hence the name micromachined dual-axis rate gyroscope. The underlying theory of operation, mechanical structure design optimization, electrical interface circuitry, and signal processing are described in detail. Several operational versions were fabricated using two different fully integrated surface micromachining processes as proof of concept. The heart of the dual-axis rate gyroscope is a ˜2 mum thick polysilicon disk or rotor suspended above the substrate by a four beam suspension. When this rotor in driven into angular oscillation about the axis perpendicular to the substrate, a rotation rate about the two axes parallel to the substrate invokes an out of plane rotor tilting motion due to Coriolis acceleration. This tilting motion is capacitively measured and on board integrated signal processing provides two output voltages proportional to angular rate input about the two axes parallel to the substrate. The design process begins with the derivation of gyroscopic dynamics. The equations suggest that tuning sense mode frequencies to the drive oscillation frequency can vastly increase mechanical sensitivity. Hence the supporting four beam suspension is designed such that electrostatic tuning can match modes despite process variations. The electrostatic tuning range is limited only by rotor collapse to the substrate when tuning-voltage induced

  4. Micromachined Integrated Transducers for Ultrasound Imaging

    DEFF Research Database (Denmark)

    la Cour, Mette Funding

    project and collaboration with a lot of partners to improve medical ultrasound imaging. The focus in this part of the project is to design, fabricate and characterize 1D CMUT arrays. Two versions of 1D transducers are made, one at Stanford University and one at DTU. Electrical and acoustical......, but two possible solutions are suggested. Two devices are assembled into probe handles and initial acoustical characterizations are promising. Even though the sensitivity is currently low, images are produced with recognizable features both on phantoms and volunteers. It can be mentioned that a -6 d......The purpose of this project is to develop capacitive micromachined ultrasonic transducers (CMUTs) for medical imaging. Medical ultrasound transducers used today are fabricated using piezoelectric materials and bulk processing. To fabricate transducers capable of delivering a higher imaging...

  5. Structure optimization and simulation analysis of the quartz micromachined gyroscope

    Science.gov (United States)

    Wu, Xuezhong; Wang, Haoxu; Xie, Liqiang; Dong, Peitao

    2014-03-01

    Structure optimization and simulation analysis of the quartz micromachined gyroscope are reported in this paper. The relationships between the structure parameters and the frequencies of work mode were analysed by finite element analysis. The structure parameters of the quartz micromachined gyroscope were optimized to reduce the difference between the frequencies of the drive mode and the sense mode. The simulation results were proved by testing the prototype gyroscope, which was fabricated by micro-electromechanical systems (MEMS) technology. Therefore, the frequencies of the drive mode and the sense mode can match each other by the structure optimization and simulation analysis of the quartz micromachined gyroscope, which is helpful in the design of the high sensitivity quartz micromachined gyroscope.

  6. Micromachined systems-on-a-chip: Technology and applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J.H. [Sandia National Labs., Albuquerque, NM (United States). Intelligent Micromachine Dept.; Lemkin, M.A. [Univ. of California, Berkeley, CA (United States). Berkeley Sensor and Actuator Center

    1997-04-01

    Sacrificial polysilicon surface micromachining is emerging as a technology that enables the mass production of complex microelectromechanical systems by themselves or integrated with microelectronic systems. Early versions of these micromachined systems-on-a-chip have already found application in the commercial world as acceleration sensors for airbag deployment (for example, ADI`s ADXL50). Two technologies described here, enable systems with increasing degrees of complexity to be fabricated. The first is a three-level polysilicon micromachining process which includes a fourth polysilicon electrical interconnect level, while the other is a single-level (+ second electrical interconnect level) polysilicon surface micromachining process integrated with 1.25 micron CMOS. Samples of systems-on-a-chip built in these processes such as combination locks, pop-up mirrors, and multi-axis accelerometers are also given.

  7. Integration of Capacitive Micromachined Ultrasound Transducers to Microfluidic Devices

    KAUST Repository

    Viržonis, Darius

    2013-10-22

    The design and manufacturing flexibility of capacitive micromachined ultrasound transducers (CMUT) makes them attractive option for integration with microfluidic devices both for sensing and fluid manipulation. CMUT concept is introduced here by presentin

  8. Structure optimization and simulation analysis of the quartz micromachined gyroscope

    Directory of Open Access Journals (Sweden)

    Xuezhong Wu

    2014-02-01

    Full Text Available Structure optimization and simulation analysis of the quartz micromachined gyroscope are reported in this paper. The relationships between the structure parameters and the frequencies of work mode were analysed by finite element analysis. The structure parameters of the quartz micromachined gyroscope were optimized to reduce the difference between the frequencies of the drive mode and the sense mode. The simulation results were proved by testing the prototype gyroscope, which was fabricated by micro-electromechanical systems (MEMS technology. Therefore, the frequencies of the drive mode and the sense mode can match each other by the structure optimization and simulation analysis of the quartz micromachined gyroscope, which is helpful in the design of the high sensitivity quartz micromachined gyroscope.

  9. Surface Micromachined Arrays of Transition-Edge Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative surface micromachining technique is described for the fabrication of closely-packed arrays of transition edge sensor (TES) x-ray microcalorimeters....

  10. Non-traditional micromachining processes fundamentals and applications

    CERN Document Server

    Bhattacharyya, B; Davim, J

    2017-01-01

    This book presents a complete coverage of micromachining processes from their basic material removal phenomena to past and recent research carried by a number of researchers worldwide. Chapters on effective utilization of material resources, improved efficiency, reliability, durability, and cost effectiveness of the products are presented. This book provides the reader with new and recent developments in the field of micromachining and microfabrication of engineering materials.

  11. Surface micromachined microengine as the driver for micromechanical gears

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, E.J.; Sniegowski, J.J.

    1995-05-01

    The transmission of mechanical power is often accomplished through the use of gearing. The recently developed surface micromachined microengine provides us with an actuator which is suitable for driving surface micromachined geared systems. In this paper we will present aspects of the microengine as they relate to the driving of geared mechanisms, issues relating to the design of micro gear mechanisms, and details of a design of a microengine-driven geared shutter mechanism.

  12. Microphone matching for hybrid-order directional arrays in hearing aid applications

    Science.gov (United States)

    Warren, Daniel M.; Thompson, Steve C.

    2003-04-01

    The ability of a hearing aid user to distinguish a single speech source amidst general background noise (for example, dinner table or cocktail party conversation) may be improved by a directional array of microphones in the hearing instrument. The theoretical maximum directivity index (DI) of a first-order pairing of microphones is 6 dB, and a second-order array of three microphones is 9.5 dB, assuming all three microphones have identical frequency responses. The close spacing of microphone ports in a hearing aid body means that directivity degrades rapidly with differences in microphone sensitivities. A hybrid of first- and second-order arrays can mitigate this effect, although close microphone matching is still necessary for high directivity. This paper explores the effect of microphone mismatch on the directivity of such arrays, and describes practical criteria for selecting matched microphones out of production batches to maximize a speech intelligibility weighted directivity index. [Work supported by Knowles Electronics, LLC.

  13. Methods for Room Acoustic Analysis and Synthesis using a Monopole-Dipole Microphone Array

    Science.gov (United States)

    Abel, J. S.; Begault, Durand R.; Null, Cynthia H. (Technical Monitor)

    1998-01-01

    In recent work, a microphone array consisting of an omnidirectional microphone and colocated dipole microphones having orthogonally aligned dipole axes was used to examine the directional nature of a room impulse response. The arrival of significant reflections was indicated by peaks in the power of the omnidirectional microphone response; reflection direction of arrival was revealed by comparing zero-lag crosscorrelations between the omnidirectional response and the dipole responses to the omnidirectional response power to estimate arrival direction cosines with respect to the dipole axes.

  14. Silicon Micromachined Microlens Array for THz Antennas

    Science.gov (United States)

    Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

    2013-01-01

    5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a

  15. Apparatus for precision micromachining with lasers

    Science.gov (United States)

    Chang, J.J.; Dragon, E.P.; Warner, B.E.

    1998-04-28

    A new material processing apparatus using a short-pulsed, high-repetition-rate visible laser for precision micromachining utilizes a near diffraction limited laser, a high-speed precision two-axis tilt-mirror for steering the laser beam, an optical system for either focusing or imaging the laser beam on the part, and a part holder that may consist of a cover plate and a back plate. The system is generally useful for precision drilling, cutting, milling and polishing of metals and ceramics, and has broad application in manufacturing precision components. Precision machining has been demonstrated through percussion drilling and trepanning using this system. With a 30 W copper vapor laser running at multi-kHz pulse repetition frequency, straight parallel holes with size varying from 500 microns to less than 25 microns and with aspect ratios up to 1:40 have been consistently drilled with good surface finish on a variety of metals. Micromilling and microdrilling on ceramics using a 250 W copper vapor laser have also been demonstrated with good results. Materialographic sections of machined parts show little (submicron scale) recast layer and heat affected zone. 1 fig.

  16. Laser micromachining of semiconductors for photonics applications

    Science.gov (United States)

    Nantel, Marc; Yashkir, Yuri; Lee, Seong K.; Mugford, Chas; Hockley, Bernard S.

    2001-10-01

    For decades, precisely machining silicon has been critical for the success of the semiconductor industry. This has traditionally been done through wet chemical etching, but in the pursuit of integrating photonics devices on a single chip, other techniques are worth exploring. This quest opens up interest in finding a non-wet, non-contact, arbitrary-shape milling technique for silicon. In this paper, we present our latest work in the laser micromachining of silicon. A kilohertz-repetition-rate diode-pumped Nd:YLF laser (in infrared, green or ultraviolet modes) is focused on the surface of silicon wafers in a chlorine atmosphere for an enhanced magnitude and control of the etching rate. In the chlorine atmosphere, much less debris is deposited on the surface around the cut, sub-damage threshold machining is achieved for a better control of the etching depth, and etching rates ranging from 20-300,000 micron-cube/s have been measured. In particular, the use of an infrared laser beam is singled out, along with the advantages that it holds. Results of simulations highlight the particular characteristics of the various wavelength chosen for the machining.

  17. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team

    Energy Technology Data Exchange (ETDEWEB)

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin [High Pressure Collaborative Access Team, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States)

    2015-07-15

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  18. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team.

    Science.gov (United States)

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-01

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  19. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team

    Science.gov (United States)

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-01

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  20. Hybrid method for determining the parameters of condenser microphones from measured membrane velocities and numerical calculations

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2009-01-01

    Typically, numerical calculations of the pressure, free-field, and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel fun...

  1. Practical considerations for a second-order directional hearing aid microphone system

    Science.gov (United States)

    Thompson, Stephen C.

    2003-04-01

    First-order directional microphone systems for hearing aids have been available for several years. Such a system uses two microphones and has a theoretical maximum free-field directivity index (DI) of 6.0 dB. A second-order microphone system using three microphones could provide a theoretical increase in free-field DI to 9.5 dB. These theoretical maximum DI values assume that the microphones have exactly matched sensitivities at all frequencies of interest. In practice, the individual microphones in the hearing aid always have slightly different sensitivities. For the small microphone separation necessary to fit in a hearing aid, these sensitivity matching errors degrade the directivity from the theoretical values, especially at low frequencies. This paper shows that, for first-order systems the directivity degradation due to sensitivity errors is relatively small. However, for second-order systems with practical microphone sensitivity matching specifications, the directivity degradation below 1 kHz is not tolerable. A hybrid order directive system is proposed that uses first-order processing at low frequencies and second-order directive processing at higher frequencies. This hybrid system is suggested as an alternative that could provide improved directivity index in the frequency regions that are important to speech intelligibility.

  2. 76 FR 68207 - Certain Silicon Microphone Packages and Products Containing the Same; Determination To Rescind in...

    Science.gov (United States)

    2011-11-03

    ...] [FR Doc No: 2011-28488] INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-720] Certain Silicon... importation, or the sale within the United States after importation of certain silicon microphone packages and...'') prohibiting the unlicensed entry into the United States of MemsTech silicon microphone packages that...

  3. MEMS Microphone Array Sensor for Air-Coupled Impact-Echo.

    Science.gov (United States)

    Groschup, Robin; Grosse, Christian U

    2015-01-01

    Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved. The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation. The proposed sensing strategy is justified with findings from numerical simulations, showing that the IE resonance in plate like structures causes coherent surface displacements on the specimen under test in an area around the impact location. Therefore, by placing several MEMS microphones on a sensor array board, the IE resonance is easier to be identified in the recorded spectra than with single point microphones or contact type transducers. A comparative measurement between the array sensor, a conventional accelerometer and a measurement microphone clearly shows the suitability of MEMS type microphones and the advantages of using these microphones in an array arrangement for IE. The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

  4. Dual axis operation of a micromachined rate gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Juneau, T. [BSAC, Berkeley, CA (United States); Pisano, A.P. [Univ. California, Berkeley, CA (United States). Dept. of Mechanical Engineering; Smith, J. [Sandia National Lab., Albuquerque, NM (United States)

    1997-04-01

    Since micromachining technology has raised the prospect of fabricating high performance sensors without the associated high cost and large size, many researchers have investigated micromachined rate gyroscopes. The vast majority of research has focused on single input axis rate gyroscopes, but this paper presents work on a dual input axis micromachined rate gyroscope. The key to successful simultaneous dual axis operation is the quad symmetry of the circular oscillating rotor design. Untuned gyroscopes with mismatched modes yielded random walk as low as 10{degrees}/{radical}hour with cross sensitivity ranging from 6% to 16%. Mode frequency matching via electrostatic tuning allowed performance better than 2{degrees}/{radical}hour, but at the expense of excessive cross sensitivity.

  5. High-performance micromachined gyroscope with a slanted suspension cantilever

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Dingbang; Wu Xuezhong; Hou Zhanqiang; Chen Zhihua; Dong Peitao; Li Shengyi, E-mail: Dingbangxiao@yahoo.com.c [Microsystem Laboratory, National University of Defense Technology, Changsha 410073 (China)

    2009-04-15

    This paper presents a novel structure for improving the stability and the mechanical noise of micromachined gyroscopes. Only one slanted cantilever is used for suspension in this gyroscope, so the asymmetry spring and the thermal stress, which most micromachined gyroscopes suffer from, are reduced. In order to reduce the mechanical noise, the proof masses are designed to be much larger than in most micromachined gyroscopes. The gyroscope chip is sealed at 0.001 Pa vacuum. A gyroscope sample and its read-out circuit are fabricated. The scale factor of this gyroscope is measured as 57.6 mV/(deg/sec) with a nonlinearity better than 0.12% in a measurement range of +-100 deg/sec. The short-term bias stability in 20 min is 60 deg/h.

  6. High-performance micromachined gyroscope with a slanted suspension cantilever

    Institute of Scientific and Technical Information of China (English)

    Xiao Dingbang; Wu Xuezhong; Hou Zhanqiang; Chen Zhihua; Dong Peitao; Li Shengyi

    2009-01-01

    This paper presents a novel structure for improving the stability and the mechanical noise of micromachined gyroscopes.Only one slanted cantilever is used for suspension in this gyroscope,so the asymmetry spring and the thermal stress,which most micromachined gyroscopes suffer from,are reduced.In order to reduce the mechanical noise,the proof masses are designed to be much larger than in most micromachined gyroscopes.The gyroscope chip is sealed at 0.00 1 Pa vacuum.A gyroscope sample and its read-out circuit are fabricated.The scale factor of this gyroscope is measured as 57.6 mV/(deg/sec) with a nonlinearity better than 0.12%in a measurement range of ±100 deg/sec.The short-term bias stability in 20 min is 60 deg/h.

  7. On determination of microphone response and other parameters by a hybrid experimental and numerical method

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Jacobsen, Finn; Rasmussen, Knud

    2008-01-01

    to this problem is to measure the velocity distribution of the membrane by means of a non-contact method, such as laser vibrometry. The measured velocity distributions can be used together with a numerical formulation such as the Boundary Element Method for estimating the microphone response and other parameters......Typically, numerical calculations of the pressure, free-field and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel...... such as the acoustic centres. In this work, a hybrid method is presented. The velocity distributions of condenser Laboratory Standard microphones were measured using a laser vibrometer. This measured velocity distribution was used for estimating the microphone responses and parameters. The agreement with experimental...

  8. Silicon bulk micromachined hybrid dimensional artifact.

    Energy Technology Data Exchange (ETDEWEB)

    Claudet, Andre A.; Tran, Hy D.; Bauer, Todd Marks; Shilling, Katherine Meghan; Oliver, Andrew David

    2010-03-01

    A mesoscale dimensional artifact based on silicon bulk micromachining fabrication has been developed and manufactured with the intention of evaluating the artifact both on a high precision coordinate measuring machine (CMM) and video-probe based measuring systems. This hybrid artifact has features that can be located by both a touch probe and a video probe system with a k=2 uncertainty of 0.4 {micro}m, more than twice as good as a glass reference artifact. We also present evidence that this uncertainty could be lowered to as little as 50 nm (k=2). While video-probe based systems are commonly used to inspect mesoscale mechanical components, a video-probe system's certified accuracy is generally much worse than its repeatability. To solve this problem, an artifact has been developed which can be calibrated using a commercially available high-accuracy tactile system and then be used to calibrate typical production vision-based measurement systems. This allows for error mapping to a higher degree of accuracy than is possible with a glass reference artifact. Details of the designed features and manufacturing process of the hybrid dimensional artifact are given and a comparison of the designed features to the measured features of the manufactured artifact is presented and discussed. Measurement results from vision and touch probe systems are compared and evaluated to determine the capability of the manufactured artifact to serve as a calibration tool for video-probe systems. An uncertainty analysis for calibration of the artifact using a CMM is presented.

  9. Deep ultraviolet laser micromachining of novel fibre optic devices

    Science.gov (United States)

    Li, J.; Dou, J.; Herman, P. R.; Fricke-Begemann, T.; Ihlemann, J.; Marowsky, G.

    2007-04-01

    A deep ultraviolet F2 laser, with output at 157-nm wavelength, has been adopted for micro-shaping the end facets of single and multi-mode silica optical fibres. The high energy 7.9-eV photons drive strong interactions in the wide-bandgap silica fibres to enable the fabrication of surface-relief microstructures with high spatial resolution and smooth surface morphology. Diffraction gratings, focusing lenses, and Mach-Zehnder interferometric structures have been micromachined onto the cleaved-fibre facets and optically characterized. F2-laser micromachining is shown to be a rapid and facile means for direct-writing of novel infibre photonic components.

  10. Numerical simulation of inclination vibration in magnetic induction micromachines

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J-Y; Zhou, J-B; Zhang, W-M; Meng, G [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: jerrycc@sjtu.edu.cn

    2008-02-15

    This paper studies the inclination vibration of an axial-flux magnetic induction micromachine which is supported by hydrostatic thrust bearings. A mechanical model for the rotor and the corresponding fluid-film bearing is combined with an electromagnetic force model to study the linear and nonlinear rotordynamics of the system. Results obtained for the stability show that magnetic induction micromachine would encounter severe instability problem at high speed operations. The model developed here could serve as a useful reference for design optimization and operation scheme.

  11. Numerical simulation of inclination vibration in magnetic induction micromachines

    Science.gov (United States)

    Chen, J.-Y.; Zhou, J.-B.; Zhang, W.-M.; Meng, G.

    2008-02-01

    This paper studies the inclination vibration of an axial-flux magnetic induction micromachine which is supported by hydrostatic thrust bearings. A mechanical model for the rotor and the corresponding fluid-film bearing is combined with an electromagnetic force model to study the linear and nonlinear rotordynamics of the system. Results obtained for the stability show that magnetic induction micromachine would encounter severe instability problem at high speed operations. The model developed here could serve as a useful reference for design optimization and operation scheme.

  12. A practical implementation of microphone free-field comparison calibration according to the standard IEC 61094-8

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Torras-Rosell, Antoni; Rasmussen, Knud;

    2012-01-01

    An international standard concerned with the calibration of microphones in a free field by comparison has recently been published. The standard contemplates two main calibration methodologies for determining the sensitivity of a microphone under test when compared against a reference microphone. ...

  13. Plane-wave decomposition by spherical-convolution microphone array

    Science.gov (United States)

    Rafaely, Boaz; Park, Munhum

    2001-05-01

    Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.

  14. A Framework for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll;

    2016-01-01

    distortion ratio, the PESQ measure, and the STOI intelligibility measure. Major findings in this work are the observed changes in the superiority of different methods for certain conditions. When perceptual quality or intelligibility of the speech are the ultimate goals, there are turning points where......Speech enhancement is vital for improved listening practices. Ad hoc microphone arrays are promising assets for this purpose. Most well-established enhancement techniques with conventional arrays can be adapted into ad hoc scenarios. Despite recent efforts to introduce various ad hoc speech...... enhancement apparatus, a common framework for integration of conventional methods into this new scheme is still missing. This paper establishes such an abstraction based on inter and intra sub-array speech coherencies. Along with measures for signal quality at the input of sub-arrays, a measure of coherency...

  15. Plane-wave decomposition by spherical-convolution microphone array

    Science.gov (United States)

    Rafaely, Boaz; Park, Munhum

    2004-05-01

    Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.

  16. Some comparisons of binaural measurements made with different dummy heads and stereo microphone techniques

    Science.gov (United States)

    Mapp, Peter A.

    2004-10-01

    Binaural measurements have been made in a number of acoustic environments, and the results from different binaural heads and stereo microphones are compared. The object of the study was not only to establish what practical differences occurred between the various head formats, but also to see if a stereo microphone or pseudohead could be used for making auditorium binaural measurements. Five measurement platforms were employed. These included two binaural dummy heads, binaural in-ear probe microphones, an SAAS pseudohead stereo microphone and a M-S (midside) stereo microphone. In the latter case, three different midside ratios were employed and compared. The measurements were made in a reverberant recital hall (2.5-s RT) and small acoustically treated listening room (RT 0.2 s). Whereas relatively minor differences were found to occur between the heads, significant differences were found to occur with the stereo microphones. It is concluded that while useful information can be obtained from a stereo microphone, it is far from being the same as binaural.

  17. Development of a focused ion beam micromachining system

    Energy Technology Data Exchange (ETDEWEB)

    Pellerin, J.G.; Griffis, D.; Russell, P.E.

    1988-12-01

    Focused ion beams are currently being investigated for many submicron fabrication and analytical purposes. An FIB micromachining system consisting of a UHV vacuum system, a liquid metal ion gun, and a control and data acquisition computer has been constructed. This system is being used to develop nanofabrication and nanomachining techniques involving focused ion beams and scanning tunneling microscopes.

  18. Crystallographic effects during micromachining — A finite-element model

    Science.gov (United States)

    Song, Shin-Hyung; Choi, Woo Chun

    2015-07-01

    Mechanical micromachining is a powerful and effective way for manufacturing small sized machine parts. Even though the micromachining process is similar to the traditional machining, the material behavior during the process is much different. In particular, many researchers report that the basic mechanics of the work material is affected by microstructures and their crystallographic orientations. For example, crystallographic orientations of the work material have significant influence on force response, chip formation and surface finish. In order to thoroughly understand the effect of crystallographic orientations on the micromachining process, finite-element model (FEM) simulating orthogonal cutting process of single crystallographic material was presented. For modeling the work material, rate sensitive single crystal plasticity of face-centered cubic (FCC) crystal was implemented. For the chip formation during the simulation, element deletion technique was used. The simulation model is developed using ABAQUS/explicit with user material subroutine via user material subroutine (VUMAT). Simulations showed that variation of the specific cutting energy at different crystallographic orientations of work material shows significant anisotropy. The developed FEM model can be a useful prediction tool of micromachining of crystalline materials.

  19. Dynamics of micromachined vibrating gimbal and wheel gyroscope

    Institute of Scientific and Technical Information of China (English)

    TijingCAI

    2000-01-01

    We deduce dynamic equations of micromachined vibrating gimbal and wheel gyroscope and give an approximate solution of enough accuracy. The comparison between the approximate solution and the solution used often in the literature is given. According to property of the approximate solution a decoupled two-axes gyroscope will be composed of two single-axes gyroscopes.

  20. Monitoring of yeast cell concentration using a micromachined impedance sensor

    NARCIS (Netherlands)

    Krommenhoek, E.E.; Gardeniers, J.G.E.; Bomer, J.G.; Berg, van den A.; Li, X.; Ottens, M.; Wielen, van der L.A.M.; Dedem, van G.W.K.; Leeuwen, M.; Gulik, van W.M.; Heijnen, J.J.

    2005-01-01

    The paper describes the design, modelling and experimental characterization of a micromachined impedance sensor for on-line monitoring of the viable yeast cell concentration (biomass) in a miniaturized cell assay. Measurements in a Saccharomyces cerevisiae cell culture show that the permittivity of

  1. A micromachined surface stress sensor with electronic readout

    NARCIS (Netherlands)

    Carlen, E.T.; Weinberg, M.S.; Zapata, A.M.; Borenstein, J.T.

    2008-01-01

    A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high frequency carrier signal, and the output signal is synchronously demodulated and filt

  2. A batch process micromachined thermoelectric energy harvester: Fabrication and characterization

    NARCIS (Netherlands)

    Su, J.; Leonov, V.; Goedbloed, M.; Andel, Y. van; Nooijer, M.C.de; Elfrink, R.; Wang, Z.; Vullers, R.J.M.

    2010-01-01

    Micromachined thermopiles are considered as a cost-effective solution for energy harvesters working at a small temperature difference and weak heat flows typical for, e.g., the human body. They can be used for powering autonomous wireless sensor nodes in a body area network. In this paper, a microma

  3. Sub-band-gap laser micromachining of lithium niobate

    DEFF Research Database (Denmark)

    Christensen, F. K.; Müllenborn, Matthias

    1995-01-01

    method is reported which enables us to do laser processing of lithium niobate using sub-band-gap photons. Using high scan speeds, moderate power densities, and sub-band-gap photon energies results in volume removal rates in excess of 106µm3/s. This enables fast micromachining of small piezoelectric...

  4. Selective Mode Excitation And Detection Of Micromachined Resonators

    NARCIS (Netherlands)

    Prak, Albert; Elwenspoek, Miko; Fluitman, Jan H.J

    1992-01-01

    Distributed mechanical systems such as micromachined resonant strain gages possess an infinite number of modes of vibration. Mostly, one is interested in only one or a few modes. A method is described with which only the desired modes are excited and detected. This is achieved by geometrically shapi

  5. Robust Speaker Recognition with Combined Use of Acoustic and Throat Microphone Speech

    DEFF Research Database (Denmark)

    Sahidullah, Md; Gonzalez Hautamäki, Rosa; Thomsen, Dennis Alexander Lehmann;

    2016-01-01

    Accuracy of automatic speaker recognition (ASV) systems degrades severely in the presence of background noise. In this paper, we study the use of additional side information provided by a body-conducted sensor, throat microphone. Throat microphone signal is much less affected by background noise...... of this additional information for both speech activity detection, feature extraction and fusion of the acoustic and throat microphone signals. We collect a pilot database consisting of 38 subjects including both clean and noisy sessions. We carry out speaker verification experiments using Gaussian mixture model...

  6. A New Calibration Method for Microphone Array with Gain, Phase, and Position Errors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Microphone array can be used in sound source localization and separation. But gain, phase, and position errors can seriously influence the performance of localization algorithms such as multiple signal classification (MUSIC) algorithm. In this paper, a new calibration method for microphone array with gain, phase, and position errors is proposed. Unlike traditional calibration methods for antenna array, the proposed method can be used in the broadband and near-field signal model such as microphone array with arbitrary sensor geometries in one plane. Computer simulations are presented and simulation results show the new method having good performance.

  7. Multi-Level Micromachined Systems-on-a-Chip: Technology and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J.J.; Krygowski, T.W.; Miller, S.L.; Montague, S.; Rodgers, M.S.; Smith, J.H.; Sniegowski, J.J.

    1998-10-27

    Researchers at Sandia have recently designed and built several research prototypes, which demonstrate that truly complex mechanical systems can now be realized in a surface micromachined technology. These MicroElectro- Mechanical Systems (MEMS) include advanced actuators, torque multiplying gear tmins, rack and pinion assemblies, positionable mirrors, and mechanical discriminators. All of tile mechanical components are batch fabricated on a single chip of silicon using the infrastructure origimdly developed to support today's highly reliabk; and robust microelectronics industry. Sand ia is also developing the technology 10 integrate microelectronic circuits onto the s,ime piece of silicon that is used to fabricate the MEMS devices. This significantly increases sensitivity and reliability, while fhrther reducing package size and fabrication costs. A review of the MEMS technology and capabilities available at Sandia National Laboratories is presented.

  8. 78 FR 21977 - Certain Silicon Microphone Packages and Products Containing the Same; Commission Determination...

    Science.gov (United States)

    2013-04-12

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Silicon Microphone Packages and Products Containing the Same; Commission Determination Not To Review an Initial Determination Terminating Investigation Based on a Settlement...

  9. Bruel and Kjaer 4944 Microphone Grid Frequency Response Function System Identification

    Science.gov (United States)

    Bennett, Reginald; Lee, Erik

    2010-01-01

    Br el & Kjaer (B&K) 4944B pressure field microphone was judiciously selected to measure acoustic environments, 400Hz 50kHz, in close proximity of the nozzle during multiple firings of solid propellant rocket motors. It is well known that protective grids can affect the frequency response of microphones. B&K recommends operation of the B&K 4944B without a protective grid when recording measurements above 10 to 15 kHz.

  10. Robustness of a Mixed-Order Ambisonics Microphone Array for Sound Field Reproduction

    DEFF Research Database (Denmark)

    Marschall, Marton; Favrot, Sylvain Emmanuel; Buchholz, Jörg

    2012-01-01

    Spherical microphone arrays can be used to capture and reproduce the spatial characteristics of acoustic scenes. A mixed-order Ambisonics (MOA) approach was recently proposed to improve the horizontal spatial resolution of microphone arrays with a given number of transducers. In this paper, the p...... errors was similar to that of HOA arrays with both strategies. The approach based on minimizing the error of the reproduced spherical harmonic functions showed better performance at high frequencies for the MOA layout....

  11. A New Trans-Tympanic Microphone Approach for Fully Implantable Hearing Devices

    Directory of Open Access Journals (Sweden)

    Seong Tak Woo

    2015-09-01

    Full Text Available Fully implantable hearing devices (FIHDs have been developed as a new technology to overcome the disadvantages of conventional acoustic hearing aids. The implantable microphones currently used in FIHDs, however, have difficulty achieving high sensitivity to environmental sounds, low sensitivity to body noise, and ease of implantation. In general, implantable microphones may be placed under the skin in the temporal bone region of the skull. In this situation, body noise picked up during mastication and touching can be significant, and the layer of skin and hair can both attenuate and distort sounds. The new approach presently proposed is a microphone implanted at the tympanic membrane. This method increases the microphone’s sensitivity by utilizing the pinna’s directionally dependent sound collection capabilities and the natural resonances of the ear canal. The sensitivity and insertion loss of this microphone were measured in human cadaveric specimens in the 0.1 to 16 kHz frequency range. In addition, the maximum stable gain due to feedback between the trans-tympanic microphone and a round-window-drive transducer, was measured. The results confirmed in situ high-performance capabilities of the proposed trans-tympanic microphone.

  12. Acoustic source localization in mixed field using spherical microphone arrays

    Science.gov (United States)

    Huang, Qinghua; Wang, Tong

    2014-12-01

    Spherical microphone arrays have been used for source localization in three-dimensional space recently. In this paper, a two-stage algorithm is developed to localize mixed far-field and near-field acoustic sources in free-field environment. In the first stage, an array signal model is constructed in the spherical harmonics domain. The recurrent relation of spherical harmonics is independent of far-field and near-field mode strengths. Therefore, it is used to develop spherical estimating signal parameter via rotational invariance technique (ESPRIT)-like approach to estimate directions of arrival (DOAs) for both far-field and near-field sources. In the second stage, based on the estimated DOAs, simple one-dimensional MUSIC spectrum is exploited to distinguish far-field and near-field sources and estimate the ranges of near-field sources. The proposed algorithm can avoid multidimensional search and parameter pairing. Simulation results demonstrate the good performance for localizing far-field sources, or near-field ones, or mixed field sources.

  13. Micromachined sensor and actuator research at Sandia`s Microelectronics Development Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J.H.

    1996-11-01

    An overview of the surface micromachining program at the Microelectronics Development Laboratory of Sandia National Laboratories is presented. Development efforts are underway for a variety of surface micromachined sensors and actuators for both defense and commercial applications. A technology that embeds micromechanical devices below the surface of the wafer prior to microelectronics fabrication has been developed for integrating microelectronics with surface-micromachined micromechanical devices. The application of chemical-mechanical polishing to increase the manufacturability of micromechanical devices is also presented.

  14. Technology trends in high temperature pressure transducers: The impact of micromachining

    Science.gov (United States)

    Mallon, Joseph R., Jr.

    1992-01-01

    This paper discusses the implications of micromachining technology on the development of high temperature pressure transducers. The introduction puts forth the thesis that micromachining will be the technology of choice for the next generation of extended temperature range pressure transducers. The term micromachining is defined, the technology is discussed and examples are presented. Several technologies for high temperature pressure transducers are discussed, including silicon on insulator, capacitive, optical, and vibrating element. Specific conclusions are presented along with recommendations for development of the technology.

  15. Design of nanosecond pulse laser micromachining system based on PMAC

    Science.gov (United States)

    Liu, Mingyan; Fu, Xing; Xu, Linyan; Lin, Qian; Gu, Shuang

    2012-10-01

    Pulse laser micromachining technology, as a branch of laser processing technology, has been widely used in MEMS device processing, aviation, instruments fabrication, circuit board design etc.. In this paper, a novel nanosecond pulse laser micromachining system is presented, which consists of nanosecond pulse LASER, optical path mechanical structure, transmission system, motion control system. Nanosecond pulse UV laser, with 355 nm wavelength and 40ns pulse width, is chosen as the light source. Optical path mechanical structure is designed to get ideal result of laser focusing. Motion control system, combining PMAC card with the PC software, can control the 3-D motion platform and complete microstructure processing. By CCD monitoring system, researchers can get real-time detection on the effect of laser beam focusing and processing process.

  16. Femtosecond Laser Micromachining Photonic and Microfluidic Devices in Transparent Materials

    CERN Document Server

    Cerullo, Giulio; Ramponi, Roberta

    2012-01-01

    Femtosecond laser micromachining of transparent material is a powerful and versatile technology. In fact, it can be applied to several materials. It is a maskless technology that allows rapid device prototyping, has intrinsic three-dimensional capabilities and can produce both photonic and microfluidic devices. For these reasons it is ideally suited for the fabrication of complex microsystems with unprecedented functionalities. The book is mainly focused on micromachining of transparent materials which, due to the nonlinear absorption mechanism of ultrashort pulses, allows unique three-dimensional capabilities and can be exploited for the fabrication of complex microsystems with unprecedented functionalities.This book presents an overview of the state of the art of this rapidly emerging topic with contributions from leading experts in the field, ranging from principles of nonlinear material modification to fabrication techniques and applications to photonics and optofluidics.

  17. Deep ultraviolet laser micromachining of novel fibre optic devices

    Energy Technology Data Exchange (ETDEWEB)

    Li, J [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Ontario M5S 3G4 (Canada); Dou, J [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Ontario M5S 3G4 (Canada); Herman, P R [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Ontario M5S 3G4 (Canada); Fricke-Begemann, T [Laser-Laboratorium Goettingen e.V., D-37077 Goettingen (Germany); Ihlemann, J [Laser-Laboratorium Goettingen e.V., D-37077 Goettingen (Germany); Marowsky, G [Laser-Laboratorium Goettingen e.V., D-37077 Goettingen (Germany)

    2007-04-15

    A deep ultraviolet F{sub 2} laser, with output at 157-nm wavelength, has been adopted for micro-shaping the end facets of single and multi-mode silica optical fibres. The high energy 7.9-eV photons drive strong interactions in the wide-bandgap silica fibres to enable the fabrication of surface-relief microstructures with high spatial resolution and smooth surface morphology. Diffraction gratings, focusing lenses, and Mach-Zehnder interferometric structures have been micromachined onto the cleaved-fibre facets and optically characterized. F{sub 2}-laser micromachining is shown to be a rapid and facile means for direct-writing of novel infibre photonic components.

  18. Artificial intelligence: Collective behaviors of synthetic micromachines

    Science.gov (United States)

    Duan, Wentao

    Synthetic nano- and micromotors function through the conversion of chemical free energy or forms of energy into mechanical motion. Ever since the first reports, such motors have been the subject of growing interest. In addition to motility in response to gradients, these motors interact with each other, resulting in emergent collective behavior like schooling, exclusion, and predator-prey. However, most of these systems only exhibit a single type of collective behavior in response to a certain stimuli. The research projects in the disseratation aim at designing synthetic micromotors that can exhibit transition between various collective behaviors in response to different stimuli, as well as quantitative understanding on the pairwise interaction and propulsion mechanism of such motors. Chapter 1 offers an overview on development of synthetic micromachines. Interactions and collective behaviors of micromotors are also summarized and included. Chapter 2 presents a silver orthophosphate microparticle system that exhibits collective behaviors. Transition between two collective patterns, clustering and dispersion, can be triggered by shift in chemical equilibrium upon the addition or removal of ammonia, in response to UV light, or under two orthogonal stimuli (UV and acoustic field) and powering mechanisms. The transitions can be explained by the self-diffusiophoresis mechanism resulting from either ionic or neutral solute gradients. Potential applications of the reported system in logic gates, microscale pumping, and hierarchical assembly have been demonstrated. Chapter 3 introduces a self-powered oscillatory micromotor system in which active colloids form clusters whose size changes periodically. The system consists of an aqueous suspension of silver orthophosphate particles under UV radiation, in the presence of a mixture of glucose and hydrogen peroxide. The colloid particles first attract with each other to form clusters. After a lag time of around 5min, chemical

  19. Development of a surface micromachined spiral-channel viscous pump

    Science.gov (United States)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

  20. Optical fiber accelerometer based on a silicon micromachined cantilever

    Science.gov (United States)

    Malki, Abdelrafik; Lecoy, Pierre; Marty, Jeanine; Renouf, Christine; Ferdinand, Pierre

    1995-12-01

    An intensity-modulated fiber-optic accelerometer based on backreflection effects has been manufactured and tested. It uses a multimode fiber placed at a spherical mirror center, and the beam intensity is modulated by a micromachined silicon cantilever. This device has applications as an accelerometer and vibrometer for rotating machines. It exhibits an amplitude linearity of +/-1.2% in the range of 0.1-22 m s-2, a frequency linearity of +/-1% in the

  1. A Silicon Micromachined Gyroscope Driven by the Rotating Carrier Self

    Institute of Scientific and Technical Information of China (English)

    Fuxue Zhang; Xu Mao; Yu Liu; Nan Zhang; Wei Zhang

    2006-01-01

    This paper reported a silicon micromachined gyroscope which is driven by the rotating carrier's angular velocity, the silicon was manufactured by anisotropy etching. The design, fabrication and packing of the sensing element were introduced in the paper. The imitation experimentation and performance test have certificated that the principle of the gyroscope is correct and the gyroscope can be used to sense yawing or pitching angular velocity of the rotating carrier, and the angular velocity of the rotating carrier itself.

  2. Bimetallic Thermal Resists for Photomask, Micromachining and Microfabrication

    OpenAIRE

    Tu, Richard Yuqiang

    2004-01-01

    Photoresists and photomasks are two of the most critical materials in microfabrication and micromachining industries. As the shift towards shorter wavelength exposure continues, conventional organic photoresists and chromelquartz photomasks start to encounter problems. This thesis investigates and presents an alternative to organic photoresists and chromium photomasks which overcomes their intrinsic problems. A bimetallic thin film, such as BilIn and SnIIn, creates an inorganic thermal resist...

  3. An overview of micromachined platforms for thermal sensing and gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Manginell, R.P.; Smith, J.H.; Ricco, A.J.

    1997-03-01

    Micromachined hotplates, membranes, filaments, and cantilevers have all been used as platforms for thermal sensing and gas detection. Compared with conventional devices, micromachined sensors are characterized by low power consumption, high sensitivity, and fast response time. Much of these gains can be attributed to the size reductions achieved by micromachining. In addition, micromachining permits easy, yet precise tailoring of the heat transfer characteristics of these devices. By simple alterations in device geometry and materials used, the relative magnitudes of radiation, convection and conduction losses and Joule heat gains can be adjusted, and in this way device response can be optimized for specific applications. The free-standing design of micromachined platforms, for example, reduces heat conduction losses to the substrate, thereby making them attractive as low power, fast-response heaters suitable for a number of applications. However, while micromachining solves some of the heat transfer problems typical of conventionally produced devices, it introduces some of its own. These trade-offs will be discussed in the context of several micromachined thermal and gas sensors present in the literature. These include micromachined flow sensors, gas thermal conductivity sensors, pressure sensors, uncooled IR sensors, metal-oxide and catalytic/calorimetric gas sensors. Recent results obtained for a microbridge-based catalytic/calorimetric gas sensor will also be presented as a means of further illustrating the concepts of thermal design in micromachined sensors.

  4. Numerical design and testing of a sound source for secondary calibration of microphones using the Boundary Element Method

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller; Barrera Figueroa, Salvador

    2009-01-01

    Secondary calibration of microphones in free field is performed by placing the microphone under calibration in an anechoic chamber with a sound source, and exposing it to a controlled sound field. A calibrated microphone is also measured as a reference. While the two measurements are usually made...... consecutively, a variation of this procedure, where the microphones are measured simultaneously, is considered more advantageous from the metrological point of view. However, it must be guaranteed that the two microphones receive the same excitation from the source, although their positions are some distance...... apart to avoid acoustic interaction. As a part of the project Euromet-792, aiming to investigate and improve methods for secondary free-field calibration of microphones, a sound source suitable for simultaneous secondary free-field calibration has been designed using the Boundary Element Method...

  5. Evaluating the Acoustic Effect of Over-the-Rotor Foam-Metal Liner Installed on a Low Speed Fan Using Virtual Rotating Microphone Imaging

    Science.gov (United States)

    Sutliff, Daniel L.; Dougherty, Robert P.; Walker, Bruce E.

    2010-01-01

    An in-duct beamforming technique for imaging rotating broadband fan sources has been used to evaluate the acoustic characteristics of a Foam-Metal Liner installed over-the-rotor of a low-speed fan. The NASA Glenn Research Center s Advanced Noise Control Fan was used as a test bed. A duct wall-mounted phased array consisting of several rings of microphones was employed. The data are mathematically resampled in the fan rotating reference frame and subsequently used in a conventional beamforming technique. The steering vectors for the beamforming technique are derived from annular duct modes, so that effects of reflections from the duct walls are reduced.

  6. A practical implementation of microphone free-field comparison calibration according to the standard IEC 61094-8

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Torras Rosell, Antoni; Rasmussen, Knud;

    2012-01-01

    An international standard concerned with the calibration of microphones in a free field by comparison has recently been published. The standard contemplates two main calibration methodologies for determining the sensitivity of a microphone under test when compared against a reference microphone....... A third method, consisting of a combination of the sequential and simultaneous methodologies, has also been investigated. Though the application of time selective techniques is not discussed, the experimental results indicate the immunity to unwanted reflections in the sequential and combined approaches...

