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Sample records for resolution photoacoustic titanium

  1. High resolution ultrasound and photoacoustic imaging of single cells

    Directory of Open Access Journals (Sweden)

    Eric M. Strohm

    2016-03-01

    Full Text Available High resolution ultrasound and photoacoustic images of stained neutrophils, lymphocytes and monocytes from a blood smear were acquired using a combined acoustic/photoacoustic microscope. Photoacoustic images were created using a pulsed 532 nm laser that was coupled to a single mode fiber to produce output wavelengths from 532 nm to 620 nm via stimulated Raman scattering. The excitation wavelength was selected using optical filters and focused onto the sample using a 20× objective. A 1000 MHz transducer was co-aligned with the laser spot and used for ultrasound and photoacoustic images, enabling micrometer resolution with both modalities. The different cell types could be easily identified due to variations in contrast within the acoustic and photoacoustic images. This technique provides a new way of probing leukocyte structure with potential applications towards detecting cellular abnormalities and diseased cells at the single cell level.

  2. Super-resolution photoacoustic imaging of single gold nanoparticles

    Science.gov (United States)

    Lee, Seunghyun; Kwon, Owoong; Jeon, Mansik; Song, Jaejung; Jo, Minguk; Kim, Sungjee; Son, Junwoo; Kim, Yunseok; Kim, Chulhong

    2016-03-01

    Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that can provide a strong optical absorption contrast using the photoacoustic (PA) effect, and breaks through the fundamental imaging depth limit of existing optical microscopy such as optical coherence tomography (OCT), confocal or two-photon microscopy. In PAI, a short-pulsed laser is illuminated to the tissue, and the PA waves are generated by thermoelastic expansion. Despite the high lateral resolution of optical-resolution photoacoustic microscopy (OR-PAM) thanks to the tight optical focus, the lateral resolution of OR-PAM is limited to the optical diffraction limit, which is approximately a half of the excitation wavelength. Here, we demonstrate a new super-resolution photoacoustic microscopy (SR-PAM) system by breaking the optical diffraction limit. The conventional microscopes with nanoscale resolutions such as a scanning electron microscope (SEM) and transmission electron microscope (TEM) are typically used to image the structures of nanomaterials, but these systems should work in a high vacuum environment and cannot provide the optical properties of the materials. Our newly developed SR-PAM system provides the optical properties with a nanoscale resolution in a normal atmosphere. We have photoacoustically imaged single gold nanoparticles with an average size of 80 nm in diameter and shown their PA expansion properties individually. The lateral resolution of this system was approximately 20 nm. Therefore, this tool will provide an unprecedented optical absorption property with an accurate nanoscale resolution and greatly impact on materials science and nanotechnology field.

  3. Integrated acoustic-resolution and optical-resolution photoacoustic microscopy using a single multifunctional acoustic lens

    Science.gov (United States)

    Guo, Heng; Xi, Lei

    2016-10-01

    With the rapid development of photoacoustic imaging, it has been widely used in various research fields such as biology, medicine and nanotechnology. Due to the huge difference among photoacoustic imaging systems, it is hard to integrate them in one platform. To solve this problem, we propose to develop a new universal photoacoustic imaging platform that integrates acoustic-resolution photoacoustic microscopy and optical-resolution photoacoustic microscopy through a multifunctional liquid lens. This lens takes advantage of an inherently low acoustic impedance and a tunable focal length that was characterized by the infusion volume of the liquid. In this paper, the liquid lens was used to realize confocal of laser illumination and acoustic detection for both acoustic-resolution and optical-resolution photoacoustic microscopy. The home-made polyvinylidene fluoride (PVDF) acoustic transducer had a center frequency of 10MHz and -6dB frequency spectrum from 4MHz to 15MHz which yielded to an axial resolution of 70 μm. The lateral resolutions of acoustic- and optical-resolution photoacoustic microscopy were evaluated to be 180 μm and 4.8 μm, respectively. The vasculature of rat ears was carried out to evaluate the performance of optical-resolution photoacoustic microscopy.

  4. Accelerated high-resolution photoacoustic tomography via compressed sensing.

    Science.gov (United States)

    Arridge, Simon; Beard, Paul; Betcke, Marta; Cox, Ben; Huynh, Nam; Lucka, Felix; Ogunlade, Olumide; Zhang, Edward

    2016-12-21

    Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue (4D PAT). A particular example is the planar Fabry-Pérot (FP) photoacoustic scanner, which yields high-resolution 3D images but takes several minutes to sequentially map the incident photoacoustic field on the 2D sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant. We demonstrate that combining model-based, variational image reconstruction methods using spatial sparsity constraints with the development of novel PAT acquisition systems capable of sub-sampling the acoustic wave field can dramatically increase the acquisition speed while maintaining a good spatial resolution: first, we describe and model two general spatial sub-sampling schemes. Then, we discuss how to implement them using the FP interferometer and demonstrate the potential of these novel compressed sensing PAT devices through simulated data from a realistic numerical phantom and through measured data from a dynamic experimental phantom as well as from in vivo experiments. Our results show that images with good spatial resolution and contrast can be obtained from highly sub-sampled PAT data if variational image reconstruction techniques that describe the tissues structures with suitable sparsity-constraints are used. In particular, we examine the use of total variation (TV) regularization enhanced by Bregman iterations. These novel reconstruction strategies offer new opportunities to dramatically increase the acquisition speed of photoacoustic scanners that employ point-by-point sequential scanning as well as reducing the channel count of parallelized schemes that use detector arrays.

  5. Accelerated high-resolution photoacoustic tomography via compressed sensing

    Science.gov (United States)

    Arridge, Simon; Beard, Paul; Betcke, Marta; Cox, Ben; Huynh, Nam; Lucka, Felix; Ogunlade, Olumide; Zhang, Edward

    2016-12-01

    Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue (4D PAT). A particular example is the planar Fabry-Pérot (FP) photoacoustic scanner, which yields high-resolution 3D images but takes several minutes to sequentially map the incident photoacoustic field on the 2D sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant. We demonstrate that combining model-based, variational image reconstruction methods using spatial sparsity constraints with the development of novel PAT acquisition systems capable of sub-sampling the acoustic wave field can dramatically increase the acquisition speed while maintaining a good spatial resolution: first, we describe and model two general spatial sub-sampling schemes. Then, we discuss how to implement them using the FP interferometer and demonstrate the potential of these novel compressed sensing PAT devices through simulated data from a realistic numerical phantom and through measured data from a dynamic experimental phantom as well as from in vivo experiments. Our results show that images with good spatial resolution and contrast can be obtained from highly sub-sampled PAT data if variational image reconstruction techniques that describe the tissues structures with suitable sparsity-constraints are used. In particular, we examine the use of total variation (TV) regularization enhanced by Bregman iterations. These novel reconstruction strategies offer new opportunities to dramatically increase the acquisition speed of photoacoustic scanners that employ point-by-point sequential scanning as well as reducing the channel count of parallelized schemes that use detector arrays.

  6. High resolution functional photoacoustic tomography of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoqi; Yao, Lei; Xi, Lei; Jiang, Huabei, E-mail: hjiang@bme.ufl.edu [Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States); Heldermon, Coy D. [Department of Medicine, University of Florida, Gainesville, Florida 32611 (United States)

    2015-09-15

    Purpose: To evaluate the feasibility of functional photoacoustic tomography (fPAT) for high resolution detection and characterization of breast cancer and to demonstrate for the first time quantitative hemoglobin concentration and oxygen saturation images of breasts that were formed with model-based reconstruction of tomographic photoacoustic data. Methods: The study was HIPAA compliant and was approved by the university institutional review board. Written informed consents were obtained from all the participants. Ten cases, including six cancer and four healthy (mean age = 50 yr; age range = 41–66 yr), were examined. Functional images of breast tissue including absolute total hemoglobin concentration (Hb{sub T}) and oxygen saturation (StO{sub 2}%) were obtained by fPAT and cross validated with magnetic resonance imaging (MRI) readings and/or histopathology. Results: Hb{sub T} and StO{sub 2}% maps from all six pathology-confirmed cancer cases (60%) show clear detection of tumor, while MR images indicate clear detection of tumor for five of six cancer cases; one small tumor was read as near-complete-resolution by MRI. The average Hb{sub T} and StO{sub 2}% value of suspicious lesion area for the cancer cases was 61.6 ± 18.9 μM/l and 67.5% ± 5.2% compared to 25.6 ± 7.4 μM/l and 65.2% ± 3.8% for background normal tissue. Conclusions: fPAT has the potential to be a significant add-on in breast cancer detection and characterization as it provides submillimeter resolution functional images of breast lesions.

  7. Patterned thin metal film for the lateral resolution measurement of photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Kim Do-Hyun

    2012-07-01

    Full Text Available Abstract Background Image quality assessment method of photoacoustic tomography has not been completely standardized yet. Due to the combined nature of photonic signal generation and ultrasonic signal transmission in biological tissue, neither optical nor ultrasonic traditional methods can be used without modification. An optical resolution measurement technique was investigated for its feasibility for resolution measurement of photoacoustic tomography. Methods A patterned thin metal film deposited on silica glass provides high contrast in optical imaging due to high reflectivity from the metal film and high transmission from the glass. It provides high contrast when it is used for photoacoustic tomography because thin metal film can absorb pulsed laser energy. An US Air Force 1951 resolution target was used to generate patterned photoacoustic signal to measure the lateral resolution. Transducer with 2.25 MHz bandwidth and a sample submerged in water and gelatinous block were tested for lateral resolution measurement. Results Photoacoustic signal generated from a thin metal film deposited on a glass can propagate along the surface or through the surrounding medium. First, a series of experiments with tilted sample confirmed that the measured photoacoustic signal is what is propagating through the medium. Lateral resolution of the photoacoustic tomography system was successfully measured for water and gelatinous block as media: 0.33 mm and 0.35 mm in water and gelatinous material, respectively, when 2.25 MHz transducer was used. Chicken embryo was tested for biomedical applications. Conclusions A patterned thin metal film sample was tested for its feasibility of measuring lateral resolution of a photoacoustic tomography system. Lateral resolutions in water and gelatinous material were successfully measured using the proposed method. Measured resolutions agreed well with theoretical values.

  8. Photoacoustic lymphatic imaging with high spatial-temporal resolution

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    Martel, Catherine; Yao, Junjie; Huang, Chih-Hsien; Zou, Jun; Randolph, Gwendalyn J.; Wang, Lihong V.

    2014-11-01

    Despite its critical function in coordinating the egress of inflammatory and immune cells out of tissues and maintaining fluid balance, the causative role of lymphatic network dysfunction in pathological settings is still understudied. Engineered-animal models and better noninvasive high spatial-temporal resolution imaging techniques in both preclinical and clinical studies will help to improve our understanding of different lymphatic-related pathologic disorders. Our aim was to take advantage of our newly optimized noninvasive wide-field fast-scanning photoacoustic (PA) microcopy system to coordinately image the lymphatic vasculature and its flow dynamics, while maintaining high resolution and detection sensitivity. Here, by combining the optical-resolution PA microscopy with a fast-scanning water-immersible microelectromechanical system scanning mirror, we have imaged the lymph dynamics over a large field-of-view, with high spatial resolution and advanced detection sensitivity. Depending on the application, lymphatic vessels (LV) were spectrally or temporally differentiated from blood vessels. Validation experiments were performed on phantoms and in vivo to identify the LV. Lymphatic flow dynamics in nonpathological and pathological conditions were also visualized. These results indicate that our newly developed PA microscopy is a promising tool for lymphatic-related biological research.

  9. Intravascular optical-resolution photoacoustic tomography with a 1.1 mm diameter catheter.

    Directory of Open Access Journals (Sweden)

    Xiaosong Bai

    Full Text Available Photoacoustic imaging is an emerging technology that can provide anatomic, functional, and molecular information about biological tissue. Intravascular spectroscopic and molecular photoacoustic imaging can potentially improve the identification of atherosclerotic plaque composition, the detection of inflammation, and ultimately the risk stratification of atherosclerosis. In this study, a first-of-its-kind intravascular optical-resolution photoacoustic tomography (OR-PAT system with a 1.1 mm diameter catheter is developed, offering optical-diffraction limited transverse resolution as fine as 19.6 μm, ∼ 10-fold finer than that of conventional intravascular photoacoustic and ultrasonic imaging. To offer complementary imaging information and depth, the system also acquires co-registered intravascular ultrasound images in parallel. Imaging of an iliac stent and a lipid phantom shows that the high resolution and contrast of OR-PAT can enable improved stent implantation guidance and lipid identification. In the future, these capabilities may ultimately improve the diagnosis and interventional treatment of vulnerable atherosclerotic plaques, which are prone to cause thrombotic complications such as myocardial infarction and stroke.

  10. Super-resolution photoacoustic imaging through a scattering wall

    CERN Document Server

    Conkey, Donald B; Dove, Jacob D; Ju, Hengyi; Murray, Todd W; Piestun, Rafael

    2013-01-01

    Imaging through opaque, highly scattering walls is a long sought after capability with potential applications in a variety of fields. The use of wavefront shaping to compensate for scattering has brought a renewed interest as a potential solution to this problem. A key to the practicality of any imaging technique is the capability to focus light without direct access behind the scattering wall. Here, we address this problem using photoacoustic feedback for wavefront optimization. By combining the spatially non-uniform sensitivity of the ultrasound transducer to the generated photoacoustic waves with an evolutionary competition among optical modes, the speckle field develops a single, high intensity focus significantly smaller than the acoustic focus used for feedback. Notably, this method is not limited by the size of the absorber to form a sub-acoustic optical focus. We demonstrate imaging behind a scattering medium with up to ten times improvement in signal-to-noise ratio (SNR) and five to six times sub-aco...

  11. Combined synthetic aperture focusing technique and three-dimensional deconvolution for resolution enhancement in photoacoustic microscopy

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    Cai, De; Li, Zhongfei; Li, Yao; Guo, Zhendong; Chen, Sung-Liang

    2017-03-01

    Acoustic-resolution photoacoustic microscopy (ARPAM) is a promising tool for deep imaging of biological tissues. Synthetic aperture focusing technique (SAFT) can improve the degraded lateral resolution in the out-of-focus region of ARPAM when using a high numerical aperture acoustic transducer. We previously reported a three-dimensional (3D) deconvolution technique to improve both lateral and axial resolutions in the focus region of ARPAM. In this work, we extended resolution enhancement of ARPAM to the out-of-focus region based on two dimensional SAFT combined with the 3D deconvolution (SAFT+Deconv). In both the focus and out-of-focus regions, depth-independent lateral and axial resolution after SAFT ensures a depth-independent point spread function for 3D deconvolution algorithm. In an extended depth of focus (DOF) of 2 mm, SAFT+Deconv ARPAM improves the -6 dB lateral resolutions from 65-700 μm to 20-29 μm, and the -6 dB axial resolutions from 35-42 μm to 12-19 μm. The signal-to-noise ratio is also increased by 6-30 dB. The enhanced resolution in extended DOF by SAFT+Deconv ARPAM may enable important applications in biomedical photoacoustic imaging.

  12. Submicron-resolution photoacoustic microscopy of endogenous light-absorbing biomolecules

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    Zhang, Chi

    Photoacoustic imaging in biomedicine has the unique advantage of probing endogenous light absorbers at various length scales with a 100% relative sensitivity. Among the several modalities of photoacoustic imaging, optical-resolution photoacoustic microscopy (OR-PAM) can achieve high spatial resolution, on the order of optical wavelength, at targets fluorescent markers, label-free PAM avoids the major concerns that the fluorescent labeling probes may disturb the function of biomolecules and may have an insufficient density. This dissertation aims to advance label-free OR-PAM to the subcellular scale. The first part of this dissertation describes the technological advancement of PAM yielding high spatial resolution in 3D. The lateral resolution was improved by using optical objectives with high numerical apertures for optical focusing. The axial resolution was improved by using broadband ultrasonic transducers for ultrasound detection. We achieved 220 nm lateral resolution in transmission mode, 0.43 microm lateral resolution in reflection mode, 7.6 microm axial resolution in normal tissue, and 5.8 microm axial resolution with silicone oil immersion/injection. The achieved lateral resolution and axial resolution were the finest reported at the time. With high-resolution in 3D, PAM was demonstrated to resolve cellular and subcellular structures in vivo, such as red blood cells and melanosomes in melanoma cells. Compared with previous PAM systems, our high-resolution PAM could resolve capillaries in mouse ears more clearly. As an example application, we demonstrated intracellular temperature imaging, assisted by fluorescence signal detection, with sub-degree temperature resolution and sub-micron lateral resolution. The second part of this dissertation describes the exploration of endogenous light-absorbing biomolecules for PAM. We demonstrated cytochromes and myoglobin as new absorption contrasts for PAM and identified the corresponding optimal wavelengths for imaging

  13. In vivo sub-femtoliter resolution photoacoustic microscopy with higher frame rates

    National Research Council Canada - National Science Library

    Lee, Szu-Yu; Lai, Yu-Hung; Huang, Kai-Chih; Cheng, Yu-Hsiang; Tseng, Tzu-Fang; Sun, Chi-Kuang

    2015-01-01

    .... In this paper, based on the two-photon photoacoustic mechanism, we demonstrated a in vivo label free laser-scanning photoacoustic imaging modality featuring high frame rates and sub-femtoliter 3D...

  14. High-resolution all-optical photoacoustic imaging system for remote interrogation of biological specimens

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    Sampathkumar, Ashwin

    2014-05-01

    Conventional photoacoustic imaging (PAI) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target tissue. The resolution of conventional PAI is limited by the sensitivity and bandwidth of the ultrasound transducer. We have developed an all-optical versatile PAI system for characterizing ex vivo and in vivo biological specimens. The system employs noncontact interferometric detection of the acoustic signals that overcomes limitations of conventional PAI. A 532-nm pump laser with a pulse duration of 5 ns excited the PA effect in tissue. Resulting acoustic waves produced surface displacements that were sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a GHz bandwidth. The pump and probe beams were coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam was demodulated using a homodyne interferometer. The detected time-domain signal was time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. Performance was assessed using PA images of ex vivo rabbit lymph node specimens and human tooth samples. A minimum peak surface displacement sensitivity of 0.19 pm was measured. The all-optical PAI (AOPAI) system is well suited for assessment of retinal diseases, caries lesion detection, skin burns, section less histology and pressure or friction ulcers.

  15. Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging.

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    U-Thainual, Paweena; Kim, Do-Hyun

    2015-12-01

    Optical-resolution photoacoustic microscopy (ORPAM) in theory provides lateral resolution equivalent to the optical diffraction limit. Scattering media, such as biological turbid media, attenuates the optical signal and also alters the diffraction-limited spot size of the focused beam. The ORPAM signal is generated only from a small voxel in scattering media with dimensions equivalent to the laser spot size after passing through scattering layers and is detected by an acoustic transducer, which is not affected by optical scattering. Thus, both ORPAM and confocal laser scanning microscopy (CLSM) reject scattered light. A multimodal optical microscopy platform that includes ORPAM and CLSM was constructed, and the lateral resolution of both modes was measured using patterned thin metal film with and without a scattering barrier. The effect of scattering media on the lateral resolution was studied using different scattering coefficients and was compared to computational results based on Monte Carlo simulations. It was found that degradation of lateral resolution due to optical scattering was not significant for either ORPAM or CLSM. The depth discrimination capability of ORPAM and CLSM was measured using microfiber embedded in a light scattering phantom material. ORPAM images demonstrated higher contrast compared to CLSM images partly due to reduced acoustic signal scattering.

  16. Non-interferometric deep optical resolution photoacoustic remote sensing microscopy (Conference Presentation)

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    HajiReza, Parsin H.; Bell, Kevan L.; Shi, Wei; Zemp, Roger J.

    2017-03-01

    A novel all-optical non-contact photoacoustic microscopy system is introduced. The confocal configuration is used to ensure detection of initial pressure shock wave-induced intensity reflections at the subsurface origin where pressures are largest. Phantom studies confirm signal dependence on optical absorption, index-contrast, and excitation fluence. Taking advantage of a focused1310 nm interrogation beam, the penetration depth of the system is improved to 2mm for an optical resolution system. High signal-to-noise ratios (>60dB) with 2.5 cm working distance from the objective lens to the sample is achieved. Real-time in-vivo imaging of microvasculature and melanoma tumors are demonstrated.

  17. Fast optical-resolution photoacoustic microscopy using a 2-axis water-proofing MEMS scanner

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    Kim, Jin Young; Lee, Changho; Park, Kyungjin; Lim, Geunbae; Kim, Chulhong

    2015-01-01

    Optical-resolution photoacoustic microscopy (OR-PAM) is a novel label-free microscopic imaging tool to provide in vivo optical absorbing contrasts. Specially, it is crucial to equip a real-time imaging capability without sacrificing high signal-to-noise ratios (SNRs) for identifying and tracking specific diseases in OR-PAM. Herein we demonstrate a 2-axis water-proofing MEMS scanner made of flexible PDMS. This flexible scanner results in a wide scanning range (9 × 4 mm2 in a transverse plane) and a fast imaging speed (5 B-scan images per second). Further, the MEMS scanner is fabricated in a compact footprint with a size of 15 × 15 × 15 mm3. More importantly, the scanning ability in water makes the MEMS scanner possible to confocally and simultaneously reflect both ultrasound and laser, and consequently we can maintain high SNRs. The lateral and axial resolutions of the OR-PAM system are 3.6 and 27.7 μm, respectively. We have successfully monitored the flow of carbon particles in vitro with a volumetric display frame rate of 0.14 Hz. Finally, we have successfully obtained in vivo PA images of microvasculatures in a mouse ear. It is expected that our compact and fast OR-PAM system can be significantly useful in both preclinical and clinical applications. PMID:25604654

  18. Lensless high-resolution photoacoustic imaging scanner for in vivo skin imaging

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    Ida, Taiichiro; Iwazaki, Hideaki; Omuro, Toshiyuki; Kawaguchi, Yasushi; Tsunoi, Yasuyuki; Kawauchi, Satoko; Sato, Shunichi

    2017-10-01

    We previously launched a high-resolution photoacoustic (PA) imaging scanner based on a unique lensless design for in vivo skin imaging. The design, imaging algorithm and characteristics of the system are described in this paper. Neither an optical lens nor an acoustic lens is used in the system. In the imaging head, four sensor elements are arranged quadrilaterally, and by checking the phase differences for PA waves detected with these four sensors, a set of PA signals only originating from a chromophore located on the sensor center axis is extracted for constructing an image. A phantom study using a carbon fiber showed a depth-independent horizontal resolution of 84.0 ± 3.5 µm, and the scan direction-dependent variation of PA signals was about ± 20%. We then performed imaging of vasculature phantoms: patterns of red ink lines with widths of 100 or 200 μm formed in an acrylic block co-polymer. The patterns were visualized with high contrast, showing the capability for imaging arterioles and venues in the skin. Vasculatures in rat burn models and healthy human skin were also clearly visualized in vivo.

  19. In vivo photoacoustic microscopy of human cuticle microvasculature with single-cell resolution

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    Hsu, Hsun-Chia; Wang, Lidai; Wang, Lihong V.

    2016-05-01

    As a window on the microcirculation, human cuticle capillaries provide rich information about the microvasculature, such as its morphology, density, dimensions, or even blood flow speed. Many imaging technologies have been employed to image human cuticle microvasculature. However, almost none of these techniques can noninvasively observe the process of oxygen release from single red blood cells (RBCs), an observation which can be used to study healthy tissue functionalities or to diagnose, stage, or monitor diseases. For the first time, we adapted single-cell resolution photoacoustic (PA) microscopy (PA flowoxigraphy) to image cuticle capillaries and quantified multiple functional parameters. Our results show more oxygen release in the curved cuticle tip region than in other regions of a cuticle capillary loop, associated with a low of RBC flow speed in the tip region. Further analysis suggests that in addition to the RBC flow speed, other factors, such as the drop of the partial oxygen pressure in the tip region, drive RBCs to release more oxygen in the tip region.

  20. Cost-efficient laser-diode-induced optical-resolution photoacoustic microscopy for two-dimensional/three-dimensional biomedical imaging.

    Science.gov (United States)

    Zeng, Lvming; Liu, Guodong; Yang, Diwu; Ji, Xuanrong

    2014-01-01

    Solid-state laser systems, such as traditional Nd:YAG-based lasers, are commonly used for noninvasive biomedical photoacoustics with nanosecond pulse duration and millijoule pulse energy. However, such lasers are both bulky and expensive for use as a handy tool for clinical applications. As an alternative, a semiconductor light source has the advantages of being compact, inexpensive, and robust. In addition, the main drawback of low peak output power may make it exactly suitable for the imaging modalities, which require relatively low pulse energies, such as acoustic- and optical-resolution photoacoustic microscopy (AR/OR-PAM). We propose a cost-efficient OR-PAM for two-dimensional/three-dimensional (2-D/3-D) biological imaging based on a pulsed near-infrared laser diode. By raster scanning, typical 2-D photoacoustic images were obtained at different scales, and 3-D surface renderings were clearly reconstructed with a marching cubes algorithm. This initial study would promote the production of portable OR-PAM technology for clinical and biomedical applications.

  1. Optical-resolution photoacoustic imaging through thick tissue with a thin capillary as a dual optical-in acoustic-out waveguide

    CERN Document Server

    Simandoux, Olivier; Gateau, Jerome; Huignard, Jean-Pierre; Moser, Christophe; Psaltis, Demetri; Bossy, Emmanuel

    2015-01-01

    We demonstrate the ability to guide high-frequency photoacoustic waves through thick tissue with a water-filled silica-capillary (150 \\mu m inner diameter and 30 mm long). An optical-resolution photoacoustic image of a 30 \\mu m diameter absorbing nylon thread was obtained by guiding the acoustic waves in the capillary through a 3 cm thick fat layer. The transmission loss through the capillary was about -20 dB, much lower than the -120 dB acoustic attenuation through the fat layer. The overwhelming acoustic attenuation of high-frequency acoustic waves by biological tissue can therefore be avoided by the use of a small footprint capillary acoustic waveguide for remote detection. We finally demonstrate that the capillary can be used as a dual optical-in acoustic-out waveguide, paving the way for the development of minimally invasive optical-resolution photoacoustic endoscopes free of any acoustic or optical elements at their imaging tip.

  2. Titanium

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    Woodruff, Laurel G.; Bedinger, George M.; Piatak, Nadine M.; Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Titanium is a mineral commodity that is essential to the smooth functioning of modern industrial economies. Most of the titanium produced is refined into titanium dioxide, which has a high refractive index and is thus able to impart a durable white color to paint, paper, plastic, rubber, and wallboard. Because of their high strength-to-weight ratio and corrosion resistance, titanium metal and titanium metal alloys are used in the aerospace industry as well as for welding rod coatings, biological implants, and consumer goods.Ilmenite and rutile are currently the principal titanium-bearing ore minerals, although other minerals, including anatase, perovskite, and titanomagnetite, could have economic importance in the future. Ilmenite is currently being mined from two large magmatic deposits hosted in rocks of Proterozoic-age anorthosite plutonic suites. Most rutile and nearly one-half of the ilmenite produced are from heavy-mineral alluvial, fluvial, and eolian deposits. Titanium-bearing minerals occur in diverse geologic settings, but many of the known deposits are currently subeconomic for titanium because of complications related to the mineralogy or because of the presence of trace contaminants that can compromise the pigment production process.Global production of titanium minerals is currently dominated by Australia, Canada, Norway, and South Africa; additional amounts are produced in Brazil, India, Madagascar, Mozambique, Sierra Leone, and Sri Lanka. The United States accounts for about 4 percent of the total world production of titanium minerals and is heavily dependent on imports of titanium mineral concentrates to meet its domestic needs.Titanium occurs only in silicate or oxide minerals and never in sulfide minerals. Environmental considerations for titanium mining are related to waste rock disposal and the impact of trace constituents on water quality. Because titanium is generally inert in the environment, human health risks from titanium and titanium

  3. Label-free optical-resolution photoacoustic microscopy of superficial microvasculature using a compact visible laser diode excitation

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    Zeng, Lvming; Piao, Zhonglie; Huang, Shenghai; Jia, Wangcun; Chen, Zhongping

    2015-01-01

    We have developed laser-diode-based optical-resolution photoacoustic microscopy (LD-OR-PAM) of superficial microvasculature which has the desirable properties of being compact, low-cost, and label-free. A 300-mW visible pulsed laser diode was operated at a 405 ± 5 nm wavelength with a pulse energy as low as 52 nJ. By using a 3.6 MHz ultrasound transducer, the system was tested on carbon fibers with a lateral resolution of 0.95 µm and an SNR of 38 dB. The subcutaneous microvasculature on a mouse back was imaged without an exogenous contrast agent which demonstrates the potential of the proposed prototype for skin chromophores. Our eventual goal is to offer a practical and affordable multi-wavelength functional LD-OR-PAM instrument suitable for clinical applications. PMID:26698732

  4. Dual-wavelength optical-resolution photoacoustic microscopy for cells with gold nanoparticle bioconjugates in three-dimensional cultures

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    Lee, Po-Yi; Liu, Wei-Wen; Chen, Shu-Ching; Li, Pai-Chi

    2016-03-01

    Three-dimensional (3D) in vitro models bridge the gap between typical two-dimensional cultures and in vivo conditions. However, conventional optical imaging methods such as confocal microscopy and two-photon microscopy cannot accurately depict cellular processing in 3D models due to limited penetration of photons. We developed a dualwavelength optical-resolution photoacoustic microscopy (OR-PAM), which provides sufficient penetration depth and spatial resolution, for studying CD8+ cytotoxic T lymphocytes (CTLs) trafficking in an in vitro 3D tumor microenvironment. CTLs play a cardinal role in host defense against tumor. Efficient trafficking of CTLs to the tumor microenvironment is a critical step for cancer immunotherapy. For the proposed system, gold nanospheres and indocyanine green (ICG) have been remarkable choices for contrast agents for photoacoustic signals due to their excellent biocompatibility and high optical absorption. With distinct absorption spectrums, targeted cells with gold nanospheres and ICG respectively can be identified by switching 523-nm and 800-nm laser irradiation. Moreover, we use an x-y galvanometer scanner to obtain high scanning rate. In the developed system, lateral and axial resolutions were designed at 1.6 μm and 5 μm, respectively. We successfully showed that dual-spectral OR-PAM can map either the distribution of CTLs with gold nanospheres at a visible wavelength of 523 nm or the 3D structure of tumor spheres with ICG in an in vitro 3D microenvironment. Our OR-PAM can provide better biological relevant information in cellular interaction and is potential for preclinical screening of anti-cancer drugs.

  5. Photoacoustic imaging and spectroscopy

    CERN Document Server

    Wang, Lihong

    2009-01-01

    Photoacoustics promises to revolutionize medical imaging and may well make as dramatic a contribution to modern medicine as the discovery of the x-ray itself once did. Combining electromagnetic and ultrasonic waves synergistically, photoacoustics can provide deep speckle-free imaging with high electromagnetic contrast at high ultrasonic resolution and without any health risk. While photoacoustic imaging is probably the fastest growing biomedical imaging technology, this book is the first comprehensive volume in this emerging field covering both the physics and the remarkable noninvasive applic

  6. Acoustic resolution photoacoustic Doppler flowmetry using a transducer array: optimising processing for velocity contrast

    Science.gov (United States)

    Bücking, T. M.; van den Berg, P. J.; Balabani, S.; Steenbergen, W.; Beard, P. C.; Brunker, J.

    2017-03-01

    This work demonstrates the first measurements of blood flow velocity using photoacoustic flowmetry (PAF) employing a transducer array. The measurements were made in a flow phantom consisting of a tube (580 μm inner diameter) containing blood flowing steadily at physiological speeds ranging from 3 mm/s to 25 mm/s. Velocity measurements were based on the generation of two successive photoacoustic (PA) signals using two laser pulses with a wavelength of 1064 nm; the PA signals were detected using a 64-element transducer array with a -6 dB detection bandwidth of 11-17 MHz. We developed a processing pipeline to optimise a cross-correlation based velocity measurement method comprising the following processing steps: image reconstruction, filtering, displacement detection, and masking. We found no difference in flow detection accuracy when choosing different image reconstruction algorithms (time reversal, Fourier transformation, and delay-and-sum). High-pass filtering and wallfiltering were however found to be essential pre-processing steps in order to recover the correct displacement information. We masked the calculated velocity map based on the amplitude of the cross-correlation function in order to define the region of interest corresponding to highest signal amplitude. These developments enabled blood flow measurements using a transducer array, bringing PAF one step closer to clinical applicability.

  7. Titanium

    Science.gov (United States)

    Bedinger, G.M.

    2013-01-01

    Titanium is the ninth most abundant element in the earth’s crust and can be found in nearly all rocks and sediments. It is a lithophile element with a strong affinity for oxygen and is not found as a pure metal in nature. Titanium was first isolated as a pure metal in 1910, but it was not until 1948 that metal was produced commercially using the Kroll process (named after its developer, William Kroll) to reduce titanium tetrachloride with magnesium to produce titanium metal.

  8. High Resolution Ultrasound and Photoacoustic Imaging of Orthotopic Lung Cancer in Mice: New Perspectives for Onco-Pharmacology.

    Directory of Open Access Journals (Sweden)

    Florian Raes

    Full Text Available We have developed a relevant preclinical model associated with a specific imaging protocol dedicated to onco-pharmacology studies in mice.We optimized both the animal model and an ultrasound imaging procedure to follow up longitudinally the lung tumor growth in mice. Moreover we proposed to measure by photoacoustic imaging the intratumoral hypoxia, which is a crucial parameter responsible for resistance to therapies. Finally, we compared ultrasound data to x-ray micro computed tomography and volumetric measurements to validate the relevance of this approach on the NCI-H460 human orthotopic lung tumor.This study demonstrates the ability of ultrasound imaging to detect and monitor the in vivo orthotopic lung tumor growth by high resolution ultrasound imaging. This approach enabled us to characterize key biological parameters such as oxygenation, perfusion status and vascularization of tumors.Such an experimental approach has never been reported previously and it would provide a nonradiative tool for assessment of anticancer therapeutic efficacy in mice. Considering the absence of ultrasound propagation through the lung parenchyma, this strategy requires the implantation of tumors strictly located in the superficial posterior part of the lung.

  9. Real-time display and functional optical-resolution photoacoustic microscopy with high-speed two wavelength illumination (Conference Presentation)

    Science.gov (United States)

    Lee, Sang-Won; Kang, Heesung; Cho, Soon-Woo; Park, Sang Min; Kim, Chang-Seok; Lee, Tae Geol

    2017-03-01

    Optical-resolution photoacoustic microscopy (OR-PAM), has been widely used and studied as noninvasive and in-vivo imaging technique, can achieve a high resolution and high contrast image. OR-PAM is combined with optical absorption contrast and detection of acoustic wave generated by thermal expansion. Recently, nanoparticles and dyes have been used as contrast agents of OR-PAM. To obtain functional OR-PAM image such as a distribution image of blood vessels and nanoparticles, a tunable dye laser or optical parametric oscillator (OPO) should be needed at more two wavelength. However, because these lasers have a low pulse repetition rate (10 Hz 10 kHz), a functional OR-PAM image with real-time display has been limited. In our previous study, we demonstrated high-speed OR-PAM using an Ytterbium fiber laser and a graphics processing unit (GPU) technique at 300 kHz-pulse repetition rates. Although this Ytterbium fiber laser has a high pulse repetition rate, it is not comfortable for functional imaging owing to lasing at only single wavelength. Therefore, in this study, we used a high-speed interlaced illumination method at 532 nm and 1064 nm for real-time display functional OR-PAM. For high-speed interlaced illumination of two wavelength, we applied second harmonic generation effect and a high-speed optical switching using an electro-optic modulator. Therefore, we could obtain maximum amplitude projection (MAP) images about distributions of blood vessels and nanoparticles, simultaneously, with 500 x 500 pixels and a real-time display of approximately 0.5 fps.