  7. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Senthil P. Theppakuttaikomaraswamy

    2001-12-31

    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 {micro}m and the spacing between holes (the distance between the centers) is 100 {micro}m. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the

  8. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Theppakuttaikomaraswamy, Senthil P. [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 μm and the spacing between holes (the distance between the centers) is 100 μm. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the interferometer

  9. The effect of microphone wind noise on the amplitude modulation of wind turbine noise and its mitigation.

    Science.gov (United States)

    Kendrick, Paul; von Hünerbein, Sabine; Cox, Trevor J

    2016-07-01

    Microphone wind noise can corrupt outdoor recordings even when wind shields are used. When monitoring wind turbine noise, microphone wind noise is almost inevitable because measurements cannot be made in still conditions. The effect of microphone wind noise on two amplitude modulation (AM) metrics is quantified in a simulation, showing that even at low wind speeds of 2.5 m/s errors of over 4 dBA can result. As microphone wind noise is intermittent, a wind noise detection algorithm is used to automatically find uncorrupted sections of the recording, and so recover the true AM metrics to within ±2/±0.5 dBA.

  10. Identifying Microphone from Noisy Recordings by Using Representative Instance One Class-Classification Approach

    Directory of Open Access Journals (Sweden)

    Huy Quan Vu

    2012-06-01

    Full Text Available Rapid growth of technical developments has created huge challenges for microphone forensics - a sub-category of audio forensic science, because of the availability of numerous digital recording devices and massive amount of recording data. Demand for fast and efficient methods to assure integrity and authenticity of information is becoming more and more important in criminal investigation nowadays. Machine learning has emerged as an important technique to support audio analysis processes of microphone forensic practitioners. However, its application to real life situations using supervised learning is still facing great challenges due to expensiveness in collecting data and updating system. In this paper, we introduce a new machine learning approach which is called One-class Classification (OCC to be applied to microphone forensics; we demonstrate its capability on a corpus of audio samples collected from several microphones. In addition, we propose a representative instance classification framework (RICF that can effectively improve performance of OCC algorithms for recording signal with noise. Experiment results and analysis indicate that OCC has the potential to benefit microphone forensic practitioners in developing new tools and techniques for effective and efficient analysis.

  11. Characteristics of Relocated Quiet Zones Using Virtual Microphone Algorithm in an Active Headrest System

    Directory of Open Access Journals (Sweden)

    Seokhoon Ryu

    2016-01-01

    Full Text Available This study displays theoretical and experimental investigation on the characteristics of the relocated zone of quiet by a virtual microphone (VM based filtered-x LMS (FxLMS algorithm which can be embedded in a real-time digital controller for an active headrest system. The attenuation changes at the relocated zones of quiet by the variation of the distance between the ear and the error microphone are mainly examined. An active headrest system was implemented for the control experiment at a chair and consists of two (left and right secondary loudspeakers, two error microphones, two observer microphones at ear positions in a HATS, and other electronics including a dSPACE 1401 controller. The VM based FxLMS algorithm achieved an attenuation of about 22 dB in the control experiment against a narrowband primary noise by the variation of the distance between the ear and the error microphone. The important factors for the algorithm are discussed as well.

  12. Characterization of a bulk-micromachined membraneless in-plane thermopile

    NARCIS (Netherlands)

    Wang, Z.; Andel, Y. van; Jambunathan, M.; Leonov, V.; Elfrink, R.; Vullers, R.J.M.

    2011-01-01

    This paper describes the characterization method and results for bulk- micromachined in-plane thermopiles. Made of poly-Si or poly-SiGe, the thermocouple legs bridge the hot and cold side of a Si frame, which is formed by bulk micromachining. The characterization of the fabricated devices is carried

  13. Acoustic Feedback and Echo Cancellation Strategies for Multiple-Microphone and Single-Loudspeaker Systems

    DEFF Research Database (Denmark)

    Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt;

    2011-01-01

    Acoustic feedback/echo cancellation in a multiple-microphone and single-loudspeaker system is often carried out using a cancellation filter for each microphone channel, and the filters are adaptively estimated, independently of each other. In this work, we consider another strategy by estimating...... cancellation performance is achievable compared to the independent estimation strategy. Furthermore, we relate the joint estimation strategy to a stereophonic echo cancellation system and provide analytic expressions for its system behavior....... all the cancellation filters jointly and in this way exploit information from all microphone channels. We determine the statistical system behavior for the joint estimation strategy in terms of the convergence rate and steady-state behavior across time and frequency. We assess if an improved...

  14. Separating the Wheat from the Chaff: Sensing Wireless Microphones in TVWS

    CERN Document Server

    Sun, Huanhuan; Zhang, Wenyi

    2012-01-01

    This paper summarizes our attempts to establish a systematic approach that overcomes a key difficulty in sensing wireless microphone signals, namely, the inability for most existing detection methods to effectively distinguish between a wireless microphone signal and a sinusoidal continuous wave (CW). Such an inability has led to an excessively high false alarm rate and thus severely limited the utility of sensing-based cognitive transmission in the TV white space (TVWS) spectrum. Having recognized the root of the difficulty, we propose two potential solutions. The first solution focuses on the periodogram as an estimate of the power spectral density (PSD), utilizing the property that a CW has a line spectral component while a wireless microphone signal has a slightly dispersed PSD. In that approach, we formulate the resulting decision model as an one-sided test for Gaussian vectors, based on Kullback-Leibler distance type of decision statistics. The second solution goes beyond the PSD and looks into the spec...

  15. Dynamic mechanism and its modelling of micromachined electrostatic ultrasonic transducers

    Institute of Scientific and Technical Information of China (English)

    葛立峰

    1999-01-01

    A tensile-plate-on-air-spring model (or called TDK model for short) for micromachined electrostatic ultrasonic transducers has been developed based on a thorough investigation of their dynamic mechanism. The mechanical stiffness effects caused by the compressibility of air gaps, bending stiffness of the diaphragm and in-plane tension applied to the diaphragm, together with an electrostatic negative stiffness effect are included completely in the model. Desired particular fundamental frequency and bandwidth can be obtained by only properly tailoring the geometry, dimensions and materials of transducers according to the model, which provides thereby a reliable theoretical basis for the understanding and optimised design of such transducers.

  16. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Lani, Shane W., E-mail: shane.w.lani@gmail.com, E-mail: karim.sabra@me.gatech.edu, E-mail: levent.degertekin@me.gatech.edu; Sabra, Karim G. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); Wasequr Rashid, M.; Hasler, Jennifer [School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States); Levent Degertekin, F. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States)

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  17. Electrochemical mechanical micromachining based on confined etchant layer technique.

    Science.gov (United States)

    Yuan, Ye; Han, Lianhuan; Zhang, Jie; Jia, Jingchun; Zhao, Xuesen; Cao, Yongzhi; Hu, Zhenjiang; Yan, Yongda; Dong, Shen; Tian, Zhong-Qun; Tian, Zhao-Wu; Zhan, Dongping

    2013-01-01

    The confined etchant layertechnique (CELT) has been proved an effective electrochemical microfabrication method since its first publication at Faraday Discussions in 1992. Recently, we have developed CELT as an electrochemical mechanical micromachining (ECMM) method by replacing the cutting tool used in conventional mechanical machining with an electrode, which can perform lathing, planing and polishing. Through the coupling between the electrochemically induced chemical etching processes and mechanical motion, ECMM can also obtain a regular surface in one step. Taking advantage of CELT, machining tolerance and surface roughness can reach micro- or nano-meter scale.

  18. A broadband micro-machined far-infrared absorber

    Science.gov (United States)

    Wollack, E. J.; Datesman, A. M.; Jhabvala, C. A.; Miller, K. H.; Quijada, M. A.

    2016-05-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is >0.95 from 1 to 20 THz (300-15 μm) over a temperature range spanning 5-300 K. The meta-material, realized from an array of tapers ≈100 μm in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  19. Micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio

    Micromachined capacitive pressure sensors for harsh environment together with interfacing electronic circuits have been studied in this project. Micro-electromechanical systems (MEMS) have been proposed as substitutes for macro scale sensor’s systems in many different fields and are the only...... a great deal of sensors are used. Pressure sensors are among the most successful MEMS and are used in a huge variety of applications. In this project an absolute capacitive pressure sensor has been developed with the aim to integrate it in pump control systems to improve the efficiency of the pump...

  20. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers

    OpenAIRE

    2016-01-01

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wi...

  1. A beam-membrane structure micromachined differential pressure flow sensor.

    Science.gov (United States)

    Chen, P; Zhao, Y L; Tian, B; Li, C; Li, Y Y

    2015-04-01

    A beam-membrane structure micromachined flow sensor is designed, depending on the principle of differential pressure caused by the mass flow, which is directly proportional to the square flow rate. The FSI (fluid structure interaction) characteristics of the differential pressure flow sensor are investigated via numerical analysis and analog simulation. The working mechanism of the flow sensor is analyzed depending on the FSI results. Then, the flow sensor is fabricated and calibrated. The calibration results show that the beam-membrane structure differential pressure flow sensor achieves ideal static characteristics and works well in the practical applications.

  2. A Broadband Micro-machined Far-Infrared Absorber

    CERN Document Server

    Wollack, Edward J; Jhabvala, Christine A; Miller, Kevin H; Quijada, Manuel A

    2016-01-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is $>\\,0.95$ from ${\\rm 1-20\\,THz}$ (${\\rm 300-15\\,\\mu m}$) over a temperature range spanning ${\\rm 5-300\\,K}$. The meta-material, realized from an array of tapers ${\\rm \\approx 100\\,\\mu m}$ in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  3. Proton beam micromachining on PMMA, Foturan and CR-39 materials

    CERN Document Server

    Rajta, I; Kiss, A Z; Gomez-Morilla, I; Abraham, M H

    2003-01-01

    Proton Beam Micromachining was demonstrated at the Institute of Nuclear Research of the Hungarian Academy of Sciences using three different types of resists: PMMA, Foturan and CR-39 type Solid State Nuclear Track Detector material. Irradiations have been performed on the nuclear microprobe facility at ATOMKI. The beam scanning was done using a National Instruments (NI) card (model 6711), and the new C++ version of the program IonScan, developed specifically for PBM applications called IonScan 2.0. (R.P.)

  4. Beamforming with a circular microphone array for localization of environmental sources of noise

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn; Fernandez Grande, Efren

    2010-01-01

    It is often enough to localize environmental sources of noise from different directions in a plane. This can be accomplished with a circular microphone array, which can be designed to have practically the same resolution over 360. The microphones can be suspended in free space or they can...... be mounted on a solid cylinder. This investigation examines and compares two techniques based on such arrays, the classical delay-and-sum beamforming and an alternative method called circular harmonics beamforming. The latter is based on decomposing the sound field into a series of circular harmonics...

  5. Beamforming with a circular microphone array for localization of environmental noise sources

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn; Fernandez Grande, Efren

    2010-01-01

    It is often enough to localize environmental sources of noise from different directions in a plane. This can be accomplished with a circular microphone array, which can be designed to have practically the same resolution over 360. The microphones can be suspended in free space or they can...... be mounted on a solid cylinder. This investigation examines and compares two techniques based on such arrays, the classical delay-and-sum beamforming and an alternative method called circular harmonics beamforming. The latter is based on decomposing the sound field into a series of circular harmonics...

  6. Comparison of Theoretical Basics of Microphone and Piezoelectric Photothermal Spectroscopy of Semiconductors

    Science.gov (United States)

    Zakrzewski, J.; Maliński, M.; Chrobak, Ł.; Pawlak, M.

    2017-01-01

    Photothermal spectroscopy has found a wide range of applications as a method of monitoring thermal, optical and recombination parameters of semiconductors. We consider microphone detection, widely used in photoacoustic spectroscopy, and piezoelectric detection. Both methods require knowledge of the temperature distribution in the sample and in its surroundings, the support surface and gas. For the microphone signal, we simulated the temperature at one of the sample surfaces; for the piezoelectric signal, we simulated the spatial temperature distribution orthogonal to the sample surface. We modeled an idealized semiconducting sample and one with surface defects. We found that the amplitude and phase spectra vary between the methods, enabling determination of optical and thermal parameters.

  7. Near field acoustic holography with microphones mounted on a rigid sphere

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Moreno, Guillermo; Fernandez Grande, Efren;

    2008-01-01

    . This is potentially very useful for source identification. On the other hand a rigid sphere is somewhat more practical than an open sphere, and it is possible to modify the existing spherical NAH theory so that a similar sound field reconstruction can be made with an array of microphones flush-mounted on a rigid...... sphere. Rigid spheres with flush-mounted microphones are also used for beamforming, and it is known that they are advantageous compared with open spheres for this application. However, whereas beamforming is a far field technique NAH is a near field technique, and spherical NAH based on a rigid sphere...

  8. Beamforming with a circular array of microphones mounted on a rigid sphere (L)

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn; Fernandez Grande, Efren

    2011-01-01

    Beamforming with uniform circular microphone arrays can be used for localizing sound sources over 360. Typically, the array microphones are suspended in free space or they are mounted on a solid cylinder. However, the cylinder is often considered to be infinitely long because the scattering problem...... has no exact solution for a finite cylinder. Alternatively one can use a solid sphere. This investigation compares the performance of a circular array mounded on a rigid sphere with that of such an array in free space and mounted on an infinite cylinder, using computer simulations. The examined...

  9. Sound-field reconstruction performance of a mixed-order Ambisonics microphone array

    DEFF Research Database (Denmark)

    Marschall, Marton; Chang, Jiho

    2013-01-01

    Recently, there has been increasing interest in using spherical microphone arrays for spatial audio recordings. Accurate recordings are important for a range of applications, from virtual sound environments for hearing research through to the evaluation of communication devices, such as hearing...... instruments and mobile phones. Previously, a mixed-order Ambisonics (MOA) approach was proposed to improve the horizontal spatial resolution of spherical arrays. This was achieved by increasing the number of microphones near the horizontal plane while keeping the total number of transducers fixed...

  10. Radiation impedance of condenser microphones and their diffuse-field responses

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2010-01-01

    The relation between the diffuse-field response and the radiation impedance of a microphone has been investigated. Such a relation can be derived from classical theory. The practical measurement of the radiation impedance requires (a) measuring the volume velocity of the membrane of the microphone....... In this way, a hybrid estimate of the radiation impedance is obtained. The resulting estimate of the diffuse-field response is compared with experimental estimates of the diffuse-field response determined using reciprocity and the random-incidence method. The different estimates are in good agreement...

  11. Metrics for performance assessment of mixed-order Ambisonics spherical microphone arrays

    DEFF Research Database (Denmark)

    Favrot, Sylvain Emmanuel; Marschall, Marton

    2012-01-01

    Mixed-order Ambisonics (MOA) combines planar (2D) higher order Ambisonics (HOA) with lower order periphonic (3D) Ambisonics. MOA encoding from spherical microphone arrays has the potential to provide versatile recordings that can be played back using 2D, 3D or mixed systems. A procedure to generate...... suitable layouts for a given MOA combination order is introduced consisting of rings of microphones at several elevation angles for any given MOA combination order. Robustness and directivity measures were evaluated for four MOA layouts. Results showed that MOA vertical directivity was similar to 3D HOA...

  12. Micromachined array-type Mirau interferometer for MEMS metrology

    Science.gov (United States)

    Gorecki, C.; Bargiel, S.; Albero, J.; Passilly, N.; Kujawinska, M.; Zeitner, U. D.

    We present the development of an array-type micromachined Mirau interferometers, operating in the regime of low coherence interferometry (LCI) and adapted for massively parallel inspection of MEMS. The system is a combination of free-space microoptical technologies and silicon micromachining, based on the vertical assembly of two glass wafers. The probing wafer is carrying an array of refractive microlenses, diffractive gratings to correct chromatic and spherical aberrations and reference micro-mirrors. The semitransparent beam splitter plate is based on the deposition of a dielectric multilayer, sandwiched between two glass wafers. The interferometer matrix is the key element of a novel inspection system aimed to perform parallel inspection of MEMS. The fabricated demonstrator, including 5x5 channels, allows consequently decreasing the measurement time by a factor of 25. In the following, the details of fabrication processes of the micro-optical components and their assembly are described. The feasibility of the LCI is demonstrated for the measurement of a wafer of MEMS sensors.

  13. Eye Vision Testing System and Eyewear Using Micromachines

    Directory of Open Access Journals (Sweden)

    Nabeel A. Riza

    2015-11-01

    Full Text Available Proposed is a novel eye vision testing system based on micromachines that uses micro-optic, micromechanic, and microelectronic technologies. The micromachines include a programmable micro-optic lens and aperture control devices, pico-projectors, Radio Frequency (RF, optical wireless communication and control links, and energy harvesting and storage devices with remote wireless energy transfer capabilities. The portable lightweight system can measure eye refractive powers, optimize light conditions for the eye under testing, conduct color-blindness tests, and implement eye strain relief and eye muscle exercises via time sequenced imaging. A basic eye vision test system is built in the laboratory for near-sighted (myopic vision spherical lens refractive error correction. Refractive error corrections from zero up to −5.0 Diopters and −2.0 Diopters are experimentally demonstrated using the Electronic-Lens (E-Lens and aperture control methods, respectively. The proposed portable eye vision test system is suited for children’s eye tests and developing world eye centers where technical expertise may be limited. Design of a novel low-cost human vision corrective eyewear is also presented based on the proposed aperture control concept. Given its simplistic and economical design, significant impact can be created for humans with vision problems in the under-developed world.

  14. Laser Beam MicroMachining (LBMM) - A review

    Science.gov (United States)

    Mishra, Sanjay; Yadava, Vinod

    2015-10-01

    The use of short and ultrashort laser pulses for micromachining application is an emerging technology. Laser Beam MicroMachining (LBMM) has revolutionized many industries by providing innovative solutions in numerous industrial micro-engineering applications. High-intensity short or ultrashort laser pulses are powerful thermal energy source for creating micro-features in wide range of materials. These lasers can precisely ablate various types of materials with little or no collateral damage. An overview of LBMM is given so that we can obtain a current view of capabilities and tradeoffs associated with LBMM of sub-micron size. The fundamental understanding of ultrafast laser ablation process has been elucidated and the various research activities performed with nanosecond, picosecond and femtosecond, lasers have been discussed to understand the physical mechanisms and the critical experimental parameters involved in the LBMM. The critical analysis of various theoretical and experimental models used to describe the performance analysis of LBMM has been elaborated so that we can identify the relevant principles underlying the process.

  15. Parametric studies on the nanosecond laser micromachining of the materials

    Science.gov (United States)

    Tański, M.; Mizeraczyk, J.

    2016-12-01

    In this paper the results of an experimental studies on nanosecond laser micromachining of selected materials are presented. Tested materials were thin plates made of aluminium, silicon, stainless steel (AISI 304) and copper. Micromachining of those materials was carried out using a solid state laser with second harmonic generation λ = 532 nm and a pulse width of τ = 45 ns. The effect of laser drilling using single laser pulse and a burst of laser pulses, as well as laser cutting was studied. The influence of laser fluence on the diameter and morphology of a post ablation holes drilled with a single laser pulse was investigated. The ablation fluence threshold (Fth) of tested materials was experimentally determined. Also the drilling rate (average depth per single laser pulse) of holes drilled with a burst of laser pulses was determined for all tested materials. The studies of laser cutting process revealed that a groove depth increases with increasing average laser power and decreasing cutting speed. It was also found that depth of the laser cut grooves is a linear function of number of repetition of a cut. The quantitative influence of those parameters on the groove depth was investigated.

  16. A note on determination of the diffuse-field sensitivity of microphones using the reciprocity technique

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Jacobsen, Finn

    2008-01-01

    angles of incidence but also on the accuracy of the frequency response at normal incidence. By contrast, this paper is concerned with determining the absolute diffuse-field response of a microphone using the reciprocity technique. To examine this possibility, a reciprocity calibration setup is used...

  17. A time-selective technique for free-field reciprocity calibration of condenser microphones

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2003-01-01

    of the diffraction of the body of the microphone, and thus, its sensitivity will change. In the two cases, a technique based on the reciprocity theorem can be applied for obtaining the absolute sensitivity either under uniform pressure or free-field conditions. In this paper, signal-processing techniques...

  18. Free-field reciprocity calibration of laboratory standard (LS) microphones using a time selective technique

    DEFF Research Database (Denmark)

    Rasmussen, Knud; Barrera Figueroa, Salvador

    2006-01-01

    Although the basic principle of reciprocity calibration of microphones in a free field is simple, the practical problems are complicated due to the low signal-to-noise ratio and the influence of cross talk and reflections from the surroundings. The influence of uncorrelated noise can be reduced...

  19. MP.EXE, a Calculation Program for Pressure Reciprocity Calibration of Microphones

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    A computer program is described which calculates the pressure sensitivity of microphones based on measurements of the electrical transfer impedance in a reciprocity calibration set-up. The calculations are performed according to the International Standard IEC 6194-2. In addition a number of options...

  20. On the influence of microphone array geometry on HRTF-based Sound Source Localization

    DEFF Research Database (Denmark)

    Farmani, Mojtaba; Pedersen, Michael Syskind; Tan, Zheng-Hua;

    2015-01-01

    . Furthermore, to demonstrate the analysis results, we show the impact of HRTFs similarities and microphone array geometry on an exemplary HRTF-based SSL algorithm, called MLSSL. This algorithm is well-suited for this purpose as it allows to estimate the Direction-of-Arrival (DoA) of the target sound using any...

  1. On Acoustic Feedback Cancellation Using Probe Noise in Multiple-Microphone and Single-Loudspeaker Systems

    DEFF Research Database (Denmark)

    Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt;

    2012-01-01

    of the adaptive estimation is significantly decreased when keeping the steady-state error unchanged. The goal of this work is to derive analytic expressions for the system behavior such as convergence rate and steady-state error for a multiple-microphone and single-loudspeaker audio system, where the acoustic...

  2. Direct Measurement of the Speed of Sound Using a Microphone and a Speaker

    Science.gov (United States)

    Gómez-Tejedor, José A.; Castro-Palacio, Juan C.; Monsoriu, Juan A.

    2014-01-01

    We present a simple and accurate experiment to obtain the speed of sound in air using a conventional speaker and a microphone connected to a computer. A free open source digital audio editor and recording computer software application allows determination of the time-of-flight of the wave for different distances, from which the speed of sound is…

  3. An investigation of methods for free-field comparison calibration of measurement microphones

    DEFF Research Database (Denmark)

    Barrera-Figueroa, Salvador; Moreno Pescador, Guillermo; Jacobsen, Finn

    2010-01-01

    method requires the sound field to have good temporal stability. The simultaneous method requires instead that the sound pressure is the same in the positions where the microphones are placed. In this paper the results of the application of the two methods are compared. A third combined method...

  4. Benefits of the Fiber Optic versus the Electret Microphone in Voice Amplification

    Science.gov (United States)

    Kyriakou, Kyriaki; Fisher, Helene R.

    2013-01-01

    Background: Voice disorders that result in reduced loudness may cause difficulty in communicating, socializing and participating in occupational activities. Amplification is often recommended in order to facilitate functional communication, reduce vocal load and avoid developing maladaptive compensatory behaviours. The most common microphone used…

  5. 76 FR 4936 - Certain Silicon Microphone Packages and Products Containing the Same; Notice of Commission...

    Science.gov (United States)

    2011-01-27

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Silicon Microphone Packages and Products Containing the Same; Notice of Commission Determination To Review in Part an Initial Determination; On Review Taking No Position on Two Issues...

  6. Efficient voice activity detection in reverberant enclosures using far field microphones

    DEFF Research Database (Denmark)

    Petsatodis, Theodore; Boukis, Christos

    2009-01-01

    An algorithm suitable for voice activity detection under reverberant conditions is proposed in this paper. Due to the use of far-filed microphones the proposed solution processes speech signals of highly-varying intensity and signal to noise ratio, that are contaminated with several echoes. The c...

  7. 100% foundry compatible packaging and full wafer release and die separation technique for surface micromachined devices

    Energy Technology Data Exchange (ETDEWEB)

    OLIVER,ANDREW D.; MATZKE,CAROLYN M.

    2000-04-06

    A completely foundry compatible chip-scale package for surface micromachines has been successfully demonstrated. A pyrex (Corning 7740) glass cover is placed over the released surface micromachined die and anodically bonded to a planarized polysilicon bonding ring. Electrical feedthroughs for the surface micromachine pass underneath the polysilicon sealing ring. The package has been found to be hermetic with a leak rate of less than 5 x 10{sup {minus}8} atm cm{sup {minus}3}/s. This technology has applications in the areas of hermetic encapsulation and wafer level release and die separation.

  8. Fatigue of micromachined stainless steel structural materials for vibrational energy harvesting

    Science.gov (United States)

    Shimizu, Y.; Van Minh, L.; Kitayoshi, H.; Kuwano, H.

    2016-11-01

    This work presents fatigue measurement for micromachined stainless steel (SUS304) structural substrate using resonant bending mode. Micromachined specimens for fatigue test had a cantilever structure with a proof mass. They were fabricated by FeCl3 wet etching and wire-discharged cutting. The SUS specimens had Young's modulus of 198 GPa on average. The endurance limit of micromachined specimens was 213 MPa on average after 108 cycles under our fracture definition. The large SUS specimens had the endurance limit of 229 MPa after 107 cycles.

  9. Data dependent random forest applied to screening for laryngeal disorders through analysis of sustained phonation: acoustic versus contact microphone.

    Science.gov (United States)

    Verikas, A; Gelzinis, A; Vaiciukynas, E; Bacauskiene, M; Minelga, J; Hållander, M; Uloza, V; Padervinskis, E

    2015-02-01

    Comprehensive evaluation of results obtained using acoustic and contact microphones in screening for laryngeal disorders through analysis of sustained phonation is the main objective of this study. Aiming to obtain a versatile characterization of voice samples recorded using microphones of both types, 14 different sets of features are extracted and used to build an accurate classifier to distinguish between normal and pathological cases. We propose a new, data dependent random forests-based, way to combine information available from the different feature sets. An approach to exploring data and decisions made by a random forest is also presented. Experimental investigations using a mixed gender database of 273 subjects have shown that the perceptual linear predictive cepstral coefficients (PLPCC) was the best feature set for both microphones. However, the linear predictive coefficients (LPC) and linear predictive cosine transform coefficients (LPCTC) exhibited good performance in the acoustic microphone case only. Models designed using the acoustic microphone data significantly outperformed the ones built using data recorded by the contact microphone. The contact microphone did not bring any additional information useful for the classification. The proposed data dependent random forest significantly outperformed the traditional random forest.

  10. Micromachined hot-wire thermal conductivity probe for biomedical applications.

    Science.gov (United States)

    Yi, Ming; Panchawagh, Hrishikesh V; Podhajsky, Ronald J; Mahajan, Roop L

    2009-10-01

    This paper presents the design, fabrication, numerical simulation, and experimental validation of a micromachined probe that measures thermal conductivity of biological tissues. The probe consists of a pair of resistive line heating elements and resistance temperature detector sensors, which were fabricated by using planar photolithography on a glass substrate. The numerical analysis revealed that the thermal conductivity and diffusivity can be determined by the temperature response induced by the uniform heat flux in the heating elements. After calibrating the probe using a material (agar gel) of known thermal conductivity, the probe was deployed to calculate the thermal conductivity of Crisco. The measured value is in agreement with that determined by the macro-hot-wire probe method to within 3%. Finally, the micro thermal probe was used to investigate the change of thermal conductivity of pig liver before and after RF ablation treatment. The results show an increase in thermal conductivity of liver after the RF ablation.

  11. A Micro-Machined Gyroscope for Rotating Aircraft

    Science.gov (United States)

    Yan, Qingwen; Zhang, Fuxue; Zhang, Wei

    2012-01-01

    In this paper we present recent work on the design, fabrication by silicon micromachining, and packaging of a new gyroscope for stabilizing the autopilot of rotating aircraft. It operates based on oscillation of the silicon pendulum between two torsion girders for detecting the Coriolis force. The oscillation of the pendulum is initiated by the rolling and deflecting motion of the rotating carrier. Therefore, the frequency and amplitude of the oscillation are proportional to the rolling frequency and deflecting angular rate of the rotating carrier, and are measured by the sensing electrodes. A modulated pulse with constant amplitude and unequal width is obtained by a linearizing process of the gyroscope output signal and used to control the deflection of the rotating aircraft. Experimental results show that the gyroscope has a resolution of 0.008 °/s and a bias of 56.18 °/h. PMID:23012572

  12. Dynamical modeling and characterization of a surface micromachined microengine

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S.L.; Sniegowski, J.J.; LaVigne, G.L.; McWhorter, P.J.

    1996-01-01

    The practical implementation of the surface micromachined microengine [1,2] to perform useful microactuation tasks requires a thorough understanding of the dynamics of the engine. This understanding is necessary in order to create appropriate drive signals, and to experimentally measure fundamental quantities associated with the engine system. We have developed and applied a dynamical model of the microengine and used it to accomplish three objectives: (1) drive inertial loads in a controlled fashion, i.e. specify and achieve a desired time dependent angular position of the output gear,( 2) minimize stress and frictional forces during operation, and (3) as a function of time, experimentally determine forces associated with the output gear, such as the load torque being applied to the output gear due to friction.

  13. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    Science.gov (United States)

    Liu, Han; LaConti, Anthony B.; Mittelsteadt, Cortney K.; McCallum, Thomas J.

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  14. A silicon micromachined piezoresistive accelerometer for health and condition monitoring

    Science.gov (United States)

    Walsh, Kevin M.; Henderson, H. Thurman

    1990-01-01

    Silicon micromachining etching techniques were utilized to batch-fabricate hundreds of general purpose microaccelerometers on a single silicon substrate. Piezoresistive sensing elements were aligned to the back-side patterns using an IR mask aligner and then diffused into the areas of maximum stress. Capping of the two-arm cantilever beam structure was achieved using a combination of electrostatic bonding and low temperature glass films. Overrange protection, critical damping, and overall protection from the outside environment are achieved by controlling the cavity depths of the top and bottom covers. Temperature compensation, amplification, and filtering are performed by a companion LSI chip that is interfaced to the accelerometer by conventional wire-bonding techniques.

  15. A novel design of micromachined capacitive Lamb wave transducers

    Science.gov (United States)

    Ge, Lifeng

    2006-11-01

    A new design for micromachined capacitive Lamb wave transducers (mCLWT) has been developed. The design is based on a theoretical TDK model previously developed for groove ultrasonic transducers. By the investigation of the dynamic behavior of a rectangular high aspect ratio diaphragm of the mCLWTs, the second order bending mode of the diaphragm is exploited to excite and detect Lamb wave. The new exiting mechanism can minimize the energy of the acoustic radiation at the normal direction of the diaphragm so as to provide more energy coupled into the Lamb wave in the silicon substrate. Also, the natural frequencies and mode shapes of such a mCLWT can be determined accurately from its geometry and materials used, so the TDK model provides guidance for the optimal design of mCLWTs.

  16. Micromachined high-performance RF passives in CMOS substrate

    Science.gov (United States)

    Li, Xinxin; Ni, Zao; Gu, Lei; Wu, Zhengzheng; Yang, Chen

    2016-11-01

    This review systematically addresses the micromachining technologies used for the fabrication of high-performance radio-frequency (RF) passives that can be integrated into low-cost complementary metal-oxide semiconductor (CMOS)-grade (i.e. low-resistivity) silicon wafers. With the development of various kinds of post-CMOS-compatible microelectromechanical systems (MEMS) processes, 3D structural inductors/transformers, variable capacitors, tunable resonators and band-pass/low-pass filters can be compatibly integrated into active integrated circuits to form monolithic RF system-on-chips. By using MEMS processes, including substrate modifying/suspending and LIGA-like metal electroplating, both the highly lossy substrate effect and the resistive loss can be largely eliminated and depressed, thereby meeting the high-performance requirements of telecommunication applications.

  17. Experimental Investigation on Complex Structures Machining by Electrochemical Micromachining Technology

    Institute of Scientific and Technical Information of China (English)

    Liu Yong; Zhu Di; Zeng Yongbin; Huang Shaofu; Yu Hongbing

    2010-01-01

    Electrochemical micromachining(EMM)technology for fabricating micro structures is presented in this article.By applying ultra short pulses,dissolution of a workpiece can be restricted to the region very close to the electrode.First,an EMM system for meeting the requirements of the EMM process is established.Second,sets of experiments is carried out to investigate the influence of some of the predominant electrochemical process parameters such as electrical parameters,feed rate,electrode geometry features and electrolyte composition on machining quality,especially the influences of pulse on time on shape precision and working end shape of electrode on machined surface quality.Finally,after the preliminary experiments,a complex microstructure with good shape precision and surface quality is successfully obtained.

  18. A Micromachined Piezoresistive Pressure Sensor with a Shield Layer.

    Science.gov (United States)

    Cao, Gang; Wang, Xiaoping; Xu, Yong; Liu, Sheng

    2016-08-13

    This paper presents a piezoresistive pressure sensor with a shield layer for improved stability. Compared with the conventional piezoresistive pressure sensors, the new one reported in this paper has an n-type shield layer that covers p-type piezoresistors. This shield layer aims to minimize the impact of electrical field and reduce the temperature sensitivity of piezoresistors. The proposed sensors have been successfully fabricated by bulk-micromachining techniques. A sensitivity of 0.022 mV/V/kPa and a maximum non-linearity of 0.085% FS are obtained in a pressure range of 1 MPa. After numerical simulation, the role of the shield layer has been experimentally investigated. It is demonstrated that the shield layer is able to reduce the drift caused by electrical field and ambient temperature variation.

  19. Efficient Sonochemistry through Microbubbles Generated with Micromachined Surfaces

    CERN Document Server

    Rivas, David Fernandez; Zijlstra, Aaldert G; Lohse, Detlef; Gardeniers, Han J G E; 10.1002/anie.201005533

    2012-01-01

    Sonochemical reactors are used in water treatment, the synthesis of fine chemicals, pharmaceutics and others. The low efficiency of sonoreactors have prevented its massive usage at industrial scales. Controlling the appearance of bubbles in place and time is the most limiting factor. A novel type of sonochemical reactor was designed making use of micro-fabrication techniques to control the nucleation sites of micro-bubbles. The efficiency was increased first by locating the nucleation sites in the most active region of a micro-chamber; additionally the desired chemical effect was significantly higher at the same powers than when not controlled. Silicon substrates were micromachined with "artificial nucleation sites" or pits, and placed at the bottom of the micro-chamber. The pits entrap gas which, upon ultrasonic excitation, sheds off a stream of microbubbles. The gas content of the pits is not depleted but is replenished by diffusion and the emission of microbubbles can continue for hours.

  20. Compact Micromachined Infrared Bandpass Filters for Planetary Spectroscopy

    Science.gov (United States)

    Merrell, Willie C., II; Aslam, Shahid; Brown, Ari D.; Chervenak, James A.; Huang, Wei-Chung; Quijada, Manuel; Wollack, Edward

    2011-01-01

    The future needs of space based observational planetary and astronomy missions include low mass and small volume radiometric instruments that can operate in high radiation and low temperature environments. Here we focus on a central spectroscopic component, the bandpass filter. We model the bandpass response of the filters to target the wavelength of the resonance peaks at 20, 40, and 60 micrometers and report good agreement between the modeled and measured response. We present a technique of using common micromachining processes for semiconductor fabrication to make compact, free standing resonant metal mesh filter arrays with silicon support frames. The process can accommodate multiple detector array architectures and the silicon frame provides lightweight mechanical support with low form factor. We also present a conceptual hybridization of the filters with a detector array.

  1. A Micro-Machined Gyroscope for Rotating Aircraft

    Directory of Open Access Journals (Sweden)

    Fuxue Zhang

    2012-07-01

    Full Text Available In this paper we present recent work on the design, fabrication by silicon micromachining, and packaging of a new gyroscope for stabilizing the autopilot of rotating aircraft. It operates based on oscillation of the silicon pendulum between two torsion girders for detecting the Coriolis force. The oscillation of the pendulum is initiated by the rolling and deflecting motion of the rotating carrier. Therefore, the frequency and amplitude of the oscillation are proportional to the rolling frequency and deflecting angular rate of the rotating carrier, and are measured by the sensing electrodes. A modulated pulse with constant amplitude and unequal width is obtained by a linearizing process of the gyroscope output signal and used to control the deflection of the rotating aircraft. Experimental results show that the gyroscope has a resolution of 0.008 °/s and a bias of 56.18 °/h.

  2. Plastic Deformation of Micromachined Silicon Diaphragms with a Sealed Cavity at High Temperatures

    Directory of Open Access Journals (Sweden)

    Juan Ren

    2016-02-01

    Full Text Available Single crystal silicon (SCS diaphragms are widely used as pressure sensitive elements in micromachined pressure sensors. However, for harsh environments applications, pure silicon diaphragms are hardly used because of the deterioration of SCS in both electrical and mechanical properties. To survive at the elevated temperature, the silicon structures must work in combination with other advanced materials, such as silicon carbide (SiC or silicon on insulator (SOI, for improved performance and reduced cost. Hence, in order to extend the operating temperatures of existing SCS microstructures, this work investigates the mechanical behavior of pressurized SCS diaphragms at high temperatures. A model was developed to predict the plastic deformation of SCS diaphragms and was verified by the experiments. The evolution of the deformation was obtained by studying the surface profiles at different anneal stages. The slow continuous deformation was considered as creep for the diaphragms with a radius of 2.5 mm at 600 °C. The occurrence of plastic deformation was successfully predicted by the model and was observed at the operating temperature of 800 °C and 900 °C, respectively.

  3. Investigation on micromachining technologies for the realization of LTCC devices and systems

    Science.gov (United States)

    Haas, T.; Zeilmann, C.; Bittner, A.; Schmid, U.

    2011-06-01

    Low temperature co-fired ceramics (LTCC) has established as a widespread platform for advanced functional ceramic devices in different applications, such as in the space and aviation sector, for micro machined sensors as well as in micro fluidics. This is due to high reliability, excellent physical properties, especially in the high frequency range, and the possibility to integrate passive components in the monolithic LTCC body, offering the potential for a high degree of miniaturisation. However, for further improvement of this technology and for an ongoing increase of the integration level, the realization of miniaturized structures is of utmost importance. Therefore, novel techniques for micro-machining are required providing channel structures and cavities inside the glass-ceramic body, enabling for further application scenarios. Those techniques are punching, laser cutting and embossing. One of the most limitations of LTCC is the poor thermal conductivity. Hence, the possibility to integrate channels enables innovative active cooling approaches using fluidic media for heat critical devices. Doing so, a by far better cooling effect can be achieved than by passive devices as heat spreaders or heat sinks. Furthermore, the realization of mechanic devices as integrated pressure sensors for operation under harsh environmental conditions can be realized by integrating the membrane directly into the ceramic body. Finally, for high power devices substantial improvement can be provided by filling those channel structures with electrical conductive material, so that the resistivity can be decreased drastically without affecting the topography of the ceramics.

  4. Study of surfactant-added TMAH for applications in DRIE and wet etching-based micromachining

    Science.gov (United States)

    Tang, B.; Shikida, M.; Sato, K.; Pal, P.; Amakawa, H.; Hida, H.; Fukuzawa, K.

    2010-06-01

    In this paper, etching anisotropy is evaluated for a number of different crystallographic orientations of silicon in a 0.1 vol% Triton-X-100 added 25 wt% tetramethylammonium hydroxide (TMAH) solution using a silicon hemisphere. The research is primarily aimed at developing advanced applications of wet etching in microelectromechanical systems (MEMS). The etching process is carried out at different temperatures in the range of 61-81 °C. The etching results of silicon hemisphere and different shapes of three-dimensional structures in {1 0 0}- and {1 1 0}-Si surfaces are analyzed. Significantly important anisotropy, different from a traditional etchant (e.g. pure KOH and TMAH), is investigated to extend the applications of the wet etching process in silicon bulk micromachining. The similar etching behavior of exact and vicinal {1 1 0} and {1 1 1} planes in TMAH + Triton is utilized selectively to remove the scalloping from deep reactive-ion etching (DRIE) etched profiles. The direct application of the present research is demonstrated by fabricating a cylindrical lens with highly smooth etched surface finish. The smoothness of a micro-lens at different locations is measured qualitatively by a scanning electron microscope and quantitatively by an atomic force microscope. The present paper provides a simple and effective fabrication method of the silicon micro-lens for optical MEMS applications.

  5. Characterization of a new class of surface micromachined pumps.

    Energy Technology Data Exchange (ETDEWEB)

    Galambos, Paul C.

    2004-12-01

    This is the latest in a series of LDRD's that we have been conducting with Florida State University/Florida A&M University (FSU/FAMU) under the campus executive program. This research builds on the earlier projects; ''Development of Highly Integrated Magnetically and Electrostatically Actuated Micropumps'' (SAND2003-4674) and ''Development of Magnetically and Electrostatically Driven Surface Micromachined Pumps'' (SAND2002-0704P). In this year's LDRD we designed 2nd generation of surface micromachined (SMM) gear and viscous pumps. Two SUMMiT{trademark} modules full of design variations of these pumps were fabricated and one SwIFT{trademark} module is still in fabrication. The SwIFT{trademark} fabrication process results in a transparent pump housing cover that will enable visualization inside the pumps. Since the SwIFT{trademark} pumps have not been tested as they are still in fabrication, this report will focus on the 2nd generation SUMMiT{trademark} designs. Pump testing (pressure vs. flow) was conducted on several of the SUMMiT{trademark} designs resulting in the first pump curve for this class of SMM pumps. A pump curve was generated for the higher torque 2nd generation gear pump designed by Jason Hendrix of FSU. The pump maximum flow rate at zero head was 6.5 nl/s for a 30V, 30 Hz square wave signal. This level of flow rate would be more than adequate for our typical SMM SUMMiT{trademark} or SwIFT{trademark} channels which have typical volumes on the order of 50 pl.

  6. Development of microphone leak detection technology in Fugen Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Shimanskiy, Sergey; Iijima, Takashi; Naoi, Yosuke [Japan Nuclear Cycle Development Inst., Fugen Nuclear Power Station, Tsuruga, Fukui (Japan)

    2002-06-01

    A method of leak detection, based on high-temperature resistant microphones, was originally developed in JNC to detect leakages with flow rates from 1 m{sup 3}/h to 500 m{sup 3}/h. The development performed in Fugen and reported here focuses on detection of a small leakage at an early stage by the same microphone method. Specifically, for the inlet feeder pipes the leak rate of 0.2 gpm (0.046 m{sup 3}/h) has been chosen as the target detection capability. Evaluation of detection sensitivity and leak localization accuracy was conducted based on various analysis methods in order to check the capability of the method to satisfy this requirement. The possibility of detecting and locating a small leakage has been demonstrated through the research. The probabilistic detection algorithm and multi-channel location-based detection are proposed in order to improve both the detection sensitivity and the localization accuracy. (author)

  7. Acoustic sensor engineering evaluation test report. [microphones for monitoring inside the space shuttle orbiter

    Science.gov (United States)

    Phillips, E. L., Jr.; Bronson, R. D.

    1976-01-01

    Two types of one-inch diameter sound pressure level sensors, which are candidates for monitoring ambient noise in the shuttle orbiter crew compartment during rest periods, were exposed to temperature, passive humidity, and vibration. One unexposed sensor of each type served as a reference unit. Except for the humidity exposures, each of the three capacitive microphones was individually tested in sequence with the essential voltage power supply and preamplifier. One unit exibited anomalous characteristics after the humidity exposure but returned to normal after being dried in an oven at 115 deg for two hours. Except for the humidity exposures, each of the three piezoelectric microphones was individually tested with a laboratory type amplifier. Two apparent failures occurred during these tests. The diaphragm on one was found ruptured after the fourth cycle of the humidity test. A second sensor showed an anomaly after the random vibration tests at which time its sensitivity was consistent at about one-half its former value.

  8. A Two-Microphone Noise Reduction System for Cochlear Implant Users with Nearby Microphones—Part II: Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Rudolf Häusler

    2008-06-01

    Full Text Available Users of cochlear implants (auditory aids, which stimulate the auditory nerve electrically at the inner ear often suffer from poor speech understanding in noise. We evaluate a small (intermicrophone distance 7 mm and computationally inexpensive adaptive noise reduction system suitable for behind-the-ear cochlear implant speech processors. The system is evaluated in simulated and real, anechoic and reverberant environments. Results from simulations show improvements of 3.4 to 9.3 dB in signal to noise ratio for rooms with realistic reverberation and more than 18 dB under anechoic conditions. Speech understanding in noise is measured in 6 adult cochlear implant users in a reverberant room, showing average improvements of 7.9–9.6 dB, when compared to a single omnidirectional microphone or 1.3–5.6 dB, when compared to a simple directional two-microphone device. Subjective evaluation in a cafeteria at lunchtime shows a preference of the cochlear implant users for the evaluated device in terms of speech understanding and sound quality.

  9. Identifying Microphone from Noisy Recordings by Using Representative Instance One Class-Classification Approach

    OpenAIRE

    Huy Quan Vu; Shaowu Liu; Xinghua Yang; Zhi Li; Yongli Ren

    2012-01-01

    Rapid growth of technical developments has created huge challenges for microphone forensics - a sub-category of audio forensic science, because of the availability of numerous digital recording devices and massive amount of recording data. Demand for fast and efficient methods to assure integrity and authenticity of information is becoming more and more important in criminal investigation nowadays. Machine learning has emerged as an important technique to support audio analysis processes of m...

  10. A dynamic multi-channel speech enhancement system for distributed microphones in a car environment

    Science.gov (United States)

    Matheja, Timo; Buck, Markus; Fingscheidt, Tim

    2013-12-01

    Supporting multiple active speakers in automotive hands-free or speech dialog applications is an interesting issue not least due to comfort reasons. Therefore, a multi-channel system for enhancement of speech signals captured by distributed distant microphones in a car environment is presented. Each of the potential speakers in the car has a dedicated directional microphone close to his position that captures the corresponding speech signal. The aim of the resulting overall system is twofold: On the one hand, a combination of an arbitrary pre-defined subset of speakers' signals can be performed, e.g., to create an output signal in a hands-free telephone conference call for a far-end communication partner. On the other hand, annoying cross-talk components from interfering sound sources occurring in multiple different mixed output signals are to be eliminated, motivated by the possibility of other hands-free applications being active in parallel. The system includes several signal processing stages. A dedicated signal processing block for interfering speaker cancellation attenuates the cross-talk components of undesired speech. Further signal enhancement comprises the reduction of residual cross-talk and background noise. Subsequently, a dynamic signal combination stage merges the processed single-microphone signals to obtain appropriate mixed signals at the system output that may be passed to applications such as telephony or a speech dialog system. Based on signal power ratios between the particular microphone signals, an appropriate speaker activity detection and therewith a robust control mechanism of the whole system is presented. The proposed system may be dynamically configured and has been evaluated for a car setup with four speakers sitting in the car cabin disturbed in various noise conditions.

  11. Dual-microphone and binaural noise reduction techniques for improved speech intelligibility by hearing aid users

    Science.gov (United States)

    Yousefian Jazi, Nima

    Spatial filtering and directional discrimination has been shown to be an effective pre-processing approach for noise reduction in microphone array systems. In dual-microphone hearing aids, fixed and adaptive beamforming techniques are the most common solutions for enhancing the desired speech and rejecting unwanted signals captured by the microphones. In fact, beamformers are widely utilized in systems where spatial properties of target source (usually in front of the listener) is assumed to be known. In this dissertation, some dual-microphone coherence-based speech enhancement techniques applicable to hearing aids are proposed. All proposed algorithms operate in the frequency domain and (like traditional beamforming techniques) are purely based on the spatial properties of the desired speech source and does not require any knowledge of noise statistics for calculating the noise reduction filter. This benefit gives our algorithms the ability to address adverse noise conditions, such as situations where interfering talker(s) speaks simultaneously with the target speaker. In such cases, the (adaptive) beamformers lose their effectiveness in suppressing interference, since the noise channel (reference) cannot be built and updated accordingly. This difference is the main advantage of the proposed techniques in the dissertation over traditional adaptive beamformers. Furthermore, since the suggested algorithms are independent of noise estimation, they offer significant improvement in scenarios that the power level of interfering sources are much more than that of target speech. The dissertation also shows the premise behind the proposed algorithms can be extended and employed to binaural hearing aids. The main purpose of the investigated techniques is to enhance the intelligibility level of speech, measured through subjective listening tests with normal hearing and cochlear implant listeners. However, the improvement in quality of the output speech achieved by the

  12. Microphone Handling Noise: Measurements of Perceptual Threshold and Effects on Audio Quality.

    Directory of Open Access Journals (Sweden)

    Paul Kendrick

    Full Text Available A psychoacoustic experiment was carried out to test the effects of microphone handling noise on perceived audio quality. Handling noise is a problem affecting both amateurs using their smartphones and cameras, as well as professionals using separate microphones and digital recorders. The noises used for the tests were measured from a variety of devices, including smartphones, laptops and handheld microphones. The signal features that characterise these noises are analysed and presented. The sounds include various types of transient, impact noises created by tapping or knocking devices, as well as more sustained sounds caused by rubbing. During the perceptual tests, listeners auditioned speech podcasts and were asked to rate the degradation of any unwanted sounds they heard. A representative design test methodology was developed that tried to encourage everyday rather than analytical listening. Signal-to-noise ratio (SNR of the handling noise events was shown to be the best predictor of quality degradation. Other factors such as noise type or background noise in the listening environment did not significantly affect quality ratings. Podcast, microphone type and reproduction equipment were found to be significant but only to a small extent. A model allowing the prediction of degradation from the SNR is presented. The SNR threshold at which 50% of subjects noticed handling noise was found to be 4.2 ± 0.6 dBA. The results from this work are important for the understanding of our perception of impact sound and resonant noises in recordings, and will inform the future development of an automated predictor of quality for handling noise.

  13. Precision Measurements of Wind Turbine Noise using a Large Aperture Microphone Array

    DEFF Research Database (Denmark)

    Bradley, Stuart; Mikkelsen, Torben Krogh; Hünerbein, Sabine Von;

    2016-01-01

    -of-flight at each microphone). An experiment was also run recording the sound from a continuous tone speaker mounted near the tip of a turbine blade, allowing testing of signal processing to correct for the very substantial Doppler shift. These various experiments are targeted at obtaining very high spatial...... and temporal resolution acoustic images of the sound emitted from turbine blades. An overview of some of the first results from this work will be given....

  14. Microphonics detuning compensation in 3.9 GHZ superconducting RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ruben Carcagno et al.

    2003-10-20

    Mechanical vibrations can detune superconducting radio frequency (SCRF) cavities unless a tuning mechanism counteracting the vibrations is present. Due to their narrow operating bandwidth and demanding mechanical structure, the 13-cell 3.9GHz SCRF cavities for the Charged Kaons at Main Injector (CKM) experiment at Fermilab are especially susceptible to this microphonic phenomena. We present early results correlating RF frequency detuning with cavity vibration measurements for CKM cavities; initial detuning compensation results with piezoelectric actuators are also presented.

  15. Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for Infrasound

    Science.gov (United States)

    2013-04-01

    polyurethane foam windshields. Some researchers suggest that closed-cell foam windshields, at infrasound frequencies, sound should pass through the...very large, so the two most popular approaches are radial lengths of porous soaker hose dispersed on the ground or large grids of pipe arrays...from reaching the microphone. The closed-cell polyurethane foam used in Shams et al. (2) had a density of 128.1 kg/m3, which is commercially

  16. Microphone Handling Noise: Measurements of Perceptual Threshold and Effects on Audio Quality.

    Science.gov (United States)

    Kendrick, Paul; Jackson, Iain R; Fazenda, Bruno M; Cox, Trevor J; Li, Francis F

    2015-01-01

    A psychoacoustic experiment was carried out to test the effects of microphone handling noise on perceived audio quality. Handling noise is a problem affecting both amateurs using their smartphones and cameras, as well as professionals using separate microphones and digital recorders. The noises used for the tests were measured from a variety of devices, including smartphones, laptops and handheld microphones. The signal features that characterise these noises are analysed and presented. The sounds include various types of transient, impact noises created by tapping or knocking devices, as well as more sustained sounds caused by rubbing. During the perceptual tests, listeners auditioned speech podcasts and were asked to rate the degradation of any unwanted sounds they heard. A representative design test methodology was developed that tried to encourage everyday rather than analytical listening. Signal-to-noise ratio (SNR) of the handling noise events was shown to be the best predictor of quality degradation. Other factors such as noise type or background noise in the listening environment did not significantly affect quality ratings. Podcast, microphone type and reproduction equipment were found to be significant but only to a small extent. A model allowing the prediction of degradation from the SNR is presented. The SNR threshold at which 50% of subjects noticed handling noise was found to be 4.2 ± 0.6 dBA. The results from this work are important for the understanding of our perception of impact sound and resonant noises in recordings, and will inform the future development of an automated predictor of quality for handling noise.

  17. Optimization of Fixed Microphone Array in High Speed Train Noises Identification Based on Far-Field Acoustic Holography

    Directory of Open Access Journals (Sweden)

    Rujia Wang

    2017-01-01

    Full Text Available Acoustical holography has been widely applied for noise sources location and sound field measurement. Performance of the microphones array directly determines the sound source recognition method. Therefore, research is very important to the performance of the microphone array, its array of applications, selection, and how to design instructive. In this paper, based on acoustic holography moving sound source identification theory, the optimization method is applied in design of the microphone array, we select the main side lobe ratio and the main lobe area as the optimization objective function and then put the optimization method use in the sound source identification based on holography, and finally we designed this paper to optimize microphone array and compare the original array of equally spaced array with optimization results; by analyzing the optimization results and objectives, we get that the array can be achieved which is optimized not only to reduce the microphone but also to change objective function results, while improving the far-field acoustic holography resolving effect. Validation experiments have showed that the optimization method is suitable for high speed trains sound source identification microphone array optimization.

  18. Comparisons of spectral characteristics of wind noise between omnidirectional and directional microphones.

    Science.gov (United States)

    Chung, King

    2012-06-01

    Wind noise reduction is a topic of ongoing research and development for hearing aids and cochlear implants. The purposes of this study were to examine spectral characteristics of wind noise generated by directional (DIR) and omnidirectional (OMNI) microphones on different styles of hearing aids and to derive wind noise reduction strategies. Three digital hearing aids (BTE, ITE, and ITC) were fitted to Knowles Electronic Manikin for Acoustic Research. They were programmed to have linear amplification and matching frequency responses between the DIR and OMNI modes. Flow noise recordings were made from 0° to 360° azimuths at flow velocities of 4.5, 9.0, and 13.5 m/s in a quiet wind tunnel. Noise levels were analyzed in one-third octave bands from 100 to 8000 Hz. Comparison of wind noise revealed that DIR generally produced higher noise levels than OMNI for all hearing aids, but it could result in lower levels than OMNI at some frequencies and head angles. Wind noise reduction algorithms can be designed to detect noise levels of DIR and OMNI outputs in each frequency channel, remove the constraint to switch to OMNI in low-frequency channel(s) only, and adopt the microphone mode with lower noise levels to take advantage of the microphone differences.

  19. Speech Recognition for Environmental Control: Effect of Microphone Type, Dysarthria, and Severity on Recognition Results.

    Science.gov (United States)

    Fager, Susan Koch; Burnfield, Judith M

    2015-01-01

    This study examines the use of commercially available automatic speech recognition (ASR) across microphone options as access to environmental control for individuals with and without dysarthria. A study of two groups of speakers (typical speech and dysarthria), was conducted to understand their performance using ASR and various microphones for environmental control. Specifically, dependent variables examined included attempts per command, recognition accuracy, frequency of error type, and perceived workload. A further sub-analysis of the group of participants with dysarthria examined the impact of severity. Results indicated a significantly larger number of attempts were required (P = 0.007), and significantly lower recognition accuracies were achieved by the dysarthric participants (P = 0.010). A sub-analysis examining severity demonstrated no significant differences between the typical speakers and participants with mild dysarthria. However, significant differences were evident (P = 0.007, P = 0.008) between mild and moderate-severe dysarthric participants. No significant differences existed across microphones. A higher frequency of threshold errors occurred for typical participants and no response errors for moderate-severe dysarthrics. There were no significant differences on the NASA Task Load Index.

  20. Analytical modeling of squeeze air film damping of biomimetic MEMS directional microphone

    Science.gov (United States)

    Ishfaque, Asif; Kim, Byungki

    2016-08-01

    Squeeze air film damping is introduced in microelectromechanical systems due to the motion of the fluid between two closely spaced oscillating micro-structures. The literature is abundant with different analytical models to address the squeeze air film damping effects, however, there is a lack of work in modeling the practical sensors like directional microphones. Here, we derive an analytical model of squeeze air film damping of first two fundamental vibration modes, namely, rocking and bending modes, of a directional microphone inspired from the fly Ormia ochracea's ear anatomy. A modified Reynolds equation that includes compressibility and rarefaction effects is used in the analysis. Pressure distribution under the vibrating diaphragm is derived by using Green's function. From mathematical modeling of the fly's inspired mechanical model, we infer that bringing the damping ratios of both modes in the critical damping range enhance the directional sensitivity cues. The microphone parameters are varied in derived damping formulas to bring the damping ratios in the vicinity of critical damping, and to show the usefulness of the analytical model in tuning the damping ratios of both modes. The accuracy of analytical damping results are also verified by finite element method (FEM) using ANSYS. The FEM results are in full compliance with the analytical results.

  1. Design and Simulation of a New Decoupled Micromachined Gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Sharaf, Abdelhameed [NCRRT, EAEA, 3 Ahmed Elzomer Street, Nasr City, Cairo (Egypt); STRC, AUC, 113 Kasr El Eini Street, 11215, Cairo (Egypt); Sedky, Sherif [STRC, AUC, 113 Kasr El Eini Street, 11215, Cairo (Egypt); Physics Department, AUC, 113 Kasr El Eini Street, 11215, Cairo (Egypt); Habib, S E-D [Electronics and Communication Department, Faculty of Engineering, Cairo University, 12613, Giza (Egypt)

    2006-04-01

    This paper reports on a new decoupled micromachined gyroscope. The proposed sensor is a dual mass type, electrostatically driven to primary mode oscillation and senses, capacitively, the output signal. Full decoupling between drive and sense modes minimizes the mechanical crosstalk. Three different designs are introduced in this work. Drive and sense amplitudes, mechanical and electrical sensitivities, quality factors and approximate bandwidths are extracted analytically and the results are confirmed using finite element analysis. The first design shows drive and sense modes resonance frequencies of 4077 Hz and 4081 Hz respectively; with a frequency mismatch lower than 0.1%. The drive and sense capacitance are 0.213 pF and 0.142 pF respectively. The mechanical and electrical sensitivities are 0.011 {mu}m/ ({sup 0}/s) and 2.75 mV/ ({sup 0}/s) respectively. The third design shows significantly improved mechanical and electrical sensitivities of 0.027 {mu}m/ ({sup 0}/s) and 6.85 mV/ ({sup 0}/s) respectively.

  2. Manufacture of Radio Frequency Micromachined Switches with Annealing

    Directory of Open Access Journals (Sweden)

    Cheng-Yang Lin

    2014-01-01

    Full Text Available The fabrication and characterization of a radio frequency (RF micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor (CMOS process. The switch requires a post-process to release the membrane and springs. The post-process uses a wet etching to remove the sacrificial silicon dioxide layer, and to obtain the suspended structures of the switch. In order to improve the residual stress of the switch, an annealing process is applied to the switch, and the membrane obtains an excellent flatness. The finite element method (FEM software CoventorWare is utilized to simulate the stress and displacement of the RF switch. Experimental results show that the RF switch has an insertion loss of 0.9 dB at 35 GHz and an isolation of 21 dB at 39 GHz. The actuation voltage of the switch is 14 V.

  3. Manufacture of radio frequency micromachined switches with annealing.

    Science.gov (United States)

    Lin, Cheng-Yang; Dai, Ching-Liang

    2014-01-17

    The fabrication and characterization of a radio frequency (RF) micromachined switch with annealing were presented. The structure of the RF switch consists of a membrane, coplanar waveguide (CPW) lines, and eight springs. The RF switch is manufactured using the complementary metal oxide semiconductor (CMOS) process. The switch requires a post-process to release the membrane and springs. The post-process uses a wet etching to remove the sacrificial silicon dioxide layer, and to obtain the suspended structures of the switch. In order to improve the residual stress of the switch, an annealing process is applied to the switch, and the membrane obtains an excellent flatness. The finite element method (FEM) software CoventorWare is utilized to simulate the stress and displacement of the RF switch. Experimental results show that the RF switch has an insertion loss of 0.9 dB at 35 GHz and an isolation of 21 dB at 39 GHz. The actuation voltage of the switch is 14 V.

  4. Surface micromachined PDMS microfluidic devices fabricated using a sacrificial photoresist

    Science.gov (United States)

    Ganapathy Subramani, Balasubramanian; Selvaganapathy, Ponnambalam Ravi

    2009-01-01

    PDMS is a widely used material for construction of microfluidic devices. The traditional PDMS microfabrication process, although versatile, cannot be used to form microfluidic devices with embedded tall topological features, such as thick-film electrodes and porous reactor beds. This paper presents an elegant surface micromachining process for microfluidic devices that allows complete leak-proof sealing and a conformal contact of the PDMS with tall pre-existing topographical features and demonstrates this approach by embedding 6 µm thick Ag/AgCl (high capacity 1680 µA s) electrodes inside the microchannels. In this process, thin spin-cast films of the PDMS are used as the structural material and a photoresist is used as the sacrificial material. A crucial parameter, namely adhesion of the spun-cast structural layer to the substrate, was characterized for different pre-polymer ratios using a standard tensile test, and a 1:3 (curing agent:base) combination was found to be the best with a maximum adhesion strength of 7.2 MPa. The elastic property of the PDMS allowed extremely fast release times of ~1 min of the fabricated microchannels. The versatility of this process was demonstrated by the fabrication of a pneumatic microvalve with multi-layered microchannel geometry. The valve closure occurred at 6.37 kPa. Preliminary results of this paper have been presented at the Canadian Workshop on MEMS and Microfluidics, Montréal, Canada, August 2007.

  5. Multiplexed operation of a micromachined ultrasonic droplet ejector array.

    Science.gov (United States)

    Forbes, Thomas P; Degertekin, F Levent; Fedorov, Andrei G

    2007-10-01

    A dual-sample ultrasonic droplet ejector array is developed for use as a soft-ionization ion source for multiplexed mass spectrometry (MS). Such a multiplexed ion source aims to reduce MS analysis time for multiple analyte streams, as well as allow for the synchronized ejection of the sample(s) and an internal standard for quantitative results and mass calibration. Multiplexing is achieved at the device level by division of the fluid reservoir and separating the active electrodes of the piezoelectric transducer for isolated application of ultrasonic wave energy to each domain. The transducer is mechanically shaped to further reduce the acoustical crosstalk between the domains. Device design is performed using finite-element analysis simulations and supported by experimental characterization. Isolated ejection of approximately 5 microm diameter water droplets from individual domains in the micromachined droplet ejector array at around 1 MHz frequency is demonstrated by experiments. The proof-of-concept demonstration using a dual-sample device also shows potential for multiplexing with larger numbers of analytes.

  6. Thermal dependence of electrical characteristics of micromachined silica microchannel plates

    Science.gov (United States)

    Tremsin, Anton S.; Vallerga, John V.; Siegmund, Oswald H. W.; Beetz, Charles P.; Boerstler, Robert W.

    2004-04-01

    Micromachined silica microchannel plates (MCPs) under development have a number of advantages over standard glass MCPs and open completely new possibilities in detector technologies. In this article we present the results of our studies on the thermal properties of silica microchannel plates (sMCPs). Similar to standard glass microchanel plates the resistance of silica MCPs was measured to change exponentially with temperature with a negative thermal coefficient of -0.036 per °C, somewhat larger than that of standard glass MCPs. The resistance also decreases linearly with the applied voltage, with the voltage coefficient of -3.1×10-4 V-1. With the knowledge of these two coefficients, our thermal model allows the calculation of the maximum voltage, which can be applied to a given MCP without inducing a thermal runaway. A typical 25 mm diam, 240 μm thick sMCP with 6 μm pores has to have the resistance larger than ˜30 MΩ to operate safely at voltages up to 800 V. With this model we can also calculate the time required for a given silica MCP to reach the point of thermal equilibrium after a voltage increase. We hope that the ongoing efforts on a proper modification of the sMCP semiconducting layer will lead to the production of new MCPs with a small negative or even a positive thermal coefficient, reducing the possibility of thermal runaways of low-resistance MCPs required for high count rate applications.

  7. Thermoelectric Device Fabrication Using Thermal Spray and Laser Micromachining

    Science.gov (United States)

    Tewolde, Mahder; Fu, Gaosheng; Hwang, David J.; Zuo, Lei; Sampath, Sanjay; Longtin, Jon P.

    2016-02-01

    Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are used in many engineering applications such as vehicle and industrial waste-heat recovery systems to provide electrical power, improve operating efficiency and reduce costs. State-of-art TEG manufacturing is based on prefabricated materials and a labor-intensive process involving soldering, epoxy bonding, and mechanical clamping for assembly. This reduces their durability and raises costs. Additive manufacturing technologies, such as thermal spray, present opportunities to overcome these challenges. In this work, TEGs have been fabricated for the first time using thermal spray technology and laser micromachining. The TEGs are fabricated directly onto engineering component surfaces. First, current fabrication techniques of TEGs are presented. Next, the steps required to fabricate a thermal spray-based TEG module, including the formation of the metallic interconnect layers and the thermoelectric legs are presented. A technique for bridging the air gap between two adjacent thermoelectric elements for the top layer using a sacrificial filler material is also demonstrated. A flat 50.8 mm × 50.8 mm TEG module is fabricated using this method and its performance is experimentally characterized and found to be in agreement with expected values of open-circuit voltage based on the materials used.

  8. Resonant gravimetric immunosensing based on capacitive micromachined ultrasound transducers

    KAUST Repository

    Viržonis, Darius

    2014-04-08

    High-frequency (40 MHz) and low-frequency (7 MHz) capacitive micromachined ultrasound transducers (CMUT) were fabricated and tested for use in gravimetric detection of biomolecules. The low-frequency CMUT sensors have a gold-coated surface, while the high-frequency sensors have a silicon nitride surface. Both surfaces were functionalized with bovine leukemia virus antigen gp51 acting as the antigen. On addition of an a specific antibody labeled with horseradish peroxidase (HRP), the antigen/antibody complex is formed on the surface and quantified by HRP-catalyzed oxidation of tetramethylbenzidine. It has been found that a considerably smaller quantity of immuno complex is formed on the high frequency sensor surface. In parallel, the loading of the surface of the CMUT was determined via resonance frequency and electromechanical resistance readings. Following the formation of the immuno complexes, the resonance frequencies of the low-frequency and high-frequency sensors decrease by up to 420 and 440 kHz, respectively. Finite element analysis reveals that the loading of the (gold-coated) low frequency sensors is several times larger than that on high frequency sensors. The formation of the protein film with pronounced elasticity and stress on the gold surface case is discussed. We also discuss the adoption of this method for the detection of DNA using a hybridization assay following polymerase chain reaction.

  9. Surface micromachined differential piezoelectric shear-stress sensors

    Science.gov (United States)

    Williams, Randall P.; Kim, Donghwan; Gawalt, David P.; Hall, Neal A.

    2017-01-01

    The ability to measure viscous wall shear stress in high-speed flows is important for verifying simulated results typically obtained from direct numerical simulation in the aerodynamics research community, and robust sensors are required to measure wall shear reliably under such high-speed conditions. This letter summarizes the design, fabrication, and testing of a surface micromachined piezoelectric shear-stress sensor which uses a thin piezoelectric film to generate a voltage proportional to an applied shear stress without additional moving parts. A differential-cell architecture is used to enhance selectivity to shear stress while canceling normal-stress sensitivity. The conceptual design, fabrication details, and experimental measurements of device sensitivity are presented. A finite element model is used to validate the device performance against measurements, and to provide insight into the potential and electric fields underlying the device concept. The potential for understanding device behavior and optimization through modeling is illustrated using finite element analysis results. The minimum detectable shear stress for the sensor is estimated to be 52.9 mPa  √Hz-1 at 1.5 kHz.

  10. Giant flexoelectric polarization in a micromachined ferroelectric diaphragm

    KAUST Repository

    Wang, Zhihong

    2012-08-14

    The coupling between dielectric polarization and strain gradient, known as flexoelectricity, becomes significantly large on the micro- and nanoscale. Here, it is shown that giant flexoelectric polarization can reverse remnant ferroelectric polarization in a bent Pb(Zr0.52Ti0.48) O3 (PZT) diaphragm fabricated by micromachining. The polarization induced by the strain gradient and the switching behaviors of the polarization in response to an external electric field are investigated by observing the electromechanical coupling of the diaphragm. The method allows determination of the absolute zero polarization state in a PZT film, which is impossible using other existing methods. Based on the observation of the absolute zero polarization state and the assumption that bending of the diaphragm is the only source of the self-polarization, the upper bound of flexoelectric coefficient of PZT film is calculated to be as large as 2.0 × 10-4 C m -1. The strain gradient induced by bending the diaphragm is measured to be on the order of 102 m-1, three orders of magnitude larger than that obtained in the bulk material. Because of this large strain gradient, the estimated giant flexoelectric polarization in the bent diaphragm is on the same order of magnitude as the normal remnant ferroelectric polarization of PZT film. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Integrated Optical Interferometers with Micromachined Diaphragms for Pressure Sensing

    Science.gov (United States)

    DeBrabander, Gregory N.; Boyd, Joseph T.

    1996-01-01

    Optical pressure sensors have been fabricated which use an integrated optical channel waveguide that is part of an interferometer to measure the pressure-induced strain in a micromachined silicon diaphragm. A silicon substrate is etched from the back of the wafer leaving a rectangular diaphragm. On the opposite side of the wafer, ring resonator and Mach-Zehnder interferometers are formed with optical channel waveguides made from a low pressure chemical vapor deposited film of silicon oxynitride. The interferometer's phase is altered by pressure-induced stress in a channel segment positioned over the long edge of the diaphragm. The phase change in the ring resonator is monitored using a link-insensitive swept frequency laser diode, while in the Mach-Zehnder it is determined using a broad band super luminescent diode with subsequent wavelength separation. The ring resonator was found to be highly temperature sensitive, while the Mach-Zehnder, which had a smaller optical path length difference, was proportionally less so. The quasi-TM mode was more sensitive to pressure, in accord with calculations. Waveguide and sensor theory, sensitivity calculations, a fabrication sequence, and experimental results are presented.

  12. Femtosecond laser micromachining of fibre Bragg gratings for simultaneous measurement of temperature and concentration of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Alemohammad, H; Toyserkani, E [Department of Mechanical and Mechatronics Engineering, University of Waterloo, ON N2L 3G1 (Canada); Pinkerton, A J [School of Mechanical, Aerospace and Civil Engineering, University of Manchester, PO Box 88, Manchester, M60 1QD (United Kingdom)], E-mail: etoyserk@uwaterloo.ca, E-mail: shalemoh@uwaterloo.ca, E-mail: andrew.pinkerton@manchester.ac.uk

    2008-09-21

    This paper is concerned with micromachining of optical fibre Bragg gratings (FBGs) using a femtosecond pulsed laser. The purpose of this work is to increase the sensitivity of FBGs for simultaneous monitoring of the concentration of chemicals and biological liquids and their temperature. A Ti : sapphire regenerative amplifier was utilized to inscribe micro-grooves with widths of 16 and 22 {mu}m in the cladding of the optical fibres. Due to the core-confined light propagation characteristics of FBGs, their sensitivity to the changes in the index of refraction of the surrounding medium is minimal. However, by creating micro-grooves in the cladding layer, the index of refraction of the surrounding medium becomes effective in the coupling of the propagating core modes. As the index of refraction of liquids depends on the composition and concentration, the FBG with micromachined cladding can provide enough sensitivity to be used in chemical sensing. The performance of the micromachined FBGs was investigated by immersing them in different liquid solutions of polyvinyl butyral (PVB) in ethanol and obtaining their thermal responses. Results showed that the optical response of the micromachined FBGs (i.e. red shift in Bragg wavelength) is different by up to 10% in PVB solutions in ethanol than in ethanol alone. The micromachined FBGs can be used to monitor the concentration as well as the temperature of a solution.

  13. Femtosecond laser micromachining of fibre Bragg gratings for simultaneous measurement of temperature and concentration of liquids

    Science.gov (United States)

    Alemohammad, H.; Toyserkani, E.; Pinkerton, A. J.

    2008-09-01

    This paper is concerned with micromachining of optical fibre Bragg gratings (FBGs) using a femtosecond pulsed laser. The purpose of this work is to increase the sensitivity of FBGs for simultaneous monitoring of the concentration of chemicals and biological liquids and their temperature. A Ti : sapphire regenerative amplifier was utilized to inscribe micro-grooves with widths of 16 and 22 µm in the cladding of the optical fibres. Due to the core-confined light propagation characteristics of FBGs, their sensitivity to the changes in the index of refraction of the surrounding medium is minimal. However, by creating micro-grooves in the cladding layer, the index of refraction of the surrounding medium becomes effective in the coupling of the propagating core modes. As the index of refraction of liquids depends on the composition and concentration, the FBG with micromachined cladding can provide enough sensitivity to be used in chemical sensing. The performance of the micromachined FBGs was investigated by immersing them in different liquid solutions of polyvinyl butyral (PVB) in ethanol and obtaining their thermal responses. Results showed that the optical response of the micromachined FBGs (i.e. red shift in Bragg wavelength) is different by up to 10% in PVB solutions in ethanol than in ethanol alone. The micromachined FBGs can be used to monitor the concentration as well as the temperature of a solution.

  14. THE SURFACE EFFECT ON THE TENSILE STRENGTH OF MICROMACHINED POLYSILICON FILMS FOR MEMS

    Institute of Scientific and Technical Information of China (English)

    Ding Jianning; Yang Jichang; Wen Shizhu

    2005-01-01

    In order to accomplish reliable mechanical design of MEMS, the influences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechanical properties of micromachined polysilicon films for MEMS are investigated. Surface effect on the fracture properties of micromachined polysilicon films is evaluated with a new microtensile testing method using a magnet-coil force actuator. Statistical analysis of the surface roughness effects on the tensile strength predicated the surface roughness characterization of polysilicon films being tested and the direct relation of the mechanical properties with the surface roughness features. The fracture strength decreases with the increase of the surface roughness. The octadecyltrichlorosilane self-assembled monolayers coating leads to an increase of the average fracture strength up to 32.46%. Surface roughness and the hydrophobic properties of specimen when coated with OTS films are the two main factors influencing the tensile strength of micromachined polysilicon films for MEMS.

  15. Characteristics of damaged layer in micro-machining of copper material

    Institute of Scientific and Technical Information of China (English)

    Dong-Hee KWON; Jeong-Suk KIM; Myung-Chang KANG; Se-Hun KWON; Jong-Hwan LEE

    2009-01-01

    The study on damaged layer is necessary for improving the machinability in micro-machining because the damaged layer affects the micro mold life and micro machine parts. This study examined the ultra-precision micro-machining characteristics, such as cutting speed, feed rate and cutting depth, of a micro-damaged layer produced by an ultra-high speed air turbine spindle. The micro cutting force, surface roughness and plastic deformation layer were investigated according to the machining conditions. The damaged layer was measured using optical microscope on samples prepared through metallographic techniques. The scale of the damaged layer depends on the cutting process parameters, particularly, the feed per tooth and axial depth of the cut. According to the experimental results, the depth of the damaged layer is increased by increasing the feed per tooth and cutting depth, also the damaged layer occurs less in down-milling compared with up-milling during the micro-machining operation.

  16. Experimental and Theoretical Study of Young Modulus in Micromachined Polysilicon Films

    Institute of Scientific and Technical Information of China (English)

    丁建宁; 孟永钢; 温诗铸

    2002-01-01

    The elastic modulus is a very important mechanical property in micromachined structures. Several design issues such as resonant frequencies and stiffness in the micromachined structures are related to the elastic modulus. In addition, the accuracy of results from finite element models is highly dependent upon the elastic modulus. In this study, the Young modulus of micromachined thin polysilicon films has been investigated with a new tensile test machine using a magnetic-solenoid force actuator with linear response, low hysteresis, no friction and direct electrical control. The tensile test results show that the measured average value of Young modulus for a typical sample, (164±1.2) GPa, falls within the theoretical bounds of the texture model. These results will provide more reliable design of polysilicon microelectromechanical systems (MEMS).

  17. First reliability test of a surface micromachined microengine using SHiMMeR

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, D.M.; Smith, N.F.; Bowman, D.J. [and others

    1997-08-01

    The first-ever reliability stress test on surface micromachined microengines developed at Sandia National Laboratories (SNL) has been completed. We stressed 41 microengines at 36,000 RPM and inspected the functionality at 60 RPM. We have observed an infant mortality region, a region of low failure rate (useful life), and no signs of wearout in the data. The reliability data are presented and interpreted using standard reliability methods. Failure analysis results on the stressed microengines are presented. In our effort to study the reliability of MEMS, we need to observe the failures of large numbers of parts to determine the failure modes. To facilitate testing of large numbers of micromachines. The Sandia High Volume Measurement of Micromachine Reliability (SHiMMeR) system has computer controlled positioning and the capability to inspect moving parts. The development of this parallel testing system is discussed in detail.

  18. The use of micromachined structures for the management of mechanical properties and adhesion of thin films

    Science.gov (United States)

    Mehregamy, Mehran; Allen, Mark G.; Senturia, Stephen D.

    The application of silicon micromachining to the measurement of mechanical properties of thin films such as intrinsic stress, Young's modulus, and adhesion is presented. The measurement is based on the deflection and subsequent peeling of suspended membrane sections of the film. The goal was to make a quantitatively reproducible adhesion test by applying micromachining techniques to the blister peel test described by Hinkley. The initial measurements demonstrated the importance of residual stress in the films, which resulted in an expanded emphasis on the basic mechanical properties of the membrane as a prelude to accurate adhesion measurements. The process for micromachining suspended membranes is discussed along with the theory leading to the determination of mechanical properties of the films, the results, and the present status of the adhesion work.

  19. Real-time dual-microphone noise classification for environment-adaptive pipelines of cochlear implants.

    Science.gov (United States)

    Mirzahasanloo, Taher; Kehtarnavaz, Nasser

    2013-01-01

    This paper presents an improved noise classification in environment-adaptive speech processing pipelines of cochlear implants. This improvement is achieved by using a dual-microphone and by using a computationally efficient feature-level combination approach to achieve real-time operation. A new measure named Suppression Advantage is also defined in order to quantify the noise suppression improvement of an entire pipeline due to noise classification. The noise classification and suppression improvement results are presented for four commonly encountered noise environments.

  20. Reconstruction of arbitrary sound fields with a rigid-sphere microphone array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    2013-01-01

    Over the last few years, several studies have examined the potential of using rigid-sphere microphone arrays for reconstructing sound fields with near-field acoustic holography (NAH). The existing methods provide a reconstruction of the sound field based on a spherical harmonic expansion. However...... on an equivalent source model is proposed, where a combination of point sources is used to describe the incident sound field on the array. This method makes it possible to reconstruct the entire sound field at any point of the source-free domain without being restricted to a spherical surface. Additionally...

  1. Comparison of Multiple-Microphone and Single-Loudspeaker Adaptive Feedback/Echo Cancellation Systems

    DEFF Research Database (Denmark)

    Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt;

    2011-01-01

    Recently, we introduced a frequency domain measure - the power transfer function - to predict the convergence rate, system stability bound and the steady-state behavior across time and frequency of a least mean square based feedback/echo cancellation algorithm in a general multiple......-microphone and single-loudspeaker system. In this work, we extend the theoretical analysis to the normalized least mean square and recursive least squares algorithms. Furthermore, we compare and discuss the system behaviors in terms of the power transfer function for all three adaptive algorithms....

  2. Detection and Separation of Speech Events in Meeting Recordings Using a Microphone Array

    Directory of Open Access Journals (Sweden)

    Yamada Miichi

    2007-01-01

    Full Text Available When applying automatic speech recognition (ASR to meeting recordings including spontaneous speech, the performance of ASR is greatly reduced by the overlap of speech events. In this paper, a method of separating the overlapping speech events by using an adaptive beamforming (ABF framework is proposed. The main feature of this method is that all the information necessary for the adaptation of ABF, including microphone calibration, is obtained from meeting recordings based on the results of speech-event detection. The performance of the separation is evaluated via ASR using real meeting recordings.

  3. Recognition of Devoiced Vowels Using Optical Microphone Made of Multipled POF-Type Moisture Sensors

    Science.gov (United States)

    Morisawa, Masayuki; Natori, Yoichi; Taki, Tomohito; Muto, Shinzo

    A novel optical fiber microphone system for recognizing devoiced vowels has been studied. This system consists of the optical detection of moisture pattern formed by devoiced breath and its recognization process using a modified DP-matching. To detect moisture pattern of devoiced vowels, five plastic optical fiber moisture sensors with fast response were developed and used. Using this system, high discernment rate over 93% was obtained for the devoiced vowels. This system will be used for verbally handicapped people to create sounds with a small effort in the near future.

  4. Temperature compensated, humidity insensitive, high-Tg TOPAS FBGs for accelerometers and microphones

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, W.; Markos, C.;

    2012-01-01

    In this paper we present our latest work on Fiber Bragg Gratings (FBGs) in microstructured polymer optical fibers (mPOFs) and their application as strain sensing transducers in devices, such as accelerometers and microphones. We demonstrate how the cross-sensitivity of the FBG to temperature...... is eliminated by using dual-FBG technology and how mPOFs fabricated from different grades of TOPAS with glass transition temperatures around 135 degrees C potentially allow high-temperature humidity insensitive operation. The results bring the mPOF FBG closer to being a viable technology for commercial...

  5. Molecular-Scale Lubricants for Micromachine Applications: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Burns, A.R.; Dugger, M.T.; Houston, J.E.; Lopez, G.P.; Mayer, T.M.; Michalske, T.A.; Miller, S.L.; Sniegowski, J.J.; Stevens, M.J.; Zhou, Y.

    1998-12-01

    The nature of this work was to develop the physics and chemistry base for understanding molecular-scale lubricants used to reduce of friction- and adhesion-induced failure in silicon micromachines (MEMS). We acquired this new knowledge by tailoring the molecular properties of the lubricants, applying local probes that can directly monitor the response of lubricants in contact conditions, and evaluating the performance of model lubricants MEMS devices. Model lubricants under investigation were the silane coupling agents that form monolayer films on native oxide silicon surfaces, which is the substrate in MEMS. These molecules bind via strong surface bonds and produce a layer of hydro- or fluoro-carbon chains normal to the substrate. "Tailoring" the lubricants entails modifying the chain length, the chain chemical reactivity (H or F), and the density of chain structures. Thus much effort went into understanding the surface chemistry of silane-silicon oxide coupling. With proximal probes such as atomic force microscopy (AFM), interracial force microscopy (FM), and shear force microscopy in combination with IFM, we examined the frictional and adhesive properties of the silane films with very high spatial resolution (< 100 nm) and sensitivity. MEMS structures are treated with silanes under identical conditions, and examined for friction and adhesion under operating conditions. Proper assessment of the lubricants required quantitative analysis of MEMS performance at high speeds and long operating times. Our proximal probe measurements and WS performance analyses form a very important link for future molecular dynamics simulations, that, in turn, should be able to predict MEMS performance under all conditions.

  6. Micromachined fiber optic Fabry-Perot underwater acoustic probe

    Science.gov (United States)

    Wang, Fuyin; Shao, Zhengzheng; Hu, Zhengliang; Luo, Hong; Xie, Jiehui; Hu, Yongming

    2014-08-01

    One of the most important branches in the development trend of the traditional fiber optic physical sensor is the miniaturization of sensor structure. Miniature fiber optic sensor can realize point measurement, and then to develop sensor networks to achieve quasi-distributed or distributed sensing as well as line measurement to area monitoring, which will greatly extend the application area of fiber optic sensors. The development of MEMS technology brings a light path to address the problems brought by the procedure of sensor miniaturization. Sensors manufactured by MEMS technology possess the advantages of small volume, light weight, easy fabricated and low cost. In this paper, a fiber optic extrinsic Fabry-Perot interferometric underwater acoustic probe utilizing micromachined diaphragm collaborated with fiber optic technology and MEMS technology has been designed and implemented to actualize underwater acoustic sensing. Diaphragm with central embossment, where the embossment is used to anti-hydrostatic pressure which would largely deflect the diaphragm that induce interferometric fringe fading, has been made by double-sided etching of silicon on insulator. By bonding the acoustic-sensitive diaphragm as well as a cleaved fiber end in ferrule with an outer sleeve, an extrinsic Fabry-Perot interferometer has been constructed. The sensor has been interrogated by quadrature-point control method and tested in field-stable acoustic standing wave tube. Results have been shown that the recovered signal detected by the sensor coincided well with the corresponding transmitted signal and the sensitivity response was flat in frequency range from 10 Hz to 2kHz with the value about -154.6 dB re. 1/μPa. It has been manifest that the designed sensor could be used as an underwater acoustic probe.