  10. Titanium

    DEFF Research Database (Denmark)

    Fage, Simon W; Muris, Joris; Jakobsen, Stig S

    2016-01-01

    Exposure to titanium (Ti) from implants and from personal care products as nanoparticles (NPs) is common. This article reviews exposure sources, ion release, skin penetration, allergenic effects, and diagnostic possibilities. We conclude that human exposure to Ti mainly derives from dental...

  11. Single-side access, isotropic resolution and multispectral 3D photoacoustic imaging with rotate-translate scanning of ultrasonic detector array

    CERN Document Server

    Gateau, Jérôme; Chassot, Jean-Marie; Bossy, Emmanuel

    2015-01-01

    Photoacoustic imaging can achieve high-resolution three-dimensional visualization of optical absorbers at penetration depths ~ 1 cm in biological tissues by detecting optically-induced high ultrasound frequencies. Tomographic acquisition with ultrasound linear arrays offers an easy implementation of single-side access, parallelized and high-frequency detection, but usually comes with an image quality impaired by the directionality of the detectors. Indeed, a simple translation of the array perpendicularly to its median imaging plane is often used, but results both in a poor resolution in the translation direction and in strong limited view artifacts. To improve the spatial resolution and the visibility of complex structures while keeping a planar detection geometry, we introduce, in this paper, a novel rotate-translate scanning scheme, and investigate the performance of a scanner implemented at 15 MHz center frequency. The developed system achieved a quasi-isotropic uniform 3D resolution of ~170 um over a cub...

  12. Molecular photoacoustic imaging

    Directory of Open Access Journals (Sweden)

    Frogh Jafarian Dehkordi

    2015-04-01

    Full Text Available Background: Hybrid imaging modalities which simultaneously benefit from capabilities of combined modalities provides an opportunity to modify quality of the images which can be obtained by each of the combined imaging systems. One of the imaging modalities, emerged in medical research area as a hybrid of ultrasound imaging and optical imaging, is photoacoustic imaging which apply ultrasound wave generated by tissue, after receiving laser pulse, to produce medical images. Materials and Methods: In this review, using keywords such as photoacoustic, optoacoustic, laser-ultrasound, thermoacoustic at databases such as PubMed and ISI, studies performed in the field of photoacoustic and related findings were evaluated. Results: Photoacoustic imaging, acquiring images with high contrast and desired resolution, provides an opportunity to perform physiologic and anatomic studies. Because this technique does not use ionizing radiation, it is not restricted by the limitation of the ionizing-based imaging systems therefore it can be used noninvasively to make images from cell, vessels, whole body imaging of the animal and distinguish tumor from normal tissue. Conclusion: Photoacoustic imaging is a new method in preclinical researches which can be used in various physiologic and anatomic studies. This method, because of application of non-ionizing radiation, may resolve limitation of radiation based method in diagnostic assessments.

  13. Femtosecond photoacoustics: integrated two-photon fluorescence and photoacoustic microscopy

    Science.gov (United States)

    van Raaij, Martijn E.; Lee, Mike; Chérin, Emmanuel; Stefanovic, Bojana; Foster, F. Stuart

    2010-02-01

    Conventional photoacoustic imaging systems excite a photoacoustic wave by illuminating an area on the order of square centimeters with millijoule laser pulses. Spatial resolution is then determined by the ultrasound transducer and is typically on the order of 100 μm. We report on a system that focuses femtosecond, nanojoule pulses to a spot with a diameter of ~ 1 μm to perform laser-scanning photoacoustics with micrometer resolution. Near-infrared femtosecond laser pulses with a pulse energy of 2.4 nanojoules excite a train of photoacoustic waves at the repetition rate of the pulsed laser (80 MHz). These photoacoustic waves are detected by an unfocused single-element ultrasound transducer tuned to 80 MHz. A radiofrequency lock-in amplifier recovers the amplitude of the frequency component of the photoacoustic signal at the pulse repetition frequency. This amplitude is an indicator of the absorption coefficient of the sample at the laser focus and at the laser wavelength. Initial experiments using a graphite rod as absorber reproducibly yield signals in the 0.2 - 2 microvolt range with a signal-to-noise ratio of 18 dB, recovered from 10 mV of broadband noise. The photoacoustic imaging system is integrated in a commercial laser-scanning two-photon fluorescence microscope, enabling simultaneous three-dimensional fluorescence- and photoacoustic imaging. One major application will be to image both morphology and oxygen saturation of microvasculature in the cerebral cortex of anesthetized rodents in vivo in the context of tumor angiogenesis. In this paper we describe the physics of femtosecond photoacoustics and demonstrate initial results.

  14. All-optical photoacoustic microscopy

    Directory of Open Access Journals (Sweden)

    Sung-Liang Chen

    2015-12-01

    Full Text Available Three-dimensional photoacoustic microscopy (PAM has gained considerable attention within the biomedical imaging community during the past decade. Detecting laser-induced photoacoustic waves by optical sensing techniques facilitates the idea of all-optical PAM (AOPAM, which is of particular interest as it provides unique advantages for achieving high spatial resolution using miniaturized embodiments of the imaging system. The review presents the technology aspects of optical-sensing techniques for ultrasound detection, such as those based on optical resonators, as well as system developments of all-optical photoacoustic systems including PAM, photoacoustic endoscopy, and multi-modality microscopy. The progress of different AOPAM systems and their representative applications are summarized.

  15. Acoustic property measurements in a photoacoustic imager

    NARCIS (Netherlands)

    Willemink, Rene; Manohar, Srirang; Slump, Cornelis H.; van der Heijden, Ferdinand; van Leeuwen, Ton; Depeursinge, C.D.

    2007-01-01

    Photoacoustics is a hybrid imaging technique that combines the contrast available to optical imaging with the resolution that is possessed by ultrasound imaging. The technique is based on generating ultrasound from absorbing structures in tissue using pulsed light. In photoacoustic (PA) computerized

  16. Double Pulse LIBS of Titanium-Based PVD-Coatings with Submicron Resolution

    Directory of Open Access Journals (Sweden)

    K. Ermalitskaia

    2016-01-01

    Full Text Available The possibility for double pulse LIBS in the process of a direct layer-by-layer analysis of the titanium-based PVD-coatings on polished flat blank samples of steel and silicon and also of the TiAlN/TiN-coating on a milling cutter is considered. A method is proposed to control thickness of the radiation evaporated layer by defocusing the laser beam with respect to the surface, making it possible to attain the depth resolution of 0.1 μm. The Ti and Ti-Zr-coatings produced using the ion-assisted condensation method and subjected to streams of the nitrogen plasma in a magnetic-plasma compressor are studied.

  17. Characterization of novel molecular photoacoustic contrast agents for in vivo photoacoustic tomography

    Science.gov (United States)

    Laoui, Samir

    Photoacoustic tomography is a hybrid imaging modality that takes advantage of the high contrast of pure optical imaging and the high intrinsic resolution of ultrasound without the necessity of ionizing radiation. Photoacoustic imaging (PM) is neither purely optical nor purely acoustical in nature, but a combination of the two. It is fundamentally based on light excitation and ultrasonic detection. Photoacoustic imaging has been successful without the introduction of exogenous contrast agents; however, to image deeper regions of biological tissue, a contrast agent is necessary. Several types of photoacoustic contrast agents have been made available for diagnostic purposes; however, the majority of literature has focused on gold nanoparticle systems for which the surface-plasmon resonance effect is important. The only option currently available for molecular PM contrast agents is to choose an existing near infrared absorbing fluorescent probes with the hope that they may generate a substantial photoacoustic (PA) response. However, these dyes have been designed with an optimized fluorescence emission response and are not anticipated to generate an adequate photoacoustic response. This dissertation addresses this lack of precedence in the literature for understanding the mechanism of a photoacoustic signal generation from strongly absorbing dye molecules including BODIPY, cyanine and curcumin systems. This work represents preliminary efforts in bringing novel molecular photoacoustic contrast agents (MPACs) into the photoacoustic imaging arena. To this end, photoacoustic and optical Z-scan experiments, and quenching studies were employed to demonstrate correlation of photoacoustic emission enhancement with excited state absorption mechanisms. To investigate further the photoacoustic emission in a practical imaging setting, MPACs were imaged using a recently developed photoacoustic imaging tomography system which was constructed exclusively for the purpose of this study.

  18. 3D noninvasive, high-resolution imaging using a photoacoustic tomography (PAT) system and rapid wavelength-cycling lasers

    Science.gov (United States)

    Sampathkumar, Ashwin; Gross, Daniel; Klosner, Marc; Chan, Gary; Wu, Chunbai; Heller, Donald F.

    2015-05-01

    Globally, cancer is a major health issue as advances in modern medicine continue to extend the human life span. Breast cancer ranks second as a cause of cancer death in women in the United States. Photoacoustic (PA) imaging (PAI) provides high molecular contrast at greater depths in tissue without the use of ionizing radiation. In this work, we describe the development of a PA tomography (PAT) system and a rapid wavelength-cycling Alexandrite laser designed for clinical PAI applications. The laser produces 450 mJ/pulse at 25 Hz to illuminate the entire breast, which eliminates the need to scan the laser source. Wavelength cycling provides a pulse sequence in which the output wavelength repeatedly alternates between 755 nm and 797 nm rapidly within milliseconds. We present imaging results of breast phantoms with inclusions of different sizes at varying depths, obtained with this laser source, a 5-MHz 128-element transducer and a 128-channel Verasonics system. Results include PA images and 3D reconstruction of the breast phantom at 755 and 797 nm, delineating the inclusions that mimic tumors in the breast.

  19. Resolution, sensitivity, and in vivo application of high-resolution computed tomography for titanium-coated polymethyl methacrylate (PMMA) dental implants.

    Science.gov (United States)

    Cuijpers, Vincent M J I; Jaroszewicz, Jacub; Anil, Sukumaran; Al Farraj Aldosari, Abdullah; Walboomers, X Frank; Jansen, John A

    2014-03-01

    The aims of this study were (i) to determine the spatial resolution and sensitivity of micro- versus nano-computed tomography (CT) techniques and (ii) to validate micro- versus nano-CT in a dog dental implant model, comparative to histological analysis. To determine spatial resolution and sensitivity, standardized reference samples containing standardized nano- and microspheres were prepared in polymer and ceramic matrices. Thereafter, 10 titanium-coated polymer dental implants (3.2 mm in Ø by 4 mm in length) were placed in the mandible of Beagle dogs. Both micro- and nano-CT, as well as histological analyses, were performed. The reference samples confirmed the high resolution of the nano-CT system, which was capable of revealing sub-micron structures embedded in radiodense matrices. The dog implantation study and subsequent statistical analysis showed equal values for bone area and bone-implant contact measurements between micro-CT and histology. However, because of the limited sample size and field of view, nano-CT was not rendering reliable data representative of the entire bone-implant specimen. Micro-CT analysis is an efficient tool to quantitate bone healing parameters at the bone-implant interface, especially when using titanium-coated PMMA implants. Nano-CT is not suitable for such quantification, but reveals complementary morphological information rivaling histology, yet with the advantage of a 3D visualization. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  20. Laser scanning laser diode photoacoustic microscopy system.

    Science.gov (United States)

    Erfanzadeh, Mohsen; Kumavor, Patrick D; Zhu, Quing

    2018-03-01

    The development of low-cost and fast photoacoustic microscopy systems enhances the clinical applicability of photoacoustic imaging systems. To this end, we present a laser scanning laser diode-based photoacoustic microscopy system. In this system, a 905 nm, 325 W maximum output peak power pulsed laser diode with 50 ns pulsewidth is utilized as the light source. A combination of aspheric and cylindrical lenses is used for collimation of the laser diode beam. Two galvanometer scanning mirrors steer the beam across a focusing aspheric lens. The lateral resolution of the system was measured to be ∼21 μm using edge spread function estimation. No averaging was performed during data acquisition. The imaging speed is ∼370 A-lines per second. Photoacoustic microscopy images of human hairs, ex vivo mouse ear, and ex vivo porcine ovary are presented to demonstrate the feasibility and potentials of the proposed system.

  1. Advances in Clinical and Biomedical Applications of Photoacoustic Imaging.

    Science.gov (United States)

    Su, Jimmy L; Wang, Bo; Wilson, Katheryne E; Bayer, Carolyn L; Chen, Yun-Sheng; Kim, Seungsoo; Homan, Kimberly A; Emelianov, Stanislav Y

    2010-11-01

    IMPORTANCE OF THE FIELD: Photoacoustic imaging is an imaging modality that derives image contrast from the optical absorption coefficient of the tissue being imaged. The imaging technique is able to differentiate between healthy and diseased tissue with either deeper penetration or higher resolution than other functional imaging modalities currently available. From a clinical standpoint, photoacoustic imaging has demonstrated safety and effectiveness in diagnosing diseased tissue regions using either endogenous tissue contrast or exogenous contrast agents. Furthermore, the potential of photoacoustic imaging has been demonstrated in various therapeutic interventions ranging from drug delivery and release to image-guided therapy and monitoring. AREAS COVERED IN THIS REVIEW: This article reviews the current state of photoacoustic imaging in biomedicine from a technological perspective, highlights various biomedical and clinical applications of photoacoustic imaging, and gives insights on future directions. WHAT THE READER WILL GAIN: Readers will learn about the various applications of photoacoustic imaging, as well as the various contrast agents that can be used to assist photoacoustic imaging. This review will highlight both pre-clinical and clinical uses for photoacoustic imaging, as well as discuss some of the challenges that must be addressed to move photoacoustic imaging into the clinical realm. TAKE HOME MESSAGE: Photoacoustic imaging offers unique advantages over existing imaging modalities. The imaging field is broad with many exciting applications for detecting and diagnosing diseased tissue or processes. Photoacoustics is also used in therapeutic applications to identify and characterize the pathology and then to monitor the treatment. Although the technology is still in its infancy, much work has been done in the pre-clinical arena, and photoacoustic imaging is fast approaching the clinical setting.

  2. Combined photoacoustic and fluorescent quenching studies on organic dyes

    Science.gov (United States)

    Viappiani, Cristiano; Small, Jeanne R.

    1992-04-01

    The development of deconvolution techniques in pulsed-laser, time-resolved photoacoustics has opened the possibility of accurately distinguishing between processes occurring on different time scales, and has given photoacoustics better resolution in determining reaction enthalpies and quantum yields. While fluorescent signals are usually generated by a single de- excitation pathway in the fluorophore, photoacoustic signals usually arise from different sources, such as excited singlet and triplet deactivation, occurring on well-distinguished time scales. The understanding of the effect of quenching on photoacoustic signals therefore requires careful analysis of the data. In this work, a model is developed to describe the effect of fluorescence quenching on photoacoustic signals. The model takes advantage of the time resolution in pulsed-laser photoacoustics. Both static and dynamic quenching are taken into account. Important photophysical parameters (fluorescence and intersystem crossing quantum yields, the bimolecular quenching rate constant, and the volume of the sphere of action) appear in the expressions describing the dependence of photoacoustic signal on quencher concentration. Data from both steady-state fluorescence and time-resolved photoacoustic quenching measurements are analyzed simultaneously using a set of equations containing common parameters. Experimental data on the quenching of organic dyes are presented which support the validity of the model.

  3. Neurovascular photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Song Hu

    2010-06-01

    Full Text Available Neurovascular coupling refers to the relationship between neuronal activities and downstream hemodynamic responses. Photoacoustic tomography (PAT, enabling comprehensive label-free imaging of hemodynamic activities with highly scalable penetration and spatial resolution, has great potential in the study of neurovascular coupling. In this review, we first introduce the technical basis of hemodynamic PAT—including label-free quantification of total hemoglobin concentration, blood oxygenation, and blood flow—as well as its applications in hemodynamic monitoring. Then, we demonstrate the potential application of PAT in neurovascular imaging by highlighting representative studies on cerebral vascular responses to whisker stimulation and Alzheimer’s disease. Finally, potential research directions and associated technical challenges are discussed.

  4. Miniaturized photoacoustic spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat; Robinson, Alex; Nielson, Gregory N.; Resnick, Paul J.

    2016-08-09

    A low-power miniaturized photoacoustic sensor uses an optical microphone made by semiconductor fabrication techniques, and optionally allows for all-optical communication to and from the sensor. This allows integration of the photoacoustic sensor into systems with special requirements, such as those that would be reactive in an electrical discharge condition. The photoacoustic sensor can also be operated in various other modes with wide application flexibility.

  5. Multifunctional Photosensitizer-Based Contrast Agents for Photoacoustic Imaging

    Science.gov (United States)

    Ho, Chris Jun Hui; Balasundaram, Ghayathri; Driessen, Wouter; McLaren, Ross; Wong, Chi Lok; Dinish, U. S.; Attia, Amalina Binte Ebrahim; Ntziachristos, Vasilis; Olivo, Malini

    2014-06-01

    Photoacoustic imaging is a novel hybrid imaging modality combining the high spatial resolution of optical imaging with the high penetration depth of ultrasound imaging. Here, for the first time, we evaluate the efficacy of various photosensitizers that are widely used as photodynamic therapeutic (PDT) agents as photoacoustic contrast agents. Photoacoustic imaging of photosensitizers exhibits advantages over fluorescence imaging, which is prone to photobleaching and autofluorescence interference. In this work, we examined the photoacoustic activity of 5 photosensitizers: zinc phthalocyanine, protoporphyrin IX, 2,4-bis [4-(N,N-dibenzylamino)-2,6-dihydroxyphenyl] squaraine, chlorin e6 and methylene blue in phantoms, among which zinc phthalocyanine showed the highest photoacoustic activity. Subsequently, we evaluated its tumor localization efficiency and biodistribution at multiple time points in a murine model using photoacoustic imaging. We observed that the probe localized at the tumor within 10 minutes post injection, reaching peak accumulation around 1 hour and was cleared within 24 hours, thus, demonstrating the potential of photosensitizers as photoacoustic imaging contrast agents in vivo. This means that the known advantages of photosensitizers such as preferential tumor uptake and PDT efficacy can be combined with photoacoustic imaging capabilities to achieve longitudinal monitoring of cancer progression and therapy in vivo.

  6. Molecular Photoacoustic Imaging of Follicular Thyroid Carcinoma

    Science.gov (United States)

    Levi, Jelena; Kothapalli, Sri-Rajashekar; Bohndiek, Sarah; Yoon, Joon-Kee; Dragulescu-Andrasi, Anca; Nielsen, Carsten; Tisma, Aleksandra; Bodapati, Sunil; Gowrishankar, Gayatri; Yan, Xinrui; Chan, Carmel; Starcevic, Daniela; Gambhir, Sanjiv Sam

    2013-01-01

    Purpose To evaluate the potential of targeted photoacoustic imaging as a non-invasive method for detection of follicular thyroid carcinoma. Experimental Design We determined the presence and activity of two members of matrix metalloproteinase family (MMP), MMP-2 and MMP-9, suggested as biomarkers for malignant thyroid lesions, in FTC133 thyroid tumors subcutaneously implanted in nude mice. The imaging agent used to visualize tumors was MMP activatable photoacoustic probe, Alexa750-CXeeeeXPLGLAGrrrrrXK-BHQ3. Cleavage of the MMP activatable agent was imaged after intratumoral and intravenous injections in living mice optically, observing the increase in Alexa750 fluorescence, and photoacoustically, using a dual wavelength imaging method. Results Active forms of both MMP2 and MMP-9 enzymes were found in FTC133 tumor homogenates, with MMP-9 detected in greater amounts. The molecular imaging agent was determined to be activated by both enzymes in vitro, with MMP-9 being more efficient in this regard. Both optical and photoacoustic imaging showed significantly higher signal in tumors of mice injected with the active agent than in tumors injected with the control, non-activatable, agent. Conclusions With the combination of high spatial resolution and signal specificity, targeted photoacoustic imaging holds great promise as a noninvasive method for early diagnosis of follicular thyroid carcinomas. PMID:23349314

  7. Photoacoustic imaging reveals hidden underdrawings in paintings.

    Science.gov (United States)

    Tserevelakis, George J; Vrouvaki, Ilianna; Siozos, Panagiotis; Melessanaki, Krystallia; Hatzigiannakis, Kostas; Fotakis, Costas; Zacharakis, Giannis

    2017-04-07

    A novel, non-invasive, imaging methodology, based on the photoacoustic effect, is introduced in the context of artwork diagnostics with emphasis on the uncovering of hidden features such as underdrawings or original sketch lines in paintings. Photoacoustic microscopy, a rapidly growing imaging method widely employed in biomedical research, exploits the ultrasonic acoustic waves, generated by light from a pulsed or intensity modulated source interacting with a medium, to map the spatial distribution of absorbing components. Having over three orders of magnitude higher transmission through strongly scattering media, compared to light in the visible and near infrared, the photoacoustic signal offers substantially improved detection sensitivity and achieves excellent optical absorption contrast at high spatial resolution. Photoacoustic images, collected from miniature oil paintings on canvas, illuminated with a nanosecond pulsed Nd:YAG laser at 1064 nm on their reverse side, reveal clearly the presence of pencil sketch lines coated over by several paint layers, exceeding 0.5 mm in thickness. By adjusting the detection bandwidth of the optically induced ultrasonic waves, photoacoustic imaging can be used for looking into a broad variety of artefacts having diverse optical properties and geometrical profiles, such as manuscripts, glass objects, plastic modern art or even stone sculpture.

  8. Photoacoustic tomography using integrating line detectors

    Science.gov (United States)

    Burgholzer, P.; Berer, T.; Gruen, H.; Roitner, H.; Bauer-Marschallinger, J.; Nuster, R.; Paltauf, G.

    2010-03-01

    Photoacoustic Imaging (also known as thermoacoustic or optoacoustic imaging) is a novel imaging method which combines the advantages of Diffuse Optical Imaging (high contrast) and Ultrasonic Imaging (high spatial resolution). In photoacoustic imaging, a short laser pulse excites the sample. The absorbed energy causes a thermoelastic expansion and thereby launches a broadband ultrasonic wave (photoacoustic signal). This way one can measure the optical contrast of a sample with ultrasonic resolution. For collecting photoacoustic signals our group introduced so called integrating detectors a few years ago. Such integrating detectors integrate the pressure in one or two dimensions (line or plane detectors). Thereby the three dimensional imaging problem is reduced to a two or a one dimensional problem for the pressure projections for line or plane detectors, respectively. Several reconstruction methods like Fourier or F-SAFT reconstruction or back projection are used for the two dimensional first step, but the model-based time reversal method shows a significant advantage: acoustical heterogeneity and attenuation, which both cause blurring of reconstructions, can be directly implemented in the reconstruction method. The integrating detectors are mainly optical detectors and thus can provide a high bandwidth up to several 100 MHz. Using these detectors the resolution is often limited by the acoustic attenuation in the sample itself, because attenuation increases with higher frequencies. For thin layers, small cylinders, and small spherical inclusions the effect of attenuation in human fat is simulated and the influence of dispersion on image reconstruction is shown.

  9. Imaging nonmelanoma skin cancers with combined ultrasound-photoacoustic microscopy

    Science.gov (United States)

    Sunar, Ulas; Rohrbach, Daniel J.; Morgan, Janet; Zeitouni, Natalie

    2013-03-01

    PDT has become a treatment of choice especially for the cases with multiple sites and large areas. However, the efficacy of PDT is limited for thicker and deeper tumors. Depth and size information as well as vascularity can provide useful information to clinicians for planning and evaluating PDT. High-resolution ultrasound and photoacoustic imaging can provide information regarding skin structure and vascularity. We utilized combined ultrasound-photoacoustic microscopy for imaging a basal cell carcinoma (BCC) tumor pre-PDT and the results indicate that combined ultrasound-photoacoustic imaging can be useful tool for PDT planning by providing both structural and functional contrasts.

  10. Early detection of dental caries using photoacoustics

    Science.gov (United States)

    Kim, K.; Witte, R.; Koh, I.; Ashkenazi, S.; O'Donnell, M.

    2006-02-01

    For decades, visual, tactile and radiographic examinations have been the standard for diagnosing caries. Nonetheless, the extent of variation in the diagnosis of dental caries is substantial among dental practitioners using these traditional techniques. Therefore, a more reliable standard for detecting incipient caries would be desirable. Using photoacoustics, near-infrared (NIR) optical contrast between sound and carious dental tissues can be relatively easily and accurately detected at ultrasound resolution. In this paper, a pulsed laser (Nd:YAG, Quanta-Ray) was used to probe extracted human molars at different disease stages determined from periapical radiographs. Both fundamental (1064nm) and first harmonic (532nm) pulses (15ns pulse length, 100mJ at fundamental and 9mJ at first harmonic , 10Hz pulse repetition rate) were used to illuminate the occlusal surface of tooth samples placed in a water tank. The photoacoustic signal was recorded with an unfocused wideband single-element piezoelectric transducer (centered at 12 MHz, bandwidth 15 MHz) positioned at small angle (less than 30 degrees) to the laser beam close to the occlusal surface. At the fundamental wavelength, total photoacoustic energy increases from normal to incipient stage disease by as much as a factor of 10. Differences between photoacoustic energy at the fundamental and first harmonic wavelength further indicate spectral absorption changes of the underlying structure with disease progression. Using a focused laser beam, an extracted molar with suspected incipient caries was scanned along the occulusal surface to help localize the caries inside enamel and dentin. The significantly increasing photoacoustic signal at a specific scan line both at fundamental and first harmonic indicates the local development of the incipient caries. The photoacoustic results compare well with visual inspection after layer by layer dissection. Preliminary results demonstrate the feasibility of detecting incipient

  11. Photoacoustic image patterns of breast carcinoma and comparisons with Magnetic Resonance Imaging and vascular stained histopathology

    NARCIS (Netherlands)

    Heijblom, M.; Piras, D.; Brinkhuis, M.; van Hespen, Johannes C.G.; van den Engh, F.M.; van der Schaaf, M.; Klaase, J.M.; van Leeuwen, Ton; Steenbergen, Wiendelt; Manohar, Srirang

    2015-01-01

    Photoacoustic (optoacoustic) imaging can visualize vasculature deep in tissue using the high contrast of hemoglobin to light, with the high-resolution possible with ultrasound detection. Since angiogenesis, one of the hallmarks of cancer, leads to increased vascularity, photoacoustics holds promise

  12. Three-dimensional photoacoustic endoscopic imaging of the rabbit esophagus.

    Directory of Open Access Journals (Sweden)

    Joon Mo Yang

    Full Text Available We report photoacoustic and ultrasonic endoscopic images of two intact rabbit esophagi. To investigate the esophageal lumen structure and microvasculature, we performed in vivo and ex vivo imaging studies using a 3.8-mm diameter photoacoustic endoscope and correlated the images with histology. Several interesting anatomic structures were newly found in both the in vivo and ex vivo images, which demonstrates the potential clinical utility of this endoscopic imaging modality. In the ex vivo imaging experiment, we acquired high-resolution motion-artifact-free three-dimensional photoacoustic images of the vasculatures distributed in the walls of the esophagi and extending to the neighboring mediastinal regions. Blood vessels with apparent diameters as small as 190 μm were resolved. Moreover, by taking advantage of the dual-mode high-resolution photoacoustic and ultrasound endoscopy, we could better identify and characterize the anatomic structures of the esophageal lumen, such as the mucosal and submucosal layers in the esophageal wall, and an esophageal branch of the thoracic aorta. In this paper, we present the first photoacoustic images showing the vasculature of a vertebrate esophagus and discuss the potential clinical applications and future development of photoacoustic endoscopy.

  13. Biomedical photoacoustic imaging.

    Science.gov (United States)

    Beard, Paul

    2011-08-06

    Photoacoustic (PA) imaging, also called optoacoustic imaging, is a new biomedical imaging modality based on the use of laser-generated ultrasound that has emerged over the last decade. It is a hybrid modality, combining the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a PA image can be regarded as an ultrasound image in which the contrast depends not on the mechanical and elastic properties of the tissue, but its optical properties, specifically optical absorption. As a consequence, it offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chomophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. As well as visualizing anatomical structures such as the microvasculature, it can also provide functional information in the form of blood oxygenation, blood flow and temperature. All of this can be achieved over a wide range of length scales from micrometres to centimetres with scalable spatial resolution. These attributes lend PA imaging to a wide variety of applications in clinical medicine, preclinical research and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. With the emergence of a variety of truly compelling in vivo images obtained by a number of groups around the world in the last 2-3 years, the technique has come of age and the promise of PA imaging is now beginning to be realized. Recent highlights include the demonstration of whole-body small-animal imaging, the first demonstrations of molecular imaging, the introduction of new microscopy modes and the first steps towards clinical breast imaging being taken as well as a myriad of in vivo preclinical imaging studies. In this article, the underlying physical principles of the technique, its practical

  14. Dual-wavelengths photoacoustic temperature measurement

    Science.gov (United States)

    Liao, Yu; Jian, Xiaohua; Dong, Fenglin; Cui, Yaoyao

    2017-02-01

    Thermal therapy is an approach applied in cancer treatment by heating local tissue to kill the tumor cells, which requires a high sensitivity of temperature monitoring during therapy. Current clinical methods like fMRI near infrared or ultrasound for temperature measurement still have limitations on penetration depth or sensitivity. Photoacoustic temperature sensing is a newly developed temperature sensing method that has a potential to be applied in thermal therapy, which usually employs a single wavelength laser for signal generating and temperature detecting. Because of the system disturbances including laser intensity, ambient temperature and complexity of target, the accidental errors of measurement is unavoidable. For solving these problems, we proposed a new method of photoacoustic temperature sensing by using two wavelengths to reduce random error and increase the measurement accuracy in this paper. Firstly a brief theoretical analysis was deduced. Then in the experiment, a temperature measurement resolution of about 1° in the range of 23-48° in ex vivo pig blood was achieved, and an obvious decrease of absolute error was observed with averagely 1.7° in single wavelength pattern while nearly 1° in dual-wavelengths pattern. The obtained results indicates that dual-wavelengths photoacoustic sensing of temperature is able to reduce random error and improve accuracy of measuring, which could be a more efficient method for photoacoustic temperature sensing in thermal therapy of tumor.

  15. Breket titanium (Titanium bracket

    Directory of Open Access Journals (Sweden)

    Sianiwati Goenharto

    2005-09-01

    Full Text Available There has been a considerable discussion in the literature about corrosion and sensitivity to the nickel present in stainless steel brackets. Titanium has been heralded as a material totally compatible in the oral environment and superior in structural integrity compared to stainless steel. Many current applications in dentistry and medicine have made titanium an obvious choice for a possible substitute material. Titanium based brackets have shown excellent corrosion resistance and possessed good biocompatibility. Evaluation of titanium brackets for orthodontic therapy showed that titanium brackets were comparable to stainless steel brackets in passive and active configuration. Study about metallographic structure, hardness, bond strength to enamel substrate, etc. showed that titanium brackets exhibited a potential for clinical application. It was concluded that titanium brackets were suitable substitute for stainless steel brackets.

  16. Mathematics of Photoacoustic and Thermoacoustic Tomography

    KAUST Repository

    Kuchment, Peter

    2011-01-01

    The chapter surveys the mathematical models, problems, and algorithms of the thermoacoustic tomography (TAT) and photoacoustic tomography (PAT). TAT and PAT represent probably the most developed of the several novel “hybrid” methods of medical imaging. These new modalities combine different physical types of waves (electromagnetic and acoustic in case of TAT and PAT) in such a way that the resolution and contrast of the resulting method are much higher than those achievable using only acoustic or electromagnetic measurements.

  17. Photoacoustic thermal flowmetry with a single light source.

    Science.gov (United States)

    Liu, Wei; Lan, Bangxin; Hu, Leo; Chen, Ruimin; Zhou, Qifa; Yao, Junjie

    2017-09-01

    We report a photoacoustic thermal flowmetry based on optical-resolution photoacoustic microscopy (OR-PAM) using a single laser source for both thermal tagging and photoacoustic excitation. When an optically absorbing medium is flowing across the optical focal zone of OR-PAM, a small volume of the medium within the optical focus is repeatedly illuminated and heated by a train of laser pulses with a high repetition rate. The average temperature of the heated volume at each laser pulse is indicated by the photoacoustic signal excited by the same laser pulse due to the well-established linear relationship between the Grueneisen coefficient and the local temperature. The thermal dynamics of the heated medium volume, which are closely related to the flow speed, can therefore be measured from the time course of the detected photoacoustic signals. Here, we have developed a lumped mathematical model to describe the time course of the photoacoustic signals as a function of the medium's flow speed. We conclude that the rising time constant of the photoacoustic signals is linearly dependent on the flow speed. Thus, the flow speed can be quantified by fitting the measured photoacoustic signals using the derived mathematical model. We first performed proof-of-concept experiments using defibrinated bovine blood flowing in a plastic tube. The experiment results have demonstrated that the proposed method has high accuracy (∼±6%) and a wide range of measurable flow speeds. We further validated the method by measuring the blood flow speeds of the microvasculature in a mouse ear in vivo. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  18. Photoacoustic thermal flowmetry with a single light source

    Science.gov (United States)

    Liu, Wei; Lan, Bangxin; Hu, Leo; Chen, Ruimin; Zhou, Qifa; Yao, Junjie

    2017-09-01

    We report a photoacoustic thermal flowmetry based on optical-resolution photoacoustic microscopy (OR-PAM) using a single laser source for both thermal tagging and photoacoustic excitation. When an optically absorbing medium is flowing across the optical focal zone of OR-PAM, a small volume of the medium within the optical focus is repeatedly illuminated and heated by a train of laser pulses with a high repetition rate. The average temperature of the heated volume at each laser pulse is indicated by the photoacoustic signal excited by the same laser pulse due to the well-established linear relationship between the Grueneisen coefficient and the local temperature. The thermal dynamics of the heated medium volume, which are closely related to the flow speed, can therefore be measured from the time course of the detected photoacoustic signals. Here, we have developed a lumped mathematical model to describe the time course of the photoacoustic signals as a function of the medium's flow speed. We conclude that the rising time constant of the photoacoustic signals is linearly dependent on the flow speed. Thus, the flow speed can be quantified by fitting the measured photoacoustic signals using the derived mathematical model. We first performed proof-of-concept experiments using defibrinated bovine blood flowing in a plastic tube. The experiment results have demonstrated that the proposed method has high accuracy (˜±6%) and a wide range of measurable flow speeds. We further validated the method by measuring the blood flow speeds of the microvasculature in a mouse ear in vivo.

  19. Multi-scale molecular photoacoustic tomography of gene expression.

    Directory of Open Access Journals (Sweden)

    Xin Cai

    Full Text Available Photoacoustic tomography (PAT is a molecular imaging technology. Unlike conventional reporter gene imaging, which is usually based on fluorescence, photoacoustic reporter gene imaging relies only on optical absorption. This work demonstrates several key merits of PAT using lacZ, one of the most widely used reporter genes in biology. We show that the expression of lacZ can be imaged by PAT as deep as 5.0 cm in biological tissue, with resolutions of ∼1.0 mm and ∼0.4 mm in the lateral and axial directions, respectively. We further demonstrate non-invasive, simultaneous imaging of a lacZ-expressing tumor and its surrounding microvasculature in vivo by dual-wavelength acoustic-resolution photoacoustic microscopy (AR-PAM, with a lateral resolution of 45 µm and an axial resolution of 15 µm. Finally, using optical-resolution photoacoustic microscopy (OR-PAM, we show intra-cellular localization of lacZ expression, with a lateral resolution of a fraction of a micron. These results suggest that PAT is a complementary tool to conventional optical fluorescence imaging of reporter genes for linking biological studies from the microscopic to the macroscopic scales.

  20. Photoacoustic and Colorimetric Visualization of Latent Fingerprints.

    Science.gov (United States)

    Song, Kai; Huang, Peng; Yi, Chenglin; Ning, Bo; Hu, Song; Nie, Liming; Chen, Xiaoyuan; Nie, Zhihong

    2015-12-22

    There is a high demand on a simple, rapid, accurate, user-friendly, cost-effective, and nondestructive universal method for latent fingerprint (LFP) detection. Herein, we describe a combination imaging strategy for LFP visualization with high resolution using poly(styrene-alt-maleic anhydride)-b-polystyrene (PSMA-b-PS) functionalized gold nanoparticles (GNPs). This general approach integrates the merits of both colorimetric imaging and photoacoustic imaging. In comparison with the previous methods, our strategy is single-step and does not require the signal amplification by silver staining. The PSMA-b-PS functionalized GNPs have good stability, tunable color, and high affinity for universal secretions (proteins/polypeptides/amino acids), which makes our approach general and flexible for visualizing LFPs on different substrates (presumably with different colors) and from different people. Moreover, the unique optical property of GNPs enables the photoacoustic imaging of GNPs-deposited LFPs with high resolution. This allows observation of level 3 hyperfine features of LFPs such as the pores and ridge contours by photoacoustic imaging. This technique can potentially be used to identify chemicals within LFP residues. We believe that this dual-modality imaging of LFPs will find widespread use in forensic investigations and medical diagnostics.

  1. Photoacoustic holographic imaging of absorbers embedded in silicone.

    Science.gov (United States)

    Olsson, Erik; Gren, Per; Sjödahl, Mikael

    2011-06-10

    Light absorbing objects embedded in silicone have been imaged using photoacoustic digital holography. The photoacoustic waves were generated using a pulsed Nd:YAG laser, λ=1064  nm, and pulse length=12  ns. When the waves reached the silicone surface, they were measured optically along a line using a scanning laser vibrometer. The acoustic waves were then digitally reconstructed using a holographic algorithm. The laser vibrometer is proven to be sensitive enough to measure the surface velocity due to photoacoustic waves generated from laser pulses with a fluence allowed for human tissue. It is also shown that combining digital holographic reconstructions for different acoustic wavelengths provides images with suppressed noise and improved depth resolution. The objects are imaged at a depth of 16.5  mm with a depth resolution of 0.5  mm.

  2. Compact photoacoustic tomography system

    Science.gov (United States)

    Kalva, Sandeep Kumar; Pramanik, Manojit

    2017-03-01

    Photoacoustic tomography (PAT) is a non-ionizing biomedical imaging modality which finds applications in brain imaging, tumor angiogenesis, monitoring of vascularization, breast cancer imaging, monitoring of oxygen saturation levels etc. Typical PAT systems uses Q-switched Nd:YAG laser light illumination, single element large ultrasound transducer (UST) as detector. By holding the UST in horizontal plane and moving it in a circular motion around the sample in full 2π radians photoacoustic data is collected and images are reconstructed. The horizontal positioning of the UST make the scanning radius large, leading to larger water tank and also increases the load on the motor that rotates the UST. To overcome this limitation, we present a compact photoacoustic tomographic (ComPAT) system. In this ComPAT system, instead of holding the UST in horizontal plane, it is held in vertical plane and the photoacoustic waves generated at the sample are detected by the UST after it is reflected at 45° by an acoustic reflector attached to the transducer body. With this we can reduce the water tank size and load on the motor, thus overall PAT system size can be reduced. Here we show that with the ComPAT system nearly similar PA images (phantom and in vivo data) can be obtained as that of the existing PAT systems using both flat and cylindrically focused transducers.

  3. Photoacoustic investigation of a neonatal skull phantom

    Science.gov (United States)

    Volinski, Bridget; Hariri, Ali; Fatima, Afreen; Xu, Qiuyun; Nasiriavanaki, Mohammadreza

    2017-03-01

    There is a need for continued research into the diagnosis, prevention and cure of neonatal brain disease and disorders. These disorders lead to fatalities and developmental disorders in infants. Non-invasive imaging techniques are being researched for this purpose. However, the availability of neonatal skull samples for this work is very low. A phantom can be used to simulate the neonatal skull and brain to improve imaging techniques. This study selects a phantom of polyurethane and titanium dioxide and proves its value as a replacement for neonatal skull in research. The methods used for this proof are validation of choice against the literature, transmissivity and acoustic experimentation compared to existing literature, and finally photoacoustic evaluation of the final choice to show its usefulness as a neonatal skull phantom.

  4. Integrated photoacoustic/ultrasound imaging: applications and new techniques

    NARCIS (Netherlands)

    van den Berg, P.J.

    2017-01-01

    Photoacoustic imaging (PAI) is a unique combination of optical sensitivity to tissue chromophores like hemoglobin, and ultrasonic resolution. Research in this PhD thesis is made possible by the development of a probe that combines PAI with regular ultrasound imaging. This probe is handheld and

  5. CO laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Abstract. Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 µm and 10.6 µm regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with ...

  6. laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 m and 10.6 m regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with conventional low ...

  7. Imaging of Small Vessels Using Photoacoustics: An In Vivo Study

    NARCIS (Netherlands)

    Siphanto, Ronald I.; Kolkman, R.G.M.; Huisjes, A.; Pilatou, M.H.; de Mul, F.F.M.; Steenbergen, Wiendelt; van Adrichem, Leon N.A.

    2004-01-01

    Background and Objectives The ability to correctly visualize the architectural arrangement of microvasculature is valuable to many diverse fields in medicine. In this study, we applied photoacoustics (PA) to obtain high-resolution images of submillimeter blood vessels. - Study Design/Materials and

  8. Multimodal subcellular imaging with microcavity photoacoustic transducer.

    Science.gov (United States)

    Tan, Zhiliang; Tang, Zhilie; Wu, Yongbo; Liao, Yanfei; Dong, Wei; Guo, Lina

    2011-01-31

    Photoacoustic microscopy (PAM) is dominantly sensitive to the endogenous optical absorption compared with the confocal microscopy which images with scattering photons. PAM has similar structure such as optical transportation system, the optical scanning, and light source with the laser scanning confocal microscopy (LSCM). In order to match the PAM with LSCM, a special design microcavity photoacoustic (PA) transducer with high sensitivity is developed to detect the photoacoustic signals induced by modulated continuous wave (CW) laser. By employing a microcavity PA transducer, a PAM can be integrated with LSCM. Thus a simultaneous multimodal imaging can be obtained with the same laser source and optical system. The lateral resolutions of the PAM and the LSCM are both tested to be better than 1.25 μm. Then subcellular multimodal imaging can be achieved. Images from the two modes are corresponding with each other but functionally complementary. Combining PAM and LSCM provides more comprehensive information for the cytological test. This technique is demonstrated for imaging red-blood cells and meristematic cells.

  9. Nanoparticle Probes for Structural and Functional Photoacoustic Molecular Tomography

    Directory of Open Access Journals (Sweden)

    Haobin Chen

    2015-01-01

    Full Text Available Nowadays, nanoparticle probes have received extensive attention largely due to its potential biomedical applications in structural, functional, and molecular imaging. In addition, photoacoustic tomography (PAT, a method based on the photoacoustic effect, is widely recognized as a robust modality to evaluate the structure and function of biological tissues with high optical contrast and high acoustic resolution. The combination of PAT with nanoparticle probes holds promises for detecting and imaging diseased tissues or monitoring their treatments with high sensitivity. This review will introduce the recent advances in the emerging field of nanoparticle probes and their preclinical applications in PAT, as well as relevant perspectives on future development.

  10. Photoacoustic remote sensing microscopy with lock-in amplification

    Science.gov (United States)

    Shi, Wei; Hajireza, Parsin; Bell, Kevan; Zemp, Roger

    2017-03-01

    High sensitive detection with lock-in amplification can provide high signal noise ratio even when noise is in orders of magnitude higher than the signal. Here we report to combine lock-in amplification with a novel photoacoustic remote sensing (PARS) technology to achieve high resolution, high contrast, all optical non-contact photoacoustic imaging at depth beyond optical scattering limitation. We demonstrate phantom measurements from PARS with lock-in technology were several orders of magnitude more sensitive than those from PARS with the broadband detection techniques.

  11. Photoacoustic microscopy of tyrosinase reporter gene in vivo

    Science.gov (United States)

    Krumholz, Arie; Vanvickle-Chavez, Sarah J.; Yao, Junjie; Fleming, Timothy P.; Gillanders, William E.; Wang, Lihong V.

    2011-08-01

    Photoacoustic tomography is a hybrid modality based on optical absorption excitation and ultrasonic detection. It is sensitive to melanin, one of the primary absorbers in skin. For cells that do not naturally contain melanin, melanin production can be induced by introducing the gene for tyrosinase, the primary enzyme responsible for expression of melanin in melanogenic cells. Optical resolution photoacoustic microscopy was used in the ex vivo study reported here, where the signal from transfected cells increased by more than 10 times over wild-type cells. A subsequent in vivo experiment was conducted to demonstrate the capability of photoacoustic microscopy to spectrally differentiate between tyrosinase-catalyzed melanin and various other absorbers in tissue.

  12. Photoacoustic computed microscopy

    Science.gov (United States)

    Yao, Lei; Xi, Lei; Jiang, Huabei

    2014-05-01

    Photoacoustic microscopy (PAM) is emerging as a powerful technique for imaging microvasculature at depths beyond the ~1 mm depth limit associated with confocal microscopy, two-photon microscopy and optical coherence tomography. PAM, however, is currently qualitative in nature and cannot quantitatively measure important functional parameters including oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), oxygen saturation (sO2), blood flow (BF) and rate of oxygen metabolism (MRO2). Here we describe a new photoacoustic microscopic method, termed photoacoustic computed microscopy (PACM) that combines current PAM technique with a model-based inverse reconstruction algorithm. We evaluate the PACM approach using tissue-mimicking phantoms and demonstrate its in vivo imaging ability of quantifying HbO2, HbR, sO2, cerebral BF and cerebral MRO2 at the small vessel level in a rodent model. This new technique provides a unique tool for neuroscience research and for visualizing microvasculature dynamics involved in tumor angiogenesis and in inflammatory joint diseases.

  13. Real-time photoacoustic tomography of cortical hemodynamics in small animals

    Science.gov (United States)

    Li, Changhui; Aguirre, Andres; Gamelin, John; Maurudis, Anastasios; Zhu, Quing; Wang, Lihong V.

    2010-01-01

    For the first time, the hemodynamics within the entire cerebral cortex of a mouse were studied by using photoacoustic tomography (PAT) in real time. The PAT system, based on a 512-element full-ring ultrasound array, received photoacoustic signals primarily from a slice of 2-mm thickness. This system can provide high-resolution brain vasculature images. We also monitored the fast wash-in process of a photoacoustic contrast agent in the mouse brain. Our results demonstrated that PAT is a powerful imaging modality that can be potentially used to study small animal neurofunctional activities.

  14. Multiscale photoacoustic microscopy and computed tomography

    Science.gov (United States)

    Wang, Lihong V.

    2009-01-01

    Photoacoustic tomography (PAT) is probably the fastest growing biomedical imaging technology owing to its capability of high-resolution sensing of rich optical contrast in vivo at depths beyond the optical transport mean free path (~1 mm in the skin). Existing high-resolution optical imaging technologies, such as confocal microscopy and two-photon microscopy, have fundamentally impacted biomedicine but cannot reach such depths. Taking advantage of low ultrasonic scattering, PAT indirectly improves tissue transparency by 100 to 1000 fold and consequently enables deeply penetrating functional and molecular imaging at high spatial resolution. Further, PAT holds the promise of in vivo imaging at multiple length scales ranging from subcellular organelles to organs with the same contrast origin, an important application in multiscale systems biology research. PMID:20161535

  15. Clinical photoacoustic imaging of cancer

    Energy Technology Data Exchange (ETDEWEB)

    Valluru, Keerthi S.; Willmann, Juergen K. [Dept. of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford (United States)

    2016-08-15

    Photoacoustic imaging is a hybrid technique that shines laser light on tissue and measures optically induced ultrasound signal. There is growing interest in the clinical community over this new technique and its possible clinical applications. One of the most prominent features of photoacoustic imaging is its ability to characterize tissue, leveraging differences in the optical absorption of underlying tissue components such as hemoglobin, lipids, melanin, collagen and water among many others. In this review, the state-of-the-art photoacoustic imaging techniques and some of the key outcomes pertaining to different cancer applications in the clinic are presented.

  16. Tissue temperature monitoring using thermoacoustic and photoacoustic techniques

    Science.gov (United States)

    Pramanik, Manojit; Erpelding, Todd N.; Jankovic, Ladislav; Wang, Lihong V.

    2010-02-01

    Real-time temperature monitoring with high spatial resolution (~1 mm) and high temperature sensitivity (1 °C or better) is needed for the safe deposition of heat energy in surrounding healthy tissue and efficient destruction of tumor and abnormal cells during thermotherapy. A temperature sensing technique using thermoacoustic and photoacoustic measurements combined with a clinical Philips ultrasound imaging system (iU22) has been explored in this study. Using a tissue phantom, this noninvasive method has been demonstrated to have high temporal resolution and temperature sensitivity. Because both photoacoustic and thermoacoustic signal amplitudes depend on the temperature of the source object, the signal amplitudes can be used to monitor the temperature. The signal is proportional to the dimensionless Grueneisen parameter of the object, which in turn varies with the temperature of the object. A temperature sensitivity of 0.5 °C was obtained at a temporal resolution as short as 3.6 s with 50 signal averages.

  17. In vivo photoacoustic imaging of nude mice vasculature using a photoacoustic imaging system based on a commercial ultrasound scanner

    Science.gov (United States)

    Jankovic, Ladislav; Shahzad, Khalid; Wang, Yao; Burcher, Michael; Scholle, Frank-Detlef; Hauff, Peter; Mofina, Sabine; Skobe, Mihaela

    2008-02-01

    In-vivo photoacoustic/ultrasound (PA/US) imaging of nude mice was investigated using a photoacoustic imaging system based on a commercial ultrasound scanner HDI-5000. Raw per-channel data was captured and beamformed to generate each individual photoacoustic image with a single laser shot. An ultra-broadband CL15-7 linear array with a center frequency of 8 MHz, combined with a Schott Glass fiber bundle, was used as a compact high resolution imaging probe, with lateral and axial PA resolutions of about 300µm and 200µm, respectively. The imaging system worked in a dual PA-US mode, with the ultrasound outlining the tissue structure and the photoacoustic image showing the blood vessels. PA signals were generated by exposing mice to ultra-short optical pulses from a Nd:YAG-pumped OPO laser operating in a wavelength range of 700-950nm. The corresponding ultrasound images were generated in the regular B-mode with standard delay-and-sum beamforming algorithm. The system resolution was sufficiently high to identify and clearly distinguish the dorsal artery and the two lateral veins in the mouse tail. Both the saphena artery and the ischiatic vein on the cross-section of the mouse leg were clearly outlined in the PA images and correctly overlaid on the ultrasound image of the tissue structure. Similarly, cross-section PA images of the mouse abdomen revealed mesenteric vasculatures located below the abdominal wall. Finally, a successful PA imaging of the mouse thoracic cavity unveiled the ascending and descending aorta. These initial results demonstrate a great potential for a dual photoacoustic/ultrasound imaging modality implemented on a commercial ultrasound imaging scanner.

  18. Resolution, sensitivity, and in vivo application of high-resolution computed tomography for titanium-coated polymethyl methacrylate (PMMA) dental implants

    NARCIS (Netherlands)

    Cuijpers, V.M.J.I.; Jaroszewicz, J.; Anil, S.; Al Farraj Aldosari, A.; Walboomers, X.F.; Jansen, J.A.

    2014-01-01

    OBJECTIVES: The aims of this study were (i) to determine the spatial resolution and sensitivity of micro- versus nano-computed tomography (CT) techniques and (ii) to validate micro- versus nano-CT in a dog dental implant model, comparative to histological analysis. MATERIAL AND METHODS: To determine

  19. Nonlinear photoacoustic spectroscopy of hemoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.; Xia, Jun; Wang, Lihong V., E-mail: LHWANG@WUSTL.EDU [Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130 (United States)

    2015-05-18

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.

  20. Photoacoustic Sounds from Meteors

    Science.gov (United States)

    Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, Gigi; Spurný, Pavel

    2017-02-01

    Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with -11 to -13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that -12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.

  1. Fiber optic photoacoustic probe with ultrasonic tracking for guiding minimally invasive procedures

    Science.gov (United States)

    Xia, Wenfeng; Mosse, Charles A.; Colchester, Richard J.; Mari, Jean Martial; Nikitichev, Daniil I.; West, Simeon J.; Ourselin, Sebastien; Beard, Paul C.; Desjardins, Adrien E.

    2015-07-01

    In a wide range of clinical procedures, accurate placement of medical devices such as needles and catheters is critical to optimize patient outcomes. Ultrasound imaging is often used to guide minimally invasive procedures, as it can provide real-time visualization of patient anatomy and medical devices. However, this modality can provide low image contrast for soft tissues, and poor visualization of medical devices that are steeply angled with respect to the incoming ultrasound beams. Photoacoustic sensors can provide information about the spatial distributions of tissue chromophores that could be valuable for guiding minimally invasive procedures. In this study, a system for guiding minimally invasive procedures using photoacoustic sensing was developed. This system included a miniature photoacoustic probe with three optical fibers: one with a bare end for photoacoustic excitation of tissue, a second for photoacoustic excitation of an optically absorbing coating at the distal end to transmit ultrasound, and a third with a Fabry-Perot cavity at the distal end for receiving ultrasound. The position of the photoacoustic probe was determined with ultrasonic tracking, which involved transmitting pulses from a linear-array ultrasound imaging probe at the tissue surface, and receiving them with the fiber-optic ultrasound receiver in the photoacoustic probe. The axial resolution of photoacoustic sensing was better than 70 μm, and the tracking accuracy was better than 1 mm in both axial and lateral dimensions. By translating the photoacoustic probe, depth scans were obtained from different spatial positions, and two-dimensional images were reconstructed using a frequency-domain algorithm.

  2. PHOTOACOUSTIC SPECTROSCOPY USING A SYNCHROTRON LIGHT SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    JACKSON, R.S.; MICHAELIAN, K.H.; HOMES, C.C.

    2001-02-05

    We have investigated the use of a synchrotron as a source for infrared photoacoustic spectroscopy. A synchrotron has an intrinsically high radiance, which is beneficial when photoacoustic spectroscopy is applied to small samples, especially at long wavelengths.

  3. Photoacoustic Imaging for Noninvasive Periodontal Probing Depth Measurements.

    Science.gov (United States)

    Lin, C Y; Chen, F; Hariri, A; Chen, C J; Wilder-Smith, P; Takesh, T; Jokerst, J V

    2018-01-01

    The periodontal probe is the gold standard tool for periodontal examinations, including probing depth measurements, but is limited by systematic and random errors. Here, we used photoacoustic ultrasound for high-spatial resolution imaging of probing depths. Specific contrast from dental pockets was achieved with food-grade cuttlefish ink as a contrast medium. Here, 39 porcine teeth (12 teeth with artificially deeper pockets) were treated with the contrast agent, and the probing depths were measured with novel photoacoustic imaging and a Williams periodontal probe. There were statistically significant differences between the 2 measurement approaches for distal, lingual, and buccal sites but not mesial. Bland-Altman analysis revealed that all bias values were < ±0.25 mm, and the coefficients of variation for 5 replicates were <11%. The photoacoustic imaging approach also offered 0.01-mm precision and could cover the entire pocket, as opposed to the probe-based approach, which is limited to only a few sites. This report is the first to use photoacoustic imaging for probing depth measurements with potential implications to the dental field, including tools for automated dental examinations or noninvasive examinations.

  4. Photoacoustic sensing with micro-tuning forks

    Science.gov (United States)

    Willer, U.; Köhring, M.; Mordmüller, M.; Schade, W.

    2015-06-01

    Different modifications of quartz enhanced photoacoustic spectroscopy (QEPAS) are discussed. An analysis of the signal-to-noise ratio for the generated photoacoustic signal gives hints for an optimized geometry of tuning fork and acoustic resonator. Furthermore, simultaneous or alternate photoacoustic and electrical driving is discussed, leading the way to new detection schemes that are capable of measuring changes in molecular relaxation dynamics.

  5. Label-free photoacoustic microscopy of cytochromes

    Science.gov (United States)

    Zhang, Chi; Zhang, Yu Shrike; Yao, Da-Kang; Xia, Younan; Wang, Lihong V.

    2013-02-01

    Photoacoustic microscopy (PAM) has achieved submicron lateral resolution in showing subcellular structures; however, relatively few endogenous subcellular contrasts have so far been imaged. Given that the hemeprotein, mostly cytochromes in general cells, is optically absorbing around the Soret peak (˜420 nm), we implemented label-free PAM of cytochromes in cytoplasm for the first time. By measuring the photoacoustic spectra of the oxidized and reduced states of fibroblast lysate and fitting the difference spectrum with three types of cytochromes, we found that the three cytochromes account for more than half the optical absorption in the cell lysate at 420 nm wavelength. Fixed fibroblasts on slides were imaged by PAM at 422 and 250 nm wavelengths to reveal cytoplasms and nuclei, respectively, as confirmed by standard staining histology. PAM was also applied to label-free histology of mouse ear sections by showing cytoplasms and nuclei of various cells. PAM of cytochromes in cytoplasm is expected to be a high-throughput, label-free technique for studying live cell functions, which cannot be accomplished by conventional histology.

  6. Toroidal sensor arrays for real-time photoacoustic imaging

    Science.gov (United States)

    Bychkov, Anton S.; Cherepetskaya, Elena B.; Karabutov, Alexander A.; Makarov, Vladimir A.

    2017-07-01

    This article addresses theoretical and numerical investigation of image formation in photoacoustic (PA) imaging with complex-shaped concave sensor arrays. The spatial resolution and the size of sensitivity region of PA and laser ultrasonic (LU) imaging systems are assessed using sensitivity maps and spatial resolution maps in the image plane. This paper also discusses the relationship between the size of high-sensitivity regions and the spatial resolution of real-time imaging systems utilizing toroidal arrays. It is shown that the use of arrays with toroidal geometry significantly improves the diagnostic capabilities of PA and LU imaging to investigate biological objects, rocks, and composite materials.

  7. Toroidal sensor arrays for real-time photoacoustic imaging.

    Science.gov (United States)

    Bychkov, Anton S; Cherepetskaya, Elena B; Karabutov, Alexander A; Makarov, Vladimir A

    2017-07-01

    This article addresses theoretical and numerical investigation of image formation in photoacoustic (PA) imaging with complex-shaped concave sensor arrays. The spatial resolution and the size of sensitivity region of PA and laser ultrasonic (LU) imaging systems are assessed using sensitivity maps and spatial resolution maps in the image plane. This paper also discusses the relationship between the size of high-sensitivity regions and the spatial resolution of real-time imaging systems utilizing toroidal arrays. It is shown that the use of arrays with toroidal geometry significantly improves the diagnostic capabilities of PA and LU imaging to investigate biological objects, rocks, and composite materials.

  8. Titanium 2013

    Science.gov (United States)

    2014-01-01

    Titanium is the ninth most abundant element in the earth's crust and can be found in nearly all rocks and sediments. It is a lithophile element with a strong affinity for oxygen and is not found as a pure metal in nature. Titanium was first isolated as a pure metal in 1910, but it was not until 1948 that the metal was produced commercially using the Kroll process (named after its developer, William Kroll) to reduce titanium tetrachloride with magnesium to produce titanium metal.

  9. Photoacoustic image patterns of breast carcinoma and comparisons with Magnetic Resonance Imaging and vascular stained histopathology

    Science.gov (United States)

    Heijblom, M.; Piras, D.; Brinkhuis, M.; van Hespen, J. C. G.; van den Engh, F. M.; van der Schaaf, M.; Klaase, J. M.; van Leeuwen, T. G.; Steenbergen, W.; Manohar, S.

    2015-07-01

    Photoacoustic (optoacoustic) imaging can visualize vasculature deep in tissue using the high contrast of hemoglobin to light, with the high-resolution possible with ultrasound detection. Since angiogenesis, one of the hallmarks of cancer, leads to increased vascularity, photoacoustics holds promise in imaging breast cancer as shown in proof-of-principle studies. Here for the first time, we investigate if there are specific photoacoustic appearances of breast malignancies which can be related to the tumor vascularity, using an upgraded research imaging system, the Twente Photoacoustic Mammoscope. In addition to comparisons with x-ray and ultrasound images, in subsets of cases the photoacoustic images were compared with MR images, and with vascular staining in histopathology. We were able to identify lesions in suspect breasts at the expected locations in 28 of 29 cases. We discovered generally three types of photoacoustic appearances reminiscent of contrast enhancement types reported in MR imaging of breast malignancies, and first insights were gained into the relationship with tumor vascularity.

  10. Photoacoustic image patterns of breast carcinoma and comparisons with Magnetic Resonance Imaging and vascular stained histopathology

    Science.gov (United States)

    Heijblom, M.; Piras, D.; Brinkhuis, M.; van Hespen, J. C. G.; van den Engh, F. M.; van der Schaaf, M.; Klaase, J. M.; van Leeuwen, T. G.; Steenbergen, W.; Manohar, S.

    2015-01-01

    Photoacoustic (optoacoustic) imaging can visualize vasculature deep in tissue using the high contrast of hemoglobin to light, with the high-resolution possible with ultrasound detection. Since angiogenesis, one of the hallmarks of cancer, leads to increased vascularity, photoacoustics holds promise in imaging breast cancer as shown in proof-of-principle studies. Here for the first time, we investigate if there are specific photoacoustic appearances of breast malignancies which can be related to the tumor vascularity, using an upgraded research imaging system, the Twente Photoacoustic Mammoscope. In addition to comparisons with x-ray and ultrasound images, in subsets of cases the photoacoustic images were compared with MR images, and with vascular staining in histopathology. We were able to identify lesions in suspect breasts at the expected locations in 28 of 29 cases. We discovered generally three types of photoacoustic appearances reminiscent of contrast enhancement types reported in MR imaging of breast malignancies, and first insights were gained into the relationship with tumor vascularity. PMID:26159440

  11. Towards non-contact photo-acoustic endoscopy using speckle pattern analysis

    Science.gov (United States)

    Lengenfelder, Benjamin; Mehari, Fanuel; Tang, Yuqi; Klämpfl, Florian; Zalevsky, Zeev; Schmidt, Michael

    2017-03-01

    Photoacoustic Tomography combines the advantages of optical and acoustic imaging as it makes use of the high optical contrast of tissue and the high resolution of ultrasound. Furthermore, high penetration depths in tissue in the order of several centimeters can be achieved by the combination of these modalities. Extensive research is being done in the field of miniaturization of photoacoustic devices, as photoacoustic imaging could be of significant benefits for the physician during endoscopic interventions. All the existing miniature systems are based on contact transducers for signal detection that are placed at the distal end of an endoscopic device. This makes the manufacturing process difficult and impedance matching to the inspected surface a requirement. The requirement for contact limits the view of the physician during the intervention. Consequently, a fiber based non-contact optical sensing technique would be highly beneficial for the development of miniaturized photoacoustic endoscopic devices. This work demonstrates the feasibility of surface displacement detection using remote speckle-sensing using a high speed camera and an imaging fiber bundle that is used in commercially available video endoscopes. The feasibility of displacement sensing is demonstrated by analysis of phantom vibrations which are induced by loudspeaker membrane oscillations. Since the usability of the remote speckle-sensing for photo-acoustic signal detection was already demonstrated, the fiber bundle approach demonstrates the potential for non-contact photoacoustic detections during endoscopy.

  12. Photoacoustic spectroscopy for chemical detection

    Science.gov (United States)

    Holthoff, Ellen L.; Pellegrino, Paul M.

    2012-06-01

    The Global War on Terror has made rapid detection and identification of chemical and biological agents a priority for Military and Homeland Defense applications. Reliable real-time detection of these threats is complicated by our enemy's use of a diverse range of materials. Therefore, an adaptable platform is necessary. Photoacoustic spectroscopy (PAS) is a useful monitoring technique that is well suited for trace detection of gaseous media. This method routinely exhibits detection limits at the parts-per-billion (ppb) or sub-ppb range. The versatility of PAS also allows for the investigation of solid and liquid analytes. Current research utilizes quantum cascade lasers (QCLs) in combination with an air-coupled solid-phase photoacoustic cell design for the detection of condensed phase material films deposited on a surface. Furthermore, variation of the QCL pulse repetition rate allows for identification and molecular discrimination of analytes based solely on photoacoustic spectra collected at different film depths.

  13. Photoacoustic tomography of ex vivo mouse hearts with myocardial infarction

    Science.gov (United States)

    Holotta, Markus; Grossauer, Harald; Kremser, Christian; Torbica, Pavle; Völkl, Jakob; Degenhart, Gerald; Esterhammer, Regina; Nuster, Robert; Paltauf, Günther; Jaschke, Werner

    2011-03-01

    In the present study, we evaluated the applicability of ex vivo photoacoustic imaging (PAI) on small animal organs. We used photoacoustic tomography (PAT) to visualize infarcted areas within murine hearts and compared these data to other imaging techniques [magnetic resonance imaging (MRI), micro-computed tomography] and histological slices. In order to induce ischemia, an in vivo ligation of the left anterior descending artery was performed on nine wild-type mice. After varying survival periods, the hearts were excised and fixed in formaldehyde. Samples were illuminated with nanosecond laser pulses delivered by a Nd:YAG pumped optical parametric oscillator. Ultrasound detection was achieved using a Mach-Zehnder interferometer (MZI) working as an integrating line detector. The voxel data were computed using a Fourier-domain based reconstruction algorithm, followed by inverse Radon transforms. The results clearly showed the capability of PAI to visualize myocardial infarction and to produce three-dimensional images with a spatial resolution of approximately 120 μm. Regions of affected muscle tissue in PAI corresponded well with the results of MRI and histology. Photoacoustic tomography utilizing a MZI for ultrasound detection allows for imaging of small tissue samples. Due to its high spatial resolution, good soft tissue contrast and comparatively low cost, PAT offers great potentials for imaging.

  14. Characterization of seeds with different moisture content by photoacoustic microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez Pacheco, Arturo; Hernandez Aguilar, Claudia; Marinez Ortiz, Efrain [Instituto Politecnico Nacional, Sepi-Esime, Zacatenco. Unidad Profesional ' Adolfo Lopez Mateos' . Col. Lindavista. Mexico D.F., CP 07738 (Mexico); Cruz-Orea, Alfredo; Ayala-Maycotte, Esther, E-mail: fartur@hotmail.co [Departamento de Fisica, CINVESTAV - IPN, A. P. 14-740, Mexico D.F., C.P. 07360 (Mexico)

    2010-03-01

    Photoacoustic (PA) technique has important applications for material characterization and nondestructive evaluation of opaque solid materials. PA microscopy allows the acquisition of information of samples with inhomogeneous structures as agricultural seeds. A determining factor for seed safe storage is their moisture content. Seeds stored at high moisture content exhibit increased respiration, heating, and fungal invasion resulting in poor seed vigor and viability. Low moisture content, in the seed to be stored, is the best prevention for these problems. In this study, Photoacoustic Microscopy (PAM) was used to characterize seeds with different moisture content. In the PAM experimental setup the photoacoustic cell and its sensor, an electret microphone, are mounted on an x-y stage of mobile axes, with spatial resolution of 70 {mu}m. The excitation light source is a fiber coupled laser diode, at 650 nm wavelength, modulated in intensity at 1 Hz of frequency, by the reference oscillator of a lock-in amplifier. By using a microscope objective the laser beam was focused on the seed surface. The resolution was enough to obtain differences in the obtained images, which are dependent on the moisture content. This method, to study differences in the seed moisture content, is nondestructive and could be useful for a sustainable Agriculture.

  15. Acoustic and photoacoustic microscopy imaging of single leukocytes

    Science.gov (United States)

    Strohm, Eric M.; Moore, Michael J.; Kolios, Michael C.

    2016-03-01

    An acoustic/photoacoustic microscope was used to create micrometer resolution images of stained cells from a blood smear. Pulse echo ultrasound images were made using a 1000 MHz transducer with 1 μm resolution. Photoacoustic images were made using a fiber coupled 532 nm laser, where energy losses through stimulated Raman scattering enabled output wavelengths from 532 nm to 620 nm. The laser was focused onto the sample using a 20x objective, and the laser spot co-aligned with the 1000 MHz transducer opposite the laser. The blood smear was stained with Wright-Giemsa, a common metachromatic dye that differentially stains the cellular components for visual identification. A neutrophil, lymphocyte and a monocyte were imaged using acoustic and photoacoustic microscopy at two different wavelengths, 532 nm and 600 nm. Unique features in each imaging modality enabled identification of the different cell types. This imaging method provides a new way of imaging stained leukocytes, with applications towards identifying and differentiating cell types, and detecting disease at the single cell level.

  16. Photoacoustic Tomography System

    Directory of Open Access Journals (Sweden)

    J. D. Martínez-Ramírez

    2012-03-01

    Full Text Available Based on the pulsed photoacoustic effect, we set up an experimental system to obtain bi-dimensional images of optically-opaque samples embedded within the bulk of turbid medium. The turbid medium was made of agar gel mixed with single-sized nanoparticles; with these materials we induce an optical absorption and an optical scattering like that appearing in human tissues. The PA signals are generated from the absorption processes in the buried target, and then traveling through the bulk of scatter medium. The optical absorption properties and the shape of target, defines the amplitude and shape of the PA signals. This time the laser pulses are set from a pulsed Nd: YAG laser, with pulse width of 10 ns, at rate repetition of 10 Hz and wavelength set at 1064 nm. The signals generated in this way are registered by means of an ultrasonic transducer with resonance cut at 10 MHz. The sample was rotated to obtain as many as 36 projections which are used to feed an image reconstruction forward-projection algorithm based on the Radon Transform. As result we obtain 2D tomographic slices of three different samples.

  17. Biomedical photoacoustics: fundamentals, instrumentation and perspectives on nanomedicine.

    Science.gov (United States)

    Zou, Chunpeng; Wu, Beibei; Dong, Yanyan; Song, Zhangwei; Zhao, Yaping; Ni, Xianwei; Yang, Yan; Liu, Zhe

    Photoacoustic imaging (PAI) is an integrated biomedical imaging modality which combines the advantages of acoustic deep penetration and optical high sensitivity. It can provide functional and structural images with satisfactory resolution and contrast which could provide abundant pathological information for disease-oriented diagnosis. Therefore, it has found vast applications so far and become a powerful tool of precision nanomedicine. However, the investigation of PAI-based imaging nanomaterials is still in its infancy. This perspective article aims to summarize the developments in photoacoustic technologies and instrumentations in the past years, and more importantly, present a bright outlook for advanced PAI-based imaging nanomaterials as well as their emerging biomedical applications in nanomedicine. Current challenges and bottleneck issues have also been discussed and elucidated in this article to bring them to the attention of the readership.

  18. Photoacoustic imaging using an 8-beam Fabry-Perot scanner

    Science.gov (United States)

    Huynh, Nam; Ogunlade, Olumide; Zhang, Edward; Cox, Ben; Beard, Paul

    2016-03-01

    The planar Fabry Perot (FP) photoacoustic scanner has been shown to provide exquisite high resolution 3D images of soft tissue structures in vivo to depths up to approximately 10mm. However a significant limitation of current embodiments of the concept is low image acquisition speed. To increase acquisition speed, a novel multi-beam scanner architecture has been developed. This enables a line of equally spaced 8 interrogation beams to be scanned simultaneously across the FP sensor and the photoacoustic signals detected in parallel. In addition, an excitation laser operating at 200Hz was used. The combination of parallelising the detection and the high pulse repetition frequency (PRF) of the excitation laser has enabled dramatic reductions in image acquisition time to be achieved. A 3D image can now be acquired in 10 seconds and 2D images at video rates are now possible.

  19. Multi-scale photoacoustic remote sensing (PARS) (Conference Presentation)

    Science.gov (United States)

    Haji Reza, Parsin; Bell, Kevan; Shi, W.; Zemp, Roger J.