  7. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers

    Science.gov (United States)

    Manwar, Rayyan; Chowdhury, Sazzadur

    2016-01-01

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding. The measured resonant frequency of 19.3 MHz using a Polytec™ laser Doppler vibrometer (Polytec™ MSA-500) is in excellent agreement with the 3-D FEA simulation result using IntelliSuite™. An Agilent ENA5061B vector network analyzer (VNA) has been used for impedance measurement and the resonance and anti-resonance values from the imaginary impedance curve were used to determine the electromechanical coupling co-efficient. The measured coupling coefficient of 0.294 at 20 V DC bias exhibits 40% higher transduction efficiency as compared to a measured value published elsewhere for a silicon nitride based CMUT. A white light interferometry method was used to measure the diaphragm deflection profiles at different DC bias. The diaphragm center velocity was measured for different sub-resonant frequencies using a Polytec™ laser Doppler vibrometer that confirms vibration of the diaphragm at different excitation frequencies and bias voltages. Transmit and receive operations of CMUT cells were characterized using a pitch-catch method and a −6 dB fractional bandwidth of 23% was extracted from the received signal in frequency domain. From the measurement, it appears that BCB-based CMUTs offer superior transduction efficiency as compared to silicon nitride or silicon dioxide insulator-based CMUTs, and provide a very uniform deflection profile thus making them a suitable candidate to fabricate highly energy efficient CMUTs. PMID:27347955

  8. Chemical vapor detection using a capacitive micromachined ultrasonic transducer.

    Science.gov (United States)

    Lee, Hyunjoo J; Park, Kwan Kyu; Kupnik, Mario; Oralkan, O; Khuri-Yakub, Butrus T

    2011-12-15

    Distributed sensing of gas-phase chemicals using highly sensitive and inexpensive sensors is of great interest for many defense and consumer applications. In this paper we present ppb-level detection of dimethyl methylphosphonate (DMMP), a common simulant for sarin gas, with a ppt-level resolution using an improved capacitive micromachined ultrasonic transducer (CMUT) as a resonant chemical sensor. The improved CMUT operates at a higher resonant frequency of 47.7 MHz and offers an improved mass sensitivity of 48.8 zg/Hz/μm(2) by a factor of 2.7 compared to the previous CMUT sensors developed. A low-noise oscillator using the CMUT resonant sensor as the frequency-selective device was developed for real-time sensing, which exhibits an Allan deviation of 1.65 Hz (3σ) in the presence of a gas flow; this translates into a mass resolution of 80.5 zg/μm(2). The CMUT resonant sensor is functionalized with a 50-nm thick DKAP polymer developed at Sandia National Laboratory for dimethyl methylphosphonate (DMMP) detection. To demonstrate ppb-level detection of the improved chemical sensor system, the sensor performance was tested at a certified lab (MIT Lincoln Laboratory), which is equipped with an experimental chemical setup that reliably and accurately delivers a wide range of low concentrations down to 10 ppb. We report a high volume sensitivity of 34.5 ± 0.79 pptv/Hz to DMMP and a good selectivity of the polymer to DMMP with respect to dodecane and 1-octanol.

  9. Micromachined infrared sensors with device-level encapsulation

    Science.gov (United States)

    Dave, Aasutosh; Celik-Butler, Zeynep; Butler, Donald P.

    2005-05-01

    There have been recent innovations to reduce the cost of packaging for MEMS devices, without deteriorating their performance. One such novel design for device-level encapsulation (self-packaged) of uncooled infrared (IR) microbolometers is documented here. Device-level vacuum encapsulation has the potential to eliminate some major problems associated with the bolometer performance such as high thermal conductance of the ambient atmosphere, the high cost associated with conventional vacuum packaging, and the degradation of optical transmission at different wavelengths through a conventional package window. The device-level encapsulated bolometers can also be fabricated with flexible substrates, which have the advantage of conforming to non-planar surfaces compared to Si or other rigid substrates. In addition, a flexible superstrate with low shear stress has applications in robotics, aerospace, defense and biomedicine as a "Smart skin", a name given to multisensory arrays on conformal substrates to emulate human skin functions on inanimate objects. Self-packaged uncooled microbolometer arrays of 40x40 μm2 and 60x60 μm2 are fabricated on top of Si wafer with a sacrificial layer using semiconducting Yttrium Barium Copper Oxide (YBCO) as the infrared sensing material. A two-layer surface micromachining technique in conjunction with a resonant cavity and a reflecting mirror are used for the sensor structure. The devices have demonstrated voltage responsivities of 7.9x103 V/W with a temperature coefficient of resistance of -2.5% K-1, and thermal conductivity of 2.95x10-6 W/K. The device performance was similar in air and vacuum, demonstrating vacuum integrity and a good device-level encapsulation.

  10. Fiber inline Michelson interferometer fabricated by one-step femtosecond laser micromachining for sensing applications

    Science.gov (United States)

    Yuan, Lei; Wu, Hongbin; Wang, Cong; Yu, Yingyu; Wang, Sumei; Xiao, Hai

    2013-12-01

    A fiber inline Michelson interferometer fiber optic sensor was presented for sensing applications, including high temperature performance and refractive index change. The sensor was fabricated using one-step femtosecond (fs) laser micromachining technique. A step structure at the tip of a single mode optical fiber was formed during the micromachining process. The device had a loss of 16 dB and an interference visibility exceeding 18 dB. The capability of this device for temperature sensing up to 1000 °C and refractive index sensing application in various concentrations of ethanol solution were all demonstrated.

  11. DESIGN, FABRICATION, TESTING AND MECHANICAL ANALYSIS OF BULK-MICROMACHINED FLOWMETERS

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaobao; Qian Jin; Zhang Dacheng

    2004-01-01

    Micromachined piezoresistive flowmeters with four different types of sensing structures have been designed, fabricated and tested. Piezoresistors were defined at the end of the sensors through p-diffusion, and their values were about 3.5 kΩ. Wheatstone bridge was configured with the piezoresistors in order to measure the output response. The output voltage increases with increasing flow rate of air, obeying determined relationships. The testing results show that the sensors that are designed for measuring 10L/M in full operational range have desired sensitivities. The sensor chip is manufactured with bulk-micromachining technologies, requiring a set of seven masks.

  12. A 540-μW digital pre-amplifier with 88-dB dynamic range for electret microphones

    Institute of Scientific and Technical Information of China (English)

    Liu Yan; Hua Siliang; Wang Donghui; Hou Chaohuan

    2009-01-01

    We design a digital pre-amplifier which can be directly connected to an electret microphone. The amplifier can convert analog signals into digital signals, has a wide voltage swing and low power consumption, as is required in portable applications. Measurement results show that the dynamic range of the digital pre-amplifier reaches 88 dB, the equivalent input referred noise is 5 μVrms, the typical power consumption is 540 μW, and in standby mode the current does not exceed 10 μA. Compared with an analog microphone, an electret microphone with digital pre-amplifier offers a better SNR, higher integration, lower power consumption, and higher immunity to system noise.

  13. Improvement of plastic optical fiber microphone based on moisture pattern sensing in devoiced breath

    Science.gov (United States)

    Taki, Tomohito; Honma, Satoshi; Morisawa, Masayuki; Muto, Shinzo

    2008-03-01

    Conversation is the most practical and common form in communication. However, people with a verbal handicap feel a difficulty to produce words due to variations in vocal chords. This research leads to develop a new devoiced microphone system based on distinguishes between the moisture patterns for each devoiced breaths, using a plastic optical fiber (POF) moisture sensor. In the experiment, five POF-type moisture sensors with fast response were fabricated by coating swell polymer with a slightly larger refractive index than that of fiber core and were set in front of mouth. When these sensors are exposed into humid air produced by devoiced breath, refractive index in cladding layer decreases by swelling and then the POF sensor heads change to guided type. Based on the above operation principle, the output light intensities from the five sensors set in front of mouth change each other. Using above mentioned output light intensity patterns, discernment of devoiced vowels in Japanese (a,i,u,e,o) was tried by means of DynamicProgramming-Matching (DP-matching) method. As the result, distinction rate over 90% was obtained to Japanese devoiced vowels. Therefore, using this system and a voice synthesizer, development of new microphone for the person with a functional disorder in the vocal chords seems to be possible.

  14. Lamb-wave (X, Y) giant tap screen panel with built-in microphone and loudspeaker.

    Science.gov (United States)

    Nikolovski, Jean-Pierre

    2013-06-01

    This paper presents a passive (X, Y) giant tap screen panel (GTP). Based on the time difference of arrival principle (TDOA), the device localizes low-energy impacts of around 1 mJ generated by fingernail taps. Selective detection of A0 Lamb waves generated in the upper frequency spectrum, around 100 kHz, makes it possible to detect light to strong impacts with equal resolution or precision, close to 1 cm and 2 mm, respectively, for a 10-mm-thick and 1-m(2) glass plate. Additionally, with glass, symmetrical beveling of the edges is used to create a tsunami effect that reduces the minimum impacting speed for light taps by a factor of three. Response time is less than 1 ms. Maximum panel size is of the order of 10 m(2). A rugged integrated flat design with embedded transducers in an electrically shielding frame features waterproof and sticker/ tag proof operation. Sophisticated electronics with floating amplification maintains the panel at its maximum possible sensitivity according to the surrounding noise. Amplification and filtering turns the panel into a microphone and loudspeaker featuring 50 mV/Pa as a microphone and up to 80 dBlin between 500 Hz and 8 kHz as a loudspeaker.

  15. Kalman filter-based microphone array signal processing using the equivalent source model

    Science.gov (United States)

    Bai, Mingsian R.; Chen, Ching-Cheng

    2012-10-01

    This paper demonstrates that microphone array signal processing can be implemented by using adaptive model-based filtering approaches. Nearfield and farfield sound propagation models are formulated into state-space forms in light of the Equivalent Source Method (ESM). In the model, the unknown source amplitudes of the virtual sources are adaptively estimated by using Kalman filters (KFs). The nearfield array aimed at noise source identification is based on a Multiple-Input-Multiple-Output (MIMO) state-space model with minimal realization, whereas the farfield array technique aimed at speech quality enhancement is based on a Single-Input-Multiple-Output (SIMO) state-space model. Performance of the nearfield array is evaluated in terms of relative error of the velocity reconstructed on the actual source surface. Numerical simulations for the nearfield array were conducted with a baffled planar piston source. From the error metric, the proposed KF algorithm proved effective in identifying noise sources. Objective simulations and subjective experiments are undertaken to validate the proposed farfield arrays in comparison with two conventional methods. The results of objective tests indicated that the farfield arrays significantly enhanced the speech quality and word recognition rate. The results of subjective tests post-processed with the analysis of variance (ANOVA) and a post-hoc Fisher's least significant difference (LSD) test have shown great promise in the KF-based microphone array signal processing techniques.

  16. A Fully On-Chip Gm-Opamp-RC Based Preamplifier for Electret Condenser Microphones

    Science.gov (United States)

    Le, Huy-Binh; Ryu, Seung-Tak; Lee, Sang-Gug

    An on-chip CMOS preamplifier for direct signal readout from an electret capacitor microphone has been designed with high immunity to common-mode and supply noise. The Gm-Opamp-RC based high impedance preamplifier helps to remove all disadvantages of the conventional JFET based amplifier and can drive a following switched-capacitor sigma-delta modulator in order to realize a compact digital electret microphone. The proposed chip is designed based on 0.18µm CMOS technology, and the simulation results show 86dB of dynamic range with 4.5µVrms of input-referred noise for an audio bandwidth of 20kHz and a total harmonic distortion (THD) of 1% at 90mVrms input. Power supply rejection ratio (PSRR) and common-mode rejection ration (CMRR) are more than 95dB at 1kHz. The proposed design dissipates 125µA and can operate over a wide supply voltage range of 1.6V to 3.3V.

  17. Wavenumber-frequency deconvolution of aeroacoustic microphone phased array data of arbitrary coherence

    Science.gov (United States)

    Bahr, Christopher J.; Cattafesta, Louis N.

    2016-11-01

    Deconvolution of aeroacoustic data acquired with microphone phased arrays is a computationally challenging task for distributed sources with arbitrary coherence. A new technique for performing such deconvolution is proposed. This technique relies on analysis of the array data in the wavenumber-frequency domain, allowing for fast convolution and reduced storage requirements when compared to traditional coherent deconvolution. A positive semidefinite constraint for the iterative deconvolution procedure is implemented and shows improved behavior in terms of quantifiable convergence metrics when compared to a standalone covariance inequality constraint. A series of simulations validates the method's ability to resolve coherence and phase angle relationships between partially coherent sources, as well as determines convergence criteria for deconvolution analysis. Simulations for point sources near the microphone phased array show potential for handling such data in the wavenumber-frequency domain. In particular, a physics-based integration boundary calculation is described, and can successfully isolate sources and track the appropriate integration bounds with and without the presence of flow. Magnitude and phase relationships between multiple sources are successfully extracted. Limitations of the deconvolution technique are determined from the simulations, particularly in the context of a simulated acoustic field in a closed test section wind tunnel with strong boundary layer contamination. A final application to a trailing edge noise experiment conducted in an open-jet wind tunnel matches best estimates of acoustic levels from traditional calculation methods and qualitatively assesses the coherence characteristics of the trailing edge noise source.

  18. Adaptation to New Microphones Using Artificial Neural Networks With Trainable Activation Functions.

    Science.gov (United States)

    Siniscalchi, Sabato Marco; Salerno, Valerio Mario

    2016-04-14

    Model adaptation is a key technique that enables a modern automatic speech recognition (ASR) system to adjust its parameters, using a small amount of enrolment data, to the nuances in the speech spectrum due to microphone mismatch in the training and test data. In this brief, we investigate four different adaptation schemes for connectionist (also known as hybrid) ASR systems that learn microphone-specific hidden unit contributions, given some adaptation material. This solution is made possible adopting one of the following schemes: 1) the use of Hermite activation functions; 2) the introduction of bias and slope parameters in the sigmoid activation functions; 3) the injection of an amplitude parameter specific for each sigmoid unit; or 4) the combination of 2) and 3). Such a simple yet effective solution allows the adapted model to be stored in a small-sized storage space, a highly desirable property of adaptation algorithms for deep neural networks that are suitable for large-scale online deployment. Experimental results indicate that the investigated approaches reduce word error rates on the standard Spoke 6 task of the Wall Street Journal corpus compared with unadapted ASR systems. Moreover, the proposed adaptation schemes all perform better than simple multicondition training and comparable favorably against conventional linear regression-based approaches while using up to 15 orders of magnitude fewer parameters. The proposed adaptation strategies are also effective when a single adaptation sentence is available.

  19. Estimation of Temporal Gait Parameters Using a Wearable Microphone-Sensor-Based System.

    Science.gov (United States)

    Wang, Cheng; Wang, Xiangdong; Long, Zhou; Yuan, Jing; Qian, Yueliang; Li, Jintao

    2016-12-17

    Most existing wearable gait analysis methods focus on the analysis of data obtained from inertial sensors. This paper proposes a novel, low-cost, wireless and wearable gait analysis system which uses microphone sensors to collect footstep sound signals during walking. This is the first time a microphone sensor is used as a wearable gait analysis device as far as we know. Based on this system, a gait analysis algorithm for estimating the temporal parameters of gait is presented. The algorithm fully uses the fusion of two feet footstep sound signals and includes three stages: footstep detection, heel-strike event and toe-on event detection, and calculation of gait temporal parameters. Experimental results show that with a total of 240 data sequences and 1732 steps collected using three different gait data collection strategies from 15 healthy subjects, the proposed system achieves an average 0.955 F1-measure for footstep detection, an average 94.52% accuracy rate for heel-strike detection and 94.25% accuracy rate for toe-on detection. Using these detection results, nine temporal related gait parameters are calculated and these parameters are consistent with their corresponding normal gait temporal parameters and labeled data calculation results. The results verify the effectiveness of our proposed system and algorithm for temporal gait parameter estimation.

  20. Estimation of Temporal Gait Parameters Using a Wearable Microphone-Sensor-Based System

    Directory of Open Access Journals (Sweden)

    Cheng Wang

    2016-12-01

    Full Text Available Most existing wearable gait analysis methods focus on the analysis of data obtained from inertial sensors. This paper proposes a novel, low-cost, wireless and wearable gait analysis system which uses microphone sensors to collect footstep sound signals during walking. This is the first time a microphone sensor is used as a wearable gait analysis device as far as we know. Based on this system, a gait analysis algorithm for estimating the temporal parameters of gait is presented. The algorithm fully uses the fusion of two feet footstep sound signals and includes three stages: footstep detection, heel-strike event and toe-on event detection, and calculation of gait temporal parameters. Experimental results show that with a total of 240 data sequences and 1732 steps collected using three different gait data collection strategies from 15 healthy subjects, the proposed system achieves an average 0.955 F1-measure for footstep detection, an average 94.52% accuracy rate for heel-strike detection and 94.25% accuracy rate for toe-on detection. Using these detection results, nine temporal related gait parameters are calculated and these parameters are consistent with their corresponding normal gait temporal parameters and labeled data calculation results. The results verify the effectiveness of our proposed system and algorithm for temporal gait parameter estimation.

  1. DFT-domain based single-microphone noise reduction for speech enhancement a survey of the state of the art

    CERN Document Server

    Hendriks, Richard C; Jensen, Jesper

    2013-01-01

    As speech processing devices like mobile phones, voice controlled devices, and hearing aids have increased in popularity, people expect them to work anywhere and at any time without user intervention. However, the presence of acoustical disturbances limits the use of these applications, degrades their performance, or causes the user difficulties in understanding the conversation or appreciating the device. A common way to reduce the effects of such disturbances is through the use of single-microphone noise reduction algorithms for speech enhancement.The field of single-microphone noise reducti

  2. A comparison measurement of nonlinear ultrasonic waves in tubes by a microphone and by an optical interferometric probe.

    Science.gov (United States)

    Slegrová, Zuzana; Bálek, Rudolf

    2005-03-01

    This paper deals with the analysis of ultrasonic fields inside waveguides generated by ultrasonic waves of high amplitude. These waves behave nonlinearly, so it is not possible to use standard linear equations to describe their behaviour. Therefore, we started with an experimental determination of the acoustic pressure of air in glass tubes. We chose two methods of measurement--by a microphone and by an optical interferometric probe. The conventional method by a microphone creates numerous problems, which can be avoided by using an optical method, a heterodyne laser interferometer.

  3. Light Dependent Resistance as a Sensor in Spectroscopy Setups Using Pulsed Light and Compared with Electret Microphones

    Directory of Open Access Journals (Sweden)

    Daniel Acosta-Avalos

    2006-05-01

    Full Text Available Light-dependent resistances (LDR are cheap light sensors. A less known lightdetector is the electret microphone, whose electret membrane functions as a perfectabsorber, but only detects pulsed light. The aim of this study was to analyze the use of aLDR and an electret microphone as a light sensor in an optical spectroscopy system usingpulsed light. A photoacoustic spectroscopy setup was used, substituting the photoacousticchamber by the light sensor proposed. The absorption spectra of two different liquids wereanalyzed. The results obtained allow the recommendation of the LDR as the first choice inthe construction of cheap homemade pulsed light spectroscopy systems.

  4. Fabrication and characterization of a smart epitaxial piezoelectric micromachined ultrasonic transducer

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, Katsuya [Department of Electrical and Electronic Information Engg, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Matin, Abdul, E-mail: matin.md.a@gmail.com [Department of Glass and Ceramic Engineering, Bangladesh University of Engg and Tech (BUET), Dhaka 1000 (Bangladesh); Numata, Yasuyuki [Department of Electrical and Electronic Information Engg, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Akai, Daisuke [Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology Toyohashi, Toyohahsi, Aichi 441-8580 (Japan); Sawada, Kazuaki; Ishida, Makoto [Department of Electrical and Electronic Information Engg, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology Toyohashi, Toyohahsi, Aichi 441-8580 (Japan)

    2014-12-15

    Highlights: • Highly [1 1 1] orientated functional PZT(1 1 1) thin film was grown on n-Si(1 1 1)/γ-Al{sub 2}O{sub 3}(1 1 1)/SrRuO{sub 3}(1 1 1). • Device performance of pMUT was studied using both experiment and modeling. • Material anisotropy played a significant role in the shifting of resonant frequency • pMUT shows high sensitivity for the transmission of ultrasonic pulses. • Successful realization of a piezoelectric ultrasonic transducer (pMUT) array. - Abstract: A novel piezoelectric micromachined ultrasonic transducer (pMUT) array was designed and fabricated using epitaxially grown functional Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) thin film on Si(1 1 1)/γ-Al{sub 2}O{sub 3}(1 1 1)/SrRuO{sub 3}(1 1 1) substrate for biomedical applications. The crystallographic orientation of PZT film was controlled by the incorporation of epitaxial γ-Al{sub 2}O{sub 3} film on Si substrate. Modal shape of pMUT was analyzed employing advanced 3D finite element modeling taking the crystallographic anisotropy of materials and the properties of immersed medium (air or water) into account. Eigenfrequency with mode shapes has shown to have significant influence on transmitting-receiving characteristics of pMUT. Modal shapes of pMUT were also quantitatively determined using Laser Doppler Vibratometry (LDV). An excellent correlation was obtained between computational and experimental results. A significantly high sensitivity of 3.9 μV/kPa was obtained in an under-water ultrasonic wave transmission experiment conducted using fabricated pMUT as wave transmitter and a commercial transducer as receiver at a fundamental frequency of 1.20 MHz. Advanced FE computation thus serves as a tool to a priori optimize device structure for the successful transmission of ultrasonic waves with sufficient power to generate high resolution 3D imaging.

  5. High aspect ratio transmission line circuits micromachined in silicon

    Science.gov (United States)

    Todd, Shane Truman

    The performance of complimentary metal-oxide-semiconductor (CMOS) monolithic microwave integrated circuits (MMICs) fabricated on silicon has improved dramatically. The scaling down of silicon transistors has increased the maximum frequency of transistors to the point where silicon MMICs have become a viable alternative to compound semiconductor MMICs in certain applications. A fundamental problem still exists in silicon MMICs however in that transmission lines fabricated on silicon can suffer from high loss due to the finite conductivity of the silicon substrate. A novel approach for creating low-loss transmission lines on silicon is presented in this work. Low-loss transmission lines are created on low resistivity silicon by using a micromachining method that combines silicon deep reactive ion etching (DRIE), thermal oxidation, electroplating, and planarization. Two types of high aspect ratio transmission lines are created with this method including high aspect ratio coplanar waveguide (hicoplanar) and semi-rectangular coaxial (semicoaxial). Transmission lines with impedances ranging from 20--80 O have been fabricated with minimum measured loss lower than 1 dB/cm at 67 GHz. Low-loss dielectrics are created for the high aspect ratio transmission lines using the mesa merging method. The mesa merging method works by creating silicon mesa arrays using DRIE and then converting and merging the mesa arrays into a solid oxide dielectric using thermal oxidation. The transmission lines are designed so that the fields penetrate the low-loss oxide dielectric and are isolated from the lossy silicon substrate. The mesa merging method has successfully created large volume oxide with depth up to 65 microm and width up to 240 microm in short oxidation times. Other advantages of the high aspect ratio transmission lines are demonstrated including low-loss over a wide impedance range, high isolation, and high coupling for coupled-line circuits. Transmission line models have been

  6. Fabrication of Micro/Nano Structures on Metals by Femtosecond Laser Micromachining

    Directory of Open Access Journals (Sweden)

    K. M. Tanvir Ahmmed

    2014-11-01

    Full Text Available Femtosecond laser micromachining has emerged in recent years as a new technique for micro/nano structure fabrication because of its applicability to virtually all kinds of materials in an easy one-step process that is scalable. In the past, much research on femtosecond laser micromachining was carried out to understand the complex ablation mechanism, whereas recent works are mostly concerned with the fabrication of surface structures because of their numerous possible applications. The state-of-the-art knowledge on the fabrication of these structures on metals with direct femtosecond laser micromachining is reviewed in this article. The effect of various parameters, such as fluence, number of pulses, laser beam polarization, wavelength, incident angle, scan velocity, number of scans, and environment, on the formation of different structures is discussed in detail wherever possible. Furthermore, a guideline for surface structures optimization is provided. The authors’ experimental work on laser-inscribed regular pattern fabrication is presented to give a complete picture of micromachining processes. Finally, possible applications of laser-machined surface structures in different fields are briefly reviewed.

  7. Long-life micro vacuum chamber for a micromachined cryogenic cooler

    NARCIS (Netherlands)

    Cao, H.; Vermeer, C.H.; Vanapalli, S.; Holland, H.J.; Brake, ter H.J.M.

    2015-01-01

    Micromachined cryogenic coolers can be used for cooling small electronic devices to improve their performance. However, for reaching cryogenic temperatures, they require a very good thermal insulation from the warm environment. This is established by a vacuum space that for adequate insulation has t

  8. New technique for fabrication of high frequency piezoelectric Micromachined Ultrasound Transducers

    DEFF Research Database (Denmark)

    Pedersen, T; Thomsen, Erik Vilain; Zawada, T;

    2008-01-01

    A novel technique for fabrication of linear arrays of high frequency piezoelectric Micromachined Ultrasound Transducers (pMUT) on silicon substrates is presented. Piezoelectric elements are formed by deposition of PZT ((PbZrxTi1-x)O3) into etched features of the silicon substrate...

  9. Analysis of Drift Errors in the JPL/UCLA Micromachined Gyroscope

    Science.gov (United States)

    Chakraborty, I.

    1996-01-01

    The model of the JPL/UCLA micromachined vibratory gyroscope will be enhanced to include time varying effects. First, they will be shown to exist through trends in the experimental results. Causes of mechanical error will be further explained by analyzing possible perturbations to the physical model.

  10. Coupling of a CMOS Optical Sensor to a Micromachined Deformable Mirror with an Adaline Neural Method

    NARCIS (Netherlands)

    De Lima Monteiro, D.W.; Ferreira, A.I.; Teixeira, F.B.; Melo, J.G.M.; Vdovin, G.V.

    2006-01-01

    We report on the preliminary results of an Adaline neural method for the coupling of a custom CMOS wavefront sensor to a micromachined adaptive mirror. The algorithm does not rely on a fixed basis matrix -as opposed to traditional methods-, offers excellent immunity to round-off errors and admits re

  11. Optical micro-metrology of structured surfaces micro-machined by jet-ECM

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Tosello, Guido; Islam, Aminul

    2015-01-01

    A procedure for statistical analysis and uncertainty evaluation is presented with regards to measurements of step height and surface texture. Measurements have been performed with a focus-variation microscope over jet electrochemical micro-machined surfaces. Traceability has been achieved using...

  12. Optical micro-metrology of structured surfaces micro-machined by jet-ECM

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Tosello, Guido; Islam, Aminul

    A procedure for statistical analysis and uncertainty evaluation is presented with regards to measurements of step height and surface texture. Measurements have been performed with a focus-variation microscope over jet electrochemical micro-machined surfaces. Traceability has been achieved using...

  13. Deflection and maximum load of microfiltration membrane sieve made with silicon micromachining

    NARCIS (Netherlands)

    Rijn, van Cees; Wekken, van der Michiel; Nijdam, Wietze; Elwenspoek, Miko

    1997-01-01

    With the use of silicon micromachining, an inorganic membrane sieve for microfiltration has been constructed having a silicon nitride membrane layer with thickness typically 1 ¿m and perforations typically between 0.5 ¿m and 10 ¿m in diameter. As a support a ¿100¿-silicon wafer with openings of 1000

  14. Micro-machining workstation for a diode pumped Nd:YAG high-brightness laser system

    NARCIS (Netherlands)

    Kleijhorst, R.A.; Offerhaus, H.L.; Bant, P.

    1998-01-01

    A Nd:YAG micro-machining workstation that allows cutting on a scale of a few microns has been developed and operated. The system incorporates a telescope viewing system that allows control during the work and a software interface to translate AutoCad files. Some examples of the performance are given

  15. Micromachined vertical Hall magnetic field sensor in standard complementary metal oxide semiconductor technology

    Science.gov (United States)

    Paranjape, M.; Ristic, Lj.

    1992-06-01

    A novel 2D micromachined vertical Hall magnetic field sensor structure has been designed and fabricated using a commercially available 3 micron CMOS process. The device can detect two magnetic field components in the plane of the chip surface. The sensor exhibits a linear response and shows no cross-sensitivity between channels.

  16. Advanced Mechatronics and MEMS Devices

    CERN Document Server

    2013-01-01

    Advanced Mechatronics and MEMS Devicesdescribes state-of-the-art MEMS devices and introduces the latest technology in electrical and mechanical microsystems. The evolution of design in microfabrication, as well as emerging issues in nanomaterials, micromachining, micromanufacturing and microassembly are all discussed at length in this volume. Advanced Mechatronics also provides a reader with knowledge of MEMS sensors array, MEMS multidimensional accelerometer, artificial skin with imbedded tactile components, as well as other topics in MEMS sensors and transducers. The book also presents a number of topics in advanced robotics and an abundance of applications of MEMS in robotics, like reconfigurable modular snake robots, magnetic MEMS robots for drug delivery and flying robots with adjustable wings, to name a few. This book also: Covers the fundamentals of advanced mechatronics and MEMS devices while also presenting new state-of-the-art methodology and technology used in the application of these devices Prese...

  17. Motherboards, Microphones and Metaphors: Re-Examining New Literacies and Black Feminist Thought through Technologies of Self

    Science.gov (United States)

    Ellison, Tisha Lewis; Kirkland, David E.

    2014-01-01

    This article examines how two African American females composed counter-selves using a computer motherboard and a stand-alone microphone as critical identity texts. Situated within sociocultural and critical traditions in new literacy studies and black feminist thought, the authors extend conceptions of language, literacy and black femininity via…

  18. A numerical study of the random-incidence and diffuse-field sensitivity of laboratory standard microphones using BEM

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Henriquez, Vicente Cutanda; Jacobsen, Finn

    2006-01-01

    room. It is widely accepted that the two definitions are equivalent. The purpose of this paper is to examine this equivalence using numerical simulations. A laboratory standard microphone can be considered rotationally symmetrical around the axis; thus, an axi-symmetric formulation of the Boundary...

  19. Practically Efficient Blind Speech Separation Using Frequency Band Selection Based on Magnitude Squared Coherence and a Small Dodecahedral Microphone Array

    Directory of Open Access Journals (Sweden)

    Kazunobu Kondo

    2012-01-01

    Full Text Available Small agglomerative microphone array systems have been proposed for use with speech communication and recognition systems. Blind source separation methods based on frequency domain independent component analysis have shown significant separation performance, and the microphone arrays are small enough to make them portable. However, the level of computational complexity involved is very high because the conventional signal collection and processing method uses 60 microphones. In this paper, we propose a band selection method based on magnitude squared coherence. Frequency bands are selected based on the spatial and geometric characteristics of the microphone array device which is strongly related to the dodecahedral shape, and the selected bands are nonuniformly spaced. The estimated reduction in the computational complexity is 90% with a 68% reduction in the number of frequency bands. Separation performance achieved during our experimental evaluation was 7.45 (dB (signal-to-noise ratio and 2.30 (dB (cepstral distortion. These results show improvement in performance compared to the use of uniformly spaced frequency band.

  20. Application of a circular 2D hard-sphere microphone array for higher-order Ambisonics auralization

    DEFF Research Database (Denmark)

    Weller, Tobias; Favrot, Sylvain Emmanuel; Buchholz, Jörg

    2011-01-01

    A circular microphone array mounted on a rigid sphere was realized and its application to higherorder Ambisonics (HOA) auralization was analysed. Besides the 2D Ambisonics application this array design provides a promising basis for the development of a mixed-order Ambisonics recording system...

  1. A novel vibration mode testing method for cylindrical resonators based on microphones.

    Science.gov (United States)

    Zhang, Yongmeng; Wu, Yulie; Wu, Xuezhong; Xi, Xiang; Wang, Jianqiu

    2015-01-16

    Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.

  2. A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones

    Directory of Open Access Journals (Sweden)

    Yongmeng Zhang

    2015-01-01

    Full Text Available Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.

  3. Compressive sensing based spinning mode detections by in-duct microphone arrays

    Science.gov (United States)

    Yu, Wenjun; Huang, Xun

    2016-05-01

    This paper presents a compressive sensing based experimental method for detecting spinning modes of sound waves propagating inside a cylindrical duct system. This method requires fewer dynamic pressure sensors than the number required by the Shannon-Nyquist sampling theorem so long as the incident waves are sparse in spinning modes. In this work, the proposed new method is firstly validated by preparing some of the numerical simulations with representative set-ups. Then, a duct acoustic testing rig with a spinning mode synthesiser and an in-duct microphone array is built to experimentally demonstrate the new approach. Both the numerical simulations and the experiment results are satisfactory, even when the practical issue of the background noise pollution is taken into account. The approach is beneficial for sensory array tests of silent aeroengines in particular and some other engineering systems with duct acoustics in general.

  4. Detecting Multi-ChannelWireless Microphone User Emulation Attacks in White Space with Noise

    Directory of Open Access Journals (Sweden)

    Dan Shan

    2014-07-01

    Full Text Available Cognitive radio networks (CRNs are susceptible to primary user emulation (PUE attacks. Conventional PUE attack detection approaches consider television broadcasting as the primary user. In this work, however, we study a special kind of PUE attack named wireless microphone user emulation (WMUE attack. Existing work on WMUE attack detection deals with single channel senario. Although multi-channelWM(MCWM systems are common, detecting WMUE attacks under a multi-channel setting in noisy environments has not been well studied. In this work, we propose a novelmulti-channelWMUEattack detection scheme which operates in low signal-to-noise ratio (SNR environments with low computational complexity, thanks to the first 1.5-bit FM demodulator whose outputs are represented by only 0, 1 and -1. Experimental results show that, the proposed scheme can effectively detect multi-channel WMUE attacks within 0.25 second when SNR is lower than 6 dB.

  5. Estimation of Road Vehicle Speed Using Two Omnidirectional Microphones: A Maximum Likelihood Approach

    Directory of Open Access Journals (Sweden)

    López-Valcarce Roberto

    2004-01-01

    Full Text Available We address the problem of estimating the speed of a road vehicle from its acoustic signature, recorded by a pair of omnidirectional microphones located next to the road. This choice of sensors is motivated by their nonintrusive nature as well as low installation and maintenance costs. A novel estimation technique is proposed, which is based on the maximum likelihood principle. It directly estimates car speed without any assumptions on the acoustic signal emitted by the vehicle. This has the advantages of bypassing troublesome intermediate delay estimation steps as well as eliminating the need for an accurate yet general enough acoustic traffic model. An analysis of the estimate for narrowband and broadband sources is provided and verified with computer simulations. The estimation algorithm uses a bank of modified crosscorrelators and therefore it is well suited to DSP implementation, performing well with preliminary field data.

  6. High frequency microphone measurements for transition detection on airfoils. NACA-0015 appendix report

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given...... to transition detection. It is argued that the transition point can be detected by observing the increase in the mean of the Fourier spectre and that thismethod is very stable froma numerical point of view. Other important issues are also discussed, e.g. the variation of pressure standard deviations (sound...... pressure) and Tollmien-Schlichting frequencies. The tests were made at Reynolds and Mach numbers corresponding to the operating conditions of a typical horizontal axis wind turbine (HAWT). The Risø B1-18, Risø C2-18 and NACA0015 profiles were tested and the measured transition points are reported....

  7. Infrastructure-Less Indoor Localization Using the Microphone, Magnetometer and Light Sensor of a Smartphone.

    Science.gov (United States)

    Galván-Tejada, Carlos E; García-Vázquez, Juan Pablo; Galván-Tejada, Jorge I; Delgado-Contreras, J Rubén; Brena, Ramon F

    2015-08-18

    In this paper, we present the development of an infrastructure-less indoor location system (ILS), which relies on the use of a microphone, a magnetometer and a light sensor of a smartphone, all three of which are essentially passive sensors, relying on signals available practically in any building in the world, no matter how developed the region is. In our work, we merge the information from those sensors to estimate the user's location in an indoor environment. A multivariate model is applied to find the user's location, and we evaluate the quality of the resulting model in terms of sensitivity and specificity. Our experiments were carried out in an office environment during summer and winter, to take into account changes in light patterns, as well as changes in the Earth's magnetic field irregularities. The experimental results clearly show the benefits of using the information fusion of multiple sensors when contrasted with the use of a single source of information.

  8. Detecting impacts of sand grains with a microphone system in field conditions

    Science.gov (United States)

    Ellis, Jean T.; Morrison, Rebecca F.; Priest, Barry H.

    2009-04-01

    This paper describes the "miniphone," an instrument to measure aeolian saltation. This instrument is a modified electret microphone that detects the impacts of individual grains. The unidirectional miniphone is inexpensive (approximately US$10), small, and poses minimal disruption to the wind field. It can be sampled at rates up to 44,100 Hz using commonly available sound card technology or it can be interfaced with a data acquisition system. Data from deployments on beaches on Marco Island, FL, USA and near Shoalhaven Heads, NSW, Australia using sample rates of 44,100 Hz and 6000 Hz, are presented. An algorithm for identifying discrete impacts of grains is described. The number of saltation impacts was not reduced when sub-sampling a record from 44,100 Hz to 6000 Hz. The most immediate use for the miniphone is for short-term deployments to detect unsteadiness in the saltation field.

  9. Directional microphone arrays: Reducing wind noise without killing your signal or filling up your disk

    Science.gov (United States)

    Zumberge, M. A.; Walker, K. T.; Dewolf, S.; Hedlin, M. A.; Shearer, P. M.; Berger, J.

    2008-12-01

    The bane of infrasound signal detection is the noise generated by the wind. While the physics of the noise is still a subject of investigation, it is clear that sampling pressure at many points over a length scale larger than the spatial coherence length of wind turbulence attenuates the noise. A dense array of microphones can exploit this approach, but this presents different challenges. Two mechanical wind filters using this approach are commonly employed by the nuclear monitoring community (rosette pipe and porous-hoses networks) and attach to a central microphone. To get large wind noise reduction and a low signal detection threshold in the frequency band of interest, these filters require large apertures. However, these wind filters with such large apertures have a poor omnidirectional instrument response for typical infrasound signals because the pressure signal propagates at the speed of sound through the pipes/hoses to the central microphone. A simple, but improved averaging approach would be to instantaneously sample a long length of the infrasound signal wavefront. Optical fiber infrasound sensors (OFIS) are an implementation of this idea. These sensors are compliant sealed tubes wrapped with two optical fibers that integrate pressure change instantaneously along the length of the tube with laser interferometery. Infrasound arrays typically consist of several microbarometers with wind filters separated by distances that provide predictable signal time separations, forming the basis for processing techniques that estimate the phase velocity direction. An analogous approach is to form an array of OFIS arms. The OFIS instrument response is a predictable function of the orientation of the arm with respect to the signal wavefront. An array of many OFIS arms with different azimuths permits at least one OFIS to record any signal without the signal attenuation inherent in equivalently-sized onmi-directional mechanical filters. OFIS arms that are wavefront

  10. Ad Hoc Microphone Array Beamforming Using the Primal-Dual Method of Multipliers

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Heusdens, Richard;

    2016-01-01

    In the recent years, there have been increasing amount of researches aiming at optimal beamforming with ad hoc microphone arrays, mostly with fusion-based schemes. However, huge amount of computational complexity and communication overhead impede many of these algorithms from being useful...... in practice. In this paper, we propose a low-footprint optimization approach to reduce the convergence time and overheads for the convex beamforming problem. We transcribe the beamforming with pseudo-coherence-based formulation which is insightful for taking into account the nature of speech. We formulate...... the distributed linearly-constrained minimum variance beamformer using the the state of the art primal-dual method of multipliers. We study the proposed algorithm with an experiment....

  11. Design of an Acoustic Target Intrusion Detection System Based on Small-Aperture Microphone Array

    Science.gov (United States)

    Zu, Xingshui; Guo, Feng; Huang, Jingchang; Zhao, Qin; Liu, Huawei; Li, Baoqing; Yuan, Xiaobing

    2017-01-01

    Automated surveillance of remote locations in a wireless sensor network is dominated by the detection algorithm because actual intrusions in such locations are a rare event. Therefore, a detection method with low power consumption is crucial for persistent surveillance to ensure longevity of the sensor networks. A simple and effective two-stage algorithm composed of energy detector (ED) and delay detector (DD) with all its operations in time-domain using small-aperture microphone array (SAMA) is proposed. The algorithm analyzes the quite different velocities between wind noise and sound waves to improve the detection capability of ED in the surveillance area. Experiments in four different fields with three types of vehicles show that the algorithm is robust to wind noise and the probability of detection and false alarm are 96.67% and 2.857%, respectively. PMID:28273838

  12. Deconvolution for the localization of sound sources using a circular microphone array

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Jacobsen, Finn

    2013-01-01

    During the last decade, the aeroacoustic community has examined various methods based on deconvolution to improve the visualization of acoustic fields scanned with planar sparse arrays of microphones. These methods assume that the beamforming map in an observation plane can be approximated...... by a convolution of the distribution of the actual sources and the beamformer's point-spread function, defined as the beamformer's response to a point source. By deconvolving the resulting map, the resolution is improved, and the side-lobes effect is reduced or even eliminated compared to conventional beamforming....... Even though these methods were originally designed for planar sparse arrays, in the present study, they are adapted to uniform circular arrays for mapping the sound over 360°. This geometry has the advantage that the beamforming output is practically independent of the focusing direction, meaning...

  13. How to measure snoring? A comparison of the microphone, cannula and piezoelectric sensor.

    Science.gov (United States)

    Arnardottir, Erna S; Isleifsson, Bardur; Agustsson, Jon S; Sigurdsson, Gunnar A; Sigurgunnarsdottir, Magdalena O; Sigurđarson, Gudjon T; Saevarsson, Gudmundur; Sveinbjarnarson, Atli T; Hoskuldsson, Sveinbjorn; Gislason, Thorarinn

    2016-04-01

    The objective of this study was to compare to each other the methods currently recommended by the American Academy of Sleep Medicine (AASM) to measure snoring: an acoustic sensor, a piezoelectric sensor and a nasal pressure transducer (cannula). Ten subjects reporting habitual snoring were included in the study, performed at Landspitali-University Hospital, Iceland. Snoring was assessed by listening to the air medium microphone located on a patient's chest, compared to listening to two overhead air medium microphones (stereo) and manual scoring of a piezoelectric sensor and nasal cannula vibrations. The chest audio picked up the highest number of snore events of the different snore sensors. The sensitivity and positive predictive value of scoring snore events from the different sensors was compared to the chest audio: overhead audio (0.78, 0.98), cannula (0.55, 0.67) and piezoelectric sensor (0.78, 0.92), respectively. The chest audio was capable of detecting snore events with lower volume and higher fundamental frequency than the other sensors. The 200 Hz sampling rate of the cannula and piezoelectric sensor was one of their limitations for detecting snore events. The different snore sensors do not measure snore events in the same manner. This lack of consistency will affect future research on the clinical significance of snoring. Standardization of objective snore measurements is therefore needed. Based on this paper, snore measurements should be audio-based and the use of the cannula as a snore sensor be discontinued, but the piezoelectric sensor could possibly be modified for improvement.

  14. Advanced characterization of carrier profiles in germanium using micro-machined contact probes

    DEFF Research Database (Denmark)

    Clarysse, T.; Konttinen, M.; Parmentier, B.;

    2012-01-01

    The accurate determination of the sheet resistance and carrier depth profile, i.e. active dopant profile, of shallow junction isolated structures involving new high mobility materials, such as germanium, is a crucial topic for future CMOS development. In this work, we discuss the capabilities...... of new concepts based on micro machined, closely spaced contact probes (10 μm pitch). When using four probes to perform sheet resistance measurements, a quantitative carrier profile extraction based on the evolution of the sheet resistance versus depth along a beveled surface is obtained. Considering...... the use of only two probes, a spreading resistance like setup is obtained with small spacing and drastically reduced electrical contact radii (~10 nm) leading to a substantial reduction of the correction factors which are normally required for converting spreading resistance profiles. We demonstrate...

  15. An Advanced Micromachined Package for the Quartz Disk Resonant Gyroscope Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this proposal is to demonstrate the feasibility of a fully packaged microelectromechanical (MEMS) gyroscope with a 7 milliarcsecond pointing...