    2016-03-01

    We introduce a novel multi-scale photoacoustic remote sensing (PARS) imaging system. Our system can provide optical resolution details for superficial structures as well as acoustic resolution for deep-tissue imaging down to 5 cm, in a non-contact setting. PARS system does not require any contact with the sample or ultrasound coupling medium. The optical resolution PARS (OR-OARS) system uses optically focused pulsed excitation with optical detection of photoacoustic signatures using a long-coherence interrogation beam co-focused and co-scanned with the excitation spot. In the OR-PARS initial pressures are sampled right at their subsurface origin where acoustic pressures are largest. The Acoustic resolution PARS (AR-PARS) picks up the surface oscillation of the tissue caused by generated photoacoustic signal using a modified version of Michelson interferometry. By taking advantage of 4-meters polarization maintaining single-mode fiber and a green fiber laser we have generated a multi-wavelength source using stimulated Raman scattering. Remote functional imaging using this multi-wavelength excitation source and PARS detection mechanism has been demonstrated. The oxygen saturation estimations are shown for both phantom and in vivo studies. Images of blood vessel structures for an In vivo chicken embryo model is demonstrated. The Phantom studies indicates ~3µm and ~300µm lateral resolution for OR-PARS and AR-PARS respectively. To the best of our knowledge this is the first dual modality non-contact optical and acoustic resolution system used for in vivo imaging.

  20. In vivo imaging of inducible tyrosinase gene expression with an ultrasound array-based photoacoustic system

    Science.gov (United States)

    Harrison, Tyler; Paproski, Robert J.; Zemp, Roger J.

    2012-02-01

    Tyrosinase, a key enzyme in the production of melanin, has shown promise as a reporter of genetic activity. While green fluorescent protein has been used extensively in this capacity, it is limited in its ability to provide information deep in tissue at a reasonable resolution. As melanin is a strong absorber of light, it is possible to image gene expression using tyrosinase with photoacoustic imaging technologies, resulting in excellent resolutions at multiple-centimeter depths. While our previous work has focused on creating and imaging MCF-7 cells with doxycycline-controlled tyrosinase expression, we have now established the viability of these cells in a murine model. Using an array-based photoacoustic imaging system with 5 MHz center frequency, we capture interleaved ultrasound and photoacoustic images of tyrosinase-expressing MCF-7 tumors both in a tissue mimicking phantom, and in vivo. Images of both the tyrosinase-expressing tumor and a control tumor are presented as both coregistered ultrasound-photoacoustic B-scan images and 3-dimensional photoacoustic volumes created by mechanically scanning the transducer. We find that the tyrosinase-expressing tumor is visible with a signal level 12dB greater than that of the control tumor in vivo. Phantom studies with excised tumors show that the tyrosinase-expressing tumor is visible at depths in excess of 2cm, and have suggested that our imaging system is sensitive to a transfection rate of less than 1%.

  1. Deep in vivo photoacoustic imaging of mammalian tissues using a tyrosinase-based genetic reporter

    Science.gov (United States)

    Jathoul, Amit P.; Laufer, Jan; Ogunlade, Olumide; Treeby, Bradley; Cox, Ben; Zhang, Edward; Johnson, Peter; Pizzey, Arnold R.; Philip, Brian; Marafioti, Teresa; Lythgoe, Mark F.; Pedley, R. Barbara; Pule, Martin A.; Beard, Paul

    2015-04-01

    Photoacoustic imaging allows absorption-based high-resolution spectroscopic in vivo imaging at a depth beyond that of optical microscopy. Until recently, photoacoustic imaging has largely been restricted to visualizing the vasculature through endogenous haemoglobin contrast, with most non-vascularized tissues remaining invisible unless exogenous contrast agents are administered. Genetically encodable photoacoustic contrast is attractive as it allows selective labelling of cells, permitting studies of, for example, specific genetic expression, cell growth or more complex biological behaviours in vivo. In this study we report a novel photoacoustic imaging scanner and a tyrosinase-based reporter system that causes human cell lines to synthesize the absorbing pigment eumelanin, thus providing strong photoacoustic contrast. Detailed three-dimensional images of xenografts formed of tyrosinase-expressing cells implanted in mice are obtained in vivo to depths approaching 10 mm with a spatial resolution below 100 μm. This scheme is a powerful tool for studying cellular and genetic processes in deep mammalian tissues.

  2. Applications in Photoacoustic Spectroscopy.

    Science.gov (United States)

    1979-08-01

    and Crystals I Interest in the titanium dioxide ( TiO2 ) semiconductor stems from its use in heterogeneous photocatalysis , in which light energy absorbed...well within experimental error of the predicted w-1 for solid samples with " WO<<Z and . A similar experiment was conducted with a mix - ture of p...was mixed w-th magnesium oxide, MgO, (Fischer Scientific Co.) a fine white powder with a low PA response. Eight mixtures ranged in concentration

  3. Multi-wavelength Laser Photoacoustics

    Science.gov (United States)

    2012-09-01

    phosphate ( TBP ), and two volatile organic compounds (VOCs), acetone (ACE) and isopropanol (ISO). Figure 3 shows absorbance spectra measured using the...photoacoustic PAS PA spectroscopy QC quantum-cascade TBP tributyl phosphate TEP triethyl phosphate VOCs volatile organic compounds 11 NO. OF

  4. Photoacoustic imaging of lymphatic pumping

    Science.gov (United States)

    Forbrich, Alex; Heinmiller, Andrew; Zemp, Roger J.

    2017-10-01

    The lymphatic system is responsible for fluid homeostasis and immune cell trafficking and has been implicated in several diseases, including obesity, diabetes, and cancer metastasis. Despite its importance, the lack of suitable in vivo imaging techniques has hampered our understanding of the lymphatic system. This is, in part, due to the limited contrast of lymphatic fluids and structures. Photoacoustic imaging, in combination with optically absorbing dyes or nanoparticles, has great potential for noninvasively visualizing the lymphatic vessels deep in tissues. Multispectral photoacoustic imaging is capable of separating the components; however, the slow wavelength switching speed of most laser systems is inadequate for imaging lymphatic pumping without motion artifacts being introduced into the processed images. We investigate two approaches for visualizing lymphatic processes in vivo. First, single-wavelength differential photoacoustic imaging is used to visualize lymphatic pumping in the hindlimb of a mouse in real time. Second, a fast-switching multiwavelength photoacoustic imaging system was used to assess the propulsion profile of dyes through the lymphatics in real time. These approaches may have profound impacts in noninvasively characterizing and investigating the lymphatic system.

  5. One laser pulse generates two photoacoustic signals

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin

    2016-01-01

    Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent, signal amplitude which is caused by the concurrent heat accumulation and ...

  6. A new acoustic lens material for large area detectors in photoacoustic breast tomography

    NARCIS (Netherlands)

    Xia, W.; Piras, D.; van Hespen, Johannes C.G.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Objectives We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. Background A large surface area detector due to its high

  7. Photoacoustic molecular imaging: from multiscale biomedical applications towards early-stage theranostics

    OpenAIRE

    Liu, Yajing; Nie, Liming; Chen, Xiaoyuan

    2016-01-01

    Photoacoustic imaging (PAI) has ushered in a new era of observing biotechnology and facilitated the exploration of fundamental biological mechanisms and clinical translational applications, which has attracted tremendous attention in recent years. By converting laser into ultrasound emission, PAI combines rich optical contrast, high ultrasonic spatial resolution, and deep penetration depth in a single modality. This evolutional technique enables multiscale and multicontrast visualization from...

  8. Automatic speed of sound correction with photoacoustic image reconstruction

    Science.gov (United States)

    Ye, Meng; Cao, Meng; Feng, Ting; Yuan, Jie; Cheng, Qian; Liu, XIaojun; Xu, Guan; Wang, Xueding

    2016-03-01

    Sound velocity measurement is of great importance to the application of biomedical especially in the research of acoustic detection and acoustic tomography. Using correct sound velocities in each medium other than one unified sound propagation speed, we can effectively enhance sound based imaging resolution. Photoacoustic tomography (PAT), is defined as cross-sectional or three-dimensional (3D) imaging of a material based on the photoacoustic effect and it is a developing, non-invasive imaging method in biomedical research. This contribution proposes a method to concurrently calculate multiple acoustic speeds in different mediums. Firstly, we get the size of infra-structure of the target by B-mode ultrasonic imaging method. Then we build the photoacoustic (PA) image of the same target with different acoustic speed in different medium. By repeatedly evaluate the quality of reconstruct PA image, we dynamically calibrate the acoustic speeds in different medium to build a finest PA image. Thus, we take these speeds of sound as the correct acoustic propagation velocities in according mediums. Experiments show that our non-invasive method can yield correct speed of sound with less than 0.3% error which might benefit future research in biomedical science.

  9. Precise diagnosis in different scenarios using photoacoustic and fluorescence imaging with dual-modality nanoparticles

    Science.gov (United States)

    Peng, Dong; Du, Yang; Shi, Yiwen; Mao, Duo; Jia, Xiaohua; Li, Hui; Zhu, Yukun; Wang, Kun; Tian, Jie

    2016-07-01

    Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide comprehensive in vivo physiological and pathological information. However, currently there are limited probes available that can realize both fluorescence and photoacoustic imaging, and advanced biomedical applications for applying this dual-modality imaging approach remain underexplored. In this study, we developed a dual-modality photoacoustic-fluorescence imaging nanoprobe, ICG-loaded Au@SiO2, which was uniquely designed, consisting of gold nanorod cores and indocyanine green with silica shell spacer layers to overcome fluorophore quenching. This nanoprobe was examined by both PAI and FMI for in vivo imaging on tumor and ischemia mouse models. Our results demonstrated that the nanoparticles can specifically accumulate at the tumor and ischemic areas and be detected by both imaging modalities. Moreover, this dual-modality imaging strategy exhibited superior advantages for a precise diagnosis in different scenarios. The new nanoprobe with the dual-modality imaging approach holds great potential for diagnosis and stage classification of tumor and ischemia related diseases.Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide

  10. Development and application of stable phantoms for the evaluation of photoacoustic imaging instruments.

    Science.gov (United States)

    Bohndiek, Sarah E; Bodapati, Sandhya; Van De Sompel, Dominique; Kothapalli, Sri-Rajasekhar; Gambhir, Sanjiv S

    2013-01-01

    Photoacoustic imaging combines the high contrast of optical imaging with the spatial resolution and penetration depth of ultrasound. This technique holds tremendous potential for imaging in small animals and importantly, is clinically translatable. At present, there is no accepted standard physical phantom that can be used to provide routine quality control and performance evaluation of photoacoustic imaging instruments. With the growing popularity of the technique and the advent of several commercial small animal imaging systems, it is important to develop a strategy for assessment of such instruments. Here, we developed a protocol for fabrication of physical phantoms for photoacoustic imaging from polyvinyl chloride plastisol (PVCP). Using this material, we designed and constructed a range of phantoms by tuning the optical properties of the background matrix and embedding spherical absorbing targets of the same material at different depths. We created specific designs to enable: routine quality control; the testing of robustness of photoacoustic signals as a function of background; and the evaluation of the maximum imaging depth available. Furthermore, we demonstrated that we could, for the first time, evaluate two small animal photoacoustic imaging systems with distinctly different light delivery, ultrasound imaging geometries and center frequencies, using stable physical phantoms and directly compare the results from both systems.

  11. Low-cost photoacoustic imaging systems based on laser diode and light-emitting diode excitation

    Directory of Open Access Journals (Sweden)

    Qingkai Yao

    2017-07-01

    Full Text Available Photoacoustic imaging, an emerging biomedical imaging modality, holds great promise for preclinical and clinical researches. It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission. In order to generate photoacoustic signal efficiently, bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization. As an alternative, the miniaturized semiconductor laser system has the advantages of being inexpensive, compact, and robust, which makes a significant effect on production-forming design. It is also desirable to obtain a wavelength in a wide range from visible to near-infrared spectrum for multispectral applications. Focussing on practical aspect, this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.

  12. Photoacoustic characterization of ovarian tissue

    Science.gov (United States)

    Aguirre, Andres; Gamelin, John; Guo, Puyun; Yan, Shikui; Sanders, Mary; Brewer, Molly; Zhu, Quing

    2009-02-01

    Ovarian cancer has the highest mortality of all gynecologic cancers with a five-year survival rate of only 30%. Because current imaging techniques (ultrasound, CT, MRI, PET) are not capable of detecting ovarian cancer early, most diagnoses occur in later stages (III/IV). Thus many women are not correctly diagnosed until the cancer becomes widely metastatic. On the other hand, while the majority of women with a detectable ultrasound abnormality do not harbor a cancer, they all undergo unnecessary oophorectomy. Hence, new imaging techniques that can provide functional and molecular contrasts are needed for improving the specificity of ovarian cancer detection and characterization. One such technique is photoacoustic imaging, which has great potential to reveal early tumor angiogenesis through intrinsic optical absorption contrast from hemoglobin or extrinsic contrast from conjugated agents binding to appropriate molecular receptors. To better understand the cancer disease process of ovarian tissue using photoacoustic imaging, it is necessary to first characterize the properties of normal ovarian tissue. We have imaged ex-vivo ovarian tissue using a 3D co-registered ultrasound and photoacoustic imaging system. The system is capable of volumetric imaging by means of electronic focusing. Detecting and visualizing small features from multiple viewing angles is possible without the need for any mechanical movement. The results show strong optical absorption from vasculature, especially highly vascularized corpora lutea, and low absorption from follicles. We will present correlation of photoacoustic images from animals with histology. Potential application of this technology would be the noninvasive imaging of the ovaries for screening or diagnostic purposes.

  13. Phasor representation for the nonlinear photoacoustic signal

    Science.gov (United States)

    Santosa, I. E.; Oetama, E. J.; Harren, F. J. M.

    2017-11-01

    In CO2 laser-based photoacoustic (PA) systems, N2 takes part in the generation of the PA signal. This process causes the nonlinear relation of the photoacoustic signal to the CO2 concentration. This phenomenon can be explained simply using a phasor diagram. The model leads to the determination of the lag in the PA signal due to CO2 relaxation.

  14. Photoacoustic 3D visualization of tumor angiogenesis

    NARCIS (Netherlands)

    ten Brinke, G.A.; Kolkman, R.G.M.; Slump, Cornelis H.; Steenbergen, Wiendelt; McAleavey, Stephen A.; D'hooge, Jan

    2008-01-01

    Photoacoustic imaging is used to obtain a range of three-dimensional images representing tumor neovascularization over a 10-day period after subcutaneous inoculation of pancreatic tumor cells in a rat. The images are reconstructed from data measured with a double-ring photoacoustic detector. The

  15. Photoacoustic Spectroscopy Analysis of Traditional Chinese Medicine

    Science.gov (United States)

    Chen, Lu; Zhao, Bin-xing; Xiao, Hong-tao; Tong, Rong-sheng; Gao, Chun-ming

    2013-09-01

    Chinese medicine is a historic cultural legacy of China. It has made a significant contribution to medicine and healthcare for generations. The development of Chinese herbal medicine analysis is emphasized by the Chinese pharmaceutical industry. This study has carried out the experimental analysis of ten kinds of Chinese herbal powder including Fritillaria powder, etc., based on the photoacoustic spectroscopy (PAS) method. First, a photoacoustic spectroscopy system was designed and constructed, especially a highly sensitive solid photoacoustic cell was established. Second, the experimental setup was verified through the characteristic emission spectrum of the light source, obtained by using carbon as a sample in the photoacoustic cell. Finally, as the photoacoustic spectroscopy analysis of Fritillaria, etc., was completed, the specificity of the Chinese herb medicine analysis was verified. This study shows that the PAS can provide a valid, highly sensitive analytical method for the specificity of Chinese herb medicine without preparing and damaging samples.

  16. Validating tyrosinase homologue melA as a photoacoustic reporter gene for imaging Escherichia coli

    Science.gov (United States)

    Paproski, Robert J.; Li, Yan; Barber, Quinn; Lewis, John D.; Campbell, Robert E.; Zemp, Roger

    2015-10-01

    To understand the pathogenic processes for infectious bacteria, appropriate research tools are required for replicating and characterizing infections. Fluorescence and bioluminescence imaging have primarily been used to image infections in animal models, but optical scattering in tissue significantly limits imaging depth and resolution. Photoacoustic imaging, which has improved depth-to-resolution ratio compared to conventional optical imaging, could be useful for visualizing melA-expressing bacteria since melA is a bacterial tyrosinase homologue which produces melanin. Escherichia coli-expressing melA was visibly dark in liquid culture. When melA-expressing bacteria in tubes were imaged with a VisualSonics Vevo LAZR system, the signal-to-noise ratio of a 9× dilution sample was 55, suggesting that ˜20 bacteria cells could be detected with our system. Multispectral (680, 700, 750, 800, 850, and 900 nm) analysis of the photoacoustic signal allowed unmixing of melA-expressing bacteria from blood. To compare photoacoustic reporter gene melA (using Vevo system) with luminescent and fluorescent reporter gene Nano-lantern (using Bruker Xtreme In-Vivo system), tubes of bacteria expressing melA or Nano-lantern were submerged 10 mm in 1% Intralipid, spaced between gene for visualizing bacteria, and further work incorporating photoacoustic reporters into infectious bacterial strains is warranted.

  17. Multispectral photoacoustic imaging of tumours in mice injected with an enzyme-activatable photoacoustic probe

    Science.gov (United States)

    Hirasawa, Takeshi; Iwatate, Ryu J.; Kamiya, Mako; Okawa, Shinpei; Urano, Yasuteru; Ishihara, Miya

    2017-01-01

    Photoacoustic (PA) imaging offers depth-resolved images of optical absorbers with the spatial resolution of ultrasound imaging. To enhance tumour contrast, tumour-specific probes are used as contrast agents. We synthesised a colourless PA probe that is activated in the presence of γ-glutamyltranspeptidase, a cancer-associated enzyme, to show its original colour and fluorescence. We have acquired high specificity fluorescence images of small tumours, using a fluorescent probe based on similar enzymatic reactions. Here, we developed a PA imaging technique to detect the PA probe. In PA imaging, depending on the concentration and excitation wavelength of the probe, the intensities of the probe signals may be lower than those of the background signals produced by intrinsic optical absorbers such as haemoglobin. For probe imaging in the presence of strong background signals, multispectral photoacoustic (MS-PA) imaging was evaluated. In MS-PA imaging, the spectral fitting method, which distinguishes the probe signals from background signals using reference spectra, has been widely used. To compensate for the decrease of fluence due to optical attenuation in biological tissue, we used a simplified compensation method that calculates fluence inside biological tissues by the Monte-Carlo model using published data on optical properties of biological tissues. The validity of the method was confirmed using tissue-mimicking phantoms. Finally, MS-PA imaging of a mouse subcutaneous tumour injected with the activatable probe was demonstrated. In conclusion, our MS-PA imaging technique afforded successful detection of the activated probe in the tumour, and time-increase of PA signals were successfully observed.

  18. Development of MEMS photoacoustic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Alex Lockwood; Eichenfield, Matthew S.; Griffin, Benjamin; Harvey, Heidi Alyssa; Nielson, Gregory N.; Okandan, Murat; Langlois, Eric; Resnick, Paul James; Shaw, Michael J.; Young, Ian; Givler, Richard C.; Reinke, Charles M.

    2014-01-01

    After years in the field, many materials suffer degradation, off-gassing, and chemical changes causing build-up of measurable chemical atmospheres. Stand-alone embedded chemical sensors are typically limited in specificity, require electrical lines, and/or calibration drift makes data reliability questionable. Along with size, these "Achilles' heels" have prevented incorporation of gas sensing into sealed, hazardous locations which would highly benefit from in-situ analysis. We report on development of an all-optical, mid-IR, fiber-optic based MEMS Photoacoustic Spectroscopy solution to address these limitations. Concurrent modeling and computational simulation are used to guide hardware design and implementation.

  19. Self-assembled nanomaterials for photoacoustic imaging.

    Science.gov (United States)

    Wang, Lei; Yang, Pei-Pei; Zhao, Xiao-Xiao; Wang, Hao

    2016-02-07

    In recent years, extensive endeavors have been paid to construct functional self-assembled nanomaterials for various applications such as catalysis, separation, energy and biomedicines. To date, different strategies have been developed for preparing nanomaterials with diversified structures and functionalities via fine tuning of self-assembled building blocks. In terms of biomedical applications, bioimaging technologies are urgently calling for high-efficient probes/contrast agents for high-performance bioimaging. Photoacoustic (PA) imaging is an emerging whole-body imaging modality offering high spatial resolution, deep penetration and high contrast in vivo. The self-assembled nanomaterials show high stability in vivo, specific tolerance to sterilization and prolonged half-life stability and desirable targeting properties, which is a kind of promising PA contrast agents for biomedical imaging. Herein, we focus on summarizing recent advances in smart self-assembled nanomaterials with NIR absorption as PA contrast agents for biomedical imaging. According to the preparation strategy of the contrast agents, the self-assembled nanomaterials are categorized into two groups, i.e., the ex situ and in situ self-assembled nanomaterials. The driving forces, assembly modes and regulation of PA properties of self-assembled nanomaterials and their applications for long-term imaging, enzyme activity detection and aggregation-induced retention (AIR) effect for diagnosis and therapy are emphasized. Finally, we conclude with an outlook towards future developments of self-assembled nanomaterials for PA imaging.

  20. Microvascular quantification based on contour-scanning photoacoustic microscopy

    Science.gov (United States)

    Yeh, Chenghung; Soetikno, Brian; Hu, Song; Maslov, Konstantin I.; Wang, Lihong V.

    2014-09-01

    Accurate quantification of microvasculature remains of interest in fundamental pathophysiological studies and clinical trials. Current photoacoustic microscopy can noninvasively quantify properties of the microvasculature, including vessel density and diameter, with a high spatial resolution. However, the depth range of focus (i.e., focal zone) of optical-resolution photoacoustic microscopy (OR-PAM) is often insufficient to encompass the depth variations of features of interest-such as blood vessels-due to uneven tissue surfaces. Thus, time-consuming image acquisitions at multiple different focal planes are required to maintain the region of interest in the focal zone. We have developed continuous three-dimensional motorized contour-scanning OR-PAM, which enables real-time adjustment of the focal plane to track the vessels' profile. We have experimentally demonstrated that contour scanning improves the signal-to-noise ratio of conventional OR-PAM by as much as 41% and shortens the image acquisition time by 3.2 times. Moreover, contour-scanning OR-PAM more accurately quantifies vessel density and diameter, and has been applied to studying tumors with uneven surfaces.

  1. Photoacoustic Multicomponent Analyzer for Atmospheric Compounds Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build a compact, rugged field-deployable laser photoacoustic spectrometric (LPAS) sensor for continuous, real-time measurements of multiple chemical...

  2. Titanium Powder Metallurgy Forgings.

    Science.gov (United States)

    TITANIUM ALLOYS, *FORGING), (* POWDER METALLURGY , TITANIUM ALLOYS), ENGINE COMPONENTS, INLET GUIDE VANES, JET ENGINES, RINGS, AIRFRAMES, ANCHORS(STRUCTURAL), COLD WORKING, SINTERING, MECHANICAL PROPERTIES

  3. Photoacoustic spectroscopy of β-hematin

    Science.gov (United States)

    Samson, Edward B.; Goldschmidt, Benjamin S.; Whiteside, Paul J. D.; Sudduth, Amanda S. M.; Custer, John R.; Beerntsen, Brenda

    2012-01-01

    Malaria affects over 200 million individuals annually, resulting in 800,000 fatalities. Current tests use blood smears and can only detect the disease when 0.1–1% of blood cells are infected. We are investigating the use of photoacoustic flowmetry to sense as few as one infected cell among 10 million or more normal blood cells, thus diagnosing infection before patients become symptomatic. Photoacoustic flowmetry is similar to conventional flow cytometry, except that rare cells are targeted by nanosecond laser pulses to induce ultrasonic responses. This system has been used to detect single melanoma cells in 10 ml of blood. Our objective is to apply photoacoustic flowmetry to detection of the malaria pigment hemozoin, which is a byproduct of parasite-digested hemoglobin in the blood. However, hemozoin is difficult to purify in quantities greater than a milligram, so a synthetic analog, known as β-hematin was derived from porcine haemin. The specific purpose of this study is to establish the efficacy of using β-hematin, rather than hemozoin, for photoacoustic measurements. We characterized β-hematin using UV-vis spectroscopy, TEM, and FTIR, then tested the effects of laser irradiation on the synthetic product. We finally determined its absorption spectrum using photoacoustic excitation. UV-vis spectroscopy verified that β-hematin was distinctly different from its precursor. TEM analysis confirmed its previously established nanorod shape, and comparison of the FTIR results with published spectroscopy data showed that our product had the distinctive absorbance peaks at 1661 and 1206 cm−1. Also, our research indicated that prolonged irradiation dramatically alters the physical and optical properties of the β-hematin, resulting in increased absorption at shorter wavelengths. Nevertheless, the photoacoustic absorption spectrum mimicked that generated by UV-vis spectroscopy, which confirms the accuracy of the photoacoustic method and strongly suggests that

  4. Photoacoustic spectroscopy of β-hematin

    Science.gov (United States)

    Samson, Edward B.; Goldschmidt, Benjamin S.; Whiteside, Paul J. D.; Sudduth, Amanda S. M.; Custer, John R.; Beerntsen, Brenda; Viator, John A.

    2012-06-01

    Malaria affects over 200 million individuals annually, resulting in 800 000 fatalities. Current tests use blood smears and can only detect the disease when 0.1-1% of blood cells are infected. We are investigating the use of photoacoustic flowmetry to sense as few as one infected cell among 10 million or more normal blood cells, thus diagnosing infection before patients become symptomatic. Photoacoustic flowmetry is similar to conventional flow cytometry, except that rare cells are targeted by nanosecond laser pulses to induce ultrasonic responses. This system has been used to detect single melanoma cells in 10 ml of blood. Our objective is to apply photoacoustic flowmetry to detection of the malaria pigment hemozoin, which is a byproduct of parasite-digested hemoglobin in the blood. However, hemozoin is difficult to purify in quantities greater than a milligram, so a synthetic analog, known as β-hematin was derived from porcine hemin. The specific purpose of this study is to establish the efficacy of using β-hematin, rather than hemozoin, for photoacoustic measurements. We characterized β-hematin using UV-vis spectroscopy, TEM, and FTIR, then tested the effects of laser irradiation on the synthetic product. We finally determined its absorption spectrum using photoacoustic excitation. UV-vis spectroscopy verified that β-hematin was distinctly different from its precursor. TEM analysis confirmed its previously established nanorod shape, and comparison of the FTIR results with published spectroscopy data showed that our product had the distinctive absorbance peaks at 1661 and 1206 cm-1. Also, our research indicated that prolonged irradiation dramatically alters the physical and optical properties of the β-hematin, resulting in increased absorption at shorter wavelengths. Nevertheless, the photoacoustic absorption spectrum mimicked that generated by UV-vis spectroscopy, which confirms the accuracy of the photoacoustic method and strongly suggests that

  5. Photoacoustic CO2-Sensor for Automotive Applications

    OpenAIRE

    Huber, J; C. Weber; Eberhardt, A.; Wöllenstein, J.

    2016-01-01

    We present a field-tested miniaturized spectroscopic CO2 sensor which is based on the photoacoustic effect. The sensor is developed for automotive applications and considers the requirements for the usage in vehicles. The sensor measures two measurement ranges simultaneously: The monitoring of the indoor air quality and the detection of possible leakages of the coolant in CO2 air-conditioning systems. The sensor consists of a miniaturized innovative photoacoustic sensor unit with integrated e...

  6. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Science.gov (United States)

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  7. Photoacoustic cell using elliptical acoustic focusing

    Science.gov (United States)

    Heritier, J.-M.; Fouquet, J. E.; Siegman, A. E.

    1982-01-01

    A photoacoustic cell has been developed in the form of an elliptical cylinder in which essentially all the acoustic energy generated by a laser beam passing down one axis is focused onto a cylindrical acoustic tranducer located along the other axis. Preliminary measurements on a liquid-filled cell of this design show high sensitivity and a notably clean impulse response. A similar design may be useful for photoacoustic measurements in vapors as well.

  8. Finite Element Simulation of Photoacoustic Pressure in a Resonant Photoacoustic Cell Using Lossy Boundary Conditions

    DEFF Research Database (Denmark)

    Duggen, Lars; Lopes, Natasha; Willatzen, Morten

    2011-01-01

    The finite-element method (FEM) is used to simulate the photoacoustic signal in a cylindrical resonant photoacoustic cell. Simulations include loss effects near the cell walls that appear in the boundary conditions for the inhomogeneous Helmholtz equation governing the acoustic pressure. Reasonab...

  9. Graphene Meets Microbubbles: A Superior Contrast Agent for Photoacoustic Imaging.

    Science.gov (United States)

    Toumia, Yosra; Domenici, Fabio; Orlanducci, Silvia; Mura, Francesco; Grishenkov, Dmitry; Trochet, Philippe; Lacerenza, Savino; Bordi, Federico; Paradossi, Gaio

    2016-06-29

    Coupling graphene with a soft polymer surface offers the possibility to build hybrid constructs with new electrical, optical, and mechanical properties. However, the low reactivity of graphene is a hurdle in the synthesis of such systems which is often bypassed by oxidizing its carbon planar structure. However, the defects introduced with this process jeopardize the properties of graphene. In this paper we present a different approach, applicable to many different polymer surfaces, which uses surfactant assisted ultrasonication to exfoliate, and simultaneously suspend, graphene in water in its intact form. Tethering pristine graphene sheets to the surfaces is accomplished by using suitable reactive functional groups of the surfactant scaffold. We focused on applying this approach to the fabrication of a hybrid system, made of pristine graphene tethered to poly(vinyl alcohol) based microbubbles (PVA MBs), designed for enhancing photoacoustic signals. Photoacoustic imaging (PAI) is a powerful preclinical diagnostic tool which provides real time images at a resolution of 40 μm. The leap toward clinical imaging has so far been hindered by the limited tissues penetration of near-infrared (NIR) pulsed laser radiation. Many academic and industrial research laboratories have met this challenge by designing devices, each with pros and cons, to enhance the photoacoustic (PA) signal. The major advantages of the hybrid graphene/PVA MBs construct, however, are (i) the preservation of graphene properties, (ii) biocompatibility, a consequence of the robust anchoring of pristine graphene to the bioinert surface of the PVA bubble, and (iii) a very good enhancement in a NIR spectral region of the PA signal, which does not overlap with the signals of PA active endogenous molecules such as hemoglobin.

  10. Pulsed photoacoustic Doppler flow measurements in blood-mimicking phantoms

    Science.gov (United States)

    Brunker, J.; Beard, P.

    2011-03-01

    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. For each flow measurement, a series of 100 waveform pairs was collected. Previous data processing methods involved rejection of poorly correlated waveform pairs; the modal velocity value and standard deviation were then extracted from the selected distribution of velocity measurements. However, the data selection criteria used in this approach is to some extent arbitrary. A new data analysis protocol, which involves averaging the 100 cross-correlation functions and thus uses all of the measured data, has been designed in order to prevent exclusion of outliers. This more rigorous approach has proved effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.14 to 1.25 ms-1. Experimental parameters, such as the time separation between the laser pulses and the transducer frequency response, were evaluated in terms of their effect on the accuracy, resolution and range of measurable velocities. The technique was subsequently applied to fluid phantoms flowing at rates less than 5 mms-1 along an optically transparent tube. Preliminary results are described for three different suspensions of phenolic resin microspheres, and also for whole blood. Velocity information was obtained even under non-optimal conditions using a low frequency transducer and a low pulse repetition frequency. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus

  11. High-resolution velocity measurements on fully identified light nuclides produced in {sup 56}Fe + protons and {sup 56}Fe + titanium systems

    Energy Technology Data Exchange (ETDEWEB)

    Napolitani, P. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Institut de Physique Nucleaire (IPN), 91 - Orsay (France); Schmidt, K.H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Botvina, A.S. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Yadernykh Issledovanij; Rejmund, F.; Tassan-Got, L. [Institut de Physique Nucleaire (IPN), 91 - Orsay (France); Villagrasa, C. [CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (FR). Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee (DAPNIA)

    2004-07-01

    New experimental results on the kinematics and the residue production are obtained for the interactions of {sup 56}Fe projectiles with protons and {sup nat}Ti target nuclei, respectively, at the incident energy of 1 A GeV. The titanium-induced reaction serves as a reference case for multifragmentation. Already in the proton-induced reaction, the characteristics of the isotopic cross sections and the shapes of the velocity spectra of light residues indicate that high thermal energy is deposited in the system during the collision. In the {sup 56}Fe+p system the high excitation seems to favour the onset of fast break-up decays dominated by very asymmetric partitions of the disassembling system. This configuration leads to the simultaneous formation of one or more light fragments together with one heavy residue. (orig.)

  12. High-Resolution Velocity Measurements on Fully Identified Light Nuclides Produced in 56Fe+Hydrogen and 56Fe+Titanium Systems

    CERN Document Server

    Napolitani, P; Botvina, A S; Rejmund, F; Tassan-Got, L; Villagrasa, L

    2004-01-01

    New experimental results on the kinematics and the residue production are obtained for the interactions of 56Fe projectiles with protons and natTi target nuclei, respectively, at the incident energy of 1 A GeV. The titanium-induced reaction serves as a reference case for multifragmentation. Already in the proton-induced reaction, the characteristics of the isotopic cross sections and the shapes of the velocity spectra of light residues indicate that high thermal energy is deposited in the system during the collision. In the 56Fe+p system the high excitation seems to favour the onset of fast break-up decays dominated by very asymmetric partitions of the disassembling system. This configuration leads to the simultaneous formation of one or more light fragments together with one heavy residue.

  13. In vivo demonstration of reflection artifact reduction in photoacoustic imaging using synthetic aperture photoacoustic-guided focused ultrasound (PAFUSion)

    NARCIS (Netherlands)

    Kuniyil Ajith Singh, M.; Jaeger, M.; Frenz, M.; Steenbergen, Wiendelt

    2016-01-01

    Reflection artifacts caused by acoustic inhomogeneities are a critical problem in epi-mode biomedical photoacoustic imaging. High light fluence beneath the probe results in photoacoustic transients, which propagate into the tissue and reflect back from echogenic structures. These reflection

  14. Multiplane spectroscopic whole-body photoacoustic imaging of small animals in vivo.

    Science.gov (United States)

    Jeon, Mansik; Kim, Jeesu; Kim, Chulhong

    2016-03-01

    We have successfully developed a multiscale acoustic-resolution photoacoustic tomography system in a single imaging platform. By switching between ultrasound transducers (center frequencies 5 and 40 MHz) and optical condensers, we have photoacoustically imaged microvasculatures of small animals in vivo at different scales. Further, we have extended the field of view of our imaging system to entire bodies of small animals. At different imaging planes, we have noninvasively imaged the major blood vessels (e.g., descending aorta, intercostal vessels, cephalic vessels, brachial vessels, femoral vessels, popliteal vessels, lateral marginal vessels, cranial mesenteric vessels, mammalian vessels, carotid artery, jugular vein, subclavian vessels, iliac vessels, and caudal vessels) as well as intact internal organs (e.g., spleen, liver, kidney, intestine, cecum, and spinal cord) of the animals in vivo. The spectroscopic whole-body photoacoustic imaging clearly reveals the spectral responses of the internal structures. Similar to other existing preclinical whole-body imaging systems, this whole-body photoacoustic tomography can be a useful tool for small-animal research.

  15. Design of a novel pulsed laser diode induced photoacoustic imaging system for tumor diagnosis

    Science.gov (United States)

    Ren, Zhong; Zeng, Lvming; Liu, Guodong; Huang, Zhen

    2012-03-01

    The tumors are one of most dangerous diseases in lots of diseases Expect for the actively treating of antitumor, the early detection of tumors is a key important step in the course of tumor treatment. Since some drawbacks existed in the traditional methods of tumor detection, such as ultrasound imaging, X radiography, CT imaging, OCT and MRI, etc, a novel hybrid and promising imaging method, that is, photoacoustic imaging (PAI) technology, is used to the tumors diagnosis(TD) in this work. This novel method has higher resolution, contrast and penetration depth due to the merits combination of ultrasonic with optics. And the detected photoacoustic signal not only reflects the structural characteristic of tissue but also the metabolic and pathological changes. So, the novel TD based on the PAI is proposed in this paper. Meanwhile, a novel single pulsed laser diode with 905nm wavelength is used as the light source, and a focused ultrasonic transducer with the forward-mode is used to acquire the photoacoustic signal. Finally, PA images were reconstructed with the improved filtered back projection algorithm. Experimental results show the signal acquisition time is less than 0.2 s in each scan of 128 averages. And it is proved that the photoacoustic imaging system for TD with a high-power pulsed laser diode is available. Therefore, this system has the potential value in the biomedical research fields.

  16. Phase transition of TiO{sub 2} thin films detected by the pulsed laser photoacoustic technique

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Pacheco, A.; Castaneda-Guzman, R.; Oliva Montes de Oca, C.; Esparza-Garcia, A. [Universidad Nacional Autonoma de Mexico, CCADET-UNAM, Laboratorio de Fotofisica y Peliculas Delgadas, Cd. Universitaria, A.P. 70-186, Mexico D.F. (Mexico); Perez Ruiz, S.J. [CCADET-UNAM, Acustica y Vibraciones, Mexico D.F. (Mexico)

    2011-03-15

    In this work, we present characterization of titanium oxide thin films by photoacoustic measurements to determine the ablation threshold and phase transitions from amorphous to crystalline states. The important advantages of this method are that it does not require amplification at the detection stage and that it is a non-destructive technique. The correlation analysis of the photoacoustic signals allows us to visualize the ablation threshold and the phase transitions with enhanced sensitivity. This correlation analysis clearly exhibits the changes in the thin-film morphology due to controlled variations of the fluence (energy/area) and the temperature of the surrounding medium. This is particularly important for those cases where the crystalline changes caused by temperature variations need to be monitored. The thin-film samples were prepared by the sputtering technique at room temperature in the amorphous state. The phase transformations were induced by controlled temperature scanning and then corroborated with Raman spectroscopy measurements. (orig.)

  17. Bessel-beam Grueneisen relaxation photoacoustic microscopy with extended depth of field.

    Science.gov (United States)

    Shi, Junhui; Wang, Lidai; Noordam, Cedric; Wang, Lihong V

    2015-11-01

    The short focal depth of a Gaussian beam limits the volumetric imaging speed of optical resolution photoacoustic microscopy (OR-PAM). A Bessel beam, which is diffraction free, provides a long focal depth, but its side lobes deteriorate image quality when the Bessel beam is directly employed to excite photoacoustic (PA) signals in OR-PAM. We present a nonlinear approach based on the Grueneisen relaxation effect to suppress the side-lobe artifacts in PA imaging. This method extends the focal depth of OR-PAM and speeds up volumetric imaging. We experimentally demonstrated a 1-mm focal depth with a 7-μm lateral resolution and volumetrically imaged a carbon fiber and red blood cell samples.

  18. Non-invasive imaging of epileptic seizures in vivo using photoacoustic tomography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qizhi; Carney, Paul R; Yuan Zhen; Jiang Huabei [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States); Liu Zhao [Department of Pediatrics, Division of Pediatric Neurology, University of Florida, Gainesville, FL 32610 (United States); Chen Huanxin; Roper, Steven N [Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0265 (United States)], E-mail: hjiang@bme.ufl.edu

    2008-04-07

    Non-invasive laser-induced photoacoustic tomography (PAT) is an emerging imaging modality that has the potential to image the dynamic function of the brain due to its unique ability of imaging biological tissues with high optical contrast and ultrasound resolution. Here we report the first application of our finite-element-based PAT for imaging of epileptic seizures in an animal model. In vivo photoacoustic images were obtained in rats with focal seizures induced by microinjection of bicuculline, a GABA{sub A} antagonist, into the neocortex. The seizure focus was accurately localized by PAT as confirmed with gold-standard electroencephalogram (EEG). Compared to the existing neuroimaging modalities, PAT not only has the unprecedented advantage of high spatial and temporal resolution in a single imaging modality, but also is portable and low in cost, making it possible to bring brain imaging to the bedside.

  19. Comparison of Deconvolution Filters for Photoacoustic Tomography.

    Directory of Open Access Journals (Sweden)

    Dominique Van de Sompel

    Full Text Available In this work, we compare the merits of three temporal data deconvolution methods for use in the filtered backprojection algorithm for photoacoustic tomography (PAT. We evaluate the standard Fourier division technique, the Wiener deconvolution filter, and a Tikhonov L-2 norm regularized matrix inversion method. Our experiments were carried out on subjects of various appearances, namely a pencil lead, two man-made phantoms, an in vivo subcutaneous mouse tumor model, and a perfused and excised mouse brain. All subjects were scanned using an imaging system with a rotatable hemispherical bowl, into which 128 ultrasound transducer elements were embedded in a spiral pattern. We characterized the frequency response of each deconvolution method, compared the final image quality achieved by each deconvolution technique, and evaluated each method's robustness to noise. The frequency response was quantified by measuring the accuracy with which each filter recovered the ideal flat frequency spectrum of an experimentally measured impulse response. Image quality under the various scenarios was quantified by computing noise versus resolution curves for a point source phantom, as well as the full width at half maximum (FWHM and contrast-to-noise ratio (CNR of selected image features such as dots and linear structures in additional imaging subjects. It was found that the Tikhonov filter yielded the most accurate balance of lower and higher frequency content (as measured by comparing the spectra of deconvolved impulse response signals to the ideal flat frequency spectrum, achieved a competitive image resolution and contrast-to-noise ratio, and yielded the greatest robustness to noise. While the Wiener filter achieved a similar image resolution, it tended to underrepresent the lower frequency content of the deconvolved signals, and hence of the reconstructed images after backprojection. In addition, its robustness to noise was poorer than that of the Tikhonov

  20. Ultrasound (US transducer of higher operating frequency detects photoacoustic (PA signals due to the contrast in elastic property

    Directory of Open Access Journals (Sweden)

    Mayanglambam Suheshkumar Singh

    2016-02-01

    Full Text Available We report our study that shows selection in operating frequency of US-transducer used for boundary detection of PA-signals, which result due to the contrast in elastic property distribution ( E ( r → in sample material other than that of optical absorption coefficient (μa. Studies were carried out, experimentally, in tissue-mimicking Agar phantoms employing acoustic resolution photoacoustic microscopy (AR-PAM system as an imaging unit. In the experiments, various transducers having different operating frequencies, ranging from 1MHz to 50MHz, were employed for studying frequency response of the photoacoustic signals. The study shows that, for detecting photoacoustic signals due to the contrast in elastic property, ultrasound transducer with higher operating frequency (∼50MHz is demanded.

  1. Titanium exposure and yellow nail syndrome

    Directory of Open Access Journals (Sweden)

    Ali Ataya

    2015-01-01

    Full Text Available Yellow nail syndrome is a rare disease of unclear etiology. We describe a patient who develops yellow nail syndrome, with primary nail and sinus manifestations, shortly after amalgam dental implants. A study of the patient's nail shedding showed elevated nail titanium levels. The patient had her dental implants removed and had complete resolution of her sinus symptoms with no change in her nail findings. Since the patient's nail findings did not resolve we do not believe titanium exposure is a cause of her yellow nail syndrome but perhaps a possible relationship exists between titanium exposure and yellow nail syndrome that requires further studies.

  2. Model based learning for accelerated, limited-view 3D photoacoustic tomography

    OpenAIRE

    Hauptmann, Andreas; Lucka, Felix; Betcke, Marta; Huynh, Nam; Cox, Ben; Beard, Paul; Ourselin, Sebastien; Arridge, Simon

    2017-01-01

    Recent advances in deep learning for tomographic reconstructions have shown great potential to create accurate and high quality images with a considerable speed-up. In this work we present a deep neural network that is specifically designed to provide high resolution 3D images from restricted photoacoustic measurements. The network is designed to represent an iterative scheme and incorporates gradient information of the data fit to compensate for limited view artefacts. Due to the high comple...

  3. Photoacoustic Detection of New Bands of HCN between 11 390 and 13 020 cm(-1).

    Science.gov (United States)

    Lecoutre; Rohart; Huet; Maki

    2000-09-01

    A laser photoacoustic technique has been used to measure the absorption spectrum of HCN in the region from 11 390 to 13 020 cm(-1) with a resolution that is limited by the Doppler- and pressure-broadened linewidth. This is a very sensitive technique that has allowed us to measure very weak bands with a small volume of gas. These measurements provide the rovibrational constants for a number of newly observed vibrational energy levels. Copyright 2000 Academic Press.

  4. Photoacoustic probe using a microring resonator ultrasonic sensor for endoscopic applications.

    Science.gov (United States)

    Dong, Biqin; Chen, Siyu; Zhang, Zhen; Sun, Cheng; Zhang, Hao F

    2014-08-01

    We designed an all-optical photoacoustic (PA) probe for endoscopic applications by employing an optically transparent, coverslip-type, polymeric microring resonator ultrasonic sensor. We experimentally quantified the axial, tangential, and radial resolutions and angular sensitive stability of this probe. Using this probe, we achieved volumetric imaging of several phantoms. Our all-optical probe design offers clear benefit in integrating PA endoscope with other optical endoscopic imaging modalities to facilitate the transformation from bench to bedside.

  5. Mapping tissue oxygen in vivo by photoacoustic lifetime imaging

    Science.gov (United States)

    Shao, Qi; Morgounova, Ekaterina; Choi, Jeung-Hwan; Jiang, Chunlan; Bischof, John; Ashkenazi, Shai

    2013-03-01

    Oxygen plays a key role in the energy metabolism of living organisms. Any imbalance in the oxygen levels will affect the metabolic homeostasis and lead to pathophysiological diseases. Hypoxia, a status of low tissue oxygen, is a key factor in tumor biology as it is highly prominent in tumor tissues. However, clinical tools for assessing tissue oxygenation are limited. The gold standard is polarographic needle electrode which is invasive and not capable of mapping (imaging) the oxygen content in tissue. We applied the method of photoacoustic lifetime imaging (PALI) of oxygen-sensitive dye to small animal tissue hypoxia research. PALI is new technology for direct, non-invasive imaging of oxygen. The technique is based on mapping the oxygen-dependent transient optical absorption of Methylene Blue (MB) by pump-probe photoacoustic imaging. Our studies show the feasibility of imaging of dissolved oxygen distribution in phantoms. In vivo experiments demonstrate that the hypoxia region is consistent with the site of subcutaneously xenografted prostate tumor in mice with adequate spatial resolution and penetration depth.

  6. Quartz-enhanced photo-acoustic spectroscopy for breath analyses

    Science.gov (United States)

    Petersen, Jan C.; Lamard, Laurent; Feng, Yuyang; Focant, Jeff-F.; Peremans, Andre; Lassen, Mikael

    2017-03-01

    An innovative and novel quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor for highly sensitive and selective breath gas analysis is introduced. The QEPAS sensor consists of two acoustically coupled micro- resonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF). The complete acoustically coupled mR system is optimized based on finite element simulations and experimentally verified. Due to the very low fabrication costs the QEPAS sensor presents a clear breakthrough in the field of photoacoustic spectroscopy by introducing novel disposable gas chambers in order to avoid cleaning after each test. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator (MIR OPO). Spectroscopic measurements of methane and methanol in the 3.1 μm to 3.7 μm wavelength region is conducted. Demonstrating a resolution bandwidth of 1 cm-1. An Allan deviation analysis shows that the detection limit at optimum integration time for the QEPAS sensor is 32 ppbv@190s for methane and that the background noise is solely due to the thermal noise of the QTF. Spectra of both individual molecules as well as mixtures of molecules were measured and analyzed. The molecules are representative of exhaled breath gasses that are bio-markers for medical diagnostics.

  7. Fiber-optic annular detector array for large depth of field photoacoustic macroscopy

    Directory of Open Access Journals (Sweden)

    Johannes Bauer-Marschallinger

    2017-03-01

    Full Text Available We report on a novel imaging system for large depth of field photoacoustic scanning macroscopy. Instead of commonly used piezoelectric transducers, fiber-optic based ultrasound detection is applied. The optical fibers are shaped into rings and mainly receive ultrasonic signals stemming from the ring symmetry axes. Four concentric fiber-optic rings with varying diameters are used in order to increase the image quality. Imaging artifacts, originating from the off-axis sensitivity of the rings, are reduced by coherence weighting. We discuss the working principle of the system and present experimental results on tissue mimicking phantoms. The lateral resolution is estimated to be below 200 μm at a depth of 1.5 cm and below 230 μm at a depth of 4.5 cm. The minimum detectable pressure is in the order of 3 Pa. The introduced method has the potential to provide larger imaging depths than acoustic resolution photoacoustic microscopy and an imaging resolution similar to that of photoacoustic computed tomography.

  8. 3-D photoacoustic and pulse echo imaging of prostate tumor progression in the mouse window chamber

    Science.gov (United States)

    Bauer, Daniel R.; Olafsson, Ragnar; Montilla, Leonardo G.; Witte, Russell S.

    2011-01-01

    Understanding the tumor microenvironment is critical to characterizing how cancers operate and predicting their response to treatment. We describe a novel, high-resolution coregistered photoacoustic (PA) and pulse echo (PE) ultrasound system used to image the tumor microenvironment. Compared to traditional optical systems, the platform provides complementary contrast and important depth information. Three mice are implanted with a dorsal skin flap window chamber and injected with PC-3 prostate tumor cells transfected with green fluorescent protein. The ensuing tumor invasion is mapped during three weeks or more using simultaneous PA and PE imaging at 25 MHz, combined with optical and fluorescent techniques. Pulse echo imaging provides details of tumor structure and the surrounding environment with 100-μm3 resolution. Tumor size increases dramatically with an average volumetric growth rate of 5.35 mm3∕day, correlating well with 2-D fluorescent imaging (R = 0.97, p < 0.01). Photoacoustic imaging is able to track the underlying vascular network and identify hemorrhaging, while PA spectroscopy helps classify blood vessels according to their optical absorption spectrum, suggesting variation in blood oxygen saturation. Photoacoustic and PE imaging are safe, translational modalities that provide enhanced depth resolution and complementary contrast to track the tumor microenvironment, evaluate new cancer therapies, and develop molecular contrast agents in vivo. PMID:21361696

  9. Photoacoustic imaging of mesenchymal stem cells in living mice via silica-coated gold nanorods

    Science.gov (United States)

    Jokerst, Jesse V.; Thangaraj, Mridhula; Gambhir, Sanjiv S.

    2014-03-01

    Imaging is crucial for stem cell therapy to monitor the location(s), numbers, and state of the implanted cells. Real-time imaging in particular can ensure proper cell delivery for best engraftment. However, established imaging tools such as MRI are limited by their temporal resolution for guidance during delivery. In contrast, photoacoustic imaging is ideally suited for real time, image-guided therapy. Here, we use silica-coated gold nanorods as photoacoustic contrast agents and deploy them to image and quantitate mesenchymal stem cells during implant into the muscle tissue of live mice. Silica-coated gold nanorods (SiGNRs) were created with standard methods and loaded into mesenchymal stem cells (MSCs) without transfection agents. There was no significant (pcytokines should only minor upregulation of inflammatory markers including interleukin-6. We used electron microscopy to illustrate vacuole-bound SiGNRs inside the cells. This cell staining increased photoacoustic signal 175% relative to MSCs without contrast agent—the silica coat itself increased signal 55% relative to uncoated GNRs. Using inductively coupled plasma spectroscopy, we found that there were 100,000 SiGNRs per MSC. This value was 5-fold higher than a MSC population stained with GNRs in the absence of silica coat. After labeling, cells were washed and injected into murine muscle tissue to simulate a muscular dystrophy patient. Mice (N=5) treated with these SiGNRlabeled MSCs exhibited no adverse events and implants up to 5 mm deep were easily visualized. The in vivo detection limit was 90,000 cells in a 100 uL bolus in mouse thigh muscle. Here, the B-mode signal is useful for orienting the treatment area and visualizing the delivery catheter while the photoacoustic mode offers cell-specific content. The photoacoustic signal was validated with histology a long-term fluorescent tracking dye after MSC transplant.

  10. Comparison between a supercontinuum source and a titanium sapphire laser in achieving ultrahigh resolution spectral domain optical coherence tomography (SD-OCT)

    Science.gov (United States)

    Caujolle, S.; Unterhuber, A.; Feuchter, T.; Podoleanu, A.; Werkmeister, R. M.

    2017-07-01

    Corneal B-scan images and signal-to-noise ratio measurements using ultra-high resolution Spectral Domain Optical Coherence Tomography (SD-OCT) are reported. A comparison of results is obtained using a Ti:Sa laser and a supercontinuum optical source, is performed. Beside some differences in the SNR, the images are strikingly similar.

  11. Molecular photoacoustic imaging of follicular thyroid carcinoma

    DEFF Research Database (Denmark)

    Levi, Jelena; Kothapalli, Sri-Rajashekar; Bohndiek, Sarah

    2013-01-01

    in living mice optically, observing the increase in Alexa750 fluorescence, and photoacoustically, using a dual wavelength imaging method. Results Active forms of both MMP2 and MMP-9 enzymes were found in FTC133 tumor homogenates, with MMP-9 detected in greater amounts. The molecular imaging agent......Purpose To evaluate the potential of targeted photoacoustic imaging as a non-invasive method for detection of follicular thyroid carcinoma. Experimental Design We determined the presence and activity of two members of matrix metalloproteinase family (MMP), MMP-2 and MMP-9, suggested as biomarkers...... for malignant thyroid lesions, in FTC133 thyroid tumors subcutaneously implanted in nude mice. The imaging agent used to visualize tumors was MMP activatable photoacoustic probe, Alexa750-CXeeeeXPLGLAGrrrrrXK-BHQ3. Cleavage of the MMP activatable agent was imaged after intratumoral and intravenous injections...

  12. Enhanced photoacoustic detection using photonic crystal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yunfei; Liu, Kaiyang [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); McClelland, John [Ames Laboratory-USDOE, Ames, Iowa 50011 (United States); Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States); Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011 (United States); Lu, Meng, E-mail: menglu@iastate.edu [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-04-21

    This paper demonstrates the enhanced photoacoustic sensing of surface-bound light absorbing molecules and metal nanoparticles using a one-dimensional photonic crystal (PC) substrate. The PC structure functions as an optical resonator at the wavelength where the analyte absorption is strong. The optical resonance of the PC sensor provides an intensified evanescent field with respect to the excitation light source and results in enhanced optical absorption by surface-immobilized samples. For the analysis of a light absorbing dye deposited on the PC surface, the intensity of photoacoustic signal was enhanced by more than 10-fold in comparison to an un-patterned acrylic substrate. The technique was also applied to detect gold nanorods and exhibited more than 40 times stronger photoacoustic signals. The demonstrated approach represents a potential path towards single molecule absorption spectroscopy with greater performance and inexpensive instrumentation.

  13. Original Research. Photoacoustic Microscopy in Dental Medicine

    Directory of Open Access Journals (Sweden)

    Stan Adrian Tudor

    2017-03-01

    Full Text Available Introduction: Photoacoustic microscopy, also known as optoacoustic imaging, is a comparatively new method of investigation in dental medicine, which uses a laser-generated ultrasound (short laser pulses to achieve images for interpretation. Photoacoustic microscopy can be used in a broad spectrum, from detecting tooth decay at its earliest stages to dental anatomy analysis. Material and methods: The energy emitted by the photoacoustic pulse is moderately absorbed by the target and exchanged into heat, leading to a local transitory temperature upsurge. The tension propagates and grows as ultrasonic waves, distinguished by the ultrasonic transducers which are planted apart from the tissue. The photoacoustic microscope has a tunable dye laser which passes through a condensing lens, an objective and ultimately an ultrasonic transducer attached to an acoustic lens to capture and receive information about the scanned probe from a sample moved on the X, Y dimensions. Results: The precise anatomy of layered concentric structures can be clearly observed in photoacoustic microscopy. The image value of the inner layer can be higher, indicating strong optical absorption, while the image value of the outer layer is lower, indicating weaker optical absorption. Meanwhile, the inner layer has the exact same size as the dentin structure and the outer layer has the exact same size as the enamel structure in this cross-section. Conclusions: The photoacoustic microscope (all-optical comes out to be a future and promising tool for detecting early-stage caries and lesions on the surface of the teeth, where micro-leakage occurs at the interface of tooth restoration, and also the anatomy of dental tissues.

  14. In vivo virtual intraoperative surgical photoacoustic microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seunghoon, E-mail: hsh860504@gmail.com; Kim, Sehui, E-mail: sehui0916@nate.com; Kim, Jeehyun, E-mail: jeehk@knu.ac.kr, E-mail: chulhong@postech.edu [School of Electrical Engineering and Computer Science, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lee, Changho, E-mail: ch31037@postech.edu; Jeon, Mansik, E-mail: msjeon@postech.edu [Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Kim, Chulhong, E-mail: jeehk@knu.ac.kr, E-mail: chulhong@postech.edu [Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Department of Biomedical Engineering, The State University of New York at Buffalo, Buffalo, New York 14221 (United States)

    2013-11-11

    We developed a virtual intraoperative surgical photoacoustic microscopy system by combining with a commercial surgical microscope and photoacoustic microscope (PAM). By sharing the common optical path in the microscope and PAM system, we could acquire the PAM and microscope images simultaneously. Moreover, by employing a beam projector to back-project 2D PAM images onto the microscope view plane as augmented reality, the conventional microscopic and 2D cross-sectional PAM images are concurrently mapped on the plane via an ocular lens of the microscope in real-time. Further, we guided needle insertion into phantom ex vivo and mice skins in vivo.

  15. Determination of Tequila Quality by Photoacoustic Analysis

    Science.gov (United States)

    Ruiz-Pérez, Atzin; Pérez-Castañeda, J. I.; Castañeda-Guzmán, R.; Pérez-Ruiz, S. J.

    2013-09-01

    A pulsed laser photoacoustic (PLPA) technique is proposed to distinguish original from adulterated tequila. In fact, it brings a reliable cheaper and more sensible method in adulteration detection, in comparison with traditional techniques. The method proposed is comparative and non-destructive, and it is based on a correlation analysis of photoacoustic signals, obtained by exciting tequila samples with short laser pulses (7 ns), in the UV region (355 nm). Eleven samples of tequila were analyzed. From a reference sample, all other samples were classified.

  16. Photo-Acoustic Spectroscopy with Infrared FEL

    CERN Document Server

    Yasumoto, Masato; Sei, Norihiro; Yamada, Kawakatsu

    2004-01-01

    Photo-acoustic spectroscopy (PAS) is a sensitive technique for measuring small absorptions of samples. In an ordinary PAS a pulse laser is used as a light source for inducing photo-acoustic signals. In our novel PAS an infrared FEL is used as the light source. The infrared FEL is continuously tunable in the wavelength with a high repetition rate. Thus, the PAS with the infrared FEL can be applied in various samples compared with the ordinary PAS. We will show the feasibility of the novel PAS.

  17. Titanium and titanium alloys fundamentals and applications

    CERN Document Server

    Peters, Manfred

    2003-01-01

    This handbook is an excellent reference for materials scientists and engineers needing to gain more knowledge about these engineering materials. Following introductory chapters on the fundamental materials properties of titanium, readers will find comprehensive descriptions of the development, processing and properties of modern titanium alloys. There then follows detailed discussion of the applications of titanium and its alloys in aerospace, medicine, energy and automotive technology.

  18. Photoacoustic microscopy of microvascular responses to cortical electrical stimulation

    Science.gov (United States)

    Tsytsarev, Vassiliy; Hu, Song; Yao, Junjie; Maslov, Konstantin; Barbour, Dennis L.; Wang, Lihong V.

    2011-07-01

    Advances in the functional imaging of cortical hemodynamics have greatly facilitated the understanding of neurovascular coupling. In this study, label-free optical-resolution photoacoustic microscopy (OR-PAM) was used to monitor microvascular responses to direct electrical stimulations of the mouse somatosensory cortex through a cranial opening. The responses appeared in two forms: vasoconstriction and vasodilatation. The transition between these two forms of response was observed in single vessels by varying the stimulation intensity. Marked correlation was found between the current-dependent responses of two daughter vessels bifurcating from the same parent vessel. Statistical analysis of twenty-seven vessels from three different animals further characterized the spatial-temporal features and the current dependence of the microvascular response. Our results demonstrate that OR-PAM is a valuable tool to study neurovascular coupling at the microscopic level.

  19. Photoacoustic microscopy of human teeth

    Science.gov (United States)

    Rao, Bin; Cai, Xin; Favazza, Christopher; Yao, Junjie; Li, Li; Duong, Steven; Liaw, Lih-Huei; Holtzman, Jennifer; Wilder-Smith, Petra; Wang, Lihong V.

    2011-03-01

    Photoacoustic microscopy (PAM) utilizes short laser pulses to deposit energy into light absorbers and sensitively detects the ultrasonic waves the absorbers generate in response. PAM directly renders a three-dimensional spatial distribution of sub-surface optical absorbers. Unlike other optical imaging technologies, PAM features label-free optical absorption contrast and excellent imaging depths. Standard dental imaging instruments are limited to X-ray and CCD cameras. Subsurface optical dental imaging is difficult due to the highly-scattering enamel and dentin tissue. Thus, very few imaging methods can detect dental decay or diagnose dental pulp, which is the innermost part of the tooth, containing the nerves, blood vessels, and other cells. Here, we conducted a feasibility study on imaging dental decay and dental pulp with PAM. Our results showed that PAM is sensitive to the color change associated with dental decay. Although the relative PA signal distribution may be affected by surface contours and subsurface reflections from deeper dental tissue, monitoring changes in the PA signals (at the same site) over time is necessary to identify the progress of dental decay. Our results also showed that deep-imaging, near-infrared (NIR) PAM can sensitively image blood in the dental pulp of an in vitro tooth. In conclusion, PAM is a promising tool for imaging both dental decay and dental pulp.

  20. Recent Advances in Photoacoustic Imaging for Deep-Tissue Biomedical Applications.

    Science.gov (United States)

    Wang, Sheng; Lin, Jing; Wang, Tianfu; Chen, Xiaoyuan; Huang, Peng

    2016-01-01

    Photoacoustic imaging (PAI), a novel imaging modality based on photoacoustic effect, shows great promise in biomedical applications. By converting pulsed laser excitation into ultrasonic emission, PAI combines the advantages of optical imaging and ultrasound imaging, which benefits rich contrast, high resolution and deep tissue penetration. In this paper, we introduced recent advances of contrast agents, applications, and signal enhancement strategies for PAI. The PA contrast agents were categorized by their components, mainly including inorganic and organic PA contrast agents. The applications of PAI were summarized as follows: deep tumor imaging, therapeutic responses monitoring, metabolic imaging, pH detection, enzyme detection, reactive oxygen species (ROS) detection, metal ions detection, and so on. The enhancement strategies of PA signals were highlighted. In the end, we elaborated on the challenges and provided perspectives of PAI for deep-tissue biomedical applications.

  1. Real-time monitoring of small animal cortical hemodynamics by photoacoustic tomography

    Science.gov (United States)

    Li, Changhui; Aquirre, Andres; Gamelin, John; Maurudis, Anastasios; Zhu, Quing; Wang, Lihong V.

    2010-02-01

    For the first time, the hemodynamics within the entire cerebral cortex of a mouse were studied by using photoacoustic tomography (PAT) non-invasively and in real time. The PAT system, based on a 512-element full-ring array with cylindrical focusing, received the PA signal primarily from a slice of about 2 mm thickness. This system can provide not only high resolution brain vasculature images but also hemodynamic functional images. We recorded the wash-in process of a photoacoustic contrast agent in a mouse brain in real time. Our results demonstrated that PAT is a powerful imaging modality to study real-time small animal neurofunctional activities that cause changes in hemodynamics.

  2. Raman Microspectroscopic Mapping with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) Applied to the High-Pressure Polymorph of Titanium Dioxide, TiO2-II.

    Science.gov (United States)

    Smith, Joseph P; Smith, Frank C; Ottaway, Joshua; Krull-Davatzes, Alexandra E; Simonson, Bruce M; Glass, Billy P; Booksh, Karl S

    2017-08-01

    The high-pressure, α-PbO2-structured polymorph of titanium dioxide (TiO2-II) was recently identified in micrometer-sized grains recovered from four Neoarchean spherule layers deposited between ∼2.65 and ∼2.54 billion years ago. Several lines of evidence support the interpretation that these layers represent distal impact ejecta layers. The presence of shock-induced TiO2-II provides physical evidence to further support an impact origin for these spherule layers. Detailed characterization of the distribution of TiO2-II in these grains may be useful for correlating the layers, estimating the paleodistances of the layers from their source craters, and providing insight into the formation of the TiO2-II. Here we report the investigation of TiO2-II-bearing grains from these four spherule layers using multivariate curve resolution-alternating least squares (MCR-ALS) applied to Raman microspectroscopic mapping. Raman spectra provide evidence of grains consisting primarily of rutile (TiO2) and TiO2-II, as shown by Raman bands at 174 cm-1 (TiO2-II), 426 cm-1 (TiO2-II), 443 cm-1 (rutile), and 610 cm-1 (rutile). Principal component analysis (PCA) yielded a predominantly three-phase system comprised of rutile, TiO2-II, and substrate-adhesive epoxy. Scanning electron microscopy (SEM) suggests heterogeneous grains containing polydispersed micrometer- and submicrometer-sized particles. Multivariate curve resolution-alternating least squares applied to the Raman microspectroscopic mapping yielded up to five distinct chemical components: three phases of TiO2 (rutile, TiO2-II, and anatase), quartz (SiO2), and substrate-adhesive epoxy. Spectral profiles and spatially resolved chemical maps of the pure chemical components were generated using MCR-ALS applied to the Raman microspectroscopic maps. The spatial resolution of the Raman microspectroscopic maps was enhanced in comparable, cost-effective analysis times by limiting spectral resolution and optimizing spectral

  3. GPU-accelerated two dimensional synthetic aperture focusing for photoacoustic microscopy

    Science.gov (United States)

    Liu, Siyu; Feng, Xiaohua; Gao, Fei; Jin, Haoran; Zhang, Ruochong; Luo, Yunqi; Zheng, Yuanjin

    2018-02-01

    Acoustic resolution photoacoustic microscopy (AR-PAM) generally suffers from limited depth of focus, which had been extended by synthetic aperture focusing techniques (SAFTs). However, for three dimensional AR-PAM, current one dimensional (1D) SAFT and its improved version like cross-shaped SAFT do not provide isotropic resolution in the lateral direction. The full potential of the SAFT remains to be tapped. To this end, two dimensional (2D) SAFT with fast computing architecture is proposed in this work. Explained by geometric modeling and Fourier acoustics theories, 2D-SAFT provide the narrowest post-focusing capability, thus to achieve best lateral resolution. Compared with previous 1D-SAFT techniques, the proposed 2D-SAFT improved the lateral resolution by at least 1.7 times and the signal-to-noise ratio (SNR) by about 10 dB in both simulation and experiments. Moreover, the improved 2D-SAFT algorithm is accelerated by a graphical processing unit that reduces the long period of reconstruction to only a few seconds. The proposed 2D-SAFT is demonstrated to outperform previous reported 1D SAFT in the aspects of improving the depth of focus, imaging resolution, and SNR with fast computational efficiency. This work facilitates future studies on in vivo deeper and high-resolution photoacoustic microscopy beyond several centimeters.

  4. A low-cost photoacoustic microscopy system with a laser diode excitation

    Science.gov (United States)

    Wang, Tianheng; Nandy, Sreyankar; Salehi, Hassan S.; Kumavor, Patrick D.; Zhu, Quing

    2014-01-01

    Photoacoustic microscopy (PAM) is capable of mapping microvasculature networks in biological tissue and has demonstrated great potential for biomedical applications. However, the clinical application of the PAM system is limited due to the use of bulky and expensive pulsed laser sources. In this paper, a low-cost optical-resolution PAM system with a pulsed laser diode excitation has been introduced. The lateral resolution of this PAM system was estimated to be 7 µm by imaging a carbon fiber. The phantoms made of polyethylene tubes filled with blood and a mouse ear were imaged to demonstrate the feasibility of this PAM system for imaging biological tissues. PMID:25401019

  5. Invasive and transcranial photoacoustic imaging of the vascular response to brain electrical stimulation

    Science.gov (United States)

    Tsytsarev, Vassiliy; Yao, Junjie; Hu, Song; Li, Li; Favazza, Christopher P.; Maslov, Konstantin I.; Wang, Lihong V.

    2010-02-01

    Advances in the brain functional imaging greatly facilitated the understanding of neurovascular coupling. For monitoring of the microvascular response to the brain electrical stimulation in vivo we used optical-resolution photoacoustic microscopy (OR-PAM) through the cranial openings as well as transcranially. Both types of the vascular response, vasoconstriction and vasodilatation, were clearly observed with good spatial and temporal resolution. Obtained results confirm one of the primary points of the neurovascular coupling theory that blood vessels could present vasoconstriction or vasodilatation in response to electrical stimulation, depending on the balance between inhibition and excitation of the different parts of the elements of the neurovascular coupling system.

  6. Multiple passive element enriched photoacoustic computed tomography

    NARCIS (Netherlands)

    Resink, Steffen; Jose, J.; Willemink, Rene; Slump, Cornelis H.; Steenbergen, Wiendelt; van Leeuwen, Ton; Manohar, Srirang

    2011-01-01

    Recently, we presented a method using laser-induced ultrasound from an external absorber (passive element) to image the ultrasound transmission parameters of an object under photoacoustic tomographic investigation. The method suffers from long measurement times due to the requirement for a large

  7. Photo-electon paramagnetic resonance and photoacoustic

    Indian Academy of Sciences (India)

    The former appears less probable in view of the relatively slower recovery of. EPR signal. Keywords. Electron paramagnetic resonance; photoacoustic spectroscopy; polyvinyl alcohol. PACS Nos 76.30; 62.65; 61.40. 1. Introduction. Development of materials for holography and non-linear optics, that respond in real time.

  8. Photoacoustic measurement of lutein in biological matrix

    NARCIS (Netherlands)

    Bicanic, D.D.; Luterotti, S.; Becucci, M.; Fogliano, V.; Versloot, P.

    2005-01-01

    Photoacoustic (PA) spectroscopy was applied for the first time to quantify lutein in a complex biological matrix. Standard addition of lutein to a biological low-lutein matrix was used for the calibration. The PA signal was found linearly proportional (R > 0.98) to lutein concentration up to 0.3%

  9. Photoacoustic Imaging of Port-Wine Stains

    NARCIS (Netherlands)

    Kolkman, R.G.M.; Mulder, M.J.; Mulder, Miranda J.; Glade, Conrad P.; Steenbergen, Wiendelt; van Leeuwen, Ton

    2008-01-01

    Background and Objective: To optimize laser therapy of port-wine stains (PWSs), information about the vasculature as well as lesion depth is valuable. In this study we investigated the use of photoacoustic imaging (PAI) to obtain this information. - Study Design/Materials and Methods: PAI uses

  10. Titanium and titanium alloys: fundamentals and applications

    National Research Council Canada - National Science Library

    Leyens, C; Peters, M

    2003-01-01

    ... number of titanium alloys have paved the way for light metals to vastly expand into many industrial applications. Titanium and its alloys stand out primarily due to their high specific strength and excellent corrosion resistance, at just half the weight of steels and Ni-based superalloys. This explains their early success in the aerospace and the...

  11. Cytotoxicity of titanium and titanium alloying elements.

    Science.gov (United States)

    Li, Y; Wong, C; Xiong, J; Hodgson, P; Wen, C

    2010-05-01

    It is commonly accepted that titanium and the titanium alloying elements of tantalum, niobium, zirconium, molybdenum, tin, and silicon are biocompatible. However, our research in the development of new titanium alloys for biomedical applications indicated that some titanium alloys containing molybdenum, niobium, and silicon produced by powder metallurgy show a certain degree of cytotoxicity. We hypothesized that the cytotoxicity is linked to the ion release from the metals. To prove this hypothesis, we assessed the cytotoxicity of titanium and titanium alloying elements in both forms of powder and bulk, using osteoblast-like SaOS(2) cells. Results indicated that the metal powders of titanium, niobium, molybdenum, and silicon are cytotoxic, and the bulk metals of silicon and molybdenum also showed cytotoxicity. Meanwhile, we established that the safe ion concentrations (below which the ion concentration is non-toxic) are 8.5, 15.5, 172.0, and 37,000.0 microg/L for molybdenum, titanium, niobium, and silicon, respectively.