  16. Deep and vertical silicon bulk micromachining using metal assisted chemical etching

    Science.gov (United States)

    Zahedinejad, Mohammad; Delaram Farimani, Saeed; Khaje, Mahdi; Mehrara, Hamed; Erfanian, Alireza; Zeinali, Firooz

    2013-05-01

    In this paper, a newfound and simple silicon bulk micromachining process based on metal-assisted chemical etching (MaCE) is proposed which opens a whole new field of research in MEMS technology. This method is anisotropic and by controlling the etching parameters, deep vertical etching, relative to substrate surface, can be achieved in micrometer size for oriented Si wafer. By utilizing gold as a catalyst and a photoresist layer as the single mask layer for etching, 60 µm deep gyroscope micromachined structures have been fabricated for 2 µm features. The results indicate that MaCE could be the only wet etching method comparable to conventional dry etching recipes in terms of achievable etch rate, aspect ratio, verticality and side wall roughness. It also does not need a vacuum chamber and the other costly instruments associated with dry etching techniques.

  17. Nanoelectrospray ion generation for high-throughput mass spectrometry using a micromachined ultrasonic ejector array

    Science.gov (United States)

    Aderogba, S.; Meacham, J. M.; Degertekin, F. L.; Fedorov, A. G.; Fernandez, F. M.

    2005-05-01

    Ultrasonic electrospray ionization (ESI) for high-throughput mass spectrometry is demonstrated using a silicon micromachined microarray. The device uses a micromachined ultrasonic atomizer operating in the 900kHz-2.5MHz range for droplet generation and a metal electrode in the fluid cavity for ionization. Since the atomization and ionization processes are separated, the ultrasonic ESI source shows the potential for operation at low voltages with a wide range of solvents in contrast with conventional capillary ESI technology. This is demonstrated using the ultrasonic ESI microarray to obtain the mass spectrum of a 10μM reserpine sample on a time of flight mass spectrometer with 197:1 signal-to-noise ratio at an ionization potential of 200V.

  18. Towards fast femtosecond laser micromachining of fused silica: The effect of deposited energy.

    Science.gov (United States)

    Rajesh, Sheeba; Bellouard, Yves

    2010-09-27

    Femtosecond laser micromachining of glass material using low-energy, sub-ablation threshold pulses find numerous applications in the fields of integrated optics, lab-on-a-chips and microsystems in general. In this paper, we study the influence of the laser-deposited energy on the performance of the micromachining process. In particular, we show that the energy deposited in the substrate affects its etching rate. Furthermore, we demonstrate the existence of an optimal energy deposition value. These results are not only important from an industrial point-of-view but also provide new evidences supporting the essential role of densification and consequently stress-generation as the main driving factor promoting enhanced etching rate following laser exposure.

  19. Digital Readout System for Micromachined Gyroscope and Analysis for its Demodulation Algorithm

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bin; GAO Zhong-yu; CHEN Huai; ZHANG Rong; CHEN Zhi-yong

    2006-01-01

    A new digital readout system for micromachined gyroscope has been proposed to implement flexible parameter adiustment,improve the control performance of gyroscope,and make error compensation.By digitalizing the output of the gyroscope,this system uses a floatingtype digital signal processor(DSP)to process the signal demodulation and achieve the feedback conffol of the gyroscope.Therefore.the small change of capacitance in the micromachined gyroscope Can be detected.A new demodulation algorithm of least mean square demodulation(LMSD)has been developed inside DSP Simulation and measurement results show that LMSD Can improve 29%of the noise performance compared with the typical multiplication method.In air pressure.a kind ofvibration-wheel micmmachined over the 100-Hz bandwidth by using this digital readout technology.

  20. Modelling of micromachining of human tooth enamel by erbium laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Belikov, A V; Skrypnik, A V; Shatilova, K V [St. Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg (Russian Federation)

    2014-08-31

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained. (laser biophotonics)

  1. ON-LINE SELF-TESTING FOR MICRO-MACHINED GYROSCOPES

    Institute of Scientific and Technical Information of China (English)

    GAISSERAlexander; GAOZhong-yu; ZHANGRong; CHENZhi-yong; ZHOUBin

    2005-01-01

    An on line self-testing for Coriolis vibratory gyroscopes (CVGs) is realized according to a digital readout electronics for capacitive sensors and micro-machined angular rate sensors. By applying some additional signals to the micro machined structure, the actual noise performance (<0.1°/s) is not worsened. The running of the primary and the secondary oscillators of CVGs is verified by self-testing. Compared with other methods, the device needs not to check the functionality. In this new approach the on-line testing is conducted at any time without disturbing the normal operational mode. Based on the approach the performance of the micro machined gyroscope can be improved and a secure availability of the functionality of the micro-machined angular rate sensor is guaranteed. Furthermore, the error signal is generated when the sensor works incorrectly.

  2. Design and Performance of a Focus-Detection System for Use in Laser Micromachining

    Directory of Open Access Journals (Sweden)

    Binh Xuan Cao

    2016-01-01

    Full Text Available We describe a new approach for locating the focal position in laser micromachining. This approach is based on a feedback system that uses a charge-coupled device (CCD camera, a beam splitter, and a mirror to focus a laser beam on the surface of a work piece. We tested the proposed method for locating the focal position by using Zemax simulations, as well as physically carrying out drilling processes. Compared with conventional methods, this approach is advantageous because: the implementation is simple, the specimen can easily be positioned at the focal position, and the dynamically adjustable scan amplitude and the CCD camera can be used to monitor the laser beam’s profile. The proposed technique will be particularly useful for locating the focal position on any surface in laser micromachining.

  3. Fabrication of three-dimensional microdisk resonators in calcium fluoride by femtosecond laser micromachining

    CERN Document Server

    Lin, Jintian; Tang, Jialei; Wang, Nengwen; Song, Jiangxin; He, Fei; Fang, Wei; Cheng, Ya

    2014-01-01

    We report on fabrication of on-chip calcium fluoride (CaF2) microdisk resonators using water-assisted femtosecond laser micromachining. Focused ion beam (FIB) milling is used to create ultra-smooth sidewalls. The quality (Q)-factors of the fabricated microresonators are measured to be 4.2x10^4 at wavelengths near 1550 nm. The Q factor is mainly limited by the scattering from the bottom surface of the disk whose roughness remains high due to the femtosecond laser micromachining process. This technique facilitates formation of on-chip microresonators on various kinds of bulk crystalline materials, which can benefit a wide range of applications such as nonlinear optics, quantum optics, and chip-level integration of photonic devices.

  4. A Laser Fabrication of Magnetic Micromachines by Using Optimized Photosensitive Ferrofluids

    Directory of Open Access Journals (Sweden)

    Ye Tian

    2016-01-01

    Full Text Available We report here a laser fabrication of magnetic micromachines by using optimized photosensitive ferrofluids. Fe3O4 nanoparticles were prepared by thermal decomposition and subsequent ligand exchange. And then, they were dispersed into photoresist. As a representative illustration, a magnetic microturbine with high surface flatness was fabricated, and its rotation speed could reach as high as 400 rpm under revolving magnetic field.

  5. A resonant miniature electric field sensor using bulk-micromachining process

    Institute of Scientific and Technical Information of China (English)

    DENG Kai; XIA Shanhong; GONG Chao; PENG Chunrong; TAO Hu; BAI Qiang; CHEN Shaofeng

    2005-01-01

    A novel design of a resonant miniature electric field sensor based on microfabrication technology is proposed. The operating principles and specifications, the design structure, and the silicon-based bulk-micromachining fabrication process are presented. The finite element simulation shows that our design can obtain good results in device parameters setting, and its simplicity and low-cost features make it an attractive product for future applications.

  6. The effect of frequency on the lifetime of a surface micromachined microengine driving a load

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, D.M.; Miller, W.M.; Eaton, W.P.; Irwin, L.W.; Peterson, K.A.; Dugger, M.T.; Senft, D.C.; Smith, N.F.; Tangyunyong, P.; Miller, S.L.

    1998-03-01

    Experiments have been performed on surface micromachined microengines driving load gears to determine the effect of the rotation frequency on median cycles to failure. The authors did observe a frequency dependence and have developed a model based on fundamental wear mechanisms and forces exhibited in resonant mechanical systems. Stressing loaded microengines caused observable wear in the rotating joints and in a few instances led to fracture of the pin joint in the drive gear.

  7. Feedback Control of Vibrations in a Micromachined Cantilever Beam with Electrostatic Actuators

    Science.gov (United States)

    Wang, P. K. C.

    1998-06-01

    The problem of feedback control of vibrations in a micromachined cantilever beam with nonlinear electrostatic actuators is considered. Various forms of nonlinear feedback controls depending on localized spatial averages of the beam velocity and displacement near the beam tip are derived by considering the time rate-of-change of the total energy of the beam. The physical implementation of the derived feedback controls is discussed briefly. The dynamic behaviour of the beam with the derived feedback controls is determined by computer simulation.

  8. Friction Reduction of Chrome-Coated Surface with Micro-Dimple Arrays Generated by Electrochemical Micromachining

    Science.gov (United States)

    Chen, Xiaolei; Qu, Ningsong; Hou, Zhibao; Wang, Xiaolei; Zhu, Di

    2017-02-01

    Surface coating and surface texture play a significant role in enhancing the tribological properties of mechanical components. In this study, to further improve the tribological properties of a chrome-coated surface, arrays of circular- and square-shaped micro-dimples were generated on chrome-coated surfaces via electrochemical machining. Through-mask electrochemical micromachining (TMEMM) is a popular electrochemical micromachining method for generating micro-dimple arrays. However, photolithography is a necessary process in conventional TMEMM before electrochemical micromachining, which is time-consuming and expensive when used in mass production. A reusable polydimethylsiloxane mask was introduced to prepare the micro-dimples. Circular micro-dimples of 120 μm diameter and square micro-dimples of 106 μm side length were fabricated on a chrome-coated surface. The results of friction tests indicated that at a load of 220 N, 10 μm deep micro-dimples reduced the coefficient of friction (CoF) significantly compared to an untextured surface. At a load of 320 and 420 N, the CoF continually decreased when the depth of the micro-dimples was increased from 0 to 20 μm. In addition, the results showed that, compared to circular micro-dimples, square micro-dimples contributed to a higher friction reduction ratio under the same conditions. The best friction reduction ratio was found for square dimples with a depth of 20 μm.

  9. Micromachined high frequency PMN-PT/epoxy 1-3 composite ultrasonic annular array.

    Science.gov (United States)

    Liu, Changgeng; Djuth, Frank; Li, Xiang; Chen, Ruimin; Zhou, Qifa; Shung, K Kirk

    2012-04-01

    This paper reports the design, fabrication, and performance of miniature micromachined high frequency PMN-PT/epoxy 1-3 composite ultrasonic annular arrays. The PMN-PT single crystal 1-3 composites were made with micromachining techniques. The area of a single crystal pillar was 9×9 μm. The width of the kerf among pillars was ∼5 μm and the kerfs were filled with a polymer. The composite thickness was 25 μm. A six-element annular transducer of equal element area of 0.2 mm(2) with 16 μm kerf widths between annuli was produced. The aperture size the array transducer is about 1.5 mm in diameter. A novel electrical interconnection strategy for high density array elements was implemented. After the transducer was attached to the electric connection board and packaged, the array transducer was tested in a pulse/echo arrangement, whereby the center frequency, bandwidth, two-way insertion loss (IL), and cross talk between adjacent elements were measured for each annulus. The center frequency was 50 MHz and -6 dB bandwidth was 90%. The average insertion loss was 19.5 dB at 50 MHz and the crosstalk between adjacent elements was about -35 dB. The micromachining techniques described in this paper are promising for the fabrication of other types of high frequency transducers, e.g. 1D and 2D arrays.

  10. Measurement of Phase Difference for Micromachined Gyros Driven by Rotating Aircraft

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2013-08-01

    Full Text Available This paper presents an approach for realizing a phase difference measurement of a new gyro. A silicon micromachined gyro was mounted on rotating aircraft for aircraft attitude control. Aircraft spin drives the silicon pendulum of a gyro rotating at a high speed so that it can sense the transverse angular velocity of the rotating aircraft based on the gyroscopic precession principle when the aircraft has transverse rotation. In applications of the rotating aircraft single channel control system, such as damping in the attitude stabilization loop, the gyro signal must be kept in sync with the control signal. Therefore, the phase difference between both signals needs to be measured accurately. Considering that phase difference is mainly produced by both the micromachined part and the signal conditioning circuit, a mathematical model has been established and analyzed to determine the gyro’s phase frequency characteristics. On the basis of theoretical analysis, a dynamic simulation has been done for a case where the spin frequency is 15 Hz. Experimental results with the proposed measurement method applied to a silicon micromachined gyro driven by a rotating aircraft demonstrate that it is effective in practical applications. Measured curve and numerical analysis of phase frequency characteristic are in accordance, and the error between measurement and simulation is only 5.3%.

  11. Enhancing structural integrity of adhesive bonds through pulsed laser surface micro-machining

    KAUST Repository

    Diaz, Edwin Hernandez

    2015-06-01

    Enhancing the effective peel resistance of plastically deforming adhesive joints through laser-based surface micro-machining Edwin Hernandez Diaz Inspired by adhesion examples commonly found in nature, we reached out to examine the effect of different kinds of heterogeneous surface properties that may replicate this behavior and the mechanisms at work. In order to do this, we used pulsed laser ablation on copper substrates (CuZn40) aiming to increase adhesion for bonding. A Yb-fiber laser was used for surface preparation of the substrates, which were probed with a Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). Heterogeneous surface properties were devised through the use of simplified laser micromachined patterns which may induce sequential events of crack arrest propagation, thereby having a leveraging effect on dissipation. The me- chanical performance of copper/epoxy joints with homogeneous and heterogeneous laser micromachined interfaces was then analyzed using the T-peel test. Fractured surfaces were analyzed using SEM to resolve the mechanism of failure and adhesive penetration within induced surface asperities from the treatment. Results confirm positive modifications of the surface morphology and chemistry from laser ablation that enable mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy, bond toughness, and effective peel force were appreciated with respect to sanded substrates as control samples.

  12. Monolithic geared-mechanisms driven by a polysilicon surface-micromachined on-chip electrostatic microengine

    Energy Technology Data Exchange (ETDEWEB)

    Sniegowski, J.J.; Miller, S.L.; LaVigne, G.F.; Rodgers, M.S.; McWhorter, P.J.

    1996-05-01

    We have previously described a practical micromachined power source: the polysilicon, surface-micromachined, electrostatically actuated microengine. Here we report on 3 aspects of implementing the microengine. First, we discuss demonstrations of the first-generation microengine actuating geared micromechanisms including gear trains with elements having dimensions comparable to the drive gear (about 50 {mu}m) and a relatively large (1600-{mu}m-diameter) rotating optical shutter element. These configurations span expected operating extremes for the microengine and address the coupling and loading issues for very-low-aspect-ratio micromechanisms which are common to the design of surface-micromachined devices. Second, we report on a second-generation of designs that utilize improved gear teeth design, a gear speed-reduction unit, and higher force-per-unit-area electrostatic comb drives. The speed-reduction unit produces an overall angular speed reduction of 9.63 and requires dual-level compound gears. Third, we discuss a dynamics model developed to accomplish 3 objectives: drive inertial loads in a controlled fashion, minimize stress and frictional forces during operation, and determine as a function of time the forces associated with the drive gear (eg load torque on drive gear from friction).

  13. Fiber laser micromachining of magnesium alloy tubes for biocompatible and biodegradable cardiovascular stents

    Science.gov (United States)

    Demir, Ali Gökhan; Previtali, Barbara; Colombo, Daniele; Ge, Qiang; Vedani, Maurizio; Petrini, Lorenza; Wu, Wei; Biffi, Carlo Alberto

    2012-02-01

    Magnesium alloys constitute an attractive solution for cardiovascular stent applications due to their intrinsic properties of biocompatibility and relatively low corrosion resistance in human-body fluids, which results in as a less intrusive treatment. Laser micromachining is the conventional process used to cut the stent mesh, which plays the key role for the accurate reproduction of the mesh design and the surface quality of the produced stent that are important factors in ensuring the mechanical and corrosion resistance properties of such a kind of devices. Traditionally continuous or pulsed laser systems working in microsecond pulse regime are employed for stent manufacturing. Pulsed fiber lasers on the other hand, are a relatively new solution which could balance productivity and quality aspects with shorter ns pulse durations and pulse energies in the order of mJ. This work reports the study of laser micromachining and of AZ31 magnesium alloy for the manufacturing of cardiovascular stents with a novel mesh design. A pulsed active fiber laser system operating in nanosecond pulse regime was employed for the micromachining. Laser parameters were studied for tubular cutting on a common stent material, AISI 316L tubes with 2 mm in diameter and 0.2 mm in thickness and on AZ31 tubes with 2.5 mm in diameter and 0.2 in thickness. In both cases process parameters conditions were examined for reactive and inert gas cutting solutions and the final stent quality is compared.

  14. A wafer mapping technique for residual stress in surface micromachined films

    Science.gov (United States)

    Schiavone, G.; Murray, J.; Smith, S.; Desmulliez, M. P. Y.; Mount, A. R.; Walton, A. J.

    2016-09-01

    The design of MEMS devices employing movable structures is crucially dependant on the mechanical behaviour of the deposited materials. It is therefore important to be able to fully characterize the micromachined films and predict with confidence the mechanical properties of patterned structures. This paper presents a characterization technique that enables the residual stress in MEMS films to be mapped at the wafer level by using microstructures released by surface micromachining. These dedicated MEMS test structures and the associated measurement techniques are used to extract localized information on the strain and Young’s modulus of the film under investigation. The residual stress is then determined by numerically coupling this data with a finite element analysis of the structure. This paper illustrates the measurement routine and demonstrates it with a case study using electrochemically deposited alloys of nickel and iron, particularly prone to develop high levels of residual stress. The results show that the technique enables wafer mapping of film non-uniformities and identifies wafer-to-wafer differences. A comparison between the results obtained from the mapping technique and conventional wafer bow measurements highlights the benefits of using a procedure tailored to films that are non-uniform, patterned and surface-micromachined, as opposed to simple standard stress extraction methods. The presented technique reveals detailed information that is generally unexplored when using conventional stress extraction methods such as wafer bow measurements.

  15. Modeling and Experimental Study on Characterization of Micromachined Thermal Gas Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Yan Su

    2010-09-01

    Full Text Available Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication.

  16. Compensating microphonics in SRF cavities to ensure beam stability for future free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Axel

    2008-07-21

    In seeded High-Gain-Harmonic-Generation free electron lasers or energy recovery linear accelerators the requirements for the bunch-to-bunch timing and energy jitter of the beam are in the femtosecond and per mill regime. This implies the ability to control the cavity radiofrequency (RF) field to an accuracy of 0.02 in phase and up to 1.10{sup -4} in amplitude. For the planned BESSY-FEL it is envisaged to operate 144 superconducting 1.3 GHz cavities of the 2.3 GeV driver linac in continuous wave mode and at a low beam current. The cavity resonance comprises a very narrow bandwidth of the order of tens of Hertz. Such cavities have been characterized under accelerator like conditions in the HoBiCaT test facility. It was possible to measure the error sources affecting the field stability in continuous wave (CW) operation. Microphonics, the main error source for a mechanical detuning of the cavities, lead to an average fluctuation of the cavity resonance of 1-5 Hz rms. Furthermore, the static and dynamic Lorentz force detuning and the helium pressure dependance of the cavity resonance have been measured. Single cavity RF control and linac bunch-to-bunch longitudinal phase space modeling containing the measured properties showed, that it is advisable to find means to minimize the microphonics detuning by mechanical tuning. Thus, several fast tuning systems have been tested for CW operation. These tuners consist of a motor driven lever for slow and coarse tuning and a piezo that is integrated into the tuner support for fast and fine tuning. Regarding the analysis of the detuning spectrum an adaptive feedforward method based on the least-mean-square filter algorithm has been developed for fast cavity tuning. A detuning compensation between a factor of two and up to a factor of seven has been achieved. Modeling the complete system including the fast tuning scheme, showed that the requirements of the BESSY-FEL are attainable. (orig.)

  17. Interface for Barge-in Free Spoken Dialogue System Based on Sound Field Reproduction and Microphone Array

    Directory of Open Access Journals (Sweden)

    Hinamoto Yoichi

    2007-01-01

    Full Text Available A barge-in free spoken dialogue interface using sound field control and microphone array is proposed. In the conventional spoken dialogue system using an acoustic echo canceller, it is indispensable to estimate a room transfer function, especially when the transfer function is changed by various interferences. However, the estimation is difficult when the user and the system speak simultaneously. To resolve the problem, we propose a sound field control technique to prevent the response sound from being observed. Combined with a microphone array, the proposed method can achieve high elimination performance with no adaptive process. The efficacy of the proposed interface is ascertained in the experiments on the basis of sound elimination and speech recognition.

  18. Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube

    CERN Document Server

    Doutres, Olivier; Atalla, Noureddine; Panneton, Raymond; 10.1016/j.apacoust.2010.01.007

    2010-01-01

    This paper presents a straightforward application of an indirect method based on a three-microphone impedance tube setup to determine the non-acoustic properties of a sound absorbing porous material. First, a three-microphone impedance tube technique is used to measure some acoustic properties of the material (i.e., sound absorption coefficient, sound transmission loss, effective density and effective bulk modulus) regarded here as an equivalent fluid. Second, an indirect characterization allows one to extract its non-acoustic properties (i.e., static airflow resistivity, tortuosity, viscous and thermal characteristic lengths) from the measured effective properties and the material open porosity. The procedure is applied to four different sound absorbing materials and results of the characterization are compared with existing direct and inverse methods. Predictions of the acoustic behavior using an equivalent fluid model and the found non-acoustic properties are in good agreement with impedance tube measureme...

  19. Real-ear measurements in conductive hearing loss: discrepancies between probe-tube microphone measurements and sound field test results.

    Science.gov (United States)

    Cleaver, V C

    1998-06-01

    This study was designed to investigate earlier observations that probe-tube microphone measurements of insertion gain overestimates the functional gain received from hearing aids by users with significant conductive hearing losses. This was originally thought to be due to artefacts in the probe-tube measurement caused by middle ear pathology, but is now believed to be the result of the bone conduction stimulation of the ear exposed to high intensities of airborne sound during sound field threshold measurements. Since the functional gain must relate to the true aided benefit in such cases, these findings suggest that probe-tube microphone measurements in ears with significant air-bone gaps should be interpreted with caution.

  20. Fiber-optical microphones and accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

    2010-01-01

    Polymer optical fibers (POFs) are ideal for applications as the sensing element in fiber-optical microphones and accelerometers based on fiber Bragg gratings (FBGs) due to their reduced Young’s Modulus of 3.2GPa, compared to 72GPa of Silica. To maximize the sensitivity and the dynamic range...... of the device the outer diameter and the length of the sensing fiber segment should be as small as possible. To this end we have fabricated 3mm FBGs in single-mode step-index POFs of diameter 115 micron, using 325nm UV writing and a phase-mask technique. 6mm POF sections with FBGs in the center have been glued...... to standard Silica SMF28 fibers. These POF FBGs have been characterized in terms of temperature and strain to find operating regimes with no hysteresis. Commercial fast wavelength interrogators (KHz) are shown to be able to track the thin POF FBGs and they are finally applied in a prototype accelerometer...

  1. Infrastructure-Less Indoor Localization Using the Microphone, Magnetometer and Light Sensor of a Smartphone

    Directory of Open Access Journals (Sweden)

    Carlos E. Galván-Tejada

    2015-08-01

    Full Text Available In this paper, we present the development of an infrastructure-less indoor location system (ILS, which relies on the use of a microphone, a magnetometer and a light sensor of a smartphone, all three of which are essentially passive sensors, relying on signals available practically in any building in the world, no matter how developed the region is. In our work, we merge the information from those sensors to estimate the user’s location in an indoor environment. A multivariate model is applied to find the user’s location, and we evaluate the quality of the resulting model in terms of sensitivity and specificity. Our experiments were carried out in an office environment during summer and winter, to take into account changes in light patterns, as well as changes in the Earth’s magnetic field irregularities. The experimental results clearly show the benefits of using the information fusion of multiple sensors when contrasted with the use of a single source of information.

  2. SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones

    Directory of Open Access Journals (Sweden)

    Moonen Marc

    2002-01-01

    Full Text Available We introduce a new SVD-based (Singular value decomposition strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998. The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII. The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.

  3. SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones

    Science.gov (United States)

    Maj, Jean-Baptiste; Moonen, Marc; Wouters, Jan

    2002-12-01

    We introduce a new SVD-based (Singular value decomposition) strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE) hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998). The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII). The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of [InlineEquation not available: see fulltext.] and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.

  4. System identification of velocity mechanomyogram measured with a capacitor microphone for muscle stiffness estimation.

    Science.gov (United States)

    Uchiyama, Takanori; Tomoshige, Taiki

    2017-04-01

    A mechanomyogram (MMG) measured with a displacement sensor (displacement MMG) can provide a better estimation of longitudinal muscle stiffness than that measured with an acceleration sensor (acceleration MMG), but the displacement MMG cannot provide transverse muscle stiffness. We propose a method to estimate both longitudinal and transverse muscle stiffness from a velocity MMG using a system identification technique. The aims of this study are to show the advantages of the proposed method. The velocity MMG was measured using a capacitor microphone and a differential circuit, and the MMG, evoked by electrical stimulation, of the tibialis anterior muscle was measured five times in seven healthy young male volunteers. The evoked MMG system was identified using the singular value decomposition method and was approximated with a fourth-order model, which provides two undamped natural frequencies corresponding to the longitudinal and transverse muscle stiffness. The fluctuation of the undamped natural frequencies estimated from the velocity MMG was significantly smaller than that from the acceleration MMG. There was no significant difference between the fluctuations of the undamped natural frequencies estimated from the velocity MMG and that from the displacement MMG. The proposed method using the velocity MMG is thus more advantageous for muscle stiffness estimation.

  5. Three-dimensional acoustic imaging with planar microphone arrays and compressive sensing

    Science.gov (United States)

    Ning, Fangli; Wei, Jingang; Qiu, Lianfang; Shi, Hongbing; Li, Xiaofan

    2016-10-01

    For obtaining super-resolution source maps, we extend compressive sensing (CS) to three-dimensional acoustic imaging. Source maps are simulated with a planar microphone array and a CS algorithm. Comparing the source maps of the CS algorithm with those of the conventional beamformer (CBF) and Tikhonov Regularization (TIKR), we find that the CS algorithm is computationally more effective and can obtain much higher resolution source maps than the CBF and TIKR. The effectiveness of the CS algorithm is analyzed. The CS algorithm can locate the sound sources exactly when the frequency is above 4000 Hz and the signal-to-noise ratio (SNR) is above 12 dB. The location error of the CS algorithm increases as the frequency drops below the threshold, and the errors in location and power increase as SNR decreases. The further from the array the source is, the larger the location error is. The lateral resolution of the CS algorithm is much better than the range resolution. Finally, experimental measurements are conducted in a semi-anechoic room. Two mobile phones are served as sound sources. The results show that the CS algorithm can reconstruct two sound sources near the bottom of the two mobile phones where the speakers are located. The feasibility of the CS algorithm is also validated with the experiment.

  6. Simultaneous Blind Separation and Recognition of Speech Mixtures Using Two Microphones to Control a Robot Cleaner

    Directory of Open Access Journals (Sweden)

    Heungkyu Lee

    2013-02-01

    Full Text Available This paper proposes a method for the simultaneous separation and recognition of speech mixtures in noisy environments using two‐channel based independent vector analysis (IVA on a home‐robot cleaner. The issues to be considered in our target application are speech recognition at a distance and noise removal to cope with a variety of noises, including TV sounds, air conditioners, babble, and so on, that can occur in a house, where people can utter a voice command to control a robot cleaner at any time and at any location, even while a robot cleaner is moving. Thus, the system should always be in a recognition‐ready state to promptly recognize a spoken word at any time, and the false acceptance rate should be lower. To cope with these issues, the keyword spotting technique is applied. In addition, a microphone alignment method and a model‐based real‐time IVA approach are proposed to effectively and simultaneously process the speech and noise sources, as well as to cover 360‐degree directions irrespective of distance. From the experimental evaluations, we show that the proposed method is robust in terms of speech recognition accuracy, even when the speaker location is unfixed and changes all the time. In addition, the proposed method shows good performance in severely noisy environments.

  7. A Sub-Space Method to Detect Multiple Wireless Microphone Signals in TV Band White Space

    CERN Document Server

    Dhillon, Harpreet S; Datla, Dinesh; Benonis, Michael; Buehrer, R Michael; Reed, Jeffrey H

    2011-01-01

    The main hurdle in the realization of dynamic spectrum access (DSA) systems from physical layer perspective is the reliable sensing of low power licensed users. One such scenario shows up in the unlicensed use of TV bands where the TV Band Devices (TVBDs) are required to sense extremely low power wireless microphones (WMs). The lack of technical standard among various wireless manufacturers and the resemblance of certain WM signals to narrow-band interference signals, such as spurious emissions, further aggravate the problem. Due to these uncertainties, it is extremely difficult to abstract the features of WM signals and hence develop robust sensing algorithms. To partly counter these challenges, we develop a two-stage sub-space algorithm that detects multiple narrow-band analog frequency-modulated signals generated by WMs. The performance of the algorithm is verified by using experimentally captured low power WM signals with received power ranging from -100 to -105 dBm. The problem of differentiating between...

  8. Infrastructure-Less Indoor Localization Using the Microphone, Magnetometer and Light Sensor of a Smartphone

    Science.gov (United States)

    Galván-Tejada, Carlos E.; García-Vázquez, Juan Pablo; Galván-Tejada, Jorge I.; Delgado-Contreras, J. Rubén; Brena, Ramon F.

    2015-01-01

    In this paper, we present the development of an infrastructure-less indoor location system (ILS), which relies on the use of a microphone, a magnetometer and a light sensor of a smartphone, all three of which are essentially passive sensors, relying on signals available practically in any building in the world, no matter how developed the region is. In our work, we merge the information from those sensors to estimate the user’s location in an indoor environment. A multivariate model is applied to find the user’s location, and we evaluate the quality of the resulting model in terms of sensitivity and specificity. Our experiments were carried out in an office environment during summer and winter, to take into account changes in light patterns, as well as changes in the Earth’s magnetic field irregularities. The experimental results clearly show the benefits of using the information fusion of multiple sensors when contrasted with the use of a single source of information. PMID:26295237

  9. 石英微机械陀螺的研究进展%Reaearch Development of Quartz Micromachined Gyroscopes

    Institute of Scientific and Technical Information of China (English)

    关冉; 张卫平; 陈文元; 张弓; 成宇翔

    2012-01-01

    首先介绍了石英微机械陀螺基于压电效应和科氏加速度的工作原理,回顾了石英微机械陀螺的发展历程,并且介绍了石英微机械陀螺的国内外发展现状.然后,针对石英微机械陀螺不同的结构进行了分类,并且对于不同结构的石英微机械陀螺的具体加工工艺、性能参数、应用领域等进行了综述.最后,对不同结构类型的石英微机械陀螺的尺寸、加工工艺,检测轴向,精度等参数进行了总结和对比,在此基础上分析了石英微机械陀螺的发展趋势,并指出了石英微机械陀螺研究中存在的问题,例如石英加工过程中产生的侧壁晶棱的不平整、石英侧壁电极的制作困难以及石英微机械陀螺多轴化应用的限制等.%Firstly, the working principle of the quartz micromachined gyroscope is introduced, which is based on the piezoelectric effect and the Coriolis acceleration, the development history of the quartz micromachined gyroscope is reviewed, and the development present situation of the quartz micromachined gyroscope is introduced both domestically and abroad. Then, the quartz micromachined gyroscope is classified into several types according to its different structures, and the specific fabrication process, performance parameter and application fields of the quartz micromachined gyroscope for the different structures are reviewed. Finally, the parameters of the quartz micromachined gyroscope for the different kinds of structures are summarized and compared, including the size, fabrication process, detection axis and accuracy, and on that basis, the development trends of the quartz micromachined gyroscope are analyzed, and the problems that limit the development of quartz micromachined gyroscope are pointed out, including the uneven crystal edges of the quartz sidewall caused by the fabrication process, the difficulties of electrode fabrication on the quartz sidewall and the limitation of the multi

  10. Simulating Capacitive Micromachined Ultrasonic Transducers (CMUTs) using Field II

    DEFF Research Database (Denmark)

    Bæk, David; Oralkan, Omer; Kupnik, Mario;

    2010-01-01

    Field II has been a recognized simulation tool for piezoceramic medical transducer arrays for more than a decade. The program has its strength in doing fast computations of the spatial impulse response (SIR) from array elements by dividing the elements into smaller mathematical elements (ME)s from...... which it calculates the SIR responses. The program features predefined models for classical transducer geometries, but currently none for the fast advancing CMUTs. This work addresses the assumptions required for modeling CMUTs with Field II. It is shown that rectangular array elements, populated...

  11. Picosecond and nanosecond pulse delivery through a hollow-core Negative Curvature Fiber for micro-machining applications.

    Science.gov (United States)

    Jaworski, Piotr; Yu, Fei; Maier, Robert R J; Wadsworth, William J; Knight, Jonathan C; Shephard, Jonathan D; Hand, Duncan P

    2013-09-23

    We present high average power picosecond and nanosecond pulse delivery at 1030 nm and 1064 nm wavelengths respectively through a novel hollow-core Negative Curvature Fiber (NCF) for high-precision micro-machining applications. Picosecond pulses with an average power above 36 W and energies of 92 µJ, corresponding to a peak power density of 1.5 TWcm⁻² have been transmitted through the fiber without introducing any damage to the input and output fiber end-faces. High-energy nanosecond pulses (>1 mJ), which are ideal for micro-machining have been successfully delivered through the NCF with a coupling efficiency of 92%. Picosecond and nanosecond pulse delivery have been demonstrated in fiber-based laser micro-machining of fused silica, aluminum and titanium.

  12. The Cooling and Lubrication Performance of Graphene Platelets in Micro-Machining Environments

    Science.gov (United States)

    Chu, Bryan

    The research presented in this thesis is aimed at investigating the use of graphene platelets (GPL) to address the challenges of excessive tool wear, reduced part quality, and high specific power consumption encountered in micro-machining processes. There are two viable methods of introducing GPL into micro-machining environments, viz., the embedded delivery method, where the platelets are embedded into the part being machined, and the external delivery method, where graphene is carried into the cutting zone by jetting or atomizing a carrier fluid. The study involving the embedded delivery method is focused on the micro-machining performance of hierarchical graphene composites. The results of this study show that the presence of graphene in the epoxy matrix improves the machinability of the composite. In general, the tool wear, cutting forces, surface roughness, and extent of delamination are all seen to be lower for the hierarchical composite when compared to the conventional two-phase glass fiber composite. These improvements are attributed to the fact that graphene platelets improve the thermal conductivity of the matrix, provide lubrication at the tool-chip interface and also improve the interface strength between the glass fibers and the matrix. The benefits of graphene are seen to also carry over to the external delivery method. The platelets provide improved cooling and lubrication performance to both environmentally-benign cutting fluids as well as to semi-synthetic cutting fluids used in micro-machining. The cutting performance is seen to be a function of the geometry (i.e., lateral size and thickness) and extent of oxygen-functionalization of the platelet. Ultrasonically exfoliated platelets (with 2--3 graphene layers and lowest in-solution characteristic lateral length of 120 nm) appear to be the most favorable for micro-machining applications. Even at the lowest concentration of 0.1 wt%, they are capable of providing a 51% reduction in the cutting

  13. The group delay and suppression pattern of the cochlear microphonic potential recorded at the round window.

    Directory of Open Access Journals (Sweden)

    Wenxuan He

    Full Text Available BACKGROUND: It is commonly assumed that the cochlear microphonic potential (CM recorded from the round window (RW is generated at the cochlear base. Based on this assumption, the low-frequency RW CM has been measured for evaluating the integrity of mechanoelectrical transduction of outer hair cells at the cochlear base and for studying sound propagation inside the cochlea. However, the group delay and the origin of the low-frequency RW CM have not been demonstrated experimentally. METHODOLOGY/PRINCIPAL FINDINGS: This study quantified the intra-cochlear group delay of the RW CM by measuring RW CM and vibrations at the stapes and basilar membrane in gerbils. At low sound levels, the RW CM showed a significant group delay and a nonlinear growth at frequencies below 2 kHz. However, at high sound levels or at frequencies above 2 kHz, the RW CM magnitude increased proportionally with sound pressure, and the CM phase in respect to the stapes showed no significant group delay. After the local application of tetrodotoxin the RW CM below 2 kHz became linear and showed a negligible group delay. In contrast to RW CM phase, the BM vibration measured at location ∼2.5 mm from the base showed high sensitivity, sharp tuning, and nonlinearity with a frequency-dependent group delay. At low or intermediate sound levels, low-frequency RW CMs were suppressed by an additional tone near the probe-tone frequency while, at high sound levels, they were partially suppressed only at high frequencies. CONCLUSIONS/SIGNIFICANCE: We conclude that the group delay of the RW CM provides no temporal information on the wave propagation inside the cochlea, and that significant group delay of low-frequency CMs results from the auditory nerve neurophonic potential. Suppression data demonstrate that the generation site of the low-frequency RW CM shifts from apex to base as the probe-tone level increases.

  14. Surface-micromachined 1MHz oscillator with low-noise Pierce configuration

    Energy Technology Data Exchange (ETDEWEB)

    Roessig, T.A.; Howe, R.T.; Pisano, A.P. [Univ. of California, Berkeley, CA (United States); Smith, J.H. [Sandia National Labs., Albuquerque, NM (United States)

    1998-06-01

    A prototype high frequency tuning fork oscillator has been fabricated and tested in an integrated surface micromachining technology. The amplifier circuitry uses a capacitive current detection method, which offers superior noise performance over previous resistive methods. The prototype device has an output frequency of 1.022 MHz and exhibits a noise floor of {minus}88 dBc/Hz at a distance of 500 Hz from the carrier. The dominant source of frequency instability is the nonlinearity introduced by the use of parallel plate actuation.

  15. Micromachined PIN-PMN-PT Crystal Composite Transducer for High-Frequency Intravascular Ultrasound (IVUS) Imaging

    OpenAIRE

    Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K. Kirk

    2014-01-01

    In this paper, we report the use of micromachined PbIn1/2Nb1/2O3–PbMg1/3Nb2/3O3–PbTiO3 (PIN-PMN-PT) single crystal 1–3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at ...

  16. A Ku-Band Novel Micromachined Bandpass Filter with Two Transmission Zeros

    CERN Document Server

    Yong, Zhang; Yuanwei, Yu; Chen, Chen; Xing, Jia Shi

    2007-01-01

    This paper presents a micromachined bandpass filter with miniature size that has relatively outstanding performance. A silicon-based eight-order microstrip bandpass filter is fabricated and measured. A novel design method of the interdigital filter that can create two transmission zeros is described. The location of the transmission zeros can be shifted arbitrarily in the stopband. By adjusting the zero location properly, the filter provides much better skirt rejection and lower insertion loss than a conventional microstrip interdigital filter. To reduce the chip size, through-silicon-substrate-via-hole is used. Good experimental results are obtained.

  17. Mask synthesis and verification based on geometric model for surface micro-machined MEMS

    Institute of Scientific and Technical Information of China (English)

    LI Jian-hua; LIU Yu-sheng; GAO Shu-ming

    2005-01-01

    Traditional MEMS (microelectromechanical system) design methodology is not a structured method and has become an obstacle for MEMS creative design. In this paper, a novel method of mask synthesis and verification for surface micro-machined MEMS is proposed, which is based on the geometric model of a MEMS device. The emphasis is focused on synthesizing the masks at the basis of the layer model generated from the geometric model of the MEMS device. The method is comprised of several steps: the correction of the layer model, the generation of initial masks and final masks including multi-layer etch masks, and mask simulation. Finally some test results are given.

  18. Micromachining And Pattering In Micro/Nano Scale On Macroscopic Areas

    Directory of Open Access Journals (Sweden)

    Marczak J.

    2015-09-01

    Full Text Available This paper presents detailed discussion of selected examples of laser technologies for the modification of solid surfaces, including topographic and microstructural changes as well as both these alterations simultaneously. Laser surface micromachining has just entered the new generation of technologies that are used in surface engineering. It will be shown on the examples of applications in bioengineering, on the base of the author’s own research, in modification of materials such as titanium and its alloys, diamond-like layers (DLC deposited on silicon and polymer substrates.

  19. A novel hybrid surface micromachined segmented mirror for large aperture laser applications

    Institute of Scientific and Technical Information of China (English)

    Jie Li; Haiqing Chen; Hongbin Yu

    2006-01-01

    @@ A novel hybrid surface micromachined segmented mirror array is described. This device is capable of scaling to large apertures for correcting time-varying aberrations in laser applications. Each mirror is composed of bottom electrode, support part, and mirror plate, in which a T-shaped beam structure is used to support the mirror plate. It can provide mirror with vertical movement and rotation around two horizontal axes. The test results show that the maximum deflection along the vertical direction of the mirror plate is 2μm, while the rotation angles around x and y axes are ±2.3° and ±1.45°, respectively.

  20. 5-level polysilicon surface micromachine technology: Application to complex mechanical systems

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, M.S.; Sniegowski, J.J.

    1998-06-01

    The authors recently reported on the development of a 5-level poly-ilicon surface micromachine fabrication process consisting of four levels of mechanical poly plus an electrical interconnect layer. They are now reporting on the first components designed for and fabricated in this process. These are demonstration systems, which definitively show that five levels of polysilicon provide greater performance, reliability, and significantly increased functionality. This new technology makes it possible to realize levels of system complexity that have so far only existed on paper, while simultaneously adding to the robustness of many of the individual subassemblies.

  1. Micro-tensile tests on micromachined metal on polymer specimens: elasticity, plasticity and rupture

    CERN Document Server

    Seguineau, C; Malhaire, C; Brida, S; Lafontan, X; Desmarres, J -M; Josserond, C; Debove, L

    2008-01-01

    This study is focused on the mechanical characterization of materials used in microelectronic and micro- electromechanical systems (MEMS) devices. In order to determine their mechanical parameters, a new deformation bench test with suitable micromachined specimens have been developed. Uniaxial tensile tests were performed on "low cost" specimens, consisting in electroplated thin copper films and structures, deposited on a polimide type substrate. Moreover, a cyclic mechanical actuation via piezoelectric actuators was tested on the same deformation bench. These experiments validate the device for performing dynamic characterization of materials, and reliability studies of different microstructures.

  2. Numerical modelling of micro-machining of f.c.c. single crystal: Influence of strain gradients

    KAUST Repository

    Demiral, Murat

    2014-11-01

    A micro-machining process becomes increasingly important with the continuous miniaturization of components used in various fields from military to civilian applications. To characterise underlying micromechanics, a 3D finite-element model of orthogonal micro-machining of f.c.c. single crystal copper was developed. The model was implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine VUMAT. Strain-gradient crystal-plasticity and conventional crystal-plasticity theories were used to demonstrate the influence of pre-existing and evolved strain gradients on the cutting process for different combinations of crystal orientations and cutting directions. Crown Copyright © 2014.

  3. WALL PRESSURE FLUCTUATIONS OF TURBULENT FLOW OVER BACKWARD-FACING STEP WITH AND WITHOUT ENTRAINMENT: MICROPHONE ARRAY MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    KE Feng; LIU Ying-zheng; WANG Wei-zhe; CHEN Han-ping

    2006-01-01

    Wall pressure fluctuations in turbulent boundary layer flow over backward-facing step with and without entrainment were investigated. Digital array pressure sensors and multi-arrayed microphones were employed to acquire the time-averaged static pressure and fluctuating pressure, respectively. The differences of two flows were scrutinized in terms of static pressure characteristics, pressure fluctuations, cross-correlation and coherence of wall pressure. Introduction of the entrainment increased scale of large-scale vortical structure and reduced its convection velocity. However, shedding frequency of large-scale vortical structures was found to be the same for both flows.