  12. Photoacoustic Doppler flow measurement in optically scattering media

    OpenAIRE

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-01-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microc...

  13. A Portable Laser Photoacoustic Methane Sensor Based on FPGA

    Directory of Open Access Journals (Sweden)

    Jianwei Wang

    2016-09-01

    Full Text Available A portable laser photoacoustic sensor for methane (CH4 detection based on a field-programmable gate array (FPGA is reported. A tunable distributed feedback (DFB diode laser in the 1654 nm wavelength range is used as an excitation source. The photoacoustic signal processing was implemented by a FPGA device. A small resonant photoacoustic cell is designed. The minimum detection limit (1σ of 10 ppm for methane is demonstrated.

  14. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  15. Fluence compensated photoacoustic tomography in small animals (Conference Presentation)

    Science.gov (United States)

    Hussain, Altaf; Pool, Martin; Daoudi, Khalid; de Vries, Liesbeth G.; Steenbergen, Wiendelt

    2017-03-01

    Light fluence inside turbid media can be experimentally mapped by measuring ultrasonically modulated light (Acousto-optics). To demonstrate the feasibility of fluence corrected Photoacoustic (PA) imaging, we have realized a tri-modality (i.e. photoacoustic, acousto-optic and ultrasound) tomographic small animal imaging system. Wherein PA imaging provides high resolution map of absorbed optical energy density, Acousto-optics yields the fluence distribution map in the corresponding PA imaging plane and Ultrasound provides morphological information. Further, normalization of the PA image with the acousto-optically measured fluence map results in an image that directly represents the optical absorption. Human epidermal growth factor receptor 2 (HER2) is commonly found overexpressed in human cancers, among which breast cancers, resulting in a more aggressive tumor phenotype. Identification of HER2-expression is clinically relevant, because cancers overexpressing this marker are amenable to HER2-directed therapies, among which antibodies trastuzumab and pertuzumab. Here, we investigate the feasibility and advantage of acousto-optically assisted fluence compensated PA imaging over PA imaging alone in visualizing and quantifying HER2 expression. For this experiment, nude mice were xenografted with human breast cancer cell lines SKBR3 and BT474 (both HER2 overexpressing), as well as HER2-negative MDA-MB-231. To visualize HER2 expression in these mice, HER2 monoclonal antibody pertuzumab (Perjeta®, Roche), was conjugated to near-infrared dye IRDye 800CW (800CW, LICOR Biosciences) at a ratio of 1∶2 antibody to 800CW. When xenograft tumors measured ≥ 100 mm3, mice received 100 µg 800CW-pertuzumab intravenously. Three days post injection, mice were scanned for fluorescence signal with an IVIS scanner. After fluorescence scans, mice were euthanized and imaged in our PA tomographic imaging system.

  16. Development of tyrosinase-based reporter genes for preclinical photoacoustic imaging of mesenchymal stem cells

    Science.gov (United States)

    Märk, Julia; Ruschke, Karen; Dortay, Hakan; Schreiber, Isabelle; Sass, Andrea; Qazi, Taimoor; Pumberger, Matthias; Laufer, Jan

    2014-03-01

    The capability to image stem cells in vivo in small animal models over extended periods of time is important to furthering our understanding of the processes involved in tissue regeneration. Photoacoustic imaging is suited to this application as it can provide high resolution (tens of microns) absorption-based images of superficial tissues (cm depths). However, stem cells are rare, highly migratory, and can divide into more specialised cells. Genetic labelling strategies are therefore advantageous for their visualisation. In this study, methods for the transfection and viral transduction of mesenchymal stem cells with reporter genes for the co-expression of tyrosinase and a fluorescent protein (mCherry). Initial photoacoustic imaging experiments of tyrosinase expressing cells in small animal models of tissue regeneration were also conducted. Lentiviral transduction methods were shown to result in stable expression of tyrosinase and mCherry in mesenchymal stem cells. The results suggest that photoacoustic imaging using reporter genes is suitable for the study of stem cell driven tissue regeneration in small animals.

  17. Tunable Semiconducting Polymer Nanoparticles with INDT-Based Conjugated Polymers for Photoacoustic Molecular Imaging.

    Science.gov (United States)

    Stahl, Thomas; Bofinger, Robin; Lam, Ivan; Fallon, Kealan J; Johnson, Peter; Ogunlade, Olumide; Vassileva, Vessela; Pedley, R Barbara; Beard, Paul C; Hailes, Helen C; Bronstein, Hugo; Tabor, Alethea B

    2017-06-21

    Photoacoustic imaging combines both excellent spatial resolution with high contrast and specificity, without the need for patients to be exposed to ionizing radiation. This makes it ideal for the study of physiological changes occurring during tumorigenesis and cardiovascular disease. In order to fully exploit the potential of this technique, new exogenous contrast agents with strong absorbance in the near-infrared range, good stability and biocompatibility, are required. In this paper, we report the formulation and characterization of a novel series of endogenous contrast agents for photoacoustic imaging in vivo. These contrast agents are based on a recently reported series of indigoid π-conjugated organic semiconductors, coformulated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, to give semiconducting polymer nanoparticles of about 150 nm diameter. These nanoparticles exhibited excellent absorption in the near-infrared region, with good photoacoustic signal generation efficiencies, high photostability, and extinction coefficients of up to three times higher than those previously reported. The absorption maximum is conveniently located in the spectral region of low absorption of chromophores within human tissue. Using the most promising semiconducting polymer nanoparticle, we have demonstrated wavelength-dependent differential contrast between vasculature and the nanoparticles, which can be used to unambiguously discriminate the presence of the contrast agent in vivo.

  18. Hybrid Photoacoustic/Ultrasound Tomograph for Real-Time Finger Imaging.

    Science.gov (United States)

    Oeri, Milan; Bost, Wolfgang; Sénégond, Nicolas; Tretbar, Steffen; Fournelle, Marc

    2017-10-01

    We report a target-enclosing, hybrid tomograph with a total of 768 elements based on capacitive micromachined ultrasound transducer technology and providing fast, high-resolution 2-D/3-D photoacoustic and ultrasound tomography tailored to finger imaging. A freely programmable ultrasound beamforming platform sampling data at 80 MHz was developed to realize plane wave transmission under multiple angles. A multiplexing unit enables the connection and control of a large number of elements. Fast image reconstruction is provided by GPU processing. The tomograph is composed of four independent and fully automated movable arc-shaped transducers, allowing imaging of all three finger joints. The system benefits from photoacoustics, yielding high optical contrast and enabling visualization of finger vascularization, and ultrasound provides morphologic information on joints and surrounding tissue. A diode-pumped, Q-switched Nd:YAG laser and an optical parametric oscillator are used to broaden the spectrum of emitted wavelengths to provide multispectral imaging. Custom-made optical fiber bundles enable illumination of the region of interest in the plane of acoustic detection. Precision in positioning of the probe in motion is ensured by use of a motor-driven guide slide. The current position of the probe is encoded by the stage and used to relate ultrasound and photoacoustic signals to the corresponding region of interest of the suspicious finger joint. The system is characterized in phantoms and a healthy human finger in vivo. The results obtained promise to provide new opportunities in finger diagnostics and establish photoacoustic/ultrasound-tomography in medical routine. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  19. Electrowinning molten titanium from titanium dioxide

    CSIR Research Space (South Africa)

    Van Vuuren, DS

    2005-10-01

    Full Text Available the Manufacturing and Materials Industry in it quest for global competitiveness CSIR Manufacturing and Materials Technology 4 Rationale - Advantages • Feed: Safe, transportable, alternative supplies (sulphate and chloride routes), decoupled from TiCl4... and Materials Industry in its quest for global competitivenessorting the Manufacturing and Materials Industry in it quest for global competitiveness CSIR Manufacturing and Materials Technology 1 Electrowinning Molten Titanium from Titanium Dioxide DS van...

  20. Photoacoustic and Photothermal Effects in Particulate Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, Gerald, J.

    2009-04-30

    A summary of the research areas investigated by the author during the grant period is given. Experiments and theory have been carried out on the photoacoustic effect arising from a number of physical and chemical processes. A number of studies of the photoacoustic effect as it occurs in transient grating experiments have been completed. The research done with the Ludwig-Soret effect on the generation of shock waves is reported. Other research, such as that carried out on interferometric and beam deflection microphones, the use of microphones in vacuum as momentum flux detectors, and chemical generation of sonoluminescence is listed. A list of published research including selected publications, a complete list of journal articles, books, review articles, and reviews are given.

  1. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    Science.gov (United States)

    Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2014-01-01

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis. PMID:24686729

  2. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    Directory of Open Access Journals (Sweden)

    Pietro Patimisco

    2014-03-01

    Full Text Available A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

  3. Quartz-enhanced photoacoustic spectroscopy: a review.

    Science.gov (United States)

    Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K; Spagnolo, Vincenzo

    2014-03-28

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

  4. Photoacoustic imaging platforms for multimodal imaging

    Directory of Open Access Journals (Sweden)

    Jeesu Kim

    2015-04-01

    Full Text Available Photoacoustic (PA imaging is a hybrid biomedical imaging method that exploits both acoustical Epub ahead of print and optical properties and can provide both functional and structural information. Therefore, PA imaging can complement other imaging methods, such as ultrasound imaging, fluorescence imaging, optical coherence tomography, and multi-photon microscopy. This article reviews techniques that integrate PA with the above imaging methods and describes their applications.

  5. Tutorial on Photoacoustic Microscopy and Computed Tomography

    OpenAIRE

    Wang, Lihong V.

    2008-01-01

    The field of photoacoustic tomography has experienced considerable growth in the past few years. Although several commercially available pure optical imaging modalities, including confocal microscopy, two-photon microscopy, and optical coherence tomography, have been highly successful, none of these technologies can provide penetration beyond ~1 mm into scattering biological tissues, because they are based on ballistic and quasi-ballistic photons. Heretofore, there has been a void in high-res...

  6. Photoacoustic microscopy of blood pulse wave

    OpenAIRE

    Yeh, Chenghung; Hu, Song; Maslov, Konstantin; Wang, Lihong V.

    2012-01-01

    Blood pulse wave velocity (PWV) is an important physiological parameter that characterizes vascular stiffness. In this letter, we present electrocardiogram-synchronized, photoacoustic microscopy for noninvasive quantification of the PWV in the peripheral vessels of living mice. Interestingly, blood pulse wave-induced fluctuations in blood flow speed were clearly observed in arteries and arterioles, but not in veins or venules. Simultaneously recorded electrocardiograms served as references to...

  7. Spatial interference encoding patterns based photoacoustic microscopy

    Science.gov (United States)

    Meiri, Amihai; Strohm, Eric M.; Kolios, Michael C.; Zalevsky, Zeev

    2017-10-01

    Single sensor (pixel) signals require scanning of the sample in order to obtain spatial information. In this paper we show that using interference, optically induced signals can be reconstructed when recorded using interference pattern excitation, rather than a point illumination. This method reduces the need for dense scanning and requires a small number of scans, or can eliminate the need for scanning in some cases. It is shown that this method can be used in particular in 2D photo-acoustic imaging.

  8. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    OpenAIRE

    Pietro Patimisco; Gaetano Scamarcio; Tittel, Frank K.; Vincenzo Spagnolo

    2014-01-01

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimen...

  9. Concomitant speed-of-sound tomography in photoacoustic imaging

    NARCIS (Netherlands)

    Manohar, Srirang; Willemink, Rene; van der Heijden, Ferdinand; Slump, Cornelis H.; van Leeuwen, Ton

    2007-01-01

    We present a method to generate quantitative cross-sectional maps of acoustic propagation speed in tissue using the photoacoustic principle. The method is based on the interaction of laser-induced ultrasound from an extraneous absorber with the object under photoacoustic investigation. The

  10. Phase transition in L-alaninium oxalate by photoacoustics

    Indian Academy of Sciences (India)

    Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at 378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is not very sharp. This is discussed in detail with reference to the other ...

  11. Near infrared photoacoustic detection of heptane in synthetic air

    DEFF Research Database (Denmark)

    Duggen, Lars; Albu, Mihaela; Willatzen, Morten

    2013-01-01

    Trace contaminations of n-heptane in synthetic air is measured in the parts-per-billion (ppb) range using near infrared photoacoustic detection. We describe the fundamental theory used in the design of the photoacoustic cell for trace gas analysis and determine the detection limit of the cell. On...

  12. Near Infrared Photoacoustic Detection of Heptane in Synthetic Air

    DEFF Research Database (Denmark)

    Duggen, Lars; Albu, Mihaela; Willatzen, Morten

    2013-01-01

    Trace contaminations of n-heptane in synthetic air is measured in the parts-per-billion (ppb) range using near infrared photoacoustic detection. We describe the fundamental theory used in the design of the photoacoustic cell for trace gas analysis and determine the detection limit of the cell. On...

  13. Photoacoustic measurement of the Gruneisen parameter using an integrating sphere

    NARCIS (Netherlands)

    Villanueva, Y.Y.; Hondebrink, Erwin; Petersen, Wilhelmina; Steenbergen, Wiendelt

    2014-01-01

    A method that uses an integrating sphere as a platform for photoacoustic measurement of the Grüneisen parameter Γ of absorbing liquids is developed. Derivation of a simple equation for determining Γ is presented. This equation only requires the voltage peak-to-peak value of the photoacoustic signal

  14. Acoustic and photoacoustic characterization of micron-sized perfluorocarbon emulsions.

    Science.gov (United States)

    Strohm, Eric M; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C

    2012-09-01

    Perfluorocarbon droplets containing nanoparticles (NPs) have recently been investigated as theranostic and dual-mode contrast agents. These droplets can be vaporized via laser irradiation or used as photoacoustic contrast agents below the vaporization threshold. This study investigates the photoacoustic mechanism of NP-loaded droplets using photoacoustic frequencies between 100 and 1000 MHz, where distinct spectral features are observed that are related to the droplet composition. The measured photoacoustic spectrum from NP-loaded perfluorocarbon droplets was compared to a theoretical model that assumes a homogenous liquid. Good agreement in the location of the spectral features was observed, which suggests the NPs act primarily as optical absorbers to induce thermal expansion of the droplet as a single homogenous object. The NP size and composition do not affect the photoacoustic spectrum; therefore, the photoacoustic signal can be maximized by optimizing the NP optical absorbing properties. To confirm the theoretical parameters in the model, photoacoustic, ultrasonic, and optical methods were used to estimate the droplet diameter. Photoacoustic and ultrasonic methods agreed to within 1.4%, while the optical measurement was 8.5% higher; this difference decreased with increasing droplet size. The small discrepancy may be attributed to the difficulty in observing the small droplets through the partially translucent phantom.

  15. New approaches in quartz-enhanced photoacoustic sensing

    Science.gov (United States)

    Sampaolo, Angelo; Patimisco, Pietro; Pennetta, Riccardo; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2015-01-01

    We report on the design and realization of custom quartz tuning forks with different geometries and sizes aimed to improve the photoacoustic effect in quartz-enhanced photoacoustic (QEPAS) sensor systems. A detailed analysis of the piezoelectric properties in terms of resonance frequencies, quality factors, gas damping was performed.

  16. Effect of whitening toothpaste on titanium and titanium alloy surfaces

    National Research Council Canada - National Science Library

    Faria, Adriana Cláudia Lapria; Bordin, Angelo Rafael de Vito; Pedrazzi, Vinícius; Rodrigues, Renata Cristina Silveira; Ribeiro, Ricardo Faria

    2012-01-01

    .... Whitening toothpastes with peroxides are available for patients with high aesthetic requirements, but the effect of whitening toothpastes on titanium surfaces is not yet known, although titanium...

  17. Imagining the future of photoacoustic mammography.

    Science.gov (United States)

    van der Burg, Simone

    2009-03-01

    How can a realistic ethical imagination about the future of a technology take shape? This article contains a reflection which is based on the experiences of an embedded ethicist in the context of biophysical research conducive to the development of photoacoustic mammography, which is intended for the non-invasive detection of breast cancer. Imagination in this context already informs the activities of the biophysical researchers, but its role is limited: biophysical future scenarios concentrate on the technological advances that photoacoustics could bring about. In this article it is argued that it is advisable to also consider the medical practice and the ways in which this practice is likely to change as an effect of the introduction of photoacoustic mammography into it. On the basis of this more encompassing imaginative endeavor it is possible to get a clearer idea about how new technologies are able to contribute to human well being, which is informative for the setting of research-goals/priorities and a responsible implementation of new technologies into the world.

  18. Dispersion of light and heavy pollutants in urban scale models: CO(2) laser photoacoustic studies.

    Science.gov (United States)

    Zelinger, Z; Strizík, M; Kubát, P; Civis, S; Grigorová, E; Janecková, R; Zavila, O; Nevrlý, V; Herecová, L; Bailleux, S; Horká, V; Ferus, M; Skrínský, J; Kozubková, M; Drábková, S; Janour, Z

    2009-04-01

    The distribution of pollutants in two urban scale models (point emission source and street canyon with extensive transport) was investigated by means of CO(2) laser photoacoustic spectroscopy in the region of the atmospheric window (9-10 mum). The experimental results of physical modeling are in a good agreement with the numerical calculations performed in the frame of computational fluid dynamic (CFD) modeling. Methanol, ethanol, and ozone (examples of light pollutants), as well as sulfur hexafluoride and 1,2 dichlorethane (examples of heavy pollutants), were selected on the basis of their high resolution spectra acquired by Fourier transform and laser diode spectroscopy.

  19. Photoacoustic reflection artifact reduction using photoacoustic-guided focused ultrasound: comparison between plane-wave and element-by-element synthetic backpropagation approach

    NARCIS (Netherlands)

    Kuniyil Ajith Singh, M.; Jaeger, M.; Frenz, M.; Steenbergen, Wiendelt

    2017-01-01

    Reflection artifacts caused by acoustic inhomogeneities constitute a major problem in epi-mode biomedical photoacoustic imaging. Photoacoustic transients from the skin and superficial optical absorbers traverse into the tissue and reflect off echogenic structures to generate reflection artifacts.

  20. Sealing glasses for titanium and titanium alloys

    Science.gov (United States)

    Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

    1997-01-01

    Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

  1. Photoacoustic-guided focused ultrasound for accurate visualization of brachytherapy seeds with the photoacoustic needle

    NARCIS (Netherlands)

    Kuniyil Ajith Singh, M.; Parameshwarappa, Vinay; Hendriksen, E.; Steenbergen, Wiendelt; Manohar, Srirang

    2016-01-01

    An important problem in minimally invasive photoacoustic (PA) imaging of brachytherapy seeds is reflection artifacts caused by the high signal from the optical fiber/needle tip reflecting off the seed. The presence of these artifacts confounds interpretation of images. In this letter, we demonstrate

  2. Development of a photoacoustic handheld probe using 2-axis MEMS scanner

    Science.gov (United States)

    Park, Kyungjin; Kim, Jin Young; Lee, Changho; Lim, Geunbae; Kim, Chulhong

    2017-03-01

    Optical resolution photoacoustic tomography (OR-PAM) is a non-invasive imaging method that uses endogenous contrast agents in the body, such as hemoglobin in the blood. OR-PAM has a resolution equivalent to a microscope, and has high optical contrast. OR-PAM has been made to expand the application to the medical field by increasing the speed of imaging and minimizing the size of the system. In this research, we accomplished these two specifications by using MEMS technology to integrate a fast scan functionality into a handheld probe. Using MEMS technology, beam guides, ultrasound guidance, and mechanical scanning subsystems were integrated into a single small probe. The measured lateral resolution is 16 μm, and the measured B-scan and volume imaging rate are 35 and 0.2 Hz to obtain a photoacoustic (PA) image with 200 and 700 pixels. We imaged a variety of phantom and in vivo samples such as carbon fibers, mouse ears, eyes, and brains.

  3. Simulation of photoacoustic tomography (PAT) system in COMSOL and comparison of two popular reconstruction techniques

    Science.gov (United States)

    Sowmiya, C.; Thittai, Arun K.

    2017-03-01

    Photoacoustic imaging is a molecular cum functional imaging modality based on differential optical absorption of the incident laser pulse by the endogeneous tissue chromophores. Several numerical simulations and finite element models have been developed in the past to describe and study Photoacoustic (PA) signal generation principles and study the effect of variation in PA parameters. Most of these simulation work concentrate on analyzing extracted 1D PA signals and each of them mostly describe only few of the building blocks of a Photoacoustic Tomography (PAT) imaging system. Papers describing simulation of the entire PAT system in one simulation platform, along with reconstruction is seemingly rare. This study attempts to describe how a commercially available Finite Element software (COMSOL(R)), can serve as a single platform for simulating PAT that couples the electromagnetic, thermodynamic and acoustic pressure physics involved in PA phenomena. Further, an array of detector elements placed at the boundary in the FE model can provide acoustic pressure data that can be exported to Matlab(R) to perform tomographic image reconstruction. The performance of two most commonly used image reconstruction techniques; namely, Filtered Backprojection (FBP) and Synthetic Aperture (SA) beamforming are compared. Results obtained showed that the lateral resolution obtained using FBP vs. SA largely depends on the aperture parameters. FBP reconstruction was able to provide a slightly better lateral resolution for smaller aperture while SA worked better for larger aperture. This interesting effect is currently being investigated further. Computationally FBP was faster, but it had artifacts along the spherical shell on which the data is projected.

  4. Biological tissue component evaluation by measuring photoacoustic spectrum

    Science.gov (United States)

    Namita, Takeshi; Murata, Yuya; Tokuyama, Junji; Kondo, Kengo; Yamakawa, Makoto; Shiina, Tsuyoshi

    2017-03-01

    Photoacoustic imaging has garnered constant attention as a non-invasive modality for visualizing details of the neovascularization structure of tumors, or the distribution of oxygen saturation, which is related to the tumor grade. However, photoacoustic imaging is applicable not only for vascular imaging but also for diagnosing properties of various tissues such as skin or muscle diseases, fat related to arteriosclerosis or fatty liver, cartilage related to arthritis, and fibrous tissues related to hepatitis. The photoacoustic signal intensity is wavelength-dependent and proportional to the absorption coefficient and thermal acoustic conversion efficiency (i.e. Grüneisen parameter) of the target biological tissue. To ascertain the appropriate wavelength range for biological tissue imaging and to evaluate tissue properties, photoacoustic spectra of various tissues (e.g., skin, muscle, and adipose tissue) were measured using a hydrophone (9 mm diameter) at 680-1600 nm wavelengths. Results confirmed that respective tissues have unique photoacoustic spectra. However, almost all samples have peaks around 1200 nm and 1400-1500 nm for wavelengths where the light absorbance of lipid or water is high. The main components of biological tissues are water, protein, and lipid. Results confirmed that photoacoustic spectra reflect the tissue components well. To evaluate the feasibility of the tissue characterization using photoacoustic methods, the photoacoustic signal intensity ratio between two wavelength regions was calculated as described above. Signal intensity ratios agreed well with the composition ratio between water and lipid in samples. These analyses verified the feasibility of evaluating tissue properties using photoacoustic methods.

  5. All-optical scanhead for ultrasound and photoacoustic imaging-Imaging mode switching by dichroic filtering.

    Science.gov (United States)

    Hsieh, Bao-Yu; Chen, Sung-Liang; Ling, Tao; Guo, L Jay; Li, Pai-Chi

    2014-03-01

    Ultrasound (US) and photoacoustic (PA) multimodality imaging has the advantage of combining good acoustic resolution with high optical contrast. The use of an all-optical scanhead for both imaging modalities can simplify integration of the two systems and miniaturize the imaging scanhead. Herein we propose and demonstrate an all-optical US/PA scanhead using a thin plate for optoacoustic generation in US imaging, a polymer microring resonator for acoustic detection, and a dichroic filter to switch between the two imaging modes by changing the laser wavelength. A synthetic-aperture focusing technique is used to improve the resolution and contrast. Phantom images demonstrate the feasibility of this design, and show that axial and lateral resolutions of 125 μm and 2.52°, respectively, are possible.

  6. Blood pulse wave velocity measured by photoacoustic microscopy

    Science.gov (United States)

    Yeh, Chenghung; Hu, Song; Maslov, Konstantin; Wang, Lihong V.

    2013-03-01

    Blood pulse wave velocity (PWV) is an important indicator for vascular stiffness. In this letter, we present electrocardiogram-synchronized photoacoustic microscopy for in vivo noninvasive quantification of the PWV in the peripheral vessels of mice. Interestingly, strong correlation between blood flow speed and ECG were clearly observed in arteries but not in veins. PWV is measured by the pulse travel time and the distance between two spot of a chose vessel, where simultaneously recorded electrocardiograms served as references. Statistical analysis shows a linear correlation between the PWV and the vessel diameter, which agrees with known physiology. Keywords: photoacoustic microscopy, photoacoustic spectroscopy, bilirubin, scattering medium.

  7. Photoacoustic Soot Spectrometer (PASS) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, M [Los Alamos National Laboratory; Springston, S [Brookhaven National Laboratory; Koontz, A [Pacific Northwest National Laboratory; Aiken, A [Los Alamos National Laboratory

    2013-01-17

    The photoacoustic soot spectrometer (PASS) measures light absorption by aerosol particles. As the particles pass through a laser beam, the absorbed energy heats the particles and in turn the surrounding air, which sets off a pressure wave that can be detected by a microphone. The PASS instruments deployed by ARM can also simultaneously measure the scattered laser light at three wavelengths and therefore provide a direct measure of the single-scattering albedo. The Operator Manual for the PASS-3100 is included here with the permission of Droplet Measurement Technologies, the instrument’s manufacturer.

  8. Synthesis, Characterization, and Biomedical Applications of a Targeted Dual-Modal Near-Infrared-II Fluorescence and Photoacoustic Imaging Nanoprobe.

    Science.gov (United States)

    Cheng, Kai; Chen, Hao; Jenkins, Cesare H; Zhang, Guanglei; Zhao, Wei; Zhang, Zhe; Han, Fei; Fung, Jonathan; Yang, Meng; Jiang, Yuxin; Xing, Lei; Cheng, Zhen

    2017-12-26

    Our development of multifunctional dual-modal imaging probes aims to integrate the benefits from both second near-infrared (NIR-II) fluorescence (1000-1700 nm) and photoacoustic imaging with an ultimate goal of improving overall cancer diagnosis efficacy. Herein we designed a donor-acceptor chromophore based nanoparticle (DAP) as a dual-modal image contrast agent has strong absorption in the NIR-I window and a strong fluorescence emission peak in the NIR-II region. The dual-modal DAPs composed of D-π-A-π-D-type chromophores were PEGylated through nanoprecipitation. The multifunctional DAP surface was thus available for subsequent bioconjugation of EGFR Affibody (Ac-Cys-Z EGFR:1907 ) to target EGFR-positive cancers. The Affibody-conjugated DAPs appeared as highly monodisperse nanoparticles (∼30 nm) with strong absorption in the NIR-I window (at ca. 680 nm) and an extremely high fluorescence in the NIR-II region (maximum peak at 1000 nm). Consequently, the Affibody-DAPs show significantly enhanced photoacoustic and NIR-II fluorescence contrast effects in both in vitro and in vivo experiments. Moreover, the Affibody-DAPs have the capability to selectively target EGFR-positive tumors in an FTC-133 subcutaneous mouse model with relatively high photoacoustic and fluorescent signals. By taking advantage of high spatial resolution and excellent temporal resolution, photoacoustic/NIR-II fluorescence imaging with targeted dual-modal contrast agents allows us to specifically image and detect various cancers and diseases in an accurate manner.

  9. Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy

    Science.gov (United States)

    Talukdar, Abdul; Faheem Khan, M.; Lee, Dongkyu; Kim, Seonghwan; Thundat, Thomas; Koley, Goutam

    2015-08-01

    Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelectric polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resolution of 12.43 fm Hz-1/2 and an outstanding responsivity of 170 nV fm-1, which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms.

  10. Photoacoustic microscopy of electronic acupuncture (EA) effect in small animals.

    Science.gov (United States)

    Yang, Jinge; Wu, Dan; Tang, Yong; Jiang, Huabei

    2017-02-01

    Acupuncture has been an effective treatment for various pain in China for several thousand years. However, the mechanisms underlying this mysterious ancient healing are still largely unknown. Here we applied photoacoustic microscopy (PAM) to investigate brain hemodynamic changes in response to electronic acupuncture (EA) at ST36 (Zusanli). Due to the high optical absorption of blood at 532 nm, PAM could sensitively probe changes in hemoglobin concentration (HbT, i.e., cerebral blood volume [CBV]) of cortical regions in high resolution. Six healthy mice were stimulated at the acupoint and three healthy mice were stimulated at sham points. Remarkable CBV changes in sensorimotor and retrosplenial agranular cortex were observed. Results showed the potential of PAM as a visualization tool to study the acupuncture effect on brain hemodynamics in animal models. (a) Schematic showing the stimulation points. (b) B-scan images overlaid with mouse atlas. (c) & (d) Statistical results of CBV changes from cortical regions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Photoacoustic and ultrasound dual-modality imaging for inflammatory arthritis

    Science.gov (United States)

    Xu, Guan; Chamberland, David; Girish, Gandikota; Wang, Xueding

    2014-03-01

    Arthritis is a leading cause of disability, affecting 46 million of the population in the U.S. Rendering new optical contrast in articular tissues at high spatial and temporal resolution, emerging photoacoustic imaging (PAI) combined with more established ultrasound (US) imaging technologies provides unique opportunities for diagnosis and treatment monitoring of inflammatory arthritis. In addition to capturing peripheral bone and soft tissue images, PAI has the capability to quantify hemodynamic properties including regional blood oxygenation and blood volume, both abnormal in synovial tissues affected by arthritis. Therefore, PAI, especially when performed together with US, should be of considerable help for further understanding the pathophysiology of arthritis as well as assisting in therapeutic decisions, including assessing the efficacy of new pharmacological therapies. In this paper, we will review our recent work on the development of PAI for application to the diagnostic imaging and therapeutic monitoring of inflammatory arthritis. We will present the imaging results from a home-built imaging system and another one based on a commercial US. The performance of PAI in evaluating pharmacological therapy on animal model of arthritis will be shown. Moreover, our resent work on PAI and US dual-modality imaging of human peripheral joints in vivo will also be presented.

  12. In vivo imaging of small animal models by photoacoustic microscopy

    Science.gov (United States)

    Ye, Shuoqi; Yang, Ran; Xiong, Jingwei; Shung, K. Kirk; Zhou, Qifa; Li, Changhui; Ren, Qiushi

    2012-02-01

    Small animal models, such as zebrafish, drosophila, C. elegan, is considered to be important models in comparative biology and diseases researches. Traditional imaging methods primarily employ several optical microscopic imaging modalities that rely on fluorescence labeling, which may have potential to affect the natural physiological progress. Thus a label-free imaging method is desired. Photoacoustic (PA) microscopy (PAM) is an emerging biomedical imaging method that combines optical contrast with ultrasonic detection, which is highly sensitive to the optical absorption contrast of living tissues, such as pigments, the vasculature and other optically absorbing organs. In this work, we reported the whole body label-free imaging of zebrafish larvae and drosophila pupa by PAM. Based on intrinsic optical absorption contrast, high resolution images of pigments, microvasculature and several other major organs have been obtained in vivo and non-invasively, and compared with their optical counterparts. We demonstrated that PAM has the potential to be a powerful non-invasive imaging method for studying larvae and pupa of various animal models.

  13. Ultra-rapid photocatalytic activity of Azadirachta indica engineered colloidal titanium dioxide nanoparticles

    Science.gov (United States)

    Sankar, Renu; Rizwana, Kadarmohideen; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2015-08-01

    Titanium dioxide nanoparticles were effectively synthesized from aqueous leaf extract of Azadirachta indica under pH and temperature-dependent condition. 5 mM titanium isopropoxide solution worked as a primary source for the synthesis of titanium dioxide nanoparticles. The green synthesized titanium dioxide nanoparticles were confirmed by UV-Vis spectroscopy. Fourier transform infrared spectrum of synthesized titanium dioxide nanoparticles authorized the presence of bioactive compounds in the leaf extract, which may play a role as capping and reducing agent. The high-resolution scanning electron microscopy and dynamic light scattering analyses results showed the interconnected spherical in shape titanium dioxide nanoparticles having a mean particle size of 124 nm and a zeta potential of -24 mV. Besides, the colloidal titanium dioxide nanoparticles energetically degrade the industrially harmful methyl red dye under bright sunlight.

  14. Characterization of multiphoton photoacoustic spectroscopy for subsurface brain tissue diagnosis and imaging

    Science.gov (United States)

    Dahal, Sudhir; Cullum, Brian M.

    2016-04-01

    The development and demonstration of a multiphoton photoacoustic imaging technique capable of providing high spatial resolution chemical images of subsurface tissue components as deep as 1.4 cm below the tissue surface is described. By combining multiphoton excitation in the diagnostic window (650 to 1100 nm), with ultrasonic detection of nonradiative relaxation events, it is possible to rapidly reconstruct three-dimensional, chemical specific, images of samples underneath overlying structures as well as chemical species of the same material. Demonstration of this technique for subsurface tissue differentiation is shown, with the ability to distinguish between grade III astrocytoma tissue and adjacent healthy tissue in blind studies. By employing photoacoustic signal detection, the high nonradiative relaxation rates of most biological tissue components (>90%) and the minimal signal attenuation of the resulting ultrasound compensate for excitation efficiency losses associated with two-photon absorption. Furthermore, the two-photon absorption process results in a highly localized excitation volume (ca., 60 μm). Characterization of the probing depth, spatial resolution, and ability to image through overlying structures is also demonstrated in this paper using tissue phantoms with well-characterized optical scattering properties, mimicking those of tissues.

  15. Photoacoustic imaging of voltage responses beyond the optical diffusion limit

    National Research Council Canada - National Science Library

    Bin Rao; Ruiying Zhang; Lei Li; Jin-Yu Shao; Lihong V Wang

    2017-01-01

    .... Although photoacoustic tomography breaks this limit by exciting the targets with diffused photons and detecting the resulting acoustic responses, it has not been demonstrated as a modality for imaging voltage responses...

  16. Towards quantitative photoacoustic tomography by acoustooptically measured light fluence

    NARCIS (Netherlands)

    Hussain, Altaf; Hondebrink, Erwin; Steenbergen, Wiendelt

    2016-01-01

    We present a method of measuring fluence using ultrasonic tagging of light in tomographic manner. Proof of concept experiments show that the combined photoacoustics and acousto optics in tomographic settings enable fluence compensated images.

  17. The Application of Quality Identification in Honey by Photoacoustic Spectroscopy.

    Science.gov (United States)

    Tao, Wen-ting; Yuan, Ping; Guo, Wen-juan; Liu, Jian-en

    2015-05-01

    The photoacoustic spectrum of glucose, sucrose and honey solutions in the visible range are measured by using the single-light photoacoustic spectrometer, and are compared with the spectra from spedtrophotometry method. The spectral characteristics of the above solutions show that the spectral background intensity and spectral profile have some differences for different kinds of solutions. The spectra of the three kinds of solutions all have strong peak value at 485 and 655 nm, but the intensity ratios between the two peaks are different. Besides, there are characteristic peak at 475, 576 and 630 nm for glucose, and the sucrose has apparent characteristic peak at 632 nm, these characteristic peaks can be used for detecting whether the natural honey has been added glucose or sucrose. By comparing two kinds of spectrum of the same solution, the intensity of photoacoustic spectrum is more responsive to the wavelength, indicating photoacoustic spectrometry has a higher sensitivity in the test of material composition.