  4. Design, Fabrication, and Testing of a Bulk Micromachined Inertial Measurement Unit

    Directory of Open Access Journals (Sweden)

    Honglong Chang

    2010-04-01

    Full Text Available A bulk micromachined inertial measurement unit (MIMU is presented in this paper. Three single-axis accelerometers and three single-axis gyroscopes were simultaneously fabricated on a silicon wafer using a bulk micromachining process; the wafer is smaller than one square centimeter. In particular, a global area optimization method based on the relationship between the sensitivity and layout area was proposed to determine the layout configuration of the six sensors. The scale factors of the X/Y-axis accelerometer and Z-axis accelerometer are about 213.3 mV/g and 226.9 mV/g, respectively. The scale factors of the X/Y-axis gyroscope and Z-axis gyroscope are about 2.2 mV/o/s and 10.8 mV/o/s, respectively. The bias stability of the X/Y-axis gyroscope and the Z-axis gyroscope are about 2135 deg/h and 80 deg/h, respectively. Finally, the resolutions of X/Y-axis accelerometers, Z-axis accelerometers, X/Y-axis gyroscopes, and Z-axis gyroscopes are 0.0012 g/ √Hz, 0.0011 g/ √Hz, 0.314 °/s/ √Hz, and 0.008 °/s/ √Hz, respectively.

  5. Picosecond laser micromachining of nitinol and platinum-iridium alloy for coronary stent applications

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, N.; Whitehead, D.; Li, L. [University of Manchester, Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, Manchester (United Kingdom); Boor, A.; Oppenlander, W. [Swiss Tec AG, Schaan, Principality of Liechtenstein (Liechtenstein); Liu, Z. [University of Manchester, Corrosion and Protection Centre, School of Materials, Manchester (United Kingdom)

    2012-03-15

    The demand for micromachining of coronary stents by means of industrial lasers rises quickly for treating coronary artery diseases, which cause more than one million deaths each year. The most widely used types of laser for stent manufacturing are Nd:YAG laser systems with a wavelength of 1064 nm with pulse lengths of 10{sup -3}-10{sup -2} seconds. Considerable post-processing is required to remove heat-affected zones (HAZ), and to improve surface finishes and geometry. Using a third harmonic laser radiation of picosecond laser (6 x 10{sup -12} s pulse duration) in UV range, the capability of the picosecond laser micromachining of nitinol and platinum-iridium alloy for coronary stent applications are presented. In this study dross-free cut of nitinol and platinum-iridium alloy tubes are demonstrated and topography analysis of the cut surface is carried out. The HAZ characteristics have been investigated by means of microscopic examinations and measurement of micro-hardness distribution near the cut zones. (orig.)

  6. Novel Micromachined Coplanar Waveguide Transmission Lines for Application in Millimeter-Wave Circuits

    Science.gov (United States)

    Park, Jae-Hyoung; Baek, Chang-Wook; Jung, Sanghwa; Kim, Hong-Teuk; Kwon, Youngwoo; Kim, Yong-Kweon

    2000-12-01

    In this paper, novel micromachined coplanar waveguide(CPW) transmission lines for application in millimeter-wave circuits are proposed. Two types of transmission lines with the length of 1 cm are fabricated and the measured characteristics are compared with those of the conventional CPW transmission line. One is the elevated CPW(ECPW) transmission line and the other is the overlay CPW(OCPW) line. These transmission lines are composed of 3-μm-thick electroplated gold lines with overhanging parts. By elevating the metal lines from the substrate using micromachining technology, the conductor and substrate dielectric loss can be reduced and easily integrated with conventional monolithic microwave integrated circuits. Compared with the conventional CPW line showing 2.65 dB/cm insertion loss at 50 GHz, the loss can be reduced to 1.9 dB/cm and 1.25 dB/cm at 50 GHz in the case of the ECPW and OCPW transmission lines, respectively. Also, the OCPW transmission line shows that the insertion loss does not vary with the change of the characteristic impedance. As shown in the measured and simulated results, the insertion loss is maintained below 1.4 dB/cm over wide impedance ranges.

  7. Micromachining of microchannel on the polycarbonate substrate with CO 2 laser direct-writing ablation

    Science.gov (United States)

    Qi, Heng; Chen, Tao; Yao, Liying; Zuo, Tiechuan

    2009-05-01

    Low-power CO 2 laser direct-writing ablation was used to micromachine a microchannel on the polycarbonate substrate in this work. The influence of the process parameters (the laser power, the moving velocity of the laser beam and the scanning times) on the micromachining quality (the depth, the width and their aspect ratio) of the microchannel was experimentally studied. The depth and width of microchannel both increase with the increase of the laser power and the decrease of the moving velocity of the laser beam. When higher laser power and slower moving velocity were used, the polycarbonate surface bore more heat irradiated from the CO 2 laser for longer time which results in the formation of deeper and wider molten pool, hence the ability to fabricate bigger microchannel. Because of the effect of the laser power on the depth and width of microchannels, higher aspect (depth/width) ratio could be achieved using slower moving velocity and higher laser power, and it would reach a steady state when the laser power increases to 9.0 W possibly caused by the effect of laser power on the different directions of microchannel. The polycarbonate-polycarbonate chip was bonded with hot-press bonding technique.

  8. Millimeter length micromachining using a heavy ion nuclear microprobe with standard magnetic scanning

    Energy Technology Data Exchange (ETDEWEB)

    Nesprías, F. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (1650), San Martín, Buenos Aires (Argentina); Debray, M.E., E-mail: debray@tandar.cnea.gov.ar [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (1650), San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología. Universidad Nacional de Gral. San Martín, M. De Irigoyen 3100 (1650), San Martín, Buenos Aires (Argentina); Davidson, J. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (1650), San Martín, Buenos Aires (Argentina); CONICET, Avda. Rivadavia 1917 (C1033AAJ), Ciudad Autónoma de Buenos Aires (Argentina); Kreiner, A.J. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (1650), San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología. Universidad Nacional de Gral. San Martín, M. De Irigoyen 3100 (1650), San Martín, Buenos Aires (Argentina); CONICET, Avda. Rivadavia 1917 (C1033AAJ), Ciudad Autónoma de Buenos Aires (Argentina); and others

    2013-04-01

    In order to increase the scanning length of our microprobe, we have developed an irradiation procedure suitable for use in any nuclear microprobe, extending at least up to 400% the length of our heavy ion direct writing facility using standard magnetic exploration. Although this method is limited to patterns of a few millimeters in only one direction, it is useful for the manufacture of curved waveguides, optical devices such Mach–Zehnder modulators, directional couplers as well as channels for micro-fluidic applications. As an example, this technique was applied to the fabrication of 3 mm 3D-Mach–Zehnder modulators in lithium niobate with short Y input/output branches and long shaped parallel-capacitor control electrodes. To extend and improve the quality of the machined structures we developed new scanning control software in LabView™ platform. The new code supports an external dose normalization, electrostatic beam blanking and is capable of scanning figures at 16 bit resolution using a National Instruments™ PCI-6731 High-Speed I/O card. A deep and vertical micromachining process using swift {sup 35}Cl ions 70 MeV bombarding energy and direct write patterning was performed on LiNbO{sub 3}, a material which exhibits a strong natural anisotropy to conventional etching. The micromachined structures show the feasibility of this method for manufacturing micro-fluidic channels as well.

  9. Graphene-enhanced environmentally-benign cutting fluids for high-performance micro-machining applications.

    Science.gov (United States)

    Chu, Bryan; Singh, Eklavya; Koratkar, Nikhil; Samuel, Johnson

    2013-08-01

    A canola-based cutting oil enhanced with graphene platelet (GPL) additives has been developed to fulfill the need for environmentally benign cutting oils for high performance micro-machining applications. Carboxyl-functionalized graphene platelets are used to enable stable GPL dispersion in the polar oil. Three oil formulations consisting of 0.05%, 0.10% and 0.15% GPL by weight are tested. The GPL-laden canola oil is first characterized based on its kinematic viscosity, thermal conductivity and coefficient of friction. Micro-turning tests are then performed to study the effect of GPL loading on the cutting temperature, cutting force, and the surface finish of the part. All tested loadings improve the cooling and lubricating properties of the canola oil. For cooling, this improvement is seen to increase with GPL loading. In the case of lubrication, there appears to be an optimal loading of around 0.10%. The presence of GPL also leads to a decrease in the surface roughness of the micro-machined surface but this improvement drops with increased GPL loading.

  10. Effects of Micromachining Processes on Electro-Osmotic Flow Mobility of Glass Surfaces

    Directory of Open Access Journals (Sweden)

    Norihisa Miki

    2013-03-01

    Full Text Available Silica glass is frequently used as a device material for micro/nano fluidic devices due to its excellent properties, such as transparency and chemical resistance. Wet etching by hydrofluoric acid and dry etching by neutral loop discharge (NLD plasma etching are currently used to micromachine glass to form micro/nano fluidic channels. Electro-osmotic flow (EOF is one of the most effective methods to drive liquids into the channels. EOF mobility is affected by a property of the micromachined glass surfaces, which includes surface roughness that is determined by the manufacturing processes. In this paper, we investigate the effect of micromaching processes on the glass surface topography and the EOF mobility. We prepared glass surfaces by either wet etching or by NLD plasma etching, investigated the surface topography using atomic force microscopy, and attempted to correlate it with EOF generated in the micro-channels of the machined glass. Experiments revealed that the EOF mobility strongly depends on the surface roughness, and therefore upon the fabrication process used. A particularly strong dependency was observed when the surface roughness was on the order of the electric double layer thickness or below. We believe that the correlation described in this paper can be of great help in the design of micro/nano fluidic devices.

  11. Differential search algorithm-based parametric optimization of electrochemical micromachining processes

    Directory of Open Access Journals (Sweden)

    Debkalpa Goswami

    2014-01-01

    Full Text Available Electrochemical micromachining (EMM appears to be a very promising micromachining process for having higher machining rate, better precision and control, reliability, flexibility, environmental acceptability, and capability of machining a wide range of materials. It permits machining of chemically resistant materials, like titanium, copper alloys, super alloys and stainless steel to be used in biomedical, electronic, micro-electromechanical system and nano-electromechanical system applications. Therefore, the optimal use of an EMM process for achieving enhanced machining rate and improved profile accuracy demands selection of its various machining parameters. Various optimization tools, primarily Derringer’s desirability function approach have been employed by the past researchers for deriving the best parametric settings of EMM processes, which inherently lead to sub-optimal or near optimal solutions. In this paper, an attempt is made to apply an almost new optimization tool, i.e. differential search algorithm (DSA for parametric optimization of three EMM processes. A comparative study of optimization performance between DSA, genetic algorithm and desirability function approach proves the wide acceptability of DSA as a global optimization tool.

  12. Development of an electrochemical micromachining instrument for the confined etching techniques

    Science.gov (United States)

    Zhou, Hang; Lai, Lei-Jie; Zhao, Xiang-Hui; Zhu, Li-Min

    2014-04-01

    This study proposes an electrochemical micromachining instrument for two confined etching techniques, namely, confined etchant layer technique (CELT) and electrochemical wet stamping (E-WETS). The proposed instrument consists of a granite bridge base, a Z-axis coarse/fine dual stage, and a force sensor. The Z-axis coarse/fine dual stage controls the vertical movement of the substrate with nanometer accuracy. The force sensor measures the contact force between the mold and the substrate. A contact detection method based on a digital lock-in amplifier is developed to make the mold-substrate contact within a five-nanometer range in CELT, and a force feedback controller is implemented to keep the contact force in E-WETS at a constant value with a noise of less than 0.2 mN. With the use of the confined etching techniques, a microlens array and a curvilinear ridge microstructure are successfully fabricated with high accuracy, thus demonstrating the promising performance of the proposed micromachining instrument.

  13. Characterization of tool-workpiece contact during the micromachining of conductive materials

    Science.gov (United States)

    Castaño, Fernando; Haber, Rodolfo E.; del Toro, Raúl M.

    2017-01-01

    The characterization of dynamic cutting in micro-machining operations is essential for real-time monitoring of tool performance. The analysis of tool-edge/material contact and its electrical resistivity is therefore an interesting avenue of research for monitoring tool-workpiece interaction. This study examines mechanical cutting operations in micromilling operations that remove material to meet the design requirements of conductive parts. It draws from previous research into the theoretical models of cutting mechanisms in milling operations, to present a mathematical characterization of the tool-edge/material contact area. The rationale behind this research is that the contact area between two conductive materials is one of the main factors in determining the magnitude of resistance to the flow of an electric current between both materials. The study also offers a theoretical analysis of tool-edge radial immersion angles on entry and exit and their dynamic behavior. The analysis is mainly centered on cutting operations and cutting-time intervals, where tool-material contact is intermittent. Our theoretical analysis is experimentally corroborated by measuring tool-edge immersion time and tool-edge/material contact time. Promising results are reported that contribute to the development of a technological method for high-precision, real-time monitoring of tool-workpiece interaction and cutting detection in micromachining operations.

  14. Micromachined low-mass RF front-end for beam steering radar

    Science.gov (United States)

    Vahidpour, M.; Moallem, M.; East, J.; Sarabandi, K.

    2012-06-01

    Sensors for autonomous small robotic platforms must be low mass, compact size and low power due to the limited space. For such applications, as the dimensions of the structures shrink, standard machining methods are not suitable because of low fabrication tolerances and high cost in assembly. Commonly, the structures show a high degree of fabrication complexity due to error in alignment, air gaps between conductive parts, poor metal contact, inaccuracy in patterning because of non-contact lithography, complex assemblies of various parts, and high number of steps needed for construction. However, micromachining offers high fabrication precision, provides easy fabrication and integration with active devices and hence is suitable for manufacturing high MMW and submillimeter-wave frequency structures. A radar design compatible with micromachining process is developed to fabricate a Y-band high resolution radar structure with a slot-fed patch array antenna. A multi-step silicon DRIE process is developed for the fabrication of the waveguide structure while the slots are suspended on a thin oxide/nitride/oxide membrane to form the top cover of the waveguide trenches and the patch elements are suspended on a thin Parylene membrane. Gold thermocompression bonding and Parylene bonding are used to assemble different parts of the antenna. These processes result in a compact (4.5 cm × 3.5 cm × 1.5 mm) and light-weight (5 g) radar.

  15. Development of an electrochemical micromachining instrument for the confined etching techniques.

    Science.gov (United States)

    Zhou, Hang; Lai, Lei-Jie; Zhao, Xiang-Hui; Zhu, Li-Min

    2014-04-01

    This study proposes an electrochemical micromachining instrument for two confined etching techniques, namely, confined etchant layer technique (CELT) and electrochemical wet stamping (E-WETS). The proposed instrument consists of a granite bridge base, a Z-axis coarse/fine dual stage, and a force sensor. The Z-axis coarse/fine dual stage controls the vertical movement of the substrate with nanometer accuracy. The force sensor measures the contact force between the mold and the substrate. A contact detection method based on a digital lock-in amplifier is developed to make the mold-substrate contact within a five-nanometer range in CELT, and a force feedback controller is implemented to keep the contact force in E-WETS at a constant value with a noise of less than 0.2 mN. With the use of the confined etching techniques, a microlens array and a curvilinear ridge microstructure are successfully fabricated with high accuracy, thus demonstrating the promising performance of the proposed micromachining instrument.

  16. Picosecond laser micromachining of nitinol and platinum-iridium alloy for coronary stent applications

    Science.gov (United States)

    Muhammad, N.; Whitehead, D.; Boor, A.; Oppenlander, W.; Liu, Z.; Li, L.

    2012-03-01

    The demand for micromachining of coronary stents by means of industrial lasers rises quickly for treating coronary artery diseases, which cause more than one million deaths each year. The most widely used types of laser for stent manufacturing are Nd:YAG laser systems with a wavelength of 1064 nm with pulse lengths of 10-3-10-2 seconds. Considerable post-processing is required to remove heat-affected zones (HAZ), and to improve surface finishes and geometry. Using a third harmonic laser radiation of picosecond laser (6×10-12 s pulse duration) in UV range, the capability of the picosecond laser micromachining of nitinol and platinum-iridium alloy for coronary stent applications are presented. In this study dross-free cut of nitinol and platinum-iridium alloy tubes are demonstrated and topography analysis of the cut surface is carried out. The HAZ characteristics have been investigated by means of microscopic examinations and measurement of micro-hardness distribution near the cut zones.

  17. Micromachined strain gauges for the determination of liquid flow friction coefficients in microchannels

    Science.gov (United States)

    Baviere, R.; Ayela, F.

    2004-02-01

    In this research program, we have performed and tested cupro-nickel (Cu-Ni) strain gauges micromachined on different sorts of silicon nitride (Si3N4) membranes. The design of the gauges obeys an electrical Wheatstone bridge configuration. We have found a good agreement between the expected electromechanical response of the bridge and the experimental signals. The results have displayed sensitivity to static pressure ranging from 50 to 100 µV V-1 bar-1 as a function of the thickness and of the diameter of the membranes. This is part of a study devoted to determining liquid flow friction coefficients in silicon-Pyrex microchannels. Preliminary attempts (Reynolds number up to 300) made using global pressure measurements and with very simple local pressure probes are discussed. Further experiments using Cu-Ni strain gauges are described. Their micromachining, characterization and integration along silicon microchannels are presented. These sensors permitted us to perform the first local and reliable pressure drop measurements in a 7.5 µm deep microchannel. The results are in good agreement with the classical laminar theory for a Reynolds number ranging from 0.2 to 3.

  18. Laser-micromachined and laminated microfluidic components for miniaturized thermal, chemical, and biological systems

    Science.gov (United States)

    Martin, Peter M.; Matson, Dean W.; Bennett, Wendy D.; Stewart, Donald C.; Lin, Yuehe

    1999-03-01

    Microchannel microfluidic components are being developed for heat transfer, chemical reactor, chemical analysis, and biological analytical applications. Specific applications include chemical sensing, DNA replication, blood analysis, capillary electrophoresis, fuel cell reactors, high temperature chemical reactors, heat pumps, combustors, and fuel processors. Two general types of component architectures have been developed and the fabrication processes defined. All involve a lamination scheme using plastic, ceramic, or metal laminates, as opposed to planar components. The first type is a stacked architecture that utilizes functionality built in each layer, with fluid flow interconnects between layers. Each layer of the laminate has specific microchannel geometry, and performs a specific function. Polymeric materials are used primarily. Fabrication processes used are laser micromachining, wet and dry etching, and coating deposition. the laminates can also be micromolded plastics. The second architecture employs laminates to form internal microchannels and interconnects. Materials include ceramic tapes and high temperature metals. Catalysts can be placed in the microchannels. Fabrication processes used are diffusion bonding, ceramic bonding and firing, photochemical etching, and electrochemical micromachining. Bonding, thus sealing, the laminates is an important issue. Process conditions have been develop to reduce distortion of the laminates and to hermetically seal the components.

  19. A Novel Piezo-Actuator-Sensor Micromachine for Mechanical Characterization of Micro-Specimens

    Directory of Open Access Journals (Sweden)

    Leila Ladani

    2010-12-01

    Full Text Available Difficulties associated with testing and characterization of materials at microscale demands for new technologies and devices that are capable of measuring forces and strains at microscale. To address this issue, a novel electroactive-based micro-electro-mechanical machine is designed. The micromachine is comprised of two electroactive (piezoelectric micro-elements mounted on a rigid frame. Electrical activation of one of the elements causes it to expand and induce a stress in the intervening micro-specimen. The response of the microspecimen to the stress is measured by the deformation and thereby voltage/resistance induced in the second electro-active element. The concept is theoretically proven using analytical modeling in conjunction with non-linear, three dimensional finite element analyses for the micromachine. Correlation of the output voltage to the specimen stiffness is shown. It is also demonstrated through finite element and analytical analysis that this technique is capable of detecting non-linear behavior of materials. A characteristic curve for an isotropic specimen exhibiting linear elastic behavior is developed. Application of the proposed device in measuring coefficient of thermal expansion is explored and analytical analysis is conducted.

  20. Construction and Operation of a 165K Microcooler with a Sorption Compressor and a Micromachined Cold Stage

    NARCIS (Netherlands)

    Burger, J.F.; Holland, H.J.; Brake, ter H.J.M.; Elwenspoek, M.C.; Rogalla, H.; Ross, R.G. jr

    2003-01-01

    This paper presents the integration and testing of a 165 K microcooler that operates with a sorption compressor and a micromachined cold stage. Attractive features of this combination are the lack of vibration and a long lifetime for a potentially very small cryocooler. The developed cold stage work

  1. STUDY ON FLAP SIDE-EDGE NOISE BASED ON THE FLY-OVER MEASUREMENTS WITH A PLANAR MICROPHONE ARRAY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A large planar microphone array, which consists of 111 microphones, was successfully applied to measure a two-dimensional mapping of the sound sources on landing aircraft. The focus was on the flap side-edge noise source in this paper. The spectra, directivity and sound pressure level of flap side-edge noise of 10 aircraft were presented in this paper. It is found that the spectrum of flap side-edge noise is a broadband noise with some tones in some cases. Two different types of tone sources are found. It is proposed that one type of these tone sources is trailing edge semi-baffled dipole source, and another is produced from the shedding of vortex from the wing cusp. The total sound pressure level of flap side-edge broadband noise has no obvious directionality. However, the directivity of the tone noise in the flap side-edge noise spectrum is obvious. It is demonstrated that the local flow field is the key to controlling the flap side-edge noise.

  2. Musical-Noise Analysis in Methods of Integrating Microphone Array and Spectral Subtraction Based on Higher-Order Statistics

    Directory of Open Access Journals (Sweden)

    Kazunobu Kondo

    2010-01-01

    Full Text Available We conduct an objective analysis on musical noise generated by two methods of integrating microphone array signal processing and spectral subtraction. To obtain better noise reduction, methods of integrating microphone array signal processing and nonlinear signal processing have been researched. However, nonlinear signal processing often generates musical noise. Since such musical noise causes discomfort to users, it is desirable that musical noise is mitigated. Moreover, it has been recently reported that higher-order statistics are strongly related to the amount of musical noise generated. This implies that it is possible to optimize the integration method from the viewpoint of not only noise reduction performance but also the amount of musical noise generated. Thus, we analyze the simplest methods of integration, that is, the delay-and-sum beamformer and spectral subtraction, and fully clarify the features of musical noise generated by each method. As a result, it is clarified that a specific structure of integration is preferable from the viewpoint of the amount of generated musical noise. The validity of the analysis is shown via a computer simulation and a subjective evaluation.

  3. Identification of Noise Sources During Rocket Engine Test Firings and a Rocket Launch Using a Microphone Phased-Array

    Science.gov (United States)

    Panda, Jayanta; Mosher, Robert N.; Porter, Barry J.

    2013-01-01

    A 70 microphone, 10-foot by 10-foot, microphone phased array was built for use in the harsh environment of rocket launches. The array was setup at NASA Wallops launch pad 0A during a static test firing of Orbital Sciences' Antares engines, and again during the first launch of the Antares vehicle. It was placed 400 feet away from the pad, and was hoisted on a scissor lift 40 feet above ground. The data sets provided unprecedented insight into rocket noise sources. The duct exit was found to be the primary source during the static test firing; the large amount of water injected beneath the nozzle exit and inside the plume duct quenched all other sources. The maps of the noise sources during launch were found to be time-dependent. As the engines came to full power and became louder, the primary source switched from the duct inlet to the duct exit. Further elevation of the vehicle caused spilling of the hot plume, resulting in a distributed noise map covering most of the pad. As the entire plume emerged from the duct, and the ondeck water system came to full power, the plume itself became the loudest noise source. These maps of the noise sources provide vital insight for optimization of sound suppression systems for future Antares launches.

  4. Musical-Noise Analysis in Methods of Integrating Microphone Array and Spectral Subtraction Based on Higher-Order Statistics

    Science.gov (United States)

    Takahashi, Yu; Saruwatari, Hiroshi; Shikano, Kiyohiro; Kondo, Kazunobu

    2010-12-01

    We conduct an objective analysis on musical noise generated by two methods of integrating microphone array signal processing and spectral subtraction. To obtain better noise reduction, methods of integrating microphone array signal processing and nonlinear signal processing have been researched. However, nonlinear signal processing often generates musical noise. Since such musical noise causes discomfort to users, it is desirable that musical noise is mitigated. Moreover, it has been recently reported that higher-order statistics are strongly related to the amount of musical noise generated. This implies that it is possible to optimize the integration method from the viewpoint of not only noise reduction performance but also the amount of musical noise generated. Thus, we analyze the simplest methods of integration, that is, the delay-and-sum beamformer and spectral subtraction, and fully clarify the features of musical noise generated by each method. As a result, it is clarified that a specific structure of integration is preferable from the viewpoint of the amount of generated musical noise. The validity of the analysis is shown via a computer simulation and a subjective evaluation.

  5. SVD-based optimal filtering for noise reduction in dual microphone hearing aids: a real time implementation and perceptual evaluation.

    Science.gov (United States)

    Maj, Jean-Baptiste; Royackers, Liesbeth; Moonen, Marc; Wouters, Jan

    2005-09-01

    In this paper, the first real-time implementation and perceptual evaluation of a singular value decomposition (SVD)-based optimal filtering technique for noise reduction in a dual microphone behind-the-ear (BTE) hearing aid is presented. This evaluation was carried out for a speech weighted noise and multitalker babble, for single and multiple jammer sound source scenarios. Two basic microphone configurations in the hearing aid were used. The SVD-based optimal filtering technique was compared against an adaptive beamformer, which is known to give significant improvements in speech intelligibility in noisy environment. The optimal filtering technique works without assumptions about a speaker position, unlike the two-stage adaptive beamformer. However this strategy needs a robust voice activity detector (VAD). A method to improve the performance of the VAD was presented and evaluated physically. By connecting the VAD to the output of the noise reduction algorithms, a good discrimination between the speech-and-noise periods and the noise-only periods of the signals was obtained. The perceptual experiments demonstrated that the SVD-based optimal filtering technique could perform as well as the adaptive beamformer in a single noise source scenario, i.e., the ideal scenario for the latter technique, and could outperform the adaptive beamformer in multiple noise source scenarios.

  6. A precision closed-loop driving scheme of silicon micromachined vibratory gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Yang Bo; Zhou Bailing; Wang Shourong [Instrument Science and Engineering Department, Southeast University Nanjing 210096 (China)

    2006-04-01

    This paper describes a precision closed-loop driving scheme for Silicon Micromachined Vibratory Gyroscope (SMVG). It decouples the angle and gain of the selfoscillation- driven, optimizes the angle to reduce the relative difference between drive frequency and resonant frequency of the drive mode and achieves the closed-loop selfoscillation- driven by nonlinear relation between DC voltage using for control and drive force. The experiments show that the standard deviation of drive frequency is 0.009Hz, with relative drift 2.2ppm and the standard deviation of the amplitude is 0.0025mV, with relative drift 15ppm in one hour respectively. The closed-loop drive scheme improves the precision and stability of drive frequency and the amplitude of the gyroscope well. The paper analyses and tests the noise of the self-oscillation-driven. The result shows that the self-oscillation-driven has a rms noise below -100dB.

  7. Laser micromachining of CNT/Fe/Al2O3 nanocomposites

    Institute of Scientific and Technical Information of China (English)

    Kwang-Ryul KIM; Byoung-Deog CHOI; Jun-Sin YI; Sung-Hak CHO; Yong-Ho CHOA; Dong-Soo SHIN; Dong-Ho BAE; Myung-Chang KANG; Young-Keun JEONG

    2009-01-01

    CNT/Fe/Al2O3 mixed powders were synthesized from Fe/Al2O3 nanopowders using thermal CVD for the homogeneous dispersion of carbon nanotubes CNTs. CNTs consisted of MWNT, and the diameter was approximately 20-30 nm. After sintering, CNTs were homogenously located throughout Al2O3 grain boundary and were buckled. A femto-second laser installed with special optical systems was used for micromachining of the nanocomposites. The relationship between material ablation rate and energy fluence was theoretically investigated and compared with experimental results from cross-sectional SEM analysis. The nanocomposites which have higher content of CNT show a fairly good machining result due to its higher thermal conductivity and smaller grain size as well as lower light transmittance.

  8. Micromachined On-Chip Dielectric Resonator Antenna Operating at 60 GHz

    KAUST Repository

    Sallam, Mai

    2015-06-01

    This paper presents a novel cylindrical Dielectric Resonator Antenna (DRA) suitable for millimeter-wave on-chip systems. The antenna was fabricated from a single high resistivity silicon wafer via micromachining technology. The new antenna was characterized using HFSS and experimentally with good agreement been found between the simulations and experiment. The proposed DRA has good radiation characteristics, where its gain and radiation efficiency are 7 dBi and 79.35%, respectively. These properties are reasonably constant over the working frequency bandwidth of the antenna. The return loss bandwidth was 2.23 GHz, which corresponds to 3.78% around 60 GHz. The antenna was primarily a broadside radiator with -15 dB cross polarization level.

  9. SYSTEM-LEVEL SIMULATION OF VIBRATORY MICROMACHINED GYROSCOPE WITH FENCE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    Che Lufeng; Xiong Bin; Wang Yuelin

    2004-01-01

    An equivalent circuit model of a novel fence structure vibratory micromachined gyroscope's oscillating properties is modeled by electrical equivalent circuits according to its dynamics equation. Equivalent circuit model of oscillating and differential detection capacitance model are implemented in the circuit simulation tool PSPICE, which is available in oscillating properties analysis such as oscillating's transient response, steady response and frequency response to angular rate to optimize working mode of the gyroscope. The model also enables sensor simulation with the interfacing electronics to analyse the performances of the whole system. Behavioral simulation of the system is performed to prove the function of detection circuits. The simulation results and measurement results show that the design of circuits is feasible.

  10. IBIC characterization of an ion-beam-micromachined multi-electrode diamond detector

    CERN Document Server

    Forneris, J; Jaksic, M; Giudice, A Lo; Olivero, P; Picollo, F; Skukan, N; Verona, C; Verona-Rinati, G; Vittone, E

    2016-01-01

    Deep Ion Beam Lithography (DIBL) has been used for the direct writing of buried graphitic regions in monocrystalline diamond with micrometric resolution. Aiming at the development and the characterization of a fully ion-beam-micromachined solid state ionization chamber, a device with interdigitated electrodes was fabricated by using a 1.8 MeV He+ ion microbeam scanning on a homoepitaxial, grown by chemical vapour deposition (CVD). In order to evaluate the ionizing-radiation-detection performance of the device, charge collection efficiency (CCE) maps were extracted from Ion Beam Induced Charge (IBIC) measurements carried out by probing different arrangements of buried microelectrodes. The analysis of the CCE maps allowed for an exhaustive evaluation of the detector features, in particular the individuation of the different role played by electrons and holes in the formation of the induced charge pulses. Finally, a comparison of the performances of the detector with buried graphitic electrodes with those releva...

  11. Design and Testing of Metal and Silicon Heat Spreaders with Embedded Micromachined Heat Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Benson, D.A.; Robino, C.V.

    1999-02-22

    The authors have developed a new type of heat spreader based on the integration of heat pipes directly within a thin planar structure suitable for use as a heat spreader or as the base layer in a substrate. The process uses micromachining methods to produce micron scale patterns that act as a wick in these small scale heat pipes. By using silicon or a low expansion metal as the wall material of these spreaders, they achieve a good match to the thermal coefficient of expansion of the die. The match allows the use of a thin high performance die attachment even on large size die. The embedded heat pipes result in high effective thermal conductivity for the new spreader technology.

  12. Numerical Analysis of Silicon Micromachined Gas Pendulum Tilt Sense Organ Temperature Field

    Institute of Scientific and Technical Information of China (English)

    Linhua Piao; Bin Zhang; Yaojie Lv; Fuxue Zhang

    2006-01-01

    An analysis of the sensitive mechanism of silicon micromachined gas pendulum tilt sense organ is made. Adopting the method of FEA (finite element analysis), the temperature field at two points heat source, when the two-dimensional enclosure was inclined, was obtained by application of the program ANSYS-FLOTRAN CFD and a series of procedures, such as modeling, meshing, loading and equation solving. The numerical results show that in the level state, the temperatures at two points heat source are two points in the same isotherm; however, the temperatures are not the same when the enclosure is inclined. The difference of the temperatures will increase with the augment of the tilt angle, and contrarily it will decrease. That is the characteristic used to sense the transformation of obliquity.

  13. Z-Axis Micromachined Tuning Fork Gyroscope with Low Air Damping

    Directory of Open Access Journals (Sweden)

    Minh Ngoc Nguyen

    2017-02-01

    Full Text Available This paper reports on the design and fabrication of a z-axis tuning fork gyroscope which has a freestanding architecture. In order to improve the performance of the tuning fork gyroscope by eliminating the influence of the squeeze-film air damping, the driving and sensing parts of the gyroscope were designed to oscillate in-plane. Furthermore, by removing the substrate underneath the device, the slide-film air damping in the gap between the proof masses and the substrate was eliminated. The proposed architecture was analyzed by the finite element method using ANSYS software. The simulated frequencies of the driving and sensing modes were 9.788 and 9.761 kHz, respectively. The gyroscope was fabricated using bulk micromachining technology. The quality factor and sensitivity of the gyroscope operating in atmospheric conditions were measured to be 111.2 and 11.56 mV/°/s, respectively.

  14. Bending-induced electromechanical coupling and large piezoelectric response in a micromachined diaphragm

    KAUST Repository

    Wang, Zhihong

    2013-11-04

    We investigated the dependence of electromechanical coupling and the piezoelectric response of a micromachined Pb(Zr 0.52 Ti 0.48)O 3 (PZT) diaphragm on its curvature by observing the impedance spectrum and central deflection responses to a small AC voltage. The curvature of the diaphragm was controlled by applying air pressure to its back. We found that a depolarized flat diaphragm does not initially exhibit electromechanical coupling or the piezoelectric response. However, upon the application of static air pressure to the diaphragm, both electromechanical coupling and the piezoelectric response can be induced in the originally depolarized diaphragm. The piezoelectric response increases as the curvature increases and a giant piezoelectric response can be obtained from a bent diaphragm. The obtained results clearly demonstrate that a high strain gradient in a diaphragm can polarize a PZT film through a flexoelectric effect, and that the induced piezoelectric response of the diaphragm can be controlled by adjusting its curvature.

  15. Lead-Free Piezoelectric Diaphragm Biosensors Based on Micro-Machining Technology and Chemical Solution Deposition.

    Science.gov (United States)

    Li, Xiaomeng; Wu, Xiaoqing; Shi, Peng; Ye, Zuo-Guang

    2016-01-12

    In this paper, we present a new approach to the fabrication of integrated silicon-based piezoelectric diaphragm-type biosensors by using sodium potassium niobate-silver niobate (0.82KNN-0.18AN) composite lead-free thin film as the piezoelectric layer. The piezoelectric diaphragms were designed and fabricated by micro-machining technology and chemical solution deposition. The fabricated device was very sensitive to the mass changes caused by various targets attached on the surface of diaphragm. The measured mass sensitivity value was about 931 Hz/μg. Its good performance shows that the piezoelectric diaphragm biosensor can be used as a cost-effective platform for nucleic acid testing.

  16. Multifrequency Excitation Method for Rapid and Accurate Dynamic Test of Micromachined Gyroscope Chips

    Directory of Open Access Journals (Sweden)

    Yan Deng

    2014-10-01

    Full Text Available A novel multifrequency excitation (MFE method is proposed to realize rapid and accurate dynamic testing of micromachined gyroscope chips. Compared with the traditional sweep-frequency excitation (SFE method, the computational time for testing one chip under four modes at a 1-Hz frequency resolution and 600-Hz bandwidth was dramatically reduced from 10 min to 6 s. A multifrequency signal with an equal amplitude and initial linear-phase-difference distribution was generated to ensure test repeatability and accuracy. The current test system based on LabVIEW using the SFE method was modified to use the MFE method without any hardware changes. The experimental results verified that the MFE method can be an ideal solution for large-scale dynamic testing of gyroscope chips and gyroscopes.

  17. Aviation-oriented Micromachining Technology-Micro-ECM in Pure Water

    Institute of Scientific and Technical Information of China (English)

    Bao Huaiqian; Xu Jiawen; Li Ying

    2008-01-01

    This article proposes a precise and ecofriendly micromachining technology for aerospace application called electrochemical machining in pure water (PW-ECM). On the basis of the principles of water dissociation, a series of test setups and tests are devised and performed under different conditions. These tests explain the need for technological conditions realizing PW-ECM, and further explore the technological principles. The results from the tests demonstrate a successful removal of electrolytic slime by means of ultrasonic vibration of the workpiece. To ensure the stability and reliability of PW-ECM process, a new combined rnachining method of PW-ECM assisted with ultrasonic vibration (PW-ECM/USV) is devised. Trilateral and square cavities and holes as well as a group of English alphabets are worked out on a stainless steel plate. It is eonfirmed that PW-ECM will be probably an efficient new aviation precision machining method.

  18. Micro thermal shear stress sensor based on vacuum anodic bonding and bulk-micromachining

    Institute of Scientific and Technical Information of China (English)

    Yi Liang; Ou Yi; Shi Sha-Li; Ma Jin; Chen Da-Peng; Ye Tian-Chun

    2008-01-01

    This paper describes a micro thermal shear stress sensor with a cavity underneath, based on vacuum anodic bonding and bulk micromachined technology. A Ti/Pt alloy strip, 2μmx100μm, is deposited on the top of a thin silicon nitride diaphragm and functioned as the thermal sensor element. By using vacuum anodic bonding and bulk-si anisotropic wet etching process instead of the sacrificial-layer technique, a cavity, functioned as the adiabatic vacuum chamber, 200μm×200μm×400μm, is placed between the silicon nitride diaphragm and glass (Corning 7740). This method totally avoid adhesion problem which is a major issue of the sacrificial-layer technique.

  19. Theoretical model and optimal design of silicon micromachined ultrasonic imaging transducers

    Institute of Scientific and Technical Information of China (English)

    GE; LiFeng

    2007-01-01

    A theoretical model and mathematical description for silicon micromachined electrostatic or capacitive ultrasonic imaging transducers have been developed. According to the model the basic performance parameters of such a transducer, such as natural frequencies, eigenfunctions, resonance and anti-resonance frequencies, and the mechanical impedance of the diaphragm can be predicted from the geometry of the transducer and property parameters of materials used. The paper reveals that this type of transducers has two basic operation modes, corresponding to the resonance of a mass-spring oscillator comprised of the diaphragm and the air cushion, and the first-order bending mode of the diaphragm itself respectively, and presents an optimal method for extending the bandwidth by making the two modes coupled, and thereby provides a theoretical basis for the optimal design.

  20. An equivalent circuit model for transmitting capacitive micromachined ultrasonic transducers in collapse mode.

    Science.gov (United States)

    Olcum, Selim; Yamaner, F Yalcin; Bozkurt, Ayhan; Köymen, Hayrettin; Atalar, Abdullah

    2011-07-01

    The collapse mode of operation of capacitive micromachined ultrasonic transducers (CMUTs) was shown to be a very effective way to achieve high output pressures. However, no accurate analytical or equivalent circuit model exists for understanding the mechanics and limits of the collapse mode. In this work, we develop an equivalent nonlinear electrical circuit that can accurately simulate the mechanical behavior of a CMUT with given dimensions and mechanical parameters under any large or small signal electrical excitation, including the collapse mode. The static and dynamic deflections of a plate predicted from the model are compared with finite element simulations. The equivalent circuit model can estimate the static deflection and transient behavior of a CMUT plate to within 5% accuracy. The circuit model is in good agreement with experimental results of pulse excitation applied to fabricated CMUTs. The model is suitable as a powerful design and optimization tool for collapsed and uncollapsed CMUTs.

  1. Planar waveguide Michelson interferometer fabricated by using 157nm mask laser micromachining

    Science.gov (United States)

    Bao, Haihong; Ran, Zengling; Wu, Xuezhong; Yang, Ke; Jiang, Yuan; Rao, Yunjiang

    2015-07-01

    A Michelson interferometer is fabricated on silica planar waveguide by using the one-step technology based on 157nm mask laser micromachining. The fabrication time for one device is ~10s. Experimental results show that such an interferometer has an excellent fringe contrast of >20dB. Its temperature and refractive index (RI) responses are tested by observing the wavelength shift of the interferometric fringes, which shows linear characteristics with a thermo-coefficient of ~9.5pm/°C and a RI-coefficient of ~36.7nm/RIU, respectively. The fabrication technology may pave a new way for direct writing of planar silica waveguide devices for sensing applications with high efficiency and quality.

  2. Fabrication of Capacitive Micromachined Ultrasonic Transducers Using a Boron Etch-Stop Method

    DEFF Research Database (Denmark)

    Diederichsen, Søren Elmin; Sandborg-Olsen, Filip; Engholm, Mathias;

    2016-01-01

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) fabricated using Silicon-On-Insulator (SOI) wafers often have large thickness variation of the flexible plate, which causes variation in both pull-in voltage and resonant frequency across the CMUT array. This work presents a bond and boron...... etch-stop scheme for fabricating the flexible plate of a CMUT. The proposed fabrication method enables precise control of the plate thickness variation and is a low cost alternative to the SOI-based process. N-type silicon wafers are doped with boron to a surface concentration of > 1020 cm−3 using...... solid planar diffusion predeposition at 1125 °C for 30, 60, and 90 min. Process simulations are used to predict the boron doping profiles and validated with secondary ion mass spectrometry measurements. The doped wafers are fusion-bonded to a silicon dioxide surface and thinned down using an 80 °C, 20...

  3. Bending-induced electromechanical coupling and large piezoelectric response in a micromachined diaphragm.

    Science.gov (United States)

    Wang, Zhihong; Yao, Yingbang; Wang, Xianbin; Yue, Weisheng; Chen, Longqing; Zhang, Xi Xiang

    2013-11-04

    We investigated the dependence of electromechanical coupling and the piezoelectric response of a micromachined Pb(Zr₀.₅₂Ti₀.₄₈)O₃ (PZT) diaphragm on its curvature by observing the impedance spectrum and central deflection responses to a small AC voltage. The curvature of the diaphragm was controlled by applying air pressure to its back. We found that a depolarized flat diaphragm does not initially exhibit electromechanical coupling or the piezoelectric response. However, upon the application of static air pressure to the diaphragm, both electromechanical coupling and the piezoelectric response can be induced in the originally depolarized diaphragm. The piezoelectric response increases as the curvature increases and a giant piezoelectric response can be obtained from a bent diaphragm. The obtained results clearly demonstrate that a high strain gradient in a diaphragm can polarize a PZT film through a flexoelectric effect, and that the induced piezoelectric response of the diaphragm can be controlled by adjusting its curvature.

  4. Multianalyte Biosensor for Simultaneous Determination of Glucose and Galactose Based on Micromachined Chamber-type Electrodes

    Institute of Scientific and Technical Information of China (English)

    JlA Neng-Qin贾能勤; ZHANG Zong-Rang章宗穰; ZHU Jiang-Zhong朱建中; ZHANG Guo-Xiong张国雄

    2004-01-01

    An amperometric multianalyte biosensor for the simultaneous determination of glucose and galactose was developed based on chamber-type electrodes, which were fabricated by micromachining technology. The dual chamber-type enzyme electrode with glucose and galactose sensor elements was integrated onto one microchip. The experimental parameters of this biosensor were optimized. The biosensor exhibited a linearity of up to 4.0 mol/L for glucose and 4.5 mol/L for galactose, and the response time was about 30 s for glucose and 40 s for galactose. No cross-talking behavior was investigated in the course of simultaneous measurement of the two analytes. Interference from electroactive species, such as ascorbic acid and uric acid, was minimized due to the permselectivity of Nation film. In addition, the biosensor displayed a storage stability of longer than one month.

  5. A 45-element continuous facesheet surface micromachined deformable mirror for optical aberration correction

    Directory of Open Access Journals (Sweden)

    Weimin Wang

    2014-02-01

    Full Text Available A 45-element continuous facesheet surface micromachined deformable mirror (DM is presented and is fabricated using the PolyMUMPs multi-user micro-electro-mechanical system processes. The effects of the structural parameters on the characteristics of the DM, such as its stroke, frequency and actuator coupling, are analyzed. In addition, the DM design has also been verified through experimental testing. This DM prototype has a surface figure of 0.5 μm and a fill factor of 95%. The DM can provide a 0.6 μm stroke with 5.9% actuator coupling. A static aberration correction based on this DM is also demonstrated, which acts as a reference for the potential adaptive optics (AO applications of the device.

  6. Design and simulation of a tuning fork micromachined gyroscope with slide film damping

    Institute of Scientific and Technical Information of China (English)

    CHE Lu-feng; XIONG Bin; JIAO Ji-wei; WANG Yue-lin

    2005-01-01

    A novel tuning fork micromachined gyroscope, based on slide-film damping, is presented. The electrostatic driving gyroscope consists of two driving masses each of which supports one sensitive mass. The angular rate is sensed by the differential capacitances consisted of movable bar electrodes and fixed bar electrodes located on the glass wafer. The gyroscope can operate at atmospheric pressure with slide film damping in the driving and sensing directions, eliminate vacuum packaging and restrain cross-axis acceleration signal. The results of design and simulation show that the driving and sensing mode frequencies are 3 106 Hz and 3 175 Hz,respectively, and the Q-values in driving and sensitive modes are 1 721 and 1 450 respectively. The design resolution is 0.025°/s.

  7. Multifrequency excitation method for rapid and accurate dynamic test of micromachined gyroscope chips.

    Science.gov (United States)

    Deng, Yan; Zhou, Bin; Xing, Chao; Zhang, Rong

    2014-10-17

    A novel multifrequency excitation (MFE) method is proposed to realize rapid and accurate dynamic testing of micromachined gyroscope chips. Compared with the traditional sweep-frequency excitation (SFE) method, the computational time for testing one chip under four modes at a 1-Hz frequency resolution and 600-Hz bandwidth was dramatically reduced from 10 min to 6 s. A multifrequency signal with an equal amplitude and initial linear-phase-difference distribution was generated to ensure test repeatability and accuracy. The current test system based on LabVIEW using the SFE method was modified to use the MFE method without any hardware changes. The experimental results verified that the MFE method can be an ideal solution for large-scale dynamic testing of gyroscope chips and gyroscopes.

  8. An FPGA-based ultrasound imaging system using capacitive micromachined ultrasonic transducers.

    Science.gov (United States)

    Wong, Lawrence L P; Chen, Albert I; Logan, Andrew S; Yeow, John T W

    2012-07-01

    We report the design and experimental results of a field-programmable gate array (FPGA)-based real-time ultrasound imaging system that uses a 16-element phased-array capacitive micromachined ultrasonic transducer fabricated using a fusion bonding process. The imaging system consists of the transducer, discrete analog components situated on a custom-made circuit board, the FPGA, and a monitor. The FPGA program consists of five functional blocks: a main counter, transmit and receive beamformer, receive signal pre-processing, envelope detection, and display. No dedicated digital signal processor or personal computer is required for the imaging system. An experiment is carried out to obtain the sector B-scan of a 4-wire target. The ultrasound imaging system demonstrates the possibility of an integrated system-in-a-package solution.

  9. Scale Factor Determination of Micro-Machined Angular Rate Sensors Without a Turntable

    Institute of Scientific and Technical Information of China (English)

    Gaisser Alexander; GAO Zhongyu; ZHOU Bin; ZHANG Rong; CHEN Zhiyong

    2006-01-01

    This paper presents a digital readout system to detect small capacitive signals of a micro-machined angular rate sensor. The flexible parameter adjustment ability and the computation speed of the digital signal processor were used to develop a new calibration procedure to determine the scale factor of a gyroscope without a turntable. The force of gravity was used to deflect the movable masses in the sensor, which resulted in a corresponding angular rate input. The gyroscope scale factor was then measured without a turntable. Test results show a maximum deviation of about 1.2% with respect to the scale factor determined on a turntable with the accuracy independent of the manufacturing process and property variations. The calibration method in combination with the improved readout electronics can minimize the calibration procedure and, thus, reduce the manufacturing costs.

  10. Lead-Free Piezoelectric Diaphragm Biosensors Based on Micro-Machining Technology and Chemical Solution Deposition

    Directory of Open Access Journals (Sweden)

    Xiaomeng Li

    2016-01-01

    Full Text Available In this paper, we present a new approach to the fabrication of integrated silicon-based piezoelectric diaphragm-type biosensors by using sodium potassium niobate-silver niobate (0.82KNN-0.18AN composite lead-free thin film as the piezoelectric layer. The piezoelectric diaphragms were designed and fabricated by micro-machining technology and chemical solution deposition. The fabricated device was very sensitive to the mass changes caused by various targets attached on the surface of diaphragm. The measured mass sensitivity value was about 931 Hz/μg. Its good performance shows that the piezoelectric diaphragm biosensor can be used as a cost-effective platform for nucleic acid testing.

  11. TOPICAL REVIEW: Micromachined polymer electrolyte membrane and direct methanol fuel cells—a review

    Science.gov (United States)

    Nguyen, Nam-Trung; Chan, Siew Hwa

    2006-04-01

    This review reports recent progress of the development of micromachined membrane-based fuel cells. The review first discusses the scaling law applied to this type of fuel cell. Impacts of miniaturization on the performance of membrane-based fuel cells are highlighted. This review includes only the two most common micro fuel cell types: proton exchange membrane micro fuel cells (PEMµFC) and direct methanol micro fuel cells (DMµFC). Furthermore, we only consider fuel cells with the active area of a single cell less than 1 square inch. Since the working principles of these fuel cell types are well known, the review only focuses on the choice of material and the design consideration of the components in the miniature fuel cell. Next, we compare and discuss the performance of different micro fuel cells published recently in the literature. Finally, this review gives an outlook on possible future development of micro fuel cell research.

  12. High efficiency on-chip Dielectric Resonator Antennna using micromachining technology

    KAUST Repository

    Sallam, Mai O.

    2015-10-26

    In this paper, a novel cylindrical Dielectric Resonator Antenna (DRA) operating at 60 GHz is introduced. The antenna is fabricated using a high-resistivity silicon wafer. The DR is defined in the wafer using micromachining technology. The feeding network is located at the other side of the wafer. The proposed antenna is simulated using HFSS and the results are verified by measurements. The antenna radiation is mainly along the broadside direction. The measured gain, radiation efficiency, and bandwidth are 7 dBi, 74.65%, and 2.23 GHz respectively. The antenna is characterized by high polarization purity where the maximum cross-polarization is -15 dB. © 2015 IEEE.

  13. Corporate array of micromachined dipoles on silicon wafer for 60 GHz communication systems

    KAUST Repository

    Sallam, M. O.

    2013-03-01

    In this paper, an antenna array operating at 60 GHz and realized on 0.675 mm thick silicon substrate is presented. The array is constructed using four micromachined half-wavelength dipoles fed by a corporate feeding network. Isolation between the antenna array and its feeding network is achieved via a ground plane. This arrangement leads to maximizing the broadside radiation with relatively high front-to-back ratio. Simulations have been carried out using both HFSS and CST, which showed very good agreement. Results reveal that the proposed antenna array has good radiation characteristics, where the directivity, gain, and radiation efficiency are around 10.5 dBi, 9.5 dBi, and 79%, respectively. © 2013 IEEE.

  14. A Flexible Ultrasound Transducer Array with Micro-Machined Bulk PZT

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    2015-01-01

    Full Text Available This paper proposes a novel flexible piezoelectric micro-machined ultrasound transducer, which is based on PZT and a polyimide substrate. The transducer is made on the polyimide substrate and packaged with medical polydimethylsiloxane. Instead of etching the PZT ceramic, this paper proposes a method of putting diced PZT blocks into holes on the polyimide which are pre-etched. The device works in d31 mode and the electromechanical coupling factor is 22.25%. Its flexibility, good conformal contacting with skin surfaces and proper resonant frequency make the device suitable for heart imaging. The flexible packaging ultrasound transducer also has a good waterproof performance after hundreds of ultrasonic electric tests in water. It is a promising ultrasound transducer and will be an effective supplementary ultrasound imaging method in the practical applications.

  15. Micromachining of monocrystalline silicon and glass for chemical analysis systems. A look into next century's technology or just a fashionable craze?

    NARCIS (Netherlands)

    Manz, A.; Fettinger, J.C.; Verpoorte, E.; Ludi, H.; Widmer, H.M.; Harrison, D.J.

    1991-01-01

    Miniaturization of already existing techniques in on-line analytical chemistry is an alternative to compound-selective chemical sensors. Theory indicates higher efficiency, faster analysis time and lower reagent consumption. Micromachining, a well known photolithographic technique for structures in

  16. Experimental procurement of the complete 3D etch rate distribution of Si in anisotropic etchants based on vertically micromachined wagon wheel samples

    Science.gov (United States)

    Gosálvez, M. A.; Pal, Prem; Ferrando, N.; Hida, H.; Sato, K.

    2011-12-01

    This is part I of a series of two papers dedicated to the presentation of a novel, large throughput, experimental procedure to determine the three-dimensional distribution of the etch rate of silicon in a wide range of anisotropic etchants, including a total of 30 different etching conditions in KOH, KOH+IPA, TMAH and TMAH+Triton solutions at various concentrations and temperatures. The method is based on the use of previously reported, vertically micromachined wagon wheels (WWs) (Wind and Hines 2000 Surf. Sci. 460 21-38 Nguyen and Elwenspoek 2007 J. Electrochem. Soc. 154 D684-91), focusing on speeding up the etch rate extraction process for each WW by combining macrophotography and image processing procedures. The proposed procedure positions the WWs as a realistic alternative to the traditional hemispherical specimen. The obtained, extensive etch rate database is used to perform wet etching simulations of advanced systems, showing good agreement with the experimental counterparts. In part II of this series (Gosálvez et al J. Micromech. Microeng. 21 125008), we provide a theoretical analysis of the etched spoke shapes, a detailed comparison to the etch rates from previous studies and a self-consistency study of the measured etch rates against maximum theoretical values derived from the spoke shape analysis.

  17. Industrial grade fiber-coupled laser systems delivering ultrashort high-power pulses for micromachining

    Science.gov (United States)

    Pricking, Sebastian; Welp, Petra; Overbuschmann, Johannes; Nutsch, Sebastian; Gebs, Raphael; Fleischhaker, Robert; Kleinbauer, Jochen; Wolf, Martin; Budnicki, Aleksander; Sutter, Dirk H.; Killi, Alexander; Mielke, Michael

    2016-03-01

    We report on an industrial fiber-delivered laser system producing ultra-short pulses in the range of a few picoseconds down to a few hundred femtoseconds with high average power suitable for high-precision micromachining. The delivery fiber is a hollow-core photonic crystal fiber with a Kagomé shaped lattice and a hypocycloid core wall enabling the guiding of laser radiation over several meters with exceptionally low losses and preservation of high beam quality (M2laser head providing a compact footprint without the need for external boxes. The laser head is carefully designed regarding its thermo-mechanical properties to allow a highly reliable coupling stability. The exchangeable delivery fiber is packaged using Trumpf's well established LLK-D connectors which offer a very high mechanical precision, the possibility to add water cooling, as well as full featured safety functions. The fiber is hermetically sealed and protected by a robust but flexible shield providing bend protection and break detection. We show the linear and nonlinear optical properties of the transported laser radiation and discuss its feasibility for pulse compression. Measurements are supported by simulation of pulse propagation by solving the nonlinear Schrödinger equation implementing the split-step Fourier method. In addition, mode properties are measured and confirmed by finite element method simulations. The presented industrial laser system offers the known advantages of ultra-short pulses combined with the flexibility of fiber delivery yielding a versatile tool perfectly suitable for all kinds of industrial micromachining applications.

  18. Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.

    Science.gov (United States)

    Li, Chunyan; Wu, Pei-Ming; Hartings, Jed A; Wu, Zhizhen; Cheyuo, Cletus; Wang, Ping; LeDoux, David; Shutter, Lori A; Ramaswamy, Bharat Ram; Ahn, Chong H; Narayan, Raj K

    2012-08-01

    This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 μA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.

  19. High-intensity fibre laser design for micro-machining applications

    Science.gov (United States)

    Ortiz-Neria, D. I.; Martinez-Piñón, F.; Hernandez-Escamilla, H.; Alvarez-Chavez, J. A.

    2010-11-01

    This work is focused on the design of a 250W high-intensity continuous-wave fibre optic laser with a 15μm spot size beam and a beam parameter product (BPP) of 1.8 for its use on Laser-assisted Cold Spray process (LCS) in the micro-machining areas. The metal-powder deposition process LCS, is a novel method based on Cold Spray technique (CS) assisted by laser technology. The LCS accelerates metal powders by the use of a high-pressure gas in order to achieve flash welding of particles over substrate. In LCS, the critical velocity of impact is lower with respect with CS while the powder particle is heated before the deposition by a laser beam. Furthermore, LCS does not heat the powder to achieve high temperatures as it happens in plasma processes. This property puts aside cooling problems which normally happen in sintered processes with high oxygen/nitrogen concentration levels. LCS will be used not only in deposition of thin layers. After careful design, proof of concept, experimental data, and prototype development, it should be feasible to perform micro-machining precise work with the use of the highintensity fibre laser presented in this work, and selective deposition of particles, in a similar way to the well-known Direct Metal Laser Sintering process (DMLS). The fibre laser consists on a large-mode area, Yb3+-doped, semi-diffraction limited, 25-m fibre laser cavity, operating in continuous wave regime. The fibre shows an arguably high slope-efficiency with no signs of roll-over. The measured M2 value is 1.8 and doping concentration of 15000ppm. It was made with a slight modification of the traditional MCVD technique. A full optical characterization will be presented.

  20. System integration design in MEMS – A case study of micromachined load cell

    Indian Academy of Sciences (India)

    Shishir Kumar; K P Venkatesh; S Sam Baskar; S P Madhavi

    2009-08-01

    One of the critical issues in large scale commercial exploitation of MEMS technology is its system integration. In MEMS, a system design approach requires integration of varied and disparate subsystems with one of a kind interface. The physical scales as well as the magnitude of signals of various subsystems vary widely. Known and proven integration techniques often lead to considerable loss in advantages the tiny MEMS sensors have to offer. Therefore, it becomes imperative to think of the entire system at the outset, at least in terms of the concept design. Such design entails various aspects of the system ranging from selection of material, transduction mechanism, structural configuration, interface electronics, and packaging. One way of handling this problem is the system-in-package approach that uses optimized technology for each function using the concurrent hybrid engineering approach. The main strength of this design approach is the fast time to prototype development. In the present work, we pursue this approach for a MEMS load cell to complete the process of system integration for high capacity load sensing. The system includes; a micromachined sensing gauge, interface electronics and a packaging module representing a system-in-package ready for end characterization. The various subsystems are presented in a modular stacked form using hybrid technologies. The micromachined sensing subsystem works on principles of piezo-resistive sensing and is fabricated using CMOS compatible processes. The structural configuration of the sensing layer is designed to reduce the offset, temperature drift, and residual stress effects of the piezo-resistive sensor. ANSYS simulations are carried out to study the effect of substrate coupling on sensor structure and its sensitivity. The load cell system has built-in electronics for signal conditioning, processing, and communication, taking into consideration the issues associated with resolution of minimum detectable signal

  1. Micromachined bulk PZT tissue contrast sensor for fine needle aspiration biopsy.

    Science.gov (United States)

    Li, Tao; Gianchandani, Roma Y; Gianchandani, Yogesh B

    2007-02-01

    This paper describes a micromachined piezoelectric sensor, integrated into a cavity at the tip of a biopsy needle, and preliminary experiments to determine if such a device can be used for real-time tissue differentiation, which is needed for needle positioning guidance during fine needle aspiration (FNA) biopsy. The sensor is fabricated from bulk lead zirconate titanate (PZT), using a customized process in which micro electro-discharge machining is used to form a steel tool that is subsequently used for batch-mode ultrasonic micromachining of bulk PZT ceramic. The resulting sensor is 50 microm thick and 200 microm in diameter. It is placed in the biopsy needle cavity, against a steel diaphragm which is 300 microm diameter and has an average thickness of 23 microm. Devices were tested in materials that mimic the ultrasound characteristics of human tissue, used in the training of physicians, and with porcine fat and muscle tissue. In both schemes, the magnitude and frequency of an electrical impedance resonance peak showed tissue-specific characteristics as the needle was inserted. For example, in the porcine tissue, the impedance peak frequency changed approximately 13 MHz from the initial 163 MHz, and the magnitude changed approximately 1600 Omega from the initial 2100 Omega, as the needle moved from fat to muscle. Samples including oils and saline solution were tested for calibration, and an empirical tissue contrast model shows an approximately proportional relationship between measured frequency shift and sample acoustic impedance. These results suggest that the device can complement existing methods for guidance during biopsies.

  2. Silicon micromachined ultrasonic scalpel for the dissection and coagulation of tissue.

    Science.gov (United States)

    Lockhart, R; Friedrich, F; Briand, D; Margairaz, P; Sandoz, J-P; Brossard, J; Keppner, H; Olson, W; Dietz, T; Tardy, Y; Meyer, H; Stadelmann, P; Robert, C; Boegli, A; Farine, P-A; de Rooij, N F; Burger, J

    2015-08-01

    This work presents a planar, longitudinal mode ultrasonic scalpel microfabricated from monocrystalline silicon wafers. Silicon was selected as the material for the ultrasonic horn due to its high speed of sound and thermal conductivity as well as its low density compared to commonly used titanium based alloys. Combined with a relatively high Young's modulus, a lighter, more efficient design for the ultrasonic scalpel can be implemented which, due to silicon batch manufacturing, can be fabricated at a lower cost. Transverse displacement of the piezoelectric actuators is coupled into the planar silicon structure and amplified by its horn-like geometry. Using finite element modeling and experimental displacement and velocity data as well as cutting tests, key design parameters have been identified that directly influence the power efficiency and robustness of the device as well as its ease of controllability when driven in resonance. Designs in which the full- and half-wave transverse modes of the transducer are matched or not matched to the natural frequencies of the piezoelectric actuators have been evaluated. The performance of the Si micromachined scalpels has been found to be comparable to existing commercial titanium based ultrasonic scalpels used in surgical operations for efficient dissection of tissue as well as coaptation and coagulation of tissue for hemostasis. Tip displacements (peak-to-peak) of the scalpels in the range of 10-50 μm with velocities ranging from 4 to 11 m/s have been achieved. The frequency of operation is in the range of 50-100 kHz depending on the transverse operating mode and the length of the scalpel. The cutting ability of the micromachined scalpels has been successfully demonstrated on chicken tissue.

  3. Unveiling the wet chemical etching characteristics of polydimethylsiloxane film for soft micromachining applications

    Science.gov (United States)

    Kakati, A.; Maji, D.; Das, S.

    2017-01-01

    Micromachining of a polydimethylsiloxane (PDMS) microstructure by wet chemical etching is explored for microelectromechanical systems (MEMS) and microfluidic applications. A 100 µm thick PDMS film was patterned with different microstructure designs by wet chemical etching using a N-methyl-2-pyrrolidone (C16H36FN) and tetra-n-butylammonium fluoride (C5H9NO) mixture solution with 3:1 volume ratio after lithography for studying etching characteristics. The patterning parameters, such as etch rate, surface roughness, pH of etchant solution with time, were thoroughly investigated. A detailed study of surface morphology with etching time revealed nonlinear behaviour of the PDMS surface roughness and etch rate. A maximum rate of 1.45 µm min-1 for 10 min etching with surface roughness of 360 nm was achieved. A new approach of wet chemical etching with pH controlled doped etchant was introduced for lower surface roughness of etched microstructures, and a constant etch rate during etching. Variation of the etching rate and surface roughness by pH controlled etching was performed by doping 5-15 gm l-1 of silicic acid (SiO2x H2O) into the traditional etchant solution. PDMS etching by silicic acid doped etchant solution showed a reduction in surface roughness from 400 nm to 220 nm for the same 15 µm etching. This study is beneficial for micromachining of various MEMS and microfluidic structures such as micropillars, microchannels, and other PDMS microstructures.

  4. Design, simulation and testing of capacitive micromachined ultrasound transducer-based phospholipidic biosensor elements

    Science.gov (United States)

    Sapeliauskas, E.; Vanagas, G.; Barauskas, D.; Mikolajunas, M.; Pakenas, E.; Pelenis, D.; Sergalis, G.; Jukna, T.; Virzonis, D.

    2015-07-01

    In this study we present theoretical proof of the principle of using interdigital capacitive micromachined ultrasound transducers (CMUT IDTs) for the detection of phospholipid membrane elasticity. Proof of principle was needed to find out whether the new type of microelectromechanical sensors of the toxins incorporated with the lipid membranes was feasible. CMUT IDTs for 10 MHz operation in water, with 146 µm spaced double fingers were designed and fabricated using the surface micromachining technique. Fabricated CMUTs were tested for their resonance in air and for Scholte-type wave transmission in deionized water and isopropanol solutions containing 0%, 10% and 20% water. The amplitude and phase velocity of the excited and received Scholte waves were measured in a 200 µm height microchannel, capped with a thick layer of soft polymer, which suppressed the production of non-informative guided waves. It was determined that the average sensitivity of Scholte wave phase velocity within the given range of solution concentrations is 2.9 m s-1 per one percent. Experimental data were also used to verify the adequacy of the finite element model, which was found to be suitable for reliable prediction of the phospholipid membrane elasticity impact on the Scholte wave phase velocity or the resonance frequency in the present IDT structure. It was determined that for the analyzed conditions (the elasticity of simulated phospholipid membrane changed from 1 to 5 GPa) the sensitivity of the measurement channel is expected to be no worse than 2 kHz GPa-1 in terms of the Scholte wave and CMUT IDT resonance frequency. This leads to a positive conclusion on the feasibility of the new sensor type.

  5. Extending the frequency range of free-field reciprocity calibration of measurement microphones to frequencies up to 150 kHz

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Torras Rosell, Antoni; Jacobsen, Finn

    2013-01-01

    Measurement microphones are typically calibrated in a free field at frequencies up to 50 kHz. This is a sufficiently high frequency for the most sound measurement applications related with noise assessment. However, other applications such as the measurement of noise emitted by ultrasound cleanin...

  6. Final report on key comparison CCAUV.A-K5: pressure calibration of laboratory standard microphones in the frequency range 2 Hz to 10 kHz

    Science.gov (United States)

    Avison, Janine; Barham, Richard

    2014-01-01

    This document and the accompanying spreadsheets constitute the final report for key comparison CCAUV.A-K5 on the pressure calibration of laboratory standard microphones in the frequency range from 2 Hz to 10 kHz. Twelve national measurement institutes took part in the key comparison and the National Physical Laboratory piloted the project. Two laboratory standard microphones IEC type LS1P were circulated to the participants and results in the form of regular calibration certificates were collected throughout the project. One of the microphones was subsequently deemed to have compromised stability for the purpose of deriving a reference value. Consequently the key comparison reference value (KCRV) has been made based on the weighted mean results for sensitivity level and for sensitivity phase from just one of the microphones. Corresponding degrees of equivalence (DoEs) have also been calculated and are presented. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. Analysis of Adaptive Feedback and Echo Cancelation Algorithms in A General Multiple-Microphone and Single-Loudspeaker System

    DEFF Research Database (Denmark)

    Guo, Meng; Elmedyb, Thomas Bo; Jensen, Søren Holdt;

    2011-01-01

    In this paper, we analyze a general multiple-microphone and single-loudspeaker system, where an adaptive algorithm is used to cancel acoustic feedback/echo and a beamformer processes the feedback/echo canceled signals. This system can be viewed as part of a typical hearing aid system and....../or a traditional acoustic echo cancelation system. We introduce and derive an approximation of a useful frequency domain measure - the power transfer function - and show how to predict the system stability bound, convergence rate and the steady-state behavior across time and frequency. Furthermore, we show how...... the derived expressions can be used to determine e.g. the step size parameter in the adaptive algorithms to achieve a desired system property e.g. convergence rate at a specific frequency....

  8. High frequency microphone measurements for transition detection on airfoils. Risø B1-18 appendix report

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given...... to transition detection. It is argued that the transition point can be detected by observing the increase in the mean of the Fourier spectre and that thismethod is very stable froma numerical point of view. Other important issues are also discussed, e.g. the variation of pressure standard deviations (sound...... pressure) and Tollmien-Schlichting frequencies. The tests were made at Reynolds and Mach numbers corresponding to the operating conditions of a typical horizontal axis wind turbine (HAWT). The Risø B1-18, Risø C2-18 and NACA0015 profiles were tested and the measured transition points are reported....

  9. High frequency microphone measurements for transition detection on airfoils. Risø C2-18 appendix report

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given...... to transition detection. It is argued that the transition point can be detected by observing the increase in the mean of the Fourier spectre and that thismethod is very stable froma numerical point of view. Other important issues are also discussed, e.g. the variation of pressure standard deviations (sound...... pressure) and Tollmien-Schlichting frequencies. The tests were made at Reynolds and Mach numbers corresponding to the operating conditions of a typical horizontal axis wind turbine (HAWT). The Risø B1-18, Risø C2-18 and NACA0015 profiles were tested and the measured transition points are reported....

  10. Development and Calibration of a Field-Deployable Microphone Phased Array for Propulsion and Airframe Noise Flyover Measurements

    Science.gov (United States)

    Humphreys, William M., Jr.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.; Ravetta, Patricio A.; Johns, Zachary

    2016-01-01

    A new aeroacoustic measurement capability has been developed consisting of a large channelcount, field-deployable microphone phased array suitable for airframe noise flyover measurements for a range of aircraft types and scales. The array incorporates up to 185 hardened, weather-resistant sensors suitable for outdoor use. A custom 4-mA current loop receiver circuit with temperature compensation was developed to power the sensors over extended cable lengths with minimal degradation of the signal to noise ratio and frequency response. Extensive laboratory calibrations and environmental testing of the sensors were conducted to verify the design's performance specifications. A compact data system combining sensor power, signal conditioning, and digitization was assembled for use with the array. Complementing the data system is a robust analysis system capable of near real-time presentation of beamformed and deconvolved contour plots and integrated spectra obtained from array data acquired during flyover passes. Additional instrumentation systems needed to process the array data were also assembled. These include a commercial weather station and a video monitoring / recording system. A detailed mock-up of the instrumentation suite (phased array, weather station, and data processor) was performed in the NASA Langley Acoustic Development Laboratory to vet the system performance. The first deployment of the system occurred at Finnegan Airfield at Fort A.P. Hill where the array was utilized to measure the vehicle noise from a number of sUAS (small Unmanned Aerial System) aircraft. A unique in-situ calibration method for the array microphones using a hovering aerial sound source was attempted for the first time during the deployment.

  11. Advanced sensing technology in environmental field.

    Science.gov (United States)

    Wakida, Shin-ichi

    2009-01-01

    Before the introduction of advanced sensing technology in environmental fields, environmental issues were discussed as several categories, such as local environmental issues in the 1970s, global environmental issues in the 1980s, living environmental issues in the 2000s and environmental stress issues in near future, which are of increasing interest in Japan. Using advanced sensing technologies, such as electrochemical sensors, chemically-sensitive field-effect transistors (ChemFETs) based on micro-electro mechanical system (MEMS) micromachining technology and subsequently electrophoretic separation and microfluidic Lab-on-a-Chip using MEMS technology, we have steered several kinds of environmental monitoring projects timely in response to the environmental issues for over the last 25 years. Among the local environmental issues, the global environmental issues and the living environmental issues, some fruits of R&D project will be introduced. Finally, our latest concern of the environmental stress monitoring was discussed and preliminary results were also introduced.

  12. Microstructures using RF sputtered PSG film as a sacrificial layer in surface micromachining

    Indian Academy of Sciences (India)

    Vivekanand Bhatt; Sudhir Chandra; Chatar Singh

    2009-08-01

    In this paper, we explore RF magnetron sputtered Phosphor–silicate–glass (PSG) film as a sacrificial layer in surface micromachining technology. For this purpose, a 76 mm diameter target of phosphorus-doped silicon dioxide was prepared by conventional solid-state reaction route using P25 and SiO2 powders. The PSG films were prepared in a RF (13·56 MHz) magnetron sputtering system at 300 watt RF power, 20 mTorr pressure and 45 mm target-to-substrate spacing without external substrate heating. Microstructures of sputtered silicon dioxide film were fabricated using sputtered PSG film as sacrificial layer in surface micromachining process.

  13. Improved hollow-core photonic crystal fiber design for delivery of nanosecond pulses in laser micromachining applications.

    Science.gov (United States)

    Shephard, Jonathan D; Couny, Francois; Russell, Phillip St J; Jones, Julian D C; Knight, Jonathan C; Hand, Duncan P

    2005-07-20

    We report the delivery of high-energy nanosecond pulses (approximately 65 ns pulse width) from a high-repetition-rate (up to 100 kHz) Q-switched Nd:YAG laser through the fundamental mode of a hollow-core photonic crystal fiber (HC-PCF) at 1064 nm. The guided mode in the HC-PCF has a low overlap with the glass, allowing delivery of pulses with energies above those attainable with other fibers. Energies greater than 0.5 mJ were delivered in a single spatial mode through the hollow-core fiber, providing the pulse energy and high beam quality required for micromachining of metals. Practical micromachining of a metal sheet by fiber delivery has been demonstrated.

  14. Experimental and theoretical study of the laser micro-machining of glass using high-repetition-rate ultrafast laser

    Science.gov (United States)

    Yashkir, Yuri; Liu, Qiang

    2006-04-01

    We present a systematic study of the ultrafast laser micro-machining of glass using a Ti:Spp laser with moderate pulse energy (<5 μJ) at a high repetition rate (50 kHz). Optimal conditions were identified for high resolution surface laser etching, and via drilling. Several practical applications were developed: glass templates for micro fluid diffraction devices, phase gratings for excimer laser projection techniques, micro fluid vertical channel-connectors, etc. It is demonstrated that the interaction of ultrafast laser pulses with glass combines several different processes (direct ablation, explosive material ejection, and thermal material modification). A dynamic numerical model was developed for this process. It was successfully used for modelling of laser micro-machining with arbitrary 3D translations of the target.

  15. Micromachining of liquid crystal polymer film with frequency converted diode-pumped Nd:YVO4 laser

    Science.gov (United States)

    Li, Mingwei; Hix, Ken; Dosser, Larry R.; Hartke, Kevin; Blackshire, Jim

    2003-07-01

    Liquid crystal polymer (LCP) is a new and innovative material being used as an alternative to polyimide in the flexible circuit industry. LCP has many intrinsic benefits over polyimide including lower moisture absorption and improved dimensional stability. However, LCP is very resistant to chemical milling or etching. As a result, other methods for processing the material are being investigated including laser micromachining. In this paper, three frequency converted diode-pumped solid-state (DPSS) Nd:YVO4 lasers at 355 nm were used to micromachine a LCP film and a copper/LCP laminate. Of them, two are Q-switched lasers operating in the nanosecond regime and the other a mode-locked laser in the picosecond regime. The Q-switched lasers can be operated at pulse repetition rates of 1 to 300 kHz while the mode-locked system is operated at 80 MHz. The micromachining experiments consisted of cutting the 50 μm thick LCP film, cutting the 18 μm thick copper on the film, and drilling micro-vias through both the copper coating and the film substrate. The laser/material interactions and processing speeds were studied and compared. The results show that, compared to polyimide film of the same thickness, LCP film can be more efficiently processed by laser micromachining. In addition, each laser has a unique advantage in processing LCP based flexible circuit materials. The Q-switched lasers are more capable of processing the copper coating while the mode-locked laser can cut LCP film faster with the smallest kerf width.

  16. Chemical and mechanical properties of silica hybrid films from NaOH catalyzed sols for micromachining with diamond cutting tools

    Energy Technology Data Exchange (ETDEWEB)

    Prenzel, T., E-mail: tprenzel@uni-bremen.de [Stiftung Institut für Werkstofftechnik, Badgasteiner Str. 3, 28359 Bremen (Germany); Mehner, A. [Stiftung Institut für Werkstofftechnik, Badgasteiner Str. 3, 28359 Bremen (Germany); Lucca, D.A.; Qi, Y.; Harriman, T.A. [School of Mechanical and Aerospace Engineering, 218 Engineering North, Oklahoma State University, Stillwater, OK 74078 (United States); Mutlugünes, Y. [Labor für Mikrozerspanung — LFM, Badgasteiner Str. 2, 28359 Bremen (Germany); Shojaee, S.A. [School of Mechanical and Aerospace Engineering, 218 Engineering North, Oklahoma State University, Stillwater, OK 74078 (United States); Wang, Y.Q.; Williams, D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Nastasi, M. [Nebraska Center for Energy Sciences Research, University of Nebraska, 230 Whittier Research Center, 2200 Vine Street Lincoln, NE 68583-0857 (United States); Zoch, H.-W. [Stiftung Institut für Werkstofftechnik, Badgasteiner Str. 3, 28359 Bremen (Germany); Swiderek, P. [Institute of Applied and Physical Chemistry, University of Bremen, Leobener Straße, 28359 Bremen (Germany)

    2013-03-01

    Manufacturing of microstructured mold surfaces was realized by the micromachining of thick sol–gel silica hybrid coatings. The films were deposited onto pre-machined steel molds by spin coating using NaOH-catalyzed sols from organosilicate precursors. The effect of the sol synthesis and the heat treatment on the mechanical and chemical properties of these films was studied in order to develop thick and crack-free films with appropriate properties for micromachining with diamond cutting tools. The hardness was measured by nanoindentation as a function of the heat treatment temperature. The transition from soft organic gel films to hard glass-like films due to the thermal treatment was characterized by X-ray photoelectron spectroscopy, elastic recoil detection, and Raman and infrared spectroscopies. The films from NaOH catalyzed sols showed a complex transition from aliphatic carbon originating from hydrocarbon groups to carbonates, carboxylates and disordered carbon clusters. - Highlights: ► Thick silica hybrid films were micromachined with diamond cutting tools. ► The nanoindentation hardness increased with the heat treatment temperature. ► The role of sodium hydroxide in base catalyzed silica sols was studied. ► Formation of carbonates, carboxylates and disordered carbon was observed.

  17. Demonstration of a micromachined planar distribution network in gap waveguide technology for a linear slot array antenna at 100 GHz

    Science.gov (United States)

    Rahiminejad, S.; Zaman, A. U.; Haasl, S.; Kildal, P.-S.; Enoksson, P.

    2016-07-01

    The need for high frequency antennas is rapidly increasing with the development of new wireless rate communication technology. Planar antennas have an attractive form factor, but they require a distribution network. Microstrip technology is most commonly used at low frequency but suffers from large dielectric and ohmic losses at higher frequencies and particularly above 100 GHz. Substrate-integrated waveguides also suffer from dielectric losses. In addition, standard rectangular waveguide interfaces are inconvenient due to the four flange screws that must be tightly fastened to the antenna to avoid leakage. The current paper presents a planar slot array antenna that does not suffer from any of these problems. The distribution network is realized by micromachining using low-loss gap waveguide technology, and it can be connected to a standard rectangular waveguide flange without using any screws or additional packaging. To realize the antenna at these frequencies, it was fabricated with micromachining, which offers the required high precision, and a low-cost fabrication method. The antenna was micromachined with DRIE in two parts, one silicon-on-insulator plate and one Si plate, which were both covered with Au to achieve conductivity. The input reflection coefficient was measured to be below 10 dB over a 15.5% bandwidth, and the antenna gain was measured to be 10.4 dBi, both of which are in agreement with simulations.

  18. Acceleration of dormant storage effects to address the reliability of silicon surface micromachined Micro-Electro-Mechanical Systems (MEMS).

    Energy Technology Data Exchange (ETDEWEB)

    Cox, James V.; Candelaria, Sam A.; Dugger, Michael Thomas; Duesterhaus, Michelle Ann; Tanner, Danelle Mary; Timpe, Shannon J.; Ohlhausen, James Anthony; Skousen, Troy J.; Jenkins, Mark W.; Jokiel, Bernhard, Jr.; Walraven, Jeremy Allen; Parson, Ted Blair

    2006-06-01

    Qualification of microsystems for weapon applications is critically dependent on our ability to build confidence in their performance, by predicting the evolution of their behavior over time in the stockpile. The objective of this work was to accelerate aging mechanisms operative in surface micromachined silicon microelectromechanical systems (MEMS) with contacting surfaces that are stored for many years prior to use, to determine the effects of aging on reliability, and relate those effects to changes in the behavior of interfaces. Hence the main focus was on 'dormant' storage effects on the reliability of devices having mechanical contacts, the first time they must move. A large number ({approx}1000) of modules containing prototype devices and diagnostic structures were packaged using the best available processes for simple electromechanical devices. The packaging processes evolved during the project to better protect surfaces from exposure to contaminants and water vapor. Packages were subjected to accelerated aging and stress tests to explore dormancy and operational environment effects on reliability and performance. Functional tests and quantitative measurements of adhesion and friction demonstrated that the main failure mechanism during dormant storage is change in adhesion and friction, precipitated by loss of the fluorinated monolayer applied after fabrication. The data indicate that damage to the monolayer can occur at water vapor concentrations as low as 500 ppm inside the package. The most common type of failure was attributed to surfaces that were in direct contact during aging. The application of quantitative methods for monolayer lubricant analysis showed that even though the coverage of vapor-deposited monolayers is generally very uniform, even on hidden surfaces, locations of intimate contact can be significantly depleted in initial concentration of lubricating molecules. These areas represent defects in the film prone to adsorption of

  19. Micromachined ultrasound transducers with improved coupling factors from a CMOS compatible process

    Science.gov (United States)

    Eccardt; Niederer

    2000-03-01

    For medical high frequency acoustic imaging purposes the reduction in size of a single transducer element for one-dimensional and even more for two-dimensional arrays is more and more limited by fabrication and cabling technology. In the fields of industrial distance measurement and simple object recognition low cost phased arrays are lacking. Both problems can be solved with micromachined ultrasound transducers (MUTs). A single transducer is made of a large number of microscopic elements. Because of the array structure of these transducers, groups of elements can be built up and used as a phased array. By integrating parts of the sensor electronics on chip, the cabling effort for arrays can be reduced markedly. In contrast to standard ultrasonic technology, which is based on massive thickness resonators, vibrating membranes are the radiating elements of the MUTs. New micromachining technologies have emerged, allowing a highly reproducible fabrication of electrostatically driven membranes with gap heights below 500 nm. A microelectronic BiCMOS process was extended for surface micromechanics (T. Scheiter et al., Proceedings 11th European Conference on Solid-State Transducers, Warsaw, Vol. 3, 1997, pp. 1595-1598). Additional process steps were included for the realization of the membranes which form sealed cavities with the underlying substrate. Membrane and substrate are the opposite electrodes of a capacitive transducer. The transducers can be integrated monolithically on one chip together with the driving, preamplifying and multiplexing circuitry, thus reducing parasitic capacities and noise level significantly. Owing to their low mass the transducers are very well matched to fluid loads, resulting in a very high bandwidth of 50-100% (C. Eccardt et al., Proceedings Ultrasonics Symposium, San Antonio, Vol. 2, 1996, pp. 959-962; P.C. Eccardt et al., Proceedings of the 1997 Ultrasonics Symposium, Toronto, Vol. 2, 1997, pp. 1609-1618). In the following it is shown how

  20. Single crystal piezoelectric composites for advanced NDT ultrasound

    Science.gov (United States)

    Jiang, Xiaoning; Snook, Kevin; Hackenberger, Wesley S.; Geng, Xuecang

    2007-04-01

    In this paper, the design, fabrication and characterization of PMN-PT single crystal/epoxy composites are reported for NDT ultrasound transducers. Specifically, 1-3 PMN-PT/epoxy composites with center frequencies of 5 MHz - 40 MHz were designed and fabricated using either the dice-and-fill method or a photolithography based micromachining process. The measured electromechanical coefficients for composites with frequency of 5 MHz - 15 MHz were about 0.78-0.83, and the coupling coefficients for composites with frequencies of 25 MHz- 40 MHz were about 0.71-0.72. The dielectric loss remains low (advanced NDT ultrasound applications.

  1. Annual meeting of the Advanced Light Source Users` Association

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-02-01

    This report contains papers on the following topics: ALS Director`s Report; ALS Operations Update; Recent Results in Machine Physics; Progress in Beamline Commissioning and Overview of New Projects; The ALS Scientific Program; First Results from the SpectroMicroscopy Beamline; Soft X-ray Fluorescence Spectroscopy of Solids; Soft X-Ray Fluorescence Spectroscopy of Molecules; Microstructures and Micromachining at the ALS; High-Resolution Photoemission from Simple Atoms and Molecules; X-Ray Diffraction at the ALS; Utilizing Synchrotron Radiation in Advanced Materials Industries; Polymer Microscopy: About Balls, Rocks and Other ``Stuff``; Infrared Research and Applications; and ALS User Program.

  2. DFT-Domain Based Single-Microphone Noise Reduction for Speech Enhancement

    DEFF Research Database (Denmark)

    C. Hendriks, Richard; Gerkmann, Timo; Jensen, Jesper

    for speech enhancement comprises a history of more than 30 years of research. In this survey, we wish to demonstrate the significant advances that have been made during the last decade in the field of discrete Fourier transform domain-based single-channel noise reduction for speech enhancement.......Furthermore, our goal is to provide a concise description of a state-of-the-art speech enhancement system, and demonstrate the relative importance of the various building blocks of such a system. This allows the non-expert DSP practitioner to judge the relevance of each building block and to implement a close...

  3. Micromachined PIN-PMN-PT crystal composite transducer for high-frequency intravascular ultrasound (IVUS) imaging.

    Science.gov (United States)

    Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K Kirk

    2014-07-01

    In this paper, we report the use of micromachined PbIn1/2Nb1/2O3-PbMg1/3Nb2/3O3-PbTiO 3 (PIN-PMNPT) single crystal 1-3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at the center frequency of 41 MHz, which resulted in a 43 μm axial resolution. Ex vivo IVUS imaging was conducted to demonstrate the improvement of axial resolution. The composite transducer was capable of identifying the three layers of a cadaver coronary artery specimen with high resolution. The PIN-PMN-PT-based composite has superior piezoelectric properties comparable to PMN-PT-based composite and its thermal stability is higher than PMN-PT. PIN-PMN-PT crystal can be an alternative approach for fabricating high-frequency composite, instead of using PMN-PT.