  18. Modeling skull's acoustic attenuation and dispersion on photoacoustic signal

    Science.gov (United States)

    Mohammadi, L.; Behnam, H.; Nasiriavanaki, M. R.

    2017-03-01

    Despite the great promising results of a recent new transcranial photoacoustic brain imaging technology, it has been shown that the presence of the skull severely affects the performance of this imaging modality. In this paper, we investigate the effect of skull on generated photoacoustic signals with a mathematical model. The developed model takes into account the frequency dependence attenuation and acoustic dispersion effects occur with the wave reflection and refraction at the skull surface. Numerical simulations based on the developed model are performed for calculating the propagation of photoacoustic waves through the skull. From the simulation results, it was found that the skull-induced distortion becomes very important and the reconstructed image would be strongly distorted without correcting these effects. In this regard, it is anticipated that an accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in transcranial photoacoustic brain imaging.

  19. Water-soluble dopamine-based polymers for photoacoustic imaging

    NARCIS (Netherlands)

    Repenko, T.; Fokong, S.; De Laporte, L.; Go, D.; Kiessling, F.; Lammers, Twan Gerardus Gertudis Maria; Kuehne, A.

    2015-01-01

    Here we present a facile synthetic method yielding a linear form of polydopamine via Kumada-coupling, which can be converted into water-soluble melanin, generating high contrast in photoacoustic imaging.

  20. Bone assessment via thermal photoacoustic measurements

    Science.gov (United States)

    Feng, Ting; Kozloff, Kenneth M.; Hsiao, Yi-Sing; Tian, Chao; Perosky, Joseph; Du, Sidan; Yuan, Jie; Deng, Cheri X.; Wang, Xueding

    2015-03-01

    The feasibility of an innovative biomedical diagnostic technique, thermal photoacoustic (TPA) measurement, for nonionizing and non-invasive assessment of bone health is investigated. Unlike conventional photoacoustic PA methods which are mostly focused on the measurement of absolute signal intensity, TPA targets the change in PA signal intensity as a function of the sample temperature, i.e. the temperature dependent Grueneisen parameter which is closely relevant to the chemical and molecular properties in the sample. Based on the differentiation measurement, the results from TPA technique is less susceptible to the variations associated with sample and system, and could be quantified with improved accurately. Due to the fact that the PA signal intensity from organic components such as blood changes faster than that from non-organic mineral under the same modulation of temperature, TPA measurement is able to objectively evaluate bone mineral density (BMD) and its loss as a result of osteoporosis. In an experiment on well established rat models of bone loss and preservation, PA measurements of rat tibia bones were conducted over a temperature range from 370 C to 440 C. The slope of PA signal intensity verses temperature was quantified for each specimen. The comparison among three groups of specimens with different BMD shows that bones with lower BMD have higher slopes, demonstrating the potential of the proposed TPA technique in future clinical management of osteoporosis.

  1. A UV-Vis photoacoustic spectrophotometer.

    Science.gov (United States)

    Wiegand, Joseph R; Mathews, L Dalila; Smith, Geoffrey D

    2014-06-17

    A novel photoacoustic spectrophotometer (PAS) for the measurement of gas-phase and aerosol absorption over the UV-visible region of the spectrum is described. Light from a broadband Hg arc lamp is filtered in eight separate bands from 300 to 700 nm using bandpass interference filters (centered at 301 nm, 314 nm, 364 nm, 405 nm, 436 nm, 546 nm, 578 and 687 nm) and modulated with an optical chopper before entering the photoacoustic cell. All wavelength bands feature a 20-s detection limit of better than 3.0 Mm(-1) with the exception of the lower-intensity 687 nm band for which it is 10.2 Mm(-1). Validation measurements of gas-phase acetone and nigrosin aerosol absorption cross sections at several wavelengths demonstrate agreement to within 10% with those measured previously (for acetone) and those predicted by Mie theory (for nigrosin). The PAS instrument is used to measure the UV-visible absorption spectrum of ambient aerosol demonstrating a dramatic increase in the UV region with absorption increasing by 300% from 405 to 301 nm. This type of measurement throughout the UV-visible region and free from artifacts associated with filter-based methods has not been possible previously, and we demonstrate its promise for classifying and quantifying different types of light-absorbing ambient particles.

  2. COMPAS: Compositional mineralogy with a photoacoustic spectrometer

    Science.gov (United States)

    Smith, W. Hayden

    1992-01-01

    There is an important need for an in situ method of mineral and rock identification and quantification that provides true absorption spectra for a wide spectral range for lunar lander/rover missions. Many common minerals such as feldspars, magnetite, ilmenite, and amorphous fine solids or glasses, can exhibit flat spectral reflectances in the 400-2500 nm spectral region that render inaccurate or difficult their spectral detection and quantitative analysis. Ideal rock and mineral spectra are, of course, pure absorption spectra that are independent of the spectral effects of scattering, particle size, and distribution that can result in a suppression or distortion of their spectral features. This ideal seldom pertains to real samples. Since sample preparation is difficult and may fundamentally alter the observed diffuse spectral reflectance, an in situ spectral measurement method for rocks and minerals on the Moon, insensitive to the sample morphology, would be invaluable. Photoacoustic spectroscopy is a well-established technique appropriate for this task that has been widely applied in condensed-phase spectral studies of complex, highly light scattering, unprepared samples of everything from coal to whole blood, including rock and mineral characterization. A Compositional Mineralogy Photoacoustic Spectrometer, or COMPAS, can enable in situ spectral measurement of rocks and minerals, bypassing the major limitations of diffuse reflectance spectroscopy. COMPAS spectral capabilities for rock and mineral samples will be incorporated into an instrument prototype specifically for lunar measurements, compatible with rover capabilities.

  3. Noncontact holographic detection for photoacoustic tomography

    Science.gov (United States)

    Buj, Christian; Münter, Michael; Schmarbeck, Benedikt; Horstmann, Jens; Hüttmann, Gereon; Brinkmann, Ralf

    2017-10-01

    A holographic method for high-speed, noncontact photoacoustic tomography is introduced and evaluated. Relative changes of the object's topography, induced by the impact of thermoelastic pressure waves, were determined at nanometer sensitivity without physical contact. The object's surface was illuminated with nanosecond laser pulses and imaged with a high-speed CMOS camera. From two interferograms measured before and after excitation of the acoustic wave, surface displacement was calculated and then used as the basis for a tomographic reconstruction of the initial pressure caused by optical absorption. The holographic detection scheme enables variable sampling rates of the photoacoustic signal of up to 50 MHz. The total acquisition times for complete volumes with 230 MVoxel is far below 1 s. Measurements of silicone and porcine skin tissue phantoms with embedded artificial absorbers, which served as a model for human subcutaneous vascular networks, were possible. Three-dimensional reconstructions of the absorbing structures show details with a diameter of 310 μm up to a depth of 2.5 mm. Theoretical limitations and the experimental sensitivity, as well as the potential for in vivo imaging depending on the detection repetition rate, are analyzed and discussed.

  4. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  5. Biomedical photoacoustics beyond thermal expansion using triggered nanodroplet vaporization for contrast-enhanced imaging.

    Science.gov (United States)

    Wilson, Katheryne; Homan, Kimberly; Emelianov, Stanislav

    2012-01-10

    Since being discovered by Alexander Bell, photoacoustics may again be seeing major resurgence in biomedical imaging. Photoacoustics is a non-ionizing, functional imaging modality capable of high contrast images of optical absorption at depths significantly greater than traditional optical imaging techniques. Optical contrast agents have been used to extend photoacoustics to molecular imaging. Here we introduce an exogenous contrast agent that utilizes vaporization for photoacoustic signal generation, providing significantly higher signal amplitude than that from the traditionally used mechanism, thermal expansion. Our agent consists of liquid perfluorocarbon nanodroplets with encapsulated plasmonic nanoparticles, entitled photoacoustic nanodroplets. Upon pulsed laser irradiation, liquid perfluorocarbon undergoes a liquid-to-gas phase transition generating giant photoacoustic transients from these dwarf nanoparticles. Once triggered, the gaseous phase provides ultrasound contrast enhancement. We demonstrate in phantom and animal studies that photoacoustic nanodroplets act as dual-contrast agents for both photoacoustic and ultrasound imaging through optically triggered vaporization.

  6. In situ photoacoustic characterization for porous silicon growing: Detection principles

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Gutierrez, C. F. [Posgrado en Ciencia e Ingeniería de Materiales, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro. (Mexico); Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro. (Mexico); Castaño-Yepes, J. D. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México Distrito Federal, C. P. 04510 (Mexico); Rodriguez-García, M. E., E-mail: marioga@fata.unam.mx [Licenciatura en Ingeniería Física, Facultad de Ingeniería, Universidad Autónoma de Querétaro, C. P. 76010 Querétaro, Qro. (Mexico); Departamento de Nanotecnología, Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México Campus Juriquilla, C.P. 76230 Querétaro, Qro. (Mexico)

    2016-05-14

    There are a few methodologies for monitoring the in-situ formation of Porous Silicon (PS). One of the methodologies is photoacoustic. Previous works that reported the use of photoacoustic to study the PS formation do not provide the physical explanation of the origin of the signal. In this paper, a physical explanation of the origin of the photoacoustic signal during the PS etching is provided. The incident modulated radiation and changes in the reflectance are taken as thermal sources. In this paper, a useful methodology is proposed to determine the etching rate, porosity, and refractive index of a PS film by the determination of the sample thickness, using scanning electron microscopy images. This method was developed by carrying out two different experiments using the same anodization conditions. The first experiment consisted of growth of the samples with different etching times to prove the periodicity of the photoacoustic signal, while the second one considered the growth samples using three different wavelengths that are correlated with the period of the photoacoustic signal. The last experiment showed that the period of the photoacoustic signal is proportional to the laser wavelength.

  7. Catheter tracking in an interventional photoacoustic surgical system

    Science.gov (United States)

    Cheng, Alexis; Itsarachaiyot, Yuttana; Kim, Younsu; Zhang, Haichong K.; Taylor, Russell H.; Boctor, Emad M.

    2017-03-01

    In laparoscopic medical procedures, accurate tracking of interventional tools such as catheters are necessary. Current practice for tracking catheters often involve using fluoroscopy, which is best avoided to minimize radiation dose to the patient and the surgical team. Photoacoustic imaging is an emerging imaging modality that can be used for this purpose and does not currently have a general tool tracking solution. Photoacoustic-based catheter tracking would increase its attractiveness, by providing both an imaging and tracking solution. We present a catheter tracking method based on the photoacoustic effect. Photoacoustic markers are simultaneously observed by a stereo camera as well as a piezoelectric element attached to the tip of a catheter. The signals received by the piezoelectric element can be used to compute its position relative to the photoacoustic markers using multilateration. This combined information can be processed to localize the position of the piezoelectric element with respect to the stereo camera system. We presented the methods to enable this work and demonstrated precisions of 1-3mm and a relative accuracy of less than 4% in four independent locations, which are comparable to conventional systems. In addition, we also showed in another experiment a reconstruction precision up to 0.4mm and an estimated accuracy up to 0.5mm. Future work will include simulations to better evaluate this method and its challenges and the development of concurrent photoacoustic marker projection and its associated methods.

  8. Low-power noncontact photoacoustic microscope for bioimaging applications

    Science.gov (United States)

    Sathiyamoorthy, Krishnan; Strohm, Eric M.; Kolios, Michael C.

    2017-04-01

    An inexpensive noncontact photoacoustic (PA) imaging system using a low-power continuous wave laser and a kilohertz-range microphone has been developed. The system operates in both optical and PA imaging modes and is designed to be compatible with conventional optical microscopes. Aqueous coupling fluids are not required for the detection of the PA signals; air is used as the coupling medium. The main component of the PA system is a custom designed PA imaging sensor that consists of an air-filled sample chamber and a resonator chamber that isolates a standard kilohertz frequency microphone from the input laser. A sample to be examined is placed on the glass substrate inside the chamber. A laser focused to a small spot by a 40× objective onto the substrate enables generation of PA signals from the sample. Raster scanning the laser over the sample with micrometer-sized steps enables high-resolution PA images to be generated. A lateral resolution of 1.37 μm was achieved in this proof of concept study, which can be further improved using a higher numerical aperture objective. The application of the system was investigated on a red blood cell, with a noise-equivalent detection sensitivity of 43,887 hemoglobin molecules (72.88×10-21 mol or 72.88 zeptomol). The minimum pressure detectable limit of the system was 19.1 μPa. This inexpensive, compact noncontact PA sensor is easily integrated with existing commercial optical microscopes, enabling optical and PA imaging of the same sample. Applications include forensic measurements, blood coagulation tests, and monitoring the penetration of drugs into human membrane.

  9. A dual function theranostic agent for near-infrared photoacoustic imaging and photothermal therapy

    Science.gov (United States)

    Upputuri, Paul Kumar; Huang, Shuo; Wang, Mingfeng; Pramanik, Manojit

    2016-03-01

    Theranostic, defined as combining diagnostic and therapeutic agents, has attracted more attention in biomedical application. It is essential to monitor diseased tissue before treatment. Photothermal therapy (PTT) is a promising treatment of cancer tissue due to minimal invasion, unharmful to normal tissue and high efficiency. Photoacoustic tomography (PAT) is a hybrid nonionizing biomedical imaging modality that combines rich optical contrast and high ultrasonic resolution in a single imaging modality. The near infra-red (NIR) wavelengths, usually used in PAT, can provide deep penetration at the expense of reduced contrast, as the blood absorption drops in the NIR range. Exogenous contrast agents with strong absorption in the NIR wavelength range can enhance the photoacoustic imaging contrast as well as imaging depth. Most theranostic agents incorporating PAT and PTT are inorganic nanomaterials that suffer from poor biocompatibility and biodegradability. Herein, we present an benzo[1,2-c;4,5-c'] bis[1,2,5] thiadiazole (BBT), based theranostic agent which not only acts as photoacoustic contrast agent but also a photothermal therapy agent. Experiments were performed on animal blood and organic nanoparticles embedded in a chicken breast tissue using PAT imaging system at ~803 nm wavelengths. Almost ten time contrast enhancement was observed from the nanoparticle in suspension. More than 6.5 time PA signal enhancement was observed in tissue at 3 cm depth. HeLa cell lines was used to test photothermal effect showing 90% cells were killed after 10 min laser irradiation. Our results indicate that the BBT - based naoparticles are promising theranostic agents for PAT imaging and cancer treatment by photothermal therapy.

  10. Photoacoustic imaging of hidden dental caries by using a fiber-based probing system

    Science.gov (United States)

    Koyama, Takuya; Kakino, Satoko; Matsuura, Yuji

    2017-04-01

    Photoacoustic method to detect hidden dental caries is proposed. It was found that high frequency ultrasonic waves are generated from hidden carious part when radiating laser light to occlusal surface of model tooth. By making a map of intensity of these high frequency components, photoacoustic images of hidden caries were successfully obtained. A photoacoustic imaging system using a bundle of hollow optical fiber was fabricated for using clinical application, and clear photoacoustic image of hidden caries was also obtained by this system.

  11. Investigation of an energy-gap model for photoacoustic O{sub 2}A-band spectra: H{sub 2}O calibration near 7180 cm{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Vess, E.M.; Anderson, C.N.; Awadalla, V.E.; Estes, E.J.; Jeon, C.; Wallace, C.J.; Hu, X.F. [Department of Chemistry and Biochemistry, James Madison University, MSC 4501, Harrisonburg, VA 22807 (United States); Havey, D.K., E-mail: haveydk@jmu.edu [Department of Chemistry and Biochemistry, James Madison University, MSC 4501, Harrisonburg, VA 22807 (United States)

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer We investigate an energy transfer model for photoacoustic measurements of the O{sub 2}A-band. Black-Right-Pointing-Pointer We measure the response of a photoacoustic spectrometer for known quantities of H{sub 2}O and O{sub 2}. Black-Right-Pointing-Pointer We fit multiple theoretical spectral line profiles to the data. Black-Right-Pointing-Pointer We bind the relative uncertainty of the energy transfer model to less than 1%. Black-Right-Pointing-Pointer We demonstrate that speed-dependence is an important line shape effect for these experiments. - Abstract: A photoacoustic spectrometer is used to evaluate the accuracy of an energy-gap model for collisional energy transfer. For photoacoustic measurements involving the b{sup 1}{Sigma}{sub g}{sup +} Leftwards-Arrow X{sup 3}{Sigma}{sub g}{sup -} transition of molecular oxygen the conversion of photon energy to thermal energy is inefficient and proceeds through the a{sup 1}{Delta}{sub g} state. This results in attenuation of the photoacoustic signal. The magnitude of the attenuation can be predicted with an energy-gap model whose accuracy has been previously confirmed to within 3 {+-} 5%. However, this prior result does not rule out incomplete rotational relaxation of O{sub 2} in the a{sup 1}{Delta}{sub g} state. In this study, high-resolution spectra of H{sub 2}O in air are used to calibrate the photoacoustic spectrometer. This work binds the relative uncertainty in the energy-gap relaxation factor for O{sub 2}A-band photoacoustic signals to be approximately 1%. During one acoustic cycle, this result implies negligible collisional relaxation to the X{sup 3}{Sigma}{sub g}{sup -} state of O{sub 2} and nearly complete collisional relaxation to the a{sup 1}{Delta}{sub g} state.

  12. A new acoustic lens material for large area detectors in photoacoustic breast tomography

    CERN Document Server

    Xia, Wenfeng; van Hespen, Johan C G; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of sensitive large surface area detectors and improve lateral resolution. However, PMMA lenses introduce image artifacts due to ultrasound internal reflections within the lenses. In this work we investigated this issue proposing a new lens material Stycast 1090SI. We characterized the acoustic properties of the proposed material in comparison with PMMA. Detector performance using negative lenses with the two materials, was tested using finite element simulation and experiment. Further the image quality of a photoacoustic tomography system was studied using k-Wave simulation and experiment. Our acoustic characterization showed that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement. However, image artifacts induced by acoustic lenses are reduced using the p...

  13. Photoacoustic sensor system for the quantification of soot aerosols (abstract)

    Science.gov (United States)

    Haisch, C.; Beck, H.; Niessner, R.

    2003-01-01

    The influence of soot particles on human health as well as global and local climate is well established by now. Hence, the need for fast and sensitive soot detection in urban and remote areas is obvious. The state of the art thermochemical detection methods for soot analysis is based on filter sampling and subsequent wet chemical analysis and combustion, which requires laborious and time consuming sample preparation. Due to the integration on a filter, a time-resolved analysis is not possible. The presented photoacoustic sensor system is optimized for a highly sensitive and fast on-line and in situ quantification of soot. Soot particles, as classical "black absorbers," absorb electromagnetic radiation over the whole spectrum. Two similar systems are introduced. The first system is designed for the development and testing of combustion engines, mainly the next generation of diesel engines. In the next decade, legal thresholds for extremely low particle emissions are foreseen. Their implementation will be only possible if a time-resolved soot detection with sufficient sensitivity can be realized as the highest particle emissions from diesel engines are generated only for seconds during load changes. During a load change, the emitted soot concentrations can rise several orders of magnitude for only a period of few seconds. The system combines a time resolution of 1 s (sampling rate 1 Hz) with an aerosol mass sensitivity better than 10 μg m-3. Up to a maximum dimension of about 800 nm the signal is independent of the particle size. The systems consist of two photoacoustic cells, which are operated in a differential mode to avoid cross sensitivities. The cells are built as acoustical resonators to increase sensitivity. A diode laser with a wavelength of 810 nm and an output power of 1.1 W is employed for excitation. Its collimated beam passes first through the reference cell and then through the measurement cell. To avoid condensation of water, the cells are heated to

  14. Effect of whitening toothpaste on titanium and titanium alloy surfaces

    OpenAIRE

    Adriana Cláudia Lapria Faria; Angelo Rafael de Vito Bordin; Vinícius Pedrazzi; Renata Cristina Silveira Rodrigues; Ricardo Faria Ribeiro

    2012-01-01

    Dental implants have increased the use of titanium and titanium alloys in prosthetic applications. Whitening toothpastes with peroxides are available for patients with high aesthetic requirements, but the effect of whitening toothpastes on titanium surfaces is not yet known, although titanium is prone to fluoride ion attack. Thus, the aim of the present study was to compare Ti-5Ta alloy to cp Ti after toothbrushing with whitening and conventional toothpastes. Ti-5Ta (%wt) alloy was melted in ...

  15. Ultrasound-guided photoacoustic imaging of lymph nodes with biocompatible gold nanoparticles as a novel contrast agent (Conference Presentation)

    Science.gov (United States)

    Sun, In-Cheol; Dumani, Diego; Emelianov, Stanislav Y.

    2017-02-01

    A key step in staging cancer is the diagnosis of metastasis that spreads through lymphatic system. For this reason, researchers develop various methods of sentinel lymph node mapping that often use a radioactive tracer. This study introduces a safe, cost-effective, high-resolution, high-sensitivity, and real-time method of visualizing the sentinel lymph node: ultrasound-guided photoacoustic (US/PA) imaging augmented by a contrast agent. In this work, we use clearable gold nanoparticles covered by a biocompatible polymer (glycol chitosan) to enhance cellular uptake by macrophages abundant in lymph nodes. We incubate macrophages with glycol-chitosan-coated gold nanoparticles (0.05 mg Au/ml), and then fix them with paraformaldehyde solution for an analysis of in vitro dark-field microscopy and cell phantom. The analysis shows enhanced cellular uptake of nanoparticles by macrophages and strong photoacoustic signal from labeled cells in tissue-mimicking cell phantoms consisting gelatin solution (6 %) with silica gel (25 μm, 0.3%) and fixed macrophages (13 X 105 cells). The in-vivo US/PA imaging of cervical lymph nodes in healthy mice (nu/nu, female, 5 weeks) indicates a strong photoacoustic signal from a lymph node 10 minutes post-injection (2.5 mg Au/ml, 80 μl). The signal intensity and the nanoparticle-labeled volume of tissue within the lymph node continues to increase until 4 h post-injection. Histological analysis further confirms the accumulation of gold nanoparticles within the lymph nodes. This work suggests the feasibility of molecular/cellular US/PA imaging with biocompatible gold nanoparticles as a photoacoustic contrast agent in the diagnosis of lymph-node-related diseases.

  16. Preparation of titanium diboride powders from titanium alkoxide and ...

    Indian Academy of Sciences (India)

    Titanium diboride powders were prepared through a sol–gel and boron carbide reduction route by using TTIP and B4C as titanium and boron sources. The influence of TTIP concentration, reaction temperature and molar ratio of precursors on the synthesis of titanium diboride was investigated. Three different concentrations ...

  17. Skeletonization algorithm-based blood vessel quantification using in vivo 3D photoacoustic imaging

    Science.gov (United States)

    Meiburger, K. M.; Nam, S. Y.; Chung, E.; Suggs, L. J.; Emelianov, S. Y.; Molinari, F.

    2016-11-01

    Blood vessels are the only system to provide nutrients and oxygen to every part of the body. Many diseases can have significant effects on blood vessel formation, so that the vascular network can be a cue to assess malicious tumor and ischemic tissues. Various imaging techniques can visualize blood vessel structure, but their applications are often constrained by either expensive costs, contrast agents, ionizing radiations, or a combination of the above. Photoacoustic imaging combines the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging, and image contrast depends on optical absorption. This enables the detection of light absorbing chromophores such as hemoglobin with a greater penetration depth compared to purely optical techniques. We present here a skeletonization algorithm for vessel architectural analysis using non-invasive photoacoustic 3D images acquired without the administration of any exogenous contrast agents. 3D photoacoustic images were acquired on rats (n  =  4) in two different time points: before and after a burn surgery. A skeletonization technique based on the application of a vesselness filter and medial axis extraction is proposed to extract the vessel structure from the image data and six vascular parameters (number of vascular trees (NT), vascular density (VD), number of branches (NB), 2D distance metric (DM), inflection count metric (ICM), and sum of angles metric (SOAM)) were calculated from the skeleton. The parameters were compared (1) in locations with and without the burn wound on the same day and (2) in the same anatomic location before (control) and after the burn surgery. Four out of the six descriptors were statistically different (VD, NB, DM, ICM, p  <  0.05) when comparing two anatomic locations on the same day and when considering the same anatomic location at two separate times (i.e. before and after burn surgery). The study demonstrates an

  18. Photoacoustic microscopy of blood pulse wave

    Science.gov (United States)

    Yeh, Chenghung; Hu, Song; Maslov, Konstantin; Wang, Lihong V.

    2012-07-01

    Blood pulse wave velocity (PWV) is an important physiological parameter that characterizes vascular stiffness. In this letter, we present electrocardiogram-synchronized, photoacoustic microscopy for noninvasive quantification of the PWV in the peripheral vessels of living mice. Interestingly, blood pulse wave-induced fluctuations in blood flow speed were clearly observed in arteries and arterioles, but not in veins or venules. Simultaneously recorded electrocardiograms served as references to measure the travel time of the pulse wave between two cross sections of a chosen vessel and vessel segmentation analysis enabled accurate quantification of the travel distance. PWVs were quantified in ten vessel segments from two mice. Statistical analysis shows a linear correlation between the PWV and the vessel diameter which agrees with known physiology.

  19. Photoacoustic flow cytometry for nanomaterial research

    Directory of Open Access Journals (Sweden)

    Dmitry A. Nedosekin

    2017-06-01

    Full Text Available Conventional flow cytometry is a versatile tool for drug research and cell characterization. However, it is poorly suited for quantification of non-fluorescent proteins and artificial nanomaterials without the use of additional labeling. The rapid growth of biomedical applications for small non-fluorescent nanoparticles (NPs for drug delivery, image contrast and therapy enhancement, as well as research focused on natural cell pigments and chromophores, demands high-throughput quantification methods for the non-fluorescent components. In this work, we present an advanced novel photoacoustic (PA fluorescence flow cytometry (PAFFC platform that integrates NP quantification though PA detection with conventional sample characterization using fluorescence labeling. PAFFC simplifies high-throughput analysis of cell-NP interactions, optimization of targeted nanodrugs, and NP toxicity assessment by providing a direct correlation between NP uptake and characterization of toxicity markers for every cell.

  20. Photoacoustic measurement of lutein in biological matrix

    Science.gov (United States)

    Bicanic, D.; Luterotti, S.; Becucci, M.; Fogliano, V.; Versloot, P.

    2005-06-01

    Photoacoustic (PA) spectroscopy was applied for the first time to quantify lutein in a complex biological matrix. Standard addition of lutein to a biological low-lutein matrix was used for the calibration. The PA signal was found linearly proportional (R > 0.98) to lutein concentration up to 0.3% (w/w). The dynamic range of concentrations extends to 1% (w/w) lutein. For a given experimental set-up the responsivity of PA detector within the range of linearity was estimated to 1.1 mV/1% lutein. Precision of repeated analyses is good with average RSD values of 4 and 5% for blanks and spiked samples, respectively. The analytical parameters indicate that the PA method is fast and sensitive enough for quantification of lutein in supplementary drugs and in the lutein-rich foods.

  1. Photoacoustic infrared spectroscopy of polymer beads.

    Science.gov (United States)

    Wen, Qing; Michaelian, Kirk H

    2009-09-01

    Photoacoustic (PA) spectra of four types of polymer resin beads, ranging in size from 35 to 150 microm, were acquired using a Fourier transform infrared spectrometer capable of both rapid- and step-scan mirror movement. Thermal diffusion lengths were on the order of the particle sizes of the beads. The PA magnitude spectra were similar to absorption spectra; both positive- and negative-going features occurred in the phase spectra. The frequency dependences of the total PA intensities of the polymer resins and carbon black differed by a factor of about f(-0.30). The intensities of the weak bands in the ratioed spectra (resin beads/carbon black) displayed a similar dependence. Partial saturation caused a more gradual variation for the stronger bands, where the intensity is proportional to approximately f(-0.1)-f(-0.2).

  2. Joining of Gamma Titanium Aluminides

    National Research Council Canada - National Science Library

    Baeslack, William

    2002-01-01

    ... aluminides, are broadly applicable. Generally, the basic welding processes and techniques utilized in the fusion and solid -state friction welding of conventional titanium alloys can also be applied to the welding of gamma titanium aluminides...

  3. A Micro-Opto-Mechanical Photoacoustic Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kotovsky, J

    2008-10-17

    This report describes progress achieved in a one-year LDRD feasibility study of a Photo Acoustic Spectrometer (PAS). Specifically, this team sought to create an all-optical and very small PhotoAcoustic Spectrometer Sensing system (PASS system). The PASS system includes all the hardware needed within a gas environment to analyze the presence of a large variety of molecules. The all-optical PASS system requires only two optical-fibers to communicate with the opto-electronic power and readout systems that exist outside of the gas environment. These systems can be at any distance from the PASS system as signal loss through the optical fibers is very small. The PASS system is intended to be placed in a small space where gases need to be measured and thus must be very small. The size and all-optical constraints placed on the PASS system demand a new design. The PASS system design includes a novel acoustic chamber, optical sensor, power fiber coupling and sensing fiber coupling. Our collaborators at the Atomic Weapons Establishment (AWE) have proven the capabilities of a complete photoacoustic spectrometer that uses a macro-scale PASS system (first 2 references). It was our goal to miniaturize the PASS system and turn it into an all-optical system to allow for its use in confined spaces that prohibit electrical devices. This goal demanded the study of all the system components, selection of an appropriate optical readout system and the design and integration of the optical sensor to the PASS system. A stretch goal was to fabricate a completed PASS system prototype.

  4. Aerosol optical absorption measurements with photoacoustic spectroscopy

    Science.gov (United States)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  5. Technique development for photoacoustic imaging guided interventions

    Science.gov (United States)

    Cheng, Qian; Zhang, Haonan; Yuan, Jie; Feng, Ting; Xu, Guan; Wang, Xueding

    2015-03-01

    Laser-induced thermotherapy (LITT), i.e. tissue destruction induced by a local increase of temperature by means of laser light energy transmission, has been frequently used for minimally invasive treatments of various diseases such as benign thyroid nodules and liver cancer. The emerging photoacoustic (PA) imaging, when integrated with ultrasound (US), could contribute to LITT procedure. PA can enable a good visualization of percutaneous apparatus deep inside tissue and, therefore, can offer accurate guidance of the optical fibers to the target tissue. Our initial experiment demonstrated that, by picking the strong photoacoustic signals generated at the tips of optical fibers as a needle, the trajectory and position of the fibers could be visualized clearly using a commercial available US unit. When working the conventional US Bscan mode, the fibers disappeared when the angle between the fibers and the probe surface was larger than 60 degree; while working on the new PA mode, the fibers could be visualized without any problem even when the angle between the fibers and the probe surface was larger than 75 degree. Moreover, with PA imaging function integrated, the optical fibers positioned into the target tissue, besides delivering optical energy for thermotherapy, can also be used to generate PA signals for on-line evaluation of LITT. Powered by our recently developed PA physio-chemical analysis, PA measurements from the tissue can provide a direct and accurate feedback of the tissue responses to laser ablation, including the changes in not only chemical compositions but also histological microstructures. The initial experiment on the rat liver model has demonstrated the excellent sensitivity of PA imaging to the changes in tissue temperature rise and tissue status (from native to coagulated) when the tissue is treated in vivo with LITT.

  6. Photoacoustic characterization of radiofrequency ablation lesions

    Science.gov (United States)

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-02-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  7. Multispectral photoacoustic imaging of nerves with a clinical ultrasound system

    Science.gov (United States)

    Mari, Jean Martial; West, Simeon; Beard, Paul C.; Desjardins, Adrien E.

    2014-03-01

    Accurate and efficient identification of nerves is of great importance during many ultrasound-guided clinical procedures, including nerve blocks and prostate biopsies. It can be challenging to visualise nerves with conventional ultrasound imaging, however. One of the challenges is that nerves can have very similar appearances to nearby structures such as tendons. Several recent studies have highlighted the potential of near-infrared optical spectroscopy for differentiating nerves and adjacent tissues, as this modality can be sensitive to optical absorption of lipids that are present in intra- and extra-neural adipose tissue and in the myelin sheaths. These studies were limited to point measurements, however. In this pilot study, a custom photoacoustic system with a clinical ultrasound imaging probe was used to acquire multi-spectral photoacoustic images of nerves and tendons from swine ex vivo, across the wavelength range of 1100 to 1300 nm. Photoacoustic images were processed and overlaid in colour onto co-registered conventional ultrasound images that were acquired with the same imaging probe. A pronounced optical absorption peak centred at 1210 nm was observed in the photoacoustic signals obtained from nerves, and it was absent in those obtained from tendons. This absorption peak, which is consistent with the presence of lipids, provides a novel image contrast mechanism to significantly enhance the visualization of nerves. In particular, image contrast for nerves was up to 5.5 times greater with photoacoustic imaging (0.82 +/- 0.15) than with conventional ultrasound imaging (0.148 +/- 0.002), with a maximum contrast of 0.95 +/- 0.02 obtained in photoacoustic mode. This pilot study demonstrates the potential of photoacoustic imaging to improve clinical outcomes in ultrasound-guided interventions in regional anaesthesia and interventional oncology.

  8. Characterization of photoacoustic sources in tissue using time domain measurements

    Science.gov (United States)

    Viator, John Andrew

    Photoacoustic phenomenon in tissue and tissue phantoms is investigated with the particular goal of discrimination of diseased and healthy tissue. Propagation of broadband photoacoustic sources in tissue phantoms is studied with emphasis on attenuation, dispersion, and diffraction. Attenuation of photoacoustic waves induced by a circular laser spot on an absorber/air interface is modeled by the on-axis approximation of the acoustic field of a baffled piston source. Dispersion is studied in a diffraction free situation, where the disk of irradiation was created by a 5 mm laser spot on a 200 cm -1 solution. The genesis of diffraction in an absorbing solution was displayed by showing the merging of a boundary wave with a plane wave from a circular laser spot on an absorbing solution. Depth profiling of absorbing tissue phantoms and stained tissue was shown using a photoacoustic method. Acrylamide gels with layers of different optical absorption and stained elastin biomaterials were irradiated with stress confined laser pulses. The resulting acoustic waves were detected with a lithium niobate wideband acoustic transducer and processed in an algorithm to determine absorption coefficient as a function of depth. Spherical photoacoustic sources were generated in optically clear and turbid tissue phantoms. Propagation time and acoustic pulse duration were used to determine location and size, respectively. The photoacoustic sources were imaged using a multiplicative backprojection scheme. Image sources from acoustic boundaries were detected and dipole sources were detected and imaged. Finally an endoscopic photoacoustic probe was designed, built, and tested for use in determining treatment depth after palliative photodynamic therapy of esophageal cancer. The probe was less than 2.5 mm in diameter and consisted of a side firing 600 mum optical fiber to deliver laser energy and a 890 mum diameter, side viewing piezoelectric detector. The sensitivity of the probe was determined

  9. Efficient discrete cosine transform model-based algorithm for photoacoustic image reconstruction

    Science.gov (United States)

    Zhang, Yan; Wang, Yuanyuan; Zhang, Chen

    2013-06-01

    The model-based algorithm is an effective reconstruction method for photoacoustic imaging (PAI). Compared with the analytical reconstruction algorithms, the model-based algorithm is able to provide a more accurate and high-resolution reconstructed image. However, the relatively heavy computational complexity and huge memory storage requirement often impose restrictions on its applications. We incorporate the discrete cosine transform (DCT) in PAI reconstruction and establish a new photoacoustic model. With this new model, an efficient algorithm is proposed for PAI reconstruction. Relatively significant DCT coefficients of the measured signals are used to reconstruct the image. As a result, the calculation can be saved. The theoretical computation complexity of the proposed algorithm is figured out and it is proved that the proposed method is efficient in calculation. The proposed algorithm is also verified through the numerical simulations and in vitro experiments. Compared with former developed model-based methods, the proposed algorithm is able to provide an equivalent reconstruction with the cost of much less time. From the theoretical analysis and the experiment results, it would be concluded that the model-based PAI reconstruction can be accelerated by using the proposed algorithm, so that the practical applicability of PAI may be enhanced.