  4. Guided lamb wave electroacoustic devices on micromachined AlN/Al plates.

    Science.gov (United States)

    Di Pietrantonio, Fabio; Benetti, Massimiliano; Cannatà, Domenico; Beccherelli, Romeo; Verona, Enrico

    2010-05-01

    An electroacoustic micro-device based on the propagation of guided acoustic Lamb waves in AlN/Al plate is described. The AlN thin film is deposited by sputtering technique, optimized to achieve a high degree of orientation (rocking curve full-width at half-maximum /sp lap/ 3.5 degrees ) of the c-axis perpendicular to the plate surface. The AlN plate is micromachined using anisotropic reactive ion etching (RIE), followed by isotropic RIE to remove the silicon underlayer. Simulation results for the dispersion phase velocity curves and the electromechanical coupling coefficient (K(2)) are obtained by the matrix method and by the finite element method and compared with experimental data. A delay line is implemented on the structure and tested for the propagation of the first symmetrical Lamb mode (s(0)) at the frequency of 1.22 GHz. Measurements have shown that the structure is suitable for implementation of arrays of electroacoustic devices on a single chip for application to both sensing devices and signal processing systems.

  5. Deposition of Low Stress Silicon Nitride Thin Film and Its Application in Surface Micromachining Device Structures

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

    Full Text Available Surface machining processes are responsible for creating microstructures that reside near the surfaces of a substrate and are characterized by the fabrication of micromechanical structures from deposited thin films. These films can be selectively removed to build three-dimensional structures whose functionality typically requires that they should be freed from the planar substrate. Silicon nitride thin film is one of these important materials. In this paper, by adjusting the SiH2Cl2/NH3 gaseous ratio, low stress silicon nitride (LS SiN is deposited by the low pressure chemical vapor deposition (LPCVD process. The internal stress generally in 135 MPa has been detected using an FLX-2320 film stress tester. Based on the wide application in surface micromachining devices, the mechanical properties of LS SiN are measured by nanoindentation, giving the value of Young’s modulus of 224 GPa and the hardness of 22.5 GPa, respectively. Dry etching and wet etching are utilized to fabricate the LS SiN thin film for structural layers. The etching rate compared with normal Si3N4 film by LPCVD is demonstrated for silicon chip manufacture.

  6. Capacitive Micromachined Ultrasonic Transducer Arrays for Integrated Diagnostic/Therapeutic Catheters

    Science.gov (United States)

    Wong, Serena H.; Wygant, Ira O.; Yeh, David T.; Zhuang, Xuefeng; Bayram, Baris; Kupnik, Mario; Oralkan, Omer; Ergun, A. Sanli; Yaralioglu, Goksen G.; Khuri-Yakub, Butrus T.

    2006-05-01

    In recent years, medical procedures have become increasingly non-invasive. These include endoscopic procedures and intracardiac interventions (e.g., pulmonary vein isolation for treatment of atrial fibrillation and plaque ablation for treatment of arteriosclerosis). However, current tools suffer from poor visualization and difficult coordination of multiple therapeutic and imaging devices. Dual-mode (imaging and therapeutic) ultrasound arrays provide a solution to these challenges. A dual-mode transducer can provide focused, noncontact ultrasound suitable for therapy and can be used to provide high quality real-time images for navigation and monitoring of the procedure. In the last decade, capacitive micromachined ultrasonic transducers (CMUTs), have become an attractive option for ultrasonic imaging systems due to their fabrication flexibility, improved bandwidth, and integration with electronics. The CMUT's potential in therapeutic applications has also been demonstrated by surface output pressures as high as 1MPa peak to peak and continuous wave (CW) operation. This paper reviews existing interventional CMUT arrays, demonstrates the feasibility of CMUTs for high intensity focused ultrasound (HIFU), and presents a design for the next-generation CMUTs for integrated imaging and HIFU endoscopic catheters.

  7. IBIC characterization of an ion-beam-micromachined multi-electrode diamond detector

    Energy Technology Data Exchange (ETDEWEB)

    Forneris, J., E-mail: forneris@to.infn.it [Università di Torino, Dipartimento di Fisica e Centro di Eccellenza NIS, INFN, sez. Torino, CNISM, sez. Torino, via P. Giuria 1, 10125 Torino (Italy); Grilj, V.; Jakšić, M. [Ruđer Bošković Institute, Bijenička cesta 54, P.O. Box 180, 10002 Zagreb (Croatia); Lo Giudice, A.; Olivero, P.; Picollo, F. [Università di Torino, Dipartimento di Fisica e Centro di Eccellenza NIS, INFN, sez. Torino, CNISM, sez. Torino, via P. Giuria 1, 10125 Torino (Italy); Skukan, N. [Ruđer Bošković Institute, Bijenička cesta 54, P.O. Box 180, 10002 Zagreb (Croatia); Verona, C.; Verona-Rinati, G. [Dipartimento di Ingegneria Industriale, Università di Roma “Tor Vergata”, Via del Politecnico 1, 00133 Roma (Italy); Vittone, E. [Università di Torino, Dipartimento di Fisica e Centro di Eccellenza NIS, INFN, sez. Torino, CNISM, sez. Torino, via P. Giuria 1, 10125 Torino (Italy)

    2013-07-01

    Deep Ion Beam Lithography (DIBL) has been used for the direct writing of buried graphitic regions in monocrystalline diamond with micrometric resolution. As part of the development and the characterization of a fully ion-beam-micromachined solid-state ionization chamber, a device with interdigitated electrodes was fabricated by using a 1.8 MeV He{sup +} ion microbeam, which scanned a 40 μm thick homoepitaxial detector grade diamond sample grown by chemical vapor deposition (CVD). In order to evaluate the ionizing-radiation-detection performance of the device, charge collection efficiency (CCE) maps were extracted from Ion Beam Induced Charge (IBIC) measurements carried out by probing different arrangements of buried micro-electrodes. The analysis of the CCE maps allowed an exhaustive evaluation of the detector features, in particular the individuation of the different role played by electrons and holes in the formation of the induced charge pulses. Finally, a comparison of the performances of the detector with buried graphitic electrodes with those relevant to conventional metallic surface electrodes evidenced the formation of a dead layer overlying the buried electrodes as a result of the fabrication process.

  8. Effects of Laser Operating Parameters on Piezoelectric Substrates Micromachining with Picosecond Laser

    Directory of Open Access Journals (Sweden)

    Lamia EL Fissi

    2014-12-01

    Full Text Available Ten picoseconds (200 kHz ultrafast laser micro-structuring of piezoelectric substrates including AT-cut quartz, Lithium Niobate and Lithium Tantalate have been studied for the purpose of piezoelectric devices application ranging from surface acoustic wave devices, e.g., bandpass filters, to photonic devices such as optical waveguides and holograms. The study examines the impact of changing several laser parameters on the resulting microstructural shapes and morphology. The micromachining rate has been observed to be strongly dependent on the operating parameters, such as the pulse fluence, the scan speed and the scan number. The results specifically indicate that ablation at low fluence and low speed scan tends to form a U-shaped cross-section, while a V-shaped profile can be obtained by using a high fluence and a high scan speed. The evolution of surface morphology revealed that laser pulses overlap in a range around 93% for both Lithium Niobate (LiNbO3 and Lithium Tantalate (LiTaO3 and 98% for AT-cut quartz can help to achieve optimal residual surface roughness.

  9. A micro-machined thin film electro-acoustic biosensor for detection of pesticide residuals

    Institute of Scientific and Technical Information of China (English)

    Jing-jing WANG; Wei-hui LIU; Da CHEN; Yan XU; Lu-yin ZHANG

    2014-01-01

    Increasing awareness concerning food safety problems has been driving the search for simple and efficient bio-chemical analytical methods. In this paper, we develop a portable electro-acoustic biosensor based on a film bulk acoustic reso-nator for the detection of pesticide residues in agricultural products. A shear mode ZnO film bulk acoustic resonator with a mi-cro-machining structure was fabricated as a mass-sensitive transducer for the real-time detection of antibody-antigen reactions in liquids. In order to obtain an ultra-low detection level, the artificial antigens were immobilized on the sensing surface of the resonator to employ a competitive format for the immunoassays. The competitive immunoreactions can be observed clearly through monitoring the frequency changes. The presence of pesticides was detected through the diminution of the frequency shift compared with the level without pesticides. The limit of detection for carbaryl (a widely used pesticide for vegetables and crops) is 2´10-10 M. The proposed device represents a potential alternative to the complex optical systems and electrochemical methods that are currently being used, and represents a significant opportunity in terms of simplicity of use and portability for on-site food safety testing.

  10. A process for SOI resonators with surface micromachined covers and reduced electrostatic gaps

    Science.gov (United States)

    Dekker, James R.; Alastalo, Ari; Kattelus, Hannu

    2010-04-01

    This paper describes work to fabricate resonators on silicon-on-insulator (SOI) wafers with sub-micron gaps and wafer level encapsulation. Non-aligned, high-temperature fusion bonding of a cover wafer over unreleased structures etched into a SOI wafer is followed by cover wafer stripping to reveal etched resonators beneath an oxide membrane. Reliable bonding is assured by bonding unreleased structures which can withstand the appropriate pre-bond cleaning operations. The bonded oxide membrane serves as the basis of a surface micromachined membrane which incorporates silicon nitride and a porous polysilicon layer to facilitate release and supercritical drying. The cavity pressure is estimated to be in the range of 1 Torr. Encapsulated resonators were also made using a gap reduction process. The process is based on sidewall oxidation of an etched sleeve to reduce the linewidth of the patterned electrostatic gaps by 200 nm before the deep trench etch. Encapsulated and electrically active devices with gaps down to 500 nm were obtained and etched through a 5 µm thick SOI device layer. SEM images showed that gaps of 300 nm could reach through the same thickness, though functional devices were not obtained. In addition, limitations on the anti-notching process limited its use during the trench etch and resulted in severe notch damage.

  11. Excimer laser micromachining of oblique microchannels on thin metal films using square laser spot

    Indian Academy of Sciences (India)

    SYED NADEEM AKHTAR; SHASHANK SHARMA; S ANANTHA RAMAKRISHNA; J RAMKUMAR

    2016-06-01

    Excimer laser micromachining of thin metal films with a sacrificial polymer coating is a novel technique that produces features with smooth edges. Using this technique, oblique microchannels are fabricated by workpiece dragging and using a square laser spot, where the axis of traverse of the workpiece is not parallel to the edges of the square laser spot. The microchannels have serrated edges that are particular to the shape of the mask producing the spot. The edge roughness of the channels, machined with a square laser spot of side 100lm, is found to be most affected by the fluence–spot overlap interaction, and the channel width by spot-overlap and the angle of tilt of the traversed path. Polymer coated metal films underwent close to ideal machining, aided by the clamping action of the polymer layer. Through this technique of machining post polymer coating, the edge roughnesses of the microchannels have been curtailed to less than 10 lm, and channel widths to 150 lm. This technique may be used in fabrication of oblique and circular patterns using excimer laser micromachiningwith rectangular and square laser spots

  12. Dynamic Analysis of Micro-machined Diamagnetic Stable Permanent Magnet Levitation System

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel micro-machined diamagnetic stable-levitation system (MDSLS) which is composed of a free permanent magnetic rotor, a ring lifting permanent magnet and two diamagnetic stabilizers was presented. The static and dynamic stable characters of MDSLS were analyzed. The coupled non-linear differential equations were used to describe six-degree-of-freedom motion of the levitated rotor, and the equivalent surface current and combined diamagnetic image current method were utilized to model the interaction forces and torques between the lifting permanent magnet and rotor permanent magnet and also between the rotor permanent magnet and diamagnetic substrates. Because of difficulty to get analytical solution, the numerical calculation based on Runge-Kutta method was used to solve the dynamic model. The vibration frequencies were identified by fast Fourier transform (FFT) analysis. According to their resonance characteristics and parameters, the translational and angular dynamic stiffness were also calculated. The results show that the levitation of the rotor in MDSLS is stable, and the MDSLS is potential for the application in levitation inertial sensor.

  13. Long-life micro vacuum chamber for a micromachined cryogenic cooler

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Haishan, E-mail: H.Cao@utwente.nl, E-mail: HaishanCao@gmail.com; Vermeer, Cristian H.; Vanapalli, Srinivas; Holland, Harry J.; Brake, H. J. Marcel ter [Energy, Materials and Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede (Netherlands)

    2015-11-15

    Micromachined cryogenic coolers can be used for cooling small electronic devices to improve their performance. However, for reaching cryogenic temperatures, they require a very good thermal insulation from the warm environment. This is established by a vacuum space that for adequate insulation has to be maintained at a pressure of 0.01 Pa or lower. In this paper, the challenge of maintaining a vacuum chamber with a volume of 3.6 × 10{sup −5} m{sup 3} and an inner wall area of 8.1 × 10{sup −3} m{sup 2} at a pressure no higher than 0.01 Pa for five years is theoretically analyzed. The possible sources of gas, the mechanisms by which these gases enter the vacuum space and their effects on the pressure in the vacuum chamber are discussed. In a long-duration experiment with four stainless steel chambers of the above dimensions and equipped with a chemical getter, the vacuum pressures were monitored for a period of two years. In that period, the measured pressure increase stayed within 0.01 Pa. This study can be used to guide the design of long-lifetime micro vacuum chambers that operate without continuous mechanical pumping.

  14. Sapphire capillaries for laser-driven wakefield acceleration in plasma. Fs-laser micromachining and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Schwinkendorf, Jan-Patrick

    2012-08-15

    Plasma wakefields are a promising approach for the acceleration of electrons with ultrahigh (10 to 100 GV/m) electric fields. Nowadays, high-intensity laser pulses are routinely utilized to excite these large-amplitude plasma waves. However, several detrimental effects such as laser diffraction, electron-wake dephasing and laser depletion may terminate the acceleration process. Two of these phenomena can be mitigated or avoided by the application of capillary waveguides, e.g. fabricated out of sapphire for longevity. Capillaries may compensate for laser diffraction like a fiber and allow for the creation of tapered gas-density profiles working against the dephasing between the accelerating wave and the particles. Additionally, they offer the possibility of controlled particle injection. This thesis is reporting on the set up of a laser for fs-micromachining of capillaries of almost arbitrary shapes and a test stand for density-profile characterization. These devices will permit the creation of tailored gas-density profiles for controlled electron injection and acceleration inside plasma.

  15. Online self-compensation for enhanced the scale factor stability of a micromachined gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Bin; Zhang Rong; Chen Zhiyong [Department of Precision Instrument, Tsinghua University, Beijing, 100084 (China)], E-mail: zhoubin98@tsinghua.org.cn

    2009-09-01

    In this paper, an online self-compensation control scheme for micromachined gyroscope has been presented to eliminate the scale factor drift due to temperature influence. Firstly, the error sources of scale factor have been analyzed. According the analysis results, a novel control scheme which contains three loops has been proposed: a phase-locked loop of driving mode is to drive the proof mass oscillation in its' resonant frequency, an AGC loop of driving mode is to keep a constant value of the drive amplitude, an additional scale factor error online detection and cancellation loop is to keep the scale factor stable. A digital hardware prototype has been implemented to perform the precision loop control and self-compensation loop. Scale factor of the gyroscope has been measured in a temperature-controlled turntable. Experiment results show that the scale factor drift is -3.5% to 5.2% over the temperature range of -45 deg. C to +80 deg. C without the self-compensation loop, while the scale factor drift decrease to -0.009% to 0.15% after the self-compensation loop is applied.

  16. Two novel measurements for the drive-mode resonant frequency of a micromachined vibratory gyroscope.

    Science.gov (United States)

    Wang, Ancheng; Hu, Xiaoping; Luo, Bing; Jiang, Mingming; He, Xiaofeng; Tang, Kanghua

    2013-01-01

    To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG), one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and inconvenient because of the requirements of many test points, a lot of data storage and off-line analyses. In this paper, we propose two novel measurement methods, the search method and track method, respectively. The former is based on the magnitude-frequency characteristics of the drive mode, utilizing a one-dimensional search technique. The latter is based on the phase-frequency characteristics, applying a feedback control loop. Their performances in precision, noise resistivity and efficiency are analyzed through detailed simulations. A test system is implemented based on a field programmable gate array (FPGA) and experiments are carried out. By comparing with the common approach, feasibility and superiorities of the proposed methods are validated. In particular, significant efficiency improvements are achieved whereby the conventional frequency method consumes nearly 5,000 s to finish a measurement, while only 5 s is needed for the track method and 1 s for the search method.

  17. Analytic solution for N-electrode actuated piezoelectric disk with application to piezoelectric micromachined ultrasonic transducers.

    Science.gov (United States)

    Smyth, Katherine; Bathurst, Stephen; Sammoura, Firas; Kim, Sang-Gook

    2013-08-01

    In this work, the deflection equation of a piezoelectrically-driven micromachined ultrasonic transducer (PMUT) is analytically determined using a Green's function approach. With the Green's function solution technique, the deflection of a circular plate with an arbitrary circular/ring electrode geometry is explicitly solved for axisymmetric vibration modes. For a PMUT with one center electrode covering ≈60% of the plate radius, the Green's function solution compares well with existing piece-wise and energy-based solutions with errors of less than 1%. The Green's function solution is also simpler than them requiring no numerical integration, and applies to any number of axisymmetric electrode geometries. Experimentally measured static deflection data collected from a fabricated piezoelectric micro ultrasonic transducer (PMUT) is further used to validate the Green's function model analysis. The center deflection and deflection profile data agree well with the Green's function solution over a range of applied bias voltages (5 to 21 V) with the average error between the experimental and Green's function data less than 9%.

  18. Fabrication and Characterization of Capacitive Micromachined Ultrasonic Transducers with Low-Temperature Wafer Direct Bonding

    Directory of Open Access Journals (Sweden)

    Xiaoqing Wang

    2016-12-01

    Full Text Available This paper presents a fabrication method of capacitive micromachined ultrasonic transducers (CMUTs by wafer direct bonding, which utilizes both the wet chemical and O2plasma activation processes to decrease the bonding temperature to 400 °C. Two key surface properties, the contact angle and surface roughness, are studied in relation to the activation processes, respectively. By optimizing the surface activation parameters, a surface roughness of 0.274 nm and a contact angle of 0° are achieved. The infrared images and static deflection of devices are assessed to prove the good bonding effect. CMUTs having silicon membranes with a radius of 60 μm and a thickness of 2 μm are fabricated. Device properties have been characterized by electrical and acoustic measurements to verify their functionality and thus to validate this low-temperature process. A resonant frequency of 2.06 MHz is obtained by the frequency response measurements. The electrical insertion loss and acoustic signal have been evaluated. This study demonstrates that the CMUT devices can be fabricated by low-temperature wafer direct bonding, which makes it possible to integrate them directly on top of integrated circuit (IC substrates.

  19. Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

    Directory of Open Access Journals (Sweden)

    M. Cihan Çakır

    2016-09-01

    Full Text Available Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption–dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

  20. Wireless Displacement Sensing of Micromachined Spiral-Coil Actuator Using Resonant Frequency Tracking

    Directory of Open Access Journals (Sweden)

    Mohamed Sultan Mohamed Ali

    2014-07-01

    Full Text Available This paper reports a method that enables real-time displacement monitoring and control of micromachined resonant-type actuators using wireless radiofrequency (RF. The method is applied to an out-of-plane, spiral-coil microactuator based on shape-memory-alloy (SMA. The SMA spiral coil forms an inductor-capacitor resonant circuit that is excited using external RF magnetic fields to thermally actuate the coil. The actuation causes a shift in the circuit’s resonance as the coil is displaced vertically, which is wirelessly monitored through an external antenna to track the displacements. Controlled actuation and displacement monitoring using the developed method is demonstrated with the microfabricated device. The device exhibits a frequency sensitivity to displacement of 10 kHz/µm or more for a full out-of-plane travel range of 466 µm and an average actuation velocity of up to 155 µm/s. The method described permits the actuator to have a self-sensing function that is passively operated, thereby eliminating the need for separate sensors and batteries on the device, thus realizing precise control while attaining a high level of miniaturization in the device.

  1. Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging

    Science.gov (United States)

    Lu, Y.; Tang, H.; Wang, Q.; Fung, S.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.

    2015-05-01

    This paper presents an 8 × 24 element, 100 μm-pitch, 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The 70 μm diameter, 220 μm long waveguides function both to direct acoustic waves and to confine acoustic energy, and also to provide mechanical protection for the PMUT array used for surface-imaging applications such as an ultrasonic fingerprint sensor. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level conductive eutectic bonding. This construction allows each PMUT in the array to have a dedicated front-end receive amplifier, which together with on-chip analog multiplexing enables individual pixel read-out with high signal-to-noise ratio through minimized parasitic capacitance between the PMUT and the front-end amplifier. Finite element method simulations demonstrate that the waveguides preserve the pressure amplitude of acoustic pulses over distances of 600 μm. Moreover, the waveguide design demonstrated here enables pixel-by-pixel readout of the ultrasound image due to improved directivity of the PMUT by directing acoustic waves and creating a pressure field with greater spatial uniformity at the end of the waveguide. Pulse-echo imaging experiments conducted using a one-dimensional steel grating demonstrate the array's ability to form a two-dimensional image of a target.

  2. Determination of precise crystallographic directions for mask alignment in wet bulk micromachining for MEMS

    Science.gov (United States)

    Singh, Sajal Sagar; Pal, Prem; Pandey, Ashok Kumar; Xing, Yan; Sato, Kazuo

    2016-12-01

    In wet bulk micromachining, the etching characteristics are orientation dependent. As a result, prolonged etching of mask openings of any geometric shape on both Si{100} and Si{110} wafers results in a structure defined by the slowest etching planes. In order to fabricate microstructures with high dimensional accuracy, it is vital to align the mask edges along the crystal directions comprising of these slowest etching planes. Thus, precise alignment of mask edges is important in micro/nano fabrication. As a result, the determination of accurate crystal directions is of utmost importance and is in fact the first step to ensure dimensionally accurate microstructures for improved performance. In this review article, we have presented a comprehensive analysis of different techniques to precisely determine the crystallographic directions. We have covered various techniques proposed in the span of more than two decades to determine the crystallographic directions on both Si{100} and Si{110} wafers. Apart from a detailed discussion of each technique along with their design and implementation, we have provided a critical analysis of the associated constraints, benefits and shortcomings. We have also summed up the critical aspects of each technique and presented in a tabular format for easy reference for readers. This review article comprises of an exhaustive discussion and is a handy reference for researchers who are new in the field of wet anisotropic etching or who want to get abreast with the techniques of determination of crystal directions.

  3. Modeling the Microstructure Curvature of Boron-Doped Silicon in Bulk Micromachined Accelerometer

    Directory of Open Access Journals (Sweden)

    Xiaoping He

    2013-01-01

    Full Text Available Microstructure curvature, or buckling, is observed in the micromachining of silicon sensors because of the doping of impurities for realizing certain electrical and mechanical processes. This behavior can be a key source of error in inertial sensors. Therefore, identifying the factors that influence the buckling value is important in designing MEMS devices. In this study, the curvature in the proof mass of an accelerometer is modeled as a multilayered solid model. Modeling is performed according to the characteristics of the solid diffusion mechanism in the bulk-dissolved wafer process (BDWP based on the self-stopped etch technique. Moreover, the proposed multilayered solid model is established as an equivalent composite structure formed by a group of thin layers that are glued together. Each layer has a different Young’s modulus value and each undergoes different volume shrinkage strain owing to boron doping in silicon. Observations of five groups of proof mass blocks of accelerometers suggest that the theoretical model is effective in determining the buckling value of a fabricated structure.

  4. Surface-micromachined microfiltration membranes for efficient isolation and functional immunophenotyping of subpopulations of immune cells.

    Science.gov (United States)

    Chen, Weiqiang; Huang, Nien-Tsu; Oh, Boram; Lam, Raymond H W; Fan, Rong; Cornell, Timothy T; Shanley, Thomas P; Kurabayashi, Katsuo; Fu, Jianping

    2013-07-01

    An accurate measurement of the immune status in patients with immune system disorders is critical in evaluating the stage of diseases and tailoring drug treatments. The functional cellular immunity test is a promising method to establish the diagnosis of immune dysfunctions. The conventional functional cellular immunity test involves measurements of the capacity of peripheral blood mononuclear cells to produce pro-inflammatory cytokines when stimulated ex vivo. However, this "bulk" assay measures the overall reactivity of a population of lymphocytes and monocytes, making it difficult to pinpoint the phenotype or real identity of the reactive immune cells involved. In this research, we develop a large surface micromachined poly-dimethylsiloxane (PDMS) microfiltration membrane (PMM) with high porosity, which is integrated in a microfluidic microfiltration platform. Using the PMM with functionalized microbeads conjugated with antibodies against specific cell surface proteins, we demonstrated rapid, efficient and high-throughput on-chip isolation, enrichment, and stimulation of subpopulations of immune cells from blood specimens. Furthermore, the PMM-integrated microfiltration platform, coupled with a no-wash homogeneous chemiluminescence assay ("AlphaLISA"), enables us to demonstrate rapid and sensitive on-chip immunophenotyping assays for subpopulations of immune cells isolated directly from minute quantities of blood samples.

  5. Piezoelectric Micromachined Ultrasound Transducer (PMUT Arrays for Integrated Sensing, Actuation and Imaging

    Directory of Open Access Journals (Sweden)

    Yongqiang Qiu

    2015-04-01

    Full Text Available Many applications of ultrasound for sensing, actuation and imaging require miniaturized and low power transducers and transducer arrays integrated with electronic systems. Piezoelectric micromachined ultrasound transducers (PMUTs, diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays. This paper presents an overview of the current development status of PMUTs and a discussion of their suitability for miniaturized and integrated devices. The thin film piezoelectric materials required to functionalize these devices are discussed, followed by the microfabrication techniques used to create PMUT elements and the constraints the fabrication imposes on device design. Approaches for electrical interconnection and integration with on-chip electronics are discussed. Electrical and acoustic measurements from fabricated PMUT arrays with up to 320 diaphragm elements are presented. The PMUTs are shown to be broadband devices with an operating frequency which is tunable by tailoring the lateral dimensions of the flexural membrane or the thicknesses of the constituent layers. Finally, the outlook for future development of PMUT technology and the potential applications made feasible by integrated PMUT devices are discussed.

  6. Piezoelectric micromachined ultrasound transducer (PMUT) arrays for integrated sensing, actuation and imaging.

    Science.gov (United States)

    Qiu, Yongqiang; Gigliotti, James V; Wallace, Margeaux; Griggio, Flavio; Demore, Christine E M; Cochran, Sandy; Trolier-McKinstry, Susan

    2015-04-03

    Many applications of ultrasound for sensing, actuation and imaging require miniaturized and low power transducers and transducer arrays integrated with electronic systems. Piezoelectric micromachined ultrasound transducers (PMUTs), diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays. This paper presents an overview of the current development status of PMUTs and a discussion of their suitability for miniaturized and integrated devices. The thin film piezoelectric materials required to functionalize these devices are discussed, followed by the microfabrication techniques used to create PMUT elements and the constraints the fabrication imposes on device design. Approaches for electrical interconnection and integration with on-chip electronics are discussed. Electrical and acoustic measurements from fabricated PMUT arrays with up to 320 diaphragm elements are presented. The PMUTs are shown to be broadband devices with an operating frequency which is tunable by tailoring the lateral dimensions of the flexural membrane or the thicknesses of the constituent layers. Finally, the outlook for future development of PMUT technology and the potential applications made feasible by integrated PMUT devices are discussed.

  7. Improved micromachined column design and fluidic interconnects for programmed high-temperature gas chromatography separations.

    Science.gov (United States)

    Gaddes, David; Westland, Jessica; Dorman, Frank L; Tadigadapa, Srinivas

    2014-07-01

    This work focuses on the development and experimental evaluation of micromachined chromatographic columns for use in a commercial gas chromatography (GC) system. A vespel/graphite ferrule based compression sealing technique is presented using which leak-proof fluidic interconnection between the inlet tubing and the microchannel was achieved. This sealing technique enabled separation at temperatures up to 350°C on a μGC column. This paper reports the first high-temperature separations in microfabricated chromatographic columns at these temperatures. A 2m microfabricated column using a double Archimedean spiral design with a square cross-section of 100μm×100μm has been developed using silicon microfabrication techniques. The microfabricated column was benchmarked against a 2m 100μm diameter commercial column and the performance between the two columns was evaluated in tests performed under identical conditions. High temperature separations of simulated distillation (ASTM2887) and polycyclic aromatic hydrocarbons (EPA8310) were performed using the μGC column in temperature programmed mode. The demonstrated μGC column along with the high temperature fixture offers one more solution toward potentially realizing a portable μGC device for the detection of semi-volatile environmental pollutants and explosives without the thermal limitations reported to date with μGC columns using epoxy based interconnect technology.

  8. Micromachining NiTi tubes for use in medical devices by using a femtosecond laser

    Science.gov (United States)

    Hung, Chia-Hung; Chang, Fuh-Yu; Chang, Tien-Li; Chang, Yu-Ting; Huang, Kai-Wen; Liang, Po-Chin

    2015-03-01

    Recent growth in medical device technology has been substantially driven by developments in laser micromachining, which is a powerful fabrication technique in which nickel-titanium (Nitinol, NiTi) alloy materials that exhibit superelastic and shape memory properties are formed (e.g., self-expanding stents). In this study a NiTi tube curve surface process is proposed, involving a femtosecond laser process and a galvano-mirror scanner. The diameter of the NiTi tube was 5.116 mm, its thickness was 0.234 mm, and its length was 100 mm. The results indicated that during the machine process the ablation mechanism of the NiTi tubes was changed by altering the machining path. The path alteration enhanced the laser ablation rate from 12.3 to 26.7 μm/J. Thus the path alteration contributed to a wide kerf line, enabling the assisted air to efficiently remove the debris deposited at the bottom of the kerf during the laser ablation process. The results indicated that the NiTi tube curve process enhanced the laser ablation rate by two times and reduced the amount of energy accumulated within the materials by 50% or more. By altering the machining path using the scanning system, this process can decrease the production of heat affected zones (the accumulation of thermal energy) in medical device applications.

  9. Underwater femtosecond laser micromachining of thin nitinol tubes for medical coronary stent manufacture

    Science.gov (United States)

    Muhammad, Noorhafiza; Li, Lin

    2012-06-01

    Microprofiling of medical coronary stents has been dominated by the use of Nd:YAG lasers with pulse lengths in the range of a few milliseconds, and material removal is based on the melt ejection with a high-pressure gas. As a result, recast and heat-affected zones are produced, and various post-processing procedures are required to remove these defects. This paper reports a new approach of machining stents in submerged conditions using a 100-fs pulsed laser. A comparison is given of dry and underwater femtosecond laser micromachining techniques of nickel-titanium alloy (nitinol) typically used as the material for coronary stents. The characteristics of laser interactions with the material have been studied. A femtosecond Ti:sapphire laser system (wavelength of 800 nm, pulse duration of 100 fs, repetition rate of 1 kHz) was used to perform the cutting process. It is observed that machining under a thin water film resulted in no presence of heat-affected zone, debris, spatter or recast with fine-cut surface quality. At the optimum parameters, the results obtained with dry cutting showed nearly the same cut surface quality as with cutting under water. However, debris and recast formation still appeared on the dry cut, which is based on material vaporization. Physical processes involved during the cutting process in a thin water film, i.e. bubble formation and shock waves, are discussed.

  10. Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

    Science.gov (United States)

    Çakır, M. Cihan; Çalışkan, Deniz; Bütün, Bayram; Özbay, Ekmel

    2016-01-01

    Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO) heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption–dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively. PMID:27690048

  11. The Effect of Humidity on the Reliability of a Surface Micromachined Microengine

    Energy Technology Data Exchange (ETDEWEB)

    Dugger, M.T.; Eaton, W.P.; Irwin, L.W.; Miller, S.L.; Miller, W.M.; Smith, N.F.; Tanner, D.M.; Walraven, J.A.

    1999-02-02

    Humidity is shown to be a strong factor in the wear of rubbing surfaces in polysilicon micromachines. We demonstrate that very low humidity can lead to very high wear without a significant change in reliability. We show that the volume of wear debris generated is a function of the humidity in an air environment. As the humidity decreases, the wear debris generated increases. For the higher humidity levels, the formation of surface hydroxides may act as a lubricant. The dominant failure mechanism has been identified as wear. The wear debris has been identified as amorphous oxidized silicon. Large slivers (approximately 1 micron in length) of debris observed at the low humidity level were also amorphous oxidized silicon. Using transmission electron microscopy, we observed that the wear debris forms spherical and rod-like shapes. We compared two surface treatment processes: a fluorinated si- lane chain, (FITl) and supercritical C02 dried (SCC02). The microengines using the SCC02 process were found to be less reliable than those released with the FIX process under two humidity levels.

  12. Linkage design effect on the reliability of surface micromachined microengines driving a load

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, D.M.; Peterson, K.A.; Irwin, L.W.; Tangyunyong, P.; Miller, W.M.; Eaton, W.P.; Smith, N.F.; Rodgers, M.S.

    1998-08-01

    The reliability of microengines is a function of the design of the mechanical linkage used to connect the electrostatic actuator to the drive. The authors have completed a series of reliability stress tests on surface micromachined microengines driving an inertial load. In these experiments, the authors used microengines that had pin mechanisms with guides connecting the drive arms to the electrostatic actuators. Comparing this data to previous results using flexure linkages revealed that the pin linkage design was less reliable. The devices were stressed to failure at eight frequencies, both above and below the measured resonance frequency of the microengine. Significant amounts of wear debris were observed both around the hub and pin joint of the drive gear. Additionally, wear tracks were observed in the area where the moving shuttle rubbed against the guides of the pin linkage. At each frequency, they analyzed the statistical data yielding a lifetime (t{sub 50}) for median cycles to failure and {sigma}, the shape parameter of the distribution. A model was developed to describe the failure data based on fundamental wear mechanisms and forces exhibited in mechanical resonant systems. The comparison to the model will be discussed.

  13. Two Novel Measurements for the Drive-Mode Resonant Frequency of a Micromachined Vibratory Gyroscope

    Directory of Open Access Journals (Sweden)

    Ancheng Wang

    2013-11-01

    Full Text Available To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG, one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and inconvenient because of the requirements of many test points, a lot of data storage and off-line analyses. In this paper, we propose two novel measurement methods, the search method and track method, respectively. The former is based on the magnitude-frequency characteristics of the drive mode, utilizing a one-dimensional search technique. The latter is based on the phase-frequency characteristics, applying a feedback control loop. Their performances in precision, noise resistivity and efficiency are analyzed through detailed simulations. A test system is implemented based on a field programmable gate array (FPGA and experiments are carried out. By comparing with the common approach, feasibility and superiorities of the proposed methods are validated. In particular, significant efficiency improvements are achieved whereby the conventional frequency method consumes nearly 5,000 s to finish a measurement, while only 5 s is needed for the track method and 1 s for the search method.

  14. NEW CLOSED-LOOP DRIVING CIRCUIT OF SILICON MICROMACHINED VIBRATORY GYROSCOPE

    Institute of Scientific and Technical Information of China (English)

    YANGBo; SUYah; ZHOUBai-ling

    2005-01-01

    A new closed-loop driving scheme for the silicon micromachined vibratory gyroscope (SMVG) is proposed. The push-pull driving is adopted and in-phase AC and reverse-phase DC voltages are applied in the driving electrodes placed in both sides of the active combs, respectively. Driving performance analyses show that the frequency spectrum between driving moments and noise signals is separated. Therefore, the model of the closed-loop control is set up with the phase lock loop (PLL). The requirements for phases and gains of the sinusoidal selfdrive-oscillation are met by PLL, thus the closed-loop circuit reaches the self-drive-oscillation. Phase conditions of the sinusoidal self-drive-oscillation and the characteristic of phase discrimination of the PLL are used to eliminate the coupling between driving and sense signals, and noise signals. Finally, experimental results show that the variations of both the driving frequency and the amplitude are all under 0.02%. The precision and the reliability of the gyroscope are greatly improved.

  15. On-chip micromachined dipole antenna with parasitic radiator for mm-wave wireless systems

    KAUST Repository

    Sallam, Mai O.

    2016-12-19

    In this paper, we present a micromachined dipole antenna with parasitic radiator. The antenna is designed for operation at 60 GHz. It consists of two Ig/2 dipole radiators fed by coplanar strips waveguide. Two slightly shorter dipoles are placed in proximity to the main radiators. They act as parasitic dipole arms which increase the bandwidth of the antenna. Two versions of the same antenna topology are presented in this paper in which one uses a high resistivity silicon substrate while the other uses a low resistivity one. The proposed antenna was optimized using HFSS and the final design was simulated using both HFSS and CST for verifying the obtained results. Both simulators are in good agreement. They show that the antenna has very good radiation characteristics where its directivity is around 7.5 dBi. The addition of the parasitic arms increased the bandwidth of the antenna from 1.3 GHz (3.62 GHz) to 4.3 GHz (7.44 GHz) when designed on high (low) resistivity silicon substrate.

  16. Fabrication of piezoelectric P(VDF-TrFE) microcantilevers by wafer-level surface micromachining

    Science.gov (United States)

    Oh, Sharon Roslyn; Yao, Kui; Eng Hock Tay, Francis

    2013-09-01

    A wafer-level microfabrication process using standard cleanroom facilities was established and implemented to batch produce free-standing poly(vinylidine fluoride-trifluoroethylene) (P(VDF-TrFE)) piezoelectric microelectromechanical systems cantilevers via surface micromachining. Furthermore, the fabrication of a prototype of double-level cantilevers was demonstrated. The fabrication of working piezoelectric polymer cantilever structures required the deposition and patterning of multiple polymer and metal layers including the pattering and removal of the sacrificial layer, which posed many challenging limitations on the chemicals and processing conditions. Dedicatedly selected chemicals and materials were used in our fabrication, including water soluble PVA with an appropriate molecular weight and degree of hydrolysis as the sacrificial layer for releasing the cantilever structure. The temperature in the whole process was kept low with controlled durations, due to the sensitivity of the polymers to thermal impacts. The P(VDF-TrFE) active layers, after going through the fabrication, exhibited ferroelectric and piezoelectric properties comparable to the intact films. Furthermore, the free-standing P(VDF-TrFE) cantilevers exhibited piezoelectric vibrations under electrical excitation. This low temperature fabrication method, which only involves mild chemicals, also has the potential to be integrated with CMOS processes.

  17. Development and validation of a field microphone-in-real-ear approach for measuring hearing protector attenuation

    Directory of Open Access Journals (Sweden)

    E H Berger

    2011-01-01

    Full Text Available Numerous studies have shown that the reliability of using laboratory measurements to predict individual or even group hearing protector attenuation for occupationally exposed workers is quite poor. This makes it difficult to properly assign hearing protectors when one wishes to closely match attenuation to actual exposure. An alternative is the use of field-measurement methods, a number of which have been proposed and are beginning to be implemented. We examine one of those methods, namely the field microphone-in-real-ear (F-MIRE approach in which a dual-element microphone probe is used to measure noise reduction by quickly sampling the difference in noise levels outside and under an earplug, with appropriate adjustments to predict real-ear attenuation at threshold (REAT. We report on experiments that validate the ability of one commercially available F-MIRE device to predict the REAT of an earplug fitted identically for two tests. Results are reported on a representative roll-down foam earplug, stemmed-style pod plug, and pre-molded earplug, demonstrating that the 95% confidence level of the Personal Attenuation Rating (PAR as a function of the number of fits varies from ±4.4 dB to ±6.3 dB, depending on the plug type, which can be reduced to ±3.1 dB to ±4.5 dB with a single repeat measurement. The added measurement improves precision substantially. However, the largest portion of the error is due to the user′s fitting variability and not the uncertainty of the measurement system. Further we evaluated the inherent uncertainty of F-MIRE vs. the putative "gold standard" REAT procedures finding, that F-MIRE measurement uncertainty is less than one-half that of REAT at most test frequencies. An American National Standards Institute (ANSI working group (S12/WG11 is currently involved in developing methods similar to those in this paper so that procedures for evaluating and reporting uncertainty on all types of field attenuation measurement

  18. Determining Sound Source Orientation from Source Directivity and Real Multi-Microphone Recordings: Experimental Comparisons using both Analytical and Measured Directivity Models

    DEFF Research Database (Denmark)

    Guarato, Francesco; Hallam, John; Vanderelst, Dieter

    2009-01-01

    This paper presents a method for estimating the orientation of a directional sound source emitting a broadband acoustic signal being recorded by a microphone array, given source directivity, microphone positions with respect to the source and recordings of the call. Such a method has been tested...... an analytical directivity model and when directivity is provided by measurements. Results show that method estimates orientations very close to the true ones, and that analytical directivity is a good approximation of the measured one. We also point out the limits we must respect to make the method precise....... The signal emitted by the source is broadband, like the signals many bats use while echolocating. Indeed, our intended final application of the method is to estimate the orientations a bat assumes while hunting over water....

  19. Phase-Based Adaptive Estimation of Magnitude-Squared Coherence Between Turbofan Internal Sensors and Far-Field Microphone Signals

    Science.gov (United States)

    Miles, Jeffrey Hilton

    2015-01-01

    A cross-power spectrum phase based adaptive technique is discussed which iteratively determines the time delay between two digitized signals that are coherent. The adaptive delay algorithm belongs to a class of algorithms that identifies a minimum of a pattern matching function. The algorithm uses a gradient technique to find the value of the adaptive delay that minimizes a cost function based in part on the slope of a linear function that fits the measured cross power spectrum phase and in part on the standard error of the curve fit. This procedure is applied to data from a Honeywell TECH977 static-engine test. Data was obtained using a combustor probe, two turbine exit probes, and far-field microphones. Signals from this instrumentation are used estimate the post-combustion residence time in the combustor. Comparison with previous studies of the post-combustion residence time validates this approach. In addition, the procedure removes the bias due to misalignment of signals in the calculation of coherence which is a first step in applying array processing methods to the magnitude squared coherence data. The procedure also provides an estimate of the cross-spectrum phase-offset.

  20. 3D-Printing of inverted pyramid suspending architecture for pyroelectric infrared detectors with inhibited microphonic effect

    Science.gov (United States)

    Xu, Qing; Zhao, Xiangyong; Li, Xiaobing; Deng, Hao; Yan, Hong; Yang, Linrong; Di, Wenning; Luo, Haosu; Neumann, Norbert

    2016-05-01

    A sensitive chip with ultralow dielectric loss based on Mn doped PMNT (71/29) has been proposed for high-end pyroelectric devices. The dielectric loss at 1 kHz is 0.005%, one order lower than the minimum value reported so far. The detective figure of merit (Fd) is up to 92.6 × 10-5 Pa-1/2 at 1 kHz and 53.5 × 10-5 Pa-1/2 at 10 Hz, respectively. In addition, an inverted pyramid suspending architecture for supporting the sensitive chip has been designed and manufactured by 3D printing technology. The combination of this sensitive chip and the proposed suspending architecture largely enhances the performance of the pyroelectric detectors. The responsivity and specific detectivity are 669,811 V/W and 3.32 × 109 cm Hz1/2/W at 10 Hz, respectively, 1.9 times and 1.5 times higher than those of the highest values in literature. Furthermore, the microphonic effect can be largely inhibited according to the theoretical and experimental analysis. This architecture will have promising applications in high-end and stable pyroelectric infrared detectors.