  10. Optimizing the optical wavelength for the photoacoustic imaging of inflammatory arthritis

    Science.gov (United States)

    Jo, Janggun; Xu, Guan; Hu, Jack; Francis, Sheeja; Marquardt, April; Yuan, Jie; Girish, Gandikota; Wang, Xueding

    2015-03-01

    With the capability of assessing high resolution optical information in soft tissues at imaging depth up to several centimeters, innovative biomedical photoacoustic imaging (PAI) offers benefits to diagnosis and treatment monitoring of inflammatory arthritis, particularly in combination with more established ultrasonography (US). In this work, a PAI and US dual-modality system facilitating both imaging functions in a real-time fashion was developed and initially tested for its clinical performance on patients with active inflammatory arthritis. Photoacoustic (PA) images of metacarpophalangeal (MCP) joints were acquired at 580-nm wavelength that provides a desired balance between optical absorption of blood and attenuation in background tissue. The results from six patients and six normal volunteers used as a control demonstrated the satisfactory sensitivity of PAI in assessing the physiological changes in the joints, specifically enhanced blood flow as a result of active synovitis. This preliminary study suggests that PAI, by revealing vascular features suggestive of joint inflammation, could be a valuable supplement to musculoskeletal US for rheumatology clinic.

  11. N-doped carbon nanodots for non-invasive photoacoustic imaging and photothermal therapy

    Science.gov (United States)

    Lee, Donghyun; Lee, Changho; Kwon, Woosung; Beack, Songeun; Kim, Chulhong

    2017-03-01

    We synthesized nitrogen-doped carbon nanodots (N-CNDs) for photoacoustic (PA) imaging and photothermal therapy (PTT) by controlling the nitrogen source and carbonizing organic acids. The N-CNDs showed strong optical absorbance in the near-infrared region, with great photostability and biodegradability. Thanks to the strong optical absorbance of NCNDs, the PA signals from N-CNDs were high enough to detect inside living animals and enabled minimally invasive PTT using N-CND. To evaluate the biodegradability and potential application of N-CNDs as a PA imaging contrast agent, we performed time-resolved PA imaging of sentinel lymph nodes (SLNs) and assessed renal clearance after hypodermic injection. SLN and vascular networks were photoacoustically visualized by an acoustic-resolution reflection-mode PA imaging system at a 680-nm optical wavelength. Furthermore, we performed whole-body PA imaging after subcutaneous injection of N-CNDs to assess their body distribution and clearance. Finally, we further investigated the use of N-CNDs for in vivo photothermal therapy in Balb/c nude xenograft HepG2-tumor model mice.

  12. Temporal evolution of low-coherence reflectometry signals in photoacoustic remote sensing microscopy (Conference Presentation)

    Science.gov (United States)

    Bell, Kevan L.; Reza, Parsin H.; Shi, Wei; Zemp, Roger J.

    2017-03-01

    We recently discovered that strong reflectivity modulations occur when a pulsed laser excites an absorption interface with an existing refractive index contrast. These modulations are observed using a low-coherence interrogation beam co-focused and co-scanned with an excitation beam to form high-resolution all-optical photoacoustic images. We call this new form of microscopy Photoacoustic Remote Sensing (PARS). To better understand the mechanism, analytical models were created of the time-evolution of these PARS signals. Shock waves propagating from the absorption interface create refractive index steps that form a time-varying multi-layer etalon. Besides an initial-pressure reflectivity change, GHz-modulations are predicted due to the propagating etalon effect. The characteristics of these modulations are related to the optical coherence length of the probe beam and the intrinsic optical properties of the sample. 1D plane-wave and 3D Mie-theory-based analytical models are compared with finite-difference time-domain simulations and experiments involving phantoms with different absorption- and refractive-index interfaces. Experimentally-observed modulations are detected with extremely high signal-to-noise ratios in phantoms and animal models. The newly predicted modulation mechanism offers a promising signature for deep all-optical absorption-contrast imaging with high fidelity.

  13. Discrimination of organic coffee via Fourier transform infrared-photoacoustic spectroscopy.

    Science.gov (United States)

    Gordillo-Delgado, Fernando; Marín, Ernesto; Cortés-Hernández, Diego Mauricio; Mejía-Morales, Claudia; García-Salcedo, Angela Janet

    2012-08-30

    Procedures for the evaluation of the origin and quality of ground and roasted coffee are constantly needed for the associated industry due to complexity of the related market. Conventional Fourier transform infrared (FTIR) spectroscopy can be used for detecting changes in functional groups of compounds, such as coffee. However, dispersion, reflection and non-homogeneity of the sample matrix can cause problems resulting in low spectral quality. On the other hand, sample preparation frequently takes place in a destructive way. To overcome these difficulties, in this work a photoacoustic cell has been adapted as a detector in a FTIR spectrophotometer to perform a study of roasted and ground coffee from three varieties of Coffea arabica grown by organic and conventional methods. Comparison between spectra of coffee recorded by FTIR-photoacoustic spectrometry (PAS) and by FTIR spectrophotometry showed a better resolution of the former method, which, aided by principal components analysis, allowed the identification of some absorption bands that allow the discrimination between organic and conventional coffee. The results obtained provide information about the spectral behavior of coffee powder which can be useful for establishing discrimination criteria. It has been demonstrated that FTIR-PAS can be a useful experimental tool for the characterization of coffee. Copyright © 2012 Society of Chemical Industry.

  14. In vivo preclinical photoacoustic imaging of tumor vasculature development and therapy

    Science.gov (United States)

    Laufer, Jan; Johnson, Peter; Zhang, Edward; Treeby, Bradley; Cox, Ben; Pedley, Barbara; Beard, Paul

    2012-05-01

    The use of a novel all-optical photoacoustic scanner for imaging the development of tumor vasculature and its response to a therapeutic vascular disrupting agent is described. The scanner employs a Fabry-Perot polymer film ultrasound sensor for mapping the photoacoustic waves and an image reconstruction algorithm based upon attenuation-compensated acoustic time reversal. The system was used to noninvasively image human colorectal tumor xenografts implanted subcutaneously in mice. Label-free three-dimensional in vivo images of whole tumors to depths of almost 10 mm with sub-100-micron spatial resolution were acquired in a longitudinal manner. This enabled the development of tumor-related vascular features, such as vessel tortuosity, feeding vessel recruitment, and necrosis to be visualized over time. The system was also used to study the temporal evolution of the response of the tumor vasculature following the administration of a therapeutic vascular disrupting agent (OXi4503). This revealed the well-known destruction and recovery phases associated with this agent. These studies illustrate the broader potential of this technology as an imaging tool for the preclinical and clinical study of tumors and other pathologies characterized by changes in the vasculature.

  15. Applying photoacoustics to quantification of melanin concentration in retinal pigment epithelium (Conference Presentation)

    Science.gov (United States)

    Shu, Xiao; Zhang, Hao F.; Liu, Wenzhong

    2016-03-01

    The melanin in the retinal pigment epithelium (RPE) protects retina and other ocular tissues by photo-screening and acting as antioxidant and free radical scavenger. It helps maintain normal visual functions since human eye is subjected to lifelong high oxygen stress and photon exposure. Loss of the RPE melanin weakens the protection mechanism and jeopardizes ocular health. Local decrease in the RPE melanin concentration is believed to be both a cause and a sign of early-stage age-related macular degeneration (AMD), the leading blinding disease in developed world. Current technology cannot quantitatively measure the RPE melanin concentration which might be a promising marker in early AMD screening. Photoacoustic ophthalmoscopy (PAOM), as an emerging optical absorption-based imaging technology, can potentially be applied to measure the RPE melanin concentration if the dependence of the detectable photoacoustic (PA) signal amplitudes on the RPE melanin concentrations is verified. In this study, we tested the feasibility of using PA signal ratio from RPE melanin and the nearby retinal blood vessels as an indicator of the RPE melanin variation. A novel whole eye optical model was designed and Monte Carlo modeling of light (MCML) was employed. We examined the influences on quantification from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness. The results show that the scheme is robust to individual histological and illumination variations. This study suggests that PAOM is capable of quantitatively measuring the RPE melanin concentration in vivo.

  16. Titanium metal: extraction to application

    Energy Technology Data Exchange (ETDEWEB)

    Gambogi, Joseph (USGS, Reston, VA); Gerdemann, Stephen J.

    2002-09-01

    In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

  17. Mineral of the month: titanium

    Science.gov (United States)

    Gambogi, Joseph

    2004-01-01

    From paint to airplanes, titanium is important in a number of applications. Commercial production comes from titanium-bearing ilmenite, rutile and leucoxene (altered ilmenite). These minerals are used to produce titanium dioxide pigment, as well as an assortment of metal and chemical products.

  18. TITANIUM DAN PADUAN TITANIUM MATERIAL PILIHAN KEDOKTERAN GIGI MASA DEPAN

    Directory of Open Access Journals (Sweden)

    Bambang Irawan

    2015-08-01

    Full Text Available Nowadays, Titanium is used for dental implants, orthodontic wires an denture bases. In Indonesia they have been widely use especially for the orthodontic treatment. Survey conducted by students from University of Indonesia showed that users have little understanding in properties of Titanium. The article describes various matters on characteristic of Titanium. Titanium has low density, low elastic modulus, high tensile strength make attractive for use in dentistry. Titanium forms a very stable oxide layers and it repassivates in a time on order of nanoseconds. Titanium oxie formation is basis for the excellent corrosion resistance an good biocompatibility. Because of their advatages and unique properties. Titanium has therefore ben called as the material of choice in dentistry.

  19. In vivo photoacoustic flow cytometry for early malaria diagnosis.

    Science.gov (United States)

    Cai, Chengzhong; Carey, Kai A; Nedosekin, Dmitry A; Menyaev, Yulian A; Sarimollaoglu, Mustafa; Galanzha, Ekaterina I; Stumhofer, Jason S; Zharov, Vladimir P

    2016-06-01

    In vivo photoacoustic (PA) flow cytometry (PAFC) has already demonstrated a great potential for the diagnosis of deadly diseases through ultrasensitive detection of rare disease-associated circulating markers in whole blood volume. Here, we demonstrate the first application of this powerful technique for early diagnosis of malaria through label-free detection of malaria parasite-produced hemozoin in infected red blood cells (iRBCs) as high-contrast PA agent. The existing malaria tests using blood smears can detect the disease at 0.001-0.1% of parasitemia. On the contrary, linear PAFC showed a potential for noninvasive malaria diagnosis at an extremely low level of parasitemia of 0.0000001%, which is ∼10(3) times better than the existing tests. Multicolor time-of-flight PAFC with high-pulse repetition rate lasers at wavelengths of 532, 671, and 820 nm demonstrated rapid spectral and spatial identification and quantitative enumeration of individual iRBCs. Integration of PAFC with fluorescence flow cytometry (FFC) provided real-time simultaneous detection of single iRBCs and parasites expressing green fluorescence proteins, respectively. A combination of linear and nonlinear nanobubble-based multicolor PAFC showed capability to real-time control therapy efficiency by counting of iRBCs before, during, and after treatment. Our results suggest that high-sensitivity, high-resolution ultrafast PAFC-FFC platform represents a powerful research tool to provide the insight on malaria progression through dynamic study of parasite-cell interactions directly in bloodstream, whereas portable hand-worn PAFC device could be broadly used in humans for early malaria diagnosis. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

  20. Biomedical applications of photoacoustic imaging with exogenous contrast agents.

    Science.gov (United States)

    Luke, Geoffrey P; Yeager, Doug; Emelianov, Stanislav Y

    2012-02-01

    Photoacoustic imaging is a biomedical imaging modality that provides functional information, and, with the help of exogenous contrast agents, cellular and molecular signatures of tissue. In this article, we review the biomedical applications of photoacoustic imaging assisted with exogenous contrast agents. Dyes, noble metal nanoparticles, and other constructs are contrast agents which absorb strongly in the near-infrared band of the optical spectrum and generate strong photoacoustic response. These contrast agents, which can be specifically targeted to molecules or cells, have been coupled with photoacoustic imaging for preclinical and clinical applications ranging from detection of cancer cells, sentinel lymph nodes, and micrometastasis to angiogenesis to characterization of atherosclerotic plaques. Multi-functional agents have also been developed, which can carry drugs or simultaneously provide contrast in multiple imaging modalities. Furthermore, contrast agents were used to guide and monitor the therapeutic procedures. Overall, photoacoustic imaging shows significant promise in its ability to assist in diagnosis, therapy planning, and monitoring of treatment outcome for cancer, cardiovascular disease, and other pathologies.

  1. The effects of pulsed laser parameters on the photoacoustic detection of glucose aqueous solution

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Huang, Zhen; Zeng, Lvming

    2017-10-01

    In this study, the photoacoustic detection system was established based on the Q switched Nd: YAG 532nm pumped optical parametric oscillator pulsed laser and the ultrasonic detector. Based on the established photoacoustic detection system, the effects of pulsed laser on the photoacoustic detection of glucose aqueous solutions were experimentally studied. The photoacoustic peak-to-peak values of glucose and pure water were obtained at different output energy of pulsed laser and at the wavelengths from 1300nm to 2200nm. Experimental results show that the photoacoustic peak-to-peak values of glucose linearly increase with the increasing of the output energy of pulsed laser. The photoacoustic peak-to-peak values were compensated because the output energy of pulsed laser exponentially decreased with the increasing of the wavelengths of pulsed laser. The characteristic wavelengths of glucose were determined according to the difference spectral between the compensated photoacoustic peak-to-peak values of glucose aqueous solution and pure water.

  2. Photoacoustic detection of blood in dental pulp by using short-time Fourier transform

    Science.gov (United States)

    Yamada, Azusa; Kakino, Satoko; Matsuura, Yuji

    2016-03-01

    A method based on photoacoustic analysis is proposed to diagnose dental pulp vitality. Photoacoustic analysis enables to get signal from deeper tissues than other optical analyses and therefore, signal detection from root canal of thick dental tissues such as molar teeth is expected. As a light source for excitation of photoacoustic waves, a microchip Q-switched YAG laser with a wavelength of 1064 nm was used and owing to large penetration depth of the near infrared laser, photoacoustic signals from dental root were successfully obtained. It was found that the photoacoustic signals from the teeth containing hemoglobin solution in the pulp cavity provide vibration in high frequency region. It was also shown that the intensities of the high frequency component have correlation with the hemoglobin concentration of solution. We applied short-time Fourier transform for evaluation of photoacoustic signals and this analysis clearly showed photoacoustic signals from dental root.

  3. Photoacoustic Imaging: Opening New Frontiers in Medical Imaging

    Directory of Open Access Journals (Sweden)

    Keerthi S Valluru

    2011-01-01

    Full Text Available In today′s world, technology is advancing at an exponential rate and medical imaging is no exception. During the last hundred years, the field of medical imaging has seen a tremendous technological growth with the invention of imaging modalities including but not limited to X-ray, ultrasound, computed tomography, magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography. These tools have led to better diagnosis and improved patient care. However, each of these modalities has its advantages as well as disadvantages and none of them can reveal all the information a physician would like to have. In the last decade, a new diagnostic technology called photoacoustic imaging has evolved which is moving rapidly from the research phase to the clinical trial phase. This article outlines the basics of photoacoustic imaging and describes our hands-on experience in developing a comprehensive photoacoustic imaging system to detect tissue abnormalities.

  4. Photoacoustic Study of Fungal Disease of Acai ( Euterpe oleracea) Seeds

    Science.gov (United States)

    Rezende, Denise V.; Nunes, O. A. C.; Oliveira, A. C.

    2009-10-01

    Photoacoustic spectroscopy is introduced as a promising experimental technique to investigate fungus infected Acai ( Euterpe oleracea) seeds. Photoacoustic spectra of healthy and infected Acai seeds with the fungus Colletotrichum gloeosporioides were recorded firstly in the modulation frequency range of 5Hz to 700 Hz, while keeping the wavelength of excitation radiation of a Xe arc-lamp constant, to ascertain the depth of penetration of infection within the seed and secondly, at variable wavelength (wavelength scanning) in the interval 250nm to 1,000 nm, while keeping the modulation frequency constant. In the former, the photoacoustic signal strength from the infected seed was found higher than that of the healthy one, and has been associated with the appearance of new biomolecules associated with the pathogen infection. In the latter, characteristics peaks and bands were observed in the range from 650 nm to 900 nm ascribed to organic compounds with carboxylates and amines (functional groups) forming the typical metabolic structures of the fungus.

  5. Multiple stimulated emission fluorescence photoacoustic sensing and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gaoming [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Key Laboratory of OptoElectronic Science and Technology for Medicine, Ministry of Education, Fujian Normal University, Fuzhou 350007 (China); Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin, E-mail: yjzheng@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Qiu, Yishen [Key Laboratory of OptoElectronic Science and Technology for Medicine, Ministry of Education, Fujian Normal University, Fuzhou 350007 (China)

    2016-07-04

    Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitation spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.

  6. Ultrasensitive photoacoustic sensor based on quantum cascade laser spectroscopy.

    Science.gov (United States)

    Kumar, Deepak; Gautam, Surya; Kumar, Subodh; Gupta, Saurabh; Srivastava, Hari B; Thakur, Surya N; Sharma, Ramesh C

    2017-04-05

    The paper focuses on development of ultra-sonic detection system based on laser photoacoustic spectroscopic technique and processing of signal for detection of very low quantity chemicals, explosive materials, and mixtures of these hazardous molecules. The detection system has been developed for the first time with specially designed one side open photo-acoustic cell having high quality factor. Explosive and Hazardous materials like RDX, DNT, PETN, Gun Powder, TATP (Tri acetone tri-peroxide) and their simulants like Acetone were detected in 7 to 9μm wavelength band. Lock in amplifier electronic instrument was used for the detection of hazardous chemicals and mixture of explosives in very low quantity. Detection limit of the photoacoustic ultrasonic sensor was also carried out of powder, liquid and adsorbed on surfaces. Copyright © 2016. Published by Elsevier B.V.

  7. Understanding climate: the role of photoacoustic spectroscopy at NIST

    Science.gov (United States)

    Gillis, Keith

    2012-02-01

    Sophisticated climate models predict that soot aerosols have a significant impact on Earth's energy budget; however, the uncertainty of these predictions is large, in part, because soot in the atmosphere and in the laboratory is poorly characterized. In the atmosphere, soot's optical and physical properties change as it combines with water vapor and sulfuric acid. We will describe a novel photoacoustic spectrometer system that measures the optical absorption cross section of various soots as they age in diverse environments. We also measure the albedo (optical scattering) of aerosols ranging from black-carbon-like to brown-carbon-like using simultaneous photoacoustic spectroscopy and cavity ring-down spectroscopy. Lastly, we developed a photoacoustic spectrometer system that measures the concentration of carbon dioxide in atmospheric air with sub-ppm uncertainty. We will report results of field tests of this spectrometer.

  8. Silver nanosystems for photoacoustic imaging and image-guided therapy

    Science.gov (United States)

    Homan, Kimberly; Shah, Jignesh; Gomez, Sobeyda; Gensler, Heidi; Karpiouk, Andrei; Brannon-Peppas, Lisa; Emelianov, Stanislav

    2010-01-01

    Due to their optical absorption properties, metallic nanoparticles are excellent photoacoustic imaging contrast agents. A silver nanosystem is presented here as a potential contrast agent for photoacoustic imaging and image-guided therapy. Currently, the nanosystem consists of a porous silver layer deposited on the surface of spherical silica cores ranging in diameter from 180 to 520 nm. The porous nature of the silver layer will allow for release of drugs or other therapeutic agents encapsulated in the core in future applications. In their current PEGylated form, the silver nanosystem is shown to be nontoxic in vitro at concentrations of silver up to 2 mg∕ml. Furthermore, the near-infrared absorbance properties of the nanosystem are demonstrated by measuring strong, concentration-dependent photoacoustic signal from the silver nanosystem embedded in an ex vivo tissue sample. Our study suggests that silver nanosystems can be used as multifunctional agents capable of augmenting image-guided therapy techniques. PMID:20459238

  9. Photoacoustic spectroscopic differences between normal and malignant thyroid tissues

    Science.gov (United States)

    Li, Li; Xie, Wengming; Li, Hui

    2012-12-01

    The thyroid is one of the main endocrine glands of human body, which plays a crucial role in the body's metabolism. Thyroid cancer mortality ranks only second to ovarian cancer in endocrine cancer. Routine diagnostic methods of thyroid diseases in present clinic exist misdiagnosis and missed diagnosis to varying degrees. Those lead to miss the best period of cancer treatment--early. Photoacoustic spectroscopy technology is a new tool, which provides an effective and noninvasive way for biomedical materials research, being highly sensitive and without sample pretreatment. In this paper, we use photoacoustic spectroscopy technology (PAST) to detect the absorption spectrum between normal and malignant thyroid tissues. The result shows that the photoacoustic spectroscopy technology (PAST) could differentiate malignant thyroid tissue from normal thyroid tissue very well. This technique combined with routine diagnostic methods has the potential to increase the diagnostic accuracy in clinical thyroid cancer diagnosis.

  10. Development of photoacoustic sensing platforms at the Army Research Laboratory.

    Science.gov (United States)

    Holthoff, Ellen L; Pellegrino, Paul M

    2017-01-20

    Traditionally, chemical sensing platforms have been hampered by the opposing concerns of increasing sensor capability while maintaining a minimal package size. Current sensors, although reasonably sized, are geared to more classical chemical threats, and the ability to expand their capabilities to a broader range of emerging threats is uncertain. Recently, photoacoustic spectroscopy, employed in a sensor format, has shown enormous potential to address these ever-changing threats. Photoacoustic spectroscopy is one of the more flexible infrared spectroscopy variants, and that flexibility allows for the construction of sensors that are designed for specific tasks. The Army Research Laboratory has, for the past 14 years, engaged in research into the development of photoacoustic sensing platforms with the goal of sensor miniaturization and the detection of a variety of chemical targets both proximally and at range. This paper reviews this work.

  11. Coregistered photoacoustic-ultrasound imaging applied to brachytherapy

    Science.gov (United States)

    Harrison, Tyler; Zemp, Roger J.

    2011-08-01

    Brachytherapy is a form of radiation therapy commonly used in the treatment of prostate cancer wherein sustained radiation doses can be precisely targeted to the tumor area by the implantation of small radioactive seeds around the treatment area. Ultrasound is a popular imaging mode for seed implantation, but the seeds are difficult to distinguish from the tissue structure. In this work, we demonstrate the feasibility of photoacoustic imaging for identifying brachytherapy seeds in a tissue phantom, comparing the received intensity to endogenous contrast. We have found that photoacoustic imaging at 1064 nm can identify brachytherapy seeds uniquely at laser penetration depths of 5 cm in biological tissue at the ANSI limit for human exposure with a contrast-to-noise ratio of 26.5 dB. Our realtime combined photoacoustic-ultrasound imaging approach may be suitable for brachytherapy seed placement and post-placement verification, potentially allowing for realtime dosimetry assessment during implantation.

  12. Ultrasensitive photoacoustic sensor based on quantum cascade laser spectroscopy

    Science.gov (United States)

    Kumar, Deepak; Gautam, Surya; Kumar, Subodh; Gupta, Saurabh; Srivastava, Hari B.; Thakur, Surya N.; Sharma, Ramesh C.

    2017-04-01

    The paper focuses on development of ultra-sonic detection system based on laser photoacoustic spectroscopic technique and processing of signal for detection of very low quantity chemicals, explosive materials, and mixtures of these hazardous molecules. The detection system has been developed for the first time with specially designed one side open photo-acoustic cell having high quality factor. Explosive and Hazardous materials like RDX, DNT, PETN, Gun Powder, TATP (Tri acetone tri-peroxide) and their simulants like Acetone were detected in 7 to 9 μm wavelength band. Lock in amplifier electronic instrument was used for the detection of hazardous chemicals and mixture of explosives in very low quantity. Detection limit of the photoacoustic ultrasonic sensor was also carried out of powder, liquid and adsorbed on surfaces.

  13. Photoacoustic-guided focused ultrasound for accurate visualization of brachytherapy seeds with the photoacoustic needle

    Science.gov (United States)

    Singh, Mithun Kuniyil Ajith; Parameshwarappa, Vinay; Hendriksen, Ellen; Steenbergen, Wiendelt; Manohar, Srirang

    2016-12-01

    An important problem in minimally invasive photoacoustic (PA) imaging of brachytherapy seeds is reflection artifacts caused by the high signal from the optical fiber/needle tip reflecting off the seed. The presence of these artifacts confounds interpretation of images. In this letter, we demonstrate a recently developed concept called photoacoustic-guided focused ultrasound (PAFUSion) for the first time in the context of interstitial illumination PA imaging to identify and remove reflection artifacts. In this method, ultrasound (US) from the transducer is focused on the region of the optical fiber/needle tip identified in a first step using PA imaging. The image developed from the US diverging from the focus zone at the tip region visualizes only the reflections from seeds and other acoustic inhomogeneities, allowing identification of the reflection artifacts of the first step. These artifacts can then be removed from the PA image. Using PAFUSion, we demonstrate reduction of reflection artifacts and thereby improved interstitial PA visualization of brachytherapy seeds in phantom and ex vivo measurements on porcine tissue.

  14. Photoacoustic trace gas sensing : application to fruit and insects

    OpenAIRE

    Persijn, Stefan Timotheüs

    2001-01-01

    A novel photoacoustic spectrometer has been applied to study trace gas emissions by fruit and insects. The spectrometer is based on a newly designed CO laser that can operate on 400 laser lines between 5.1-8.0 and 2.8-4.1 micrometer (delta v=1 and 2 mode, respectively). The spectrometer is equipped with three intracavity photoacoustic cells which introduces additional losses in the laser cavity, but still a proper operation in the delta v=2 mode with its low gain is possible. Fast switching b...

  15. DMD-based spatially Fourier-encoded photoacoustic microscopy

    Science.gov (United States)

    Liang, Jinyang; Gao, Liang; Li, Chiye; Wang, Lihong V.

    2015-03-01

    We present spatially Fourier-encoded photoacoustic microscopy using a digital micromirror device (DMD). The spatial fluence distribution of laser pulses is Fourier-encoded by the DMD, and a series of such encoded photoacoustic (PA) measurements enables decoding of the spatial distribution of optical absorption. By imaging a chromium target, we demonstrated the throughput and Fellgett advantages, which increased the PA signal-to-noise ratio (SNR) compared to raster scanning. The system was used to image two biological targets, a monolayer of red blood cells, and melanoma cells. The enhanced SNR benefited PA images by increasing the image's contrast-to-noise ratio and target identifiability.

  16. Full field-of-view photoacoustic endoscopy in vivo

    Science.gov (United States)

    Lin, Riqiang; Li, Yan; Chen, Jianhua; Song, Liang

    2017-03-01

    We developed a miniaturized, simple and full field-of-view photoacoustic/ultrasonic endoscopy system, and used a flexible coil to transmit the rotational torque from the rotary stage, which enables a 360o field-of-view imaging in vivo. The developed imaging catheter was fully encapsulated by a single-use protective polyamide tube. A B-scan rate up to 5 Hz (200 A-lines/B-scan) was achieved. Three-dimensional photoacoustic and ultrasound images of the rectum from a SD rat were acquired in vivo. It suggests that this PAE system can be of great interest for clinical translation for a variety of endoscopic applications.

  17. Photoacoustic ultrasound sources from diffusion-limited aggregates

    Science.gov (United States)

    Patel, Krutik; Brubaker, Morgan; Kotlerman, Alexander; Salazar, Robert; Wolf, Eli; Weld, David M.

    2016-10-01

    Metallic diffusion-limited aggregate (DLA) films are well-known to exhibit near-perfect broadband optical absorption. We demonstrate that such films also manifest a substantial and relatively material-independent photoacoustic response, as a consequence of their random nanostructure. We theoretically and experimentally analyze the photoacoustic phenomena in DLA films and show that they can be used to create broadband air-coupled acoustic sources. These sources are inexpensive and simple to fabricate and work into the ultrasonic regime. We illustrate the device possibilities by building and testing an optically addressed acoustic phased array capable of producing virtually arbitrary acoustic intensity patterns in air.

  18. Using high-power light emitting diodes for photoacoustic imaging

    DEFF Research Database (Denmark)

    Hansen, René Skov

    The preliminary result of using a high-power light emitting diode, LED, for photoacoustic imaging is presented. The pulsed light source is created by a 1Watt red Luxeon LED. The LED delivers light pulses with 25W peak power when supplied by 40A peak, 60ns wide current pulses. The phantom used...... for the experiment consists of a 3mm high x 5mm wide slice of green colored gelatine overlaid by a 3cm layer of colorless gelatine. The light pulses from the LED is focused on the green gelatine. The photoacoustic response from the green gelatine is detected by a single transducer on the opposite (top) surface...

  19. Optimal laser wavelength for photoacoustic imaging of breast microcalcifications

    Science.gov (United States)

    Kang, Jeeun; Kim, Eun-Kyung; Young Kwak, Jin; Yoo, Yangmo; Song, Tai-Kyong; Ho Chang, Jin

    2011-10-01

    This paper presents photoacoustic imaging (PAI) for real-time detection of micro-scale calcifications (e.g., breast, which are an indicator of the cancer occurrence. Optimal wavelength of incident laser for the microcalcification imaging was ascertained through ex vivo experiments with seven breast specimens of volunteers. In the ex vivo experiments, the maximum amplitude of photoacoustic signals from the microcalcifications occurred when the laser wavelength ranged from 690 to 700 nm. This result demonstrated that PAI can serve as a real-time imaging and guidance tool for diagnosis and biopsy of the breast microcalcifications.

  20. Off-beam quartz-enhanced photoacoustic spectroscopy.

    Science.gov (United States)

    Liu, Kun; Guo, Xiaoyong; Yi, Hongming; Chen, Weidong; Zhang, Weijun; Gao, Xiaoming

    2009-05-15

    An off-beam (OB) detection approach is suggested and experimentally investigated and optimized for quartz-enhanced photoacoustic spectroscopy (QEPAS). This OB-QEPAS configuration, very simple in assembly, not only allows for use of larger excitation optical beams and facilitating optical alignment but also provides higher enhancement of photoacoustic signals than previously published results based on the common on-beam QEPAS under the same experimental conditions. A normalized noise equivalent absorption coefficient (1sigma) of 5.9 x 10(-9) cm(-1)W/Hz(1/2) was obtained for water vapor detection at normal atmospheric pressure.

  1. Novel compact photoacoustic imaging system to explore the applications in the medical imaging field

    Science.gov (United States)

    Irisawa, Kaku; Wada, Takatsugu; Hayakawa, Toshiro; Ishihara, Miya

    2017-04-01

    PhotoAcoustic (PA) imaging is a promising imaging method using the pulsed-laser light source and ultrasound detector. PA image shows the features of optical contrast in biological tissue with ultrasound-like depth and resolution. In the human body, Hemoglobin of the blood is strong optical absorber, so the high-contrast blood distribution (vascular) image is obtained by PA imaging. Recently, FUJIFILM has developed the PA imaging system to explore its application in medical imaging field. In this system, the fusion of PA and conventional ultrasound image is realized, for example, ultrasound Doppler image is superposed to the PA and B-mode image. The system features and some results of clinical studies will be introduced.

  2. Photoacoustic Molecular Imaging: From Multiscale Biomedical Applications Towards Early-Stage Theranostics.

    Science.gov (United States)

    Liu, Yajing; Nie, Liming; Chen, Xiaoyuan

    2016-05-01

    Photoacoustic imaging (PAI) has ushered in a new era of observational biotechnology and has facilitated the exploration of fundamental biological mechanisms and clinical translational applications, which has attracted tremendous attention in recent years. By converting laser into ultrasound emission, PAI combines rich optical contrast, high ultrasonic spatial resolution, and deep penetration depth in a single modality. This evolutional technique enables multiscale and multicontrast visualization from cells to organs, anatomy to function, and molecules to metabolism with high sensitivity and specificity. The state-of-the-art developments and applications of PAI are described in this review. Future prospects for clinical use are also highlighted. Collectively, PAI holds great promise to drive biomedical applications towards early-stage theranostics. Published by Elsevier Ltd.

  3. A cost-effective functional connectivity photoacoustic tomography (fcPAT) of the mouse brain

    Science.gov (United States)

    Hariri, Ali; Fatima, Afreen; Nasiriavanaki, Mohammadreza

    2017-03-01

    The study of functional connectivity among different regions of the brain is tremendously valuable in the diagnosis and monitoring of various neurological disorders. While the conventional techniques fail to provide optimum results in terms of resolution, field of view and efficiency, Photo-acoustic based imaging is being considered as an alternative and complimentary modality. The cost and size are the factors that limit the further research and clinical advancements of fcPAT. Therefore we proposed an inexpensive fcPAT system. We determined its feasibility by imaging a graphite leads embedded in an agar phantom and demonstrated its application by imaging a microtubes filled with blood embedded in the chicken's breast at a scan time of 50 seconds and number of angles as 300.

  4. A charge amplification approach for photoacoustic tomography (PAT) with parallel acoustic delay line (PADL) arrays

    Science.gov (United States)

    Fang, Cheng; Ustun, Arif; Cho, Young; Zou, Jun

    2017-05-01

    This paper reports the development of a new charge amplification approach for photoacoustic tomography (PAT) based on parallel acoustic delay line (PADL) arrays. By using a PADL array to create different time delays, multiple-channel PA signals can be received simultaneously with a single-element transducer followed by single-channel DAQ electronics for image reconstruction. Unlike the conventional voltage amplifiers whose output voltage drops with increasing transducer capacitance, both theoretical analysis and experimental results have shown that the charge amplification can provide almost constant transducer-amplifier gain, which is not affected by the transducer capacitance. Therefore, it allows the use of a large single-element transducer to interface many PADLs without sacrificing the SNR of each channel. This opens the possibility of using large PADL arrays to achieve PAT with a wide field of view and high lateral resolution.

  5. Tumor glucose metabolism imaged in vivo in small animals with whole-body photoacoustic computed tomography

    Science.gov (United States)

    Chatni, Muhammad Rameez; Xia, Jun; Sohn, Rebecca; Maslov, Konstantin; Guo, Zijian; Zhang, Yu; Wang, Kun; Xia, Younan; Anastasio, Mark; Arbeit, Jeffrey; Wang, Lihong V.

    2012-07-01

    With the increasing use of small animals for human disease studies, small-animal whole-body molecular imaging plays an important role in biomedical research. Currently, none of the existing imaging modalities can provide both anatomical and glucose molecular information, leading to higher costs of building dual-modality systems. Even with image co-registration, the spatial resolution of the molecular imaging modality is not improved. Utilizing a ring-shaped confocal photoacoustic computed tomography system, we demonstrate, for the first time, that both anatomy and glucose uptake can be imaged in a single modality. Anatomy was imaged with the endogenous hemoglobin contrast, and glucose metabolism was imaged with a near-infrared dye-labeled 2-deoxyglucose.

  6. Laser photoacoustic technique for ultrasonic surface acoustic wave velocity evaluation on porcelain

    Science.gov (United States)

    Qian, K.; Tu, S. J.; Gao, L.; Xu, J.; Li, S. D.; Yu, W. C.; Liao, H. H.

    2016-10-01

    A laser photoacoustic technique has been developed to evaluate the surface acoustic wave (SAW) velocity of porcelain. A Q-switched Nd:YAG laser at 1064 nm was focused by a cylindrical lens to initiate broadband SAW impulses, which were detected by an optical fiber interferometer with high spatial resolution. Multiple near-field surface acoustic waves were observed on the sample surface at various locations along the axis perpendicular to the laser line source as the detector moved away from the source in the same increments. The frequency spectrum and dispersion curves were obtained by operating on the recorded waveforms with cross-correlation and FFT. The SAW phase velocities of the porcelain of the same source are similar while they are different from those of different sources. The marked differences of Rayleigh phase velocities in our experiment suggest that this technique has the potential for porcelain identification.

  7. Biomechanical and morphological multi-parameter photoacoustic endoscope for identification of early esophageal disease

    Science.gov (United States)

    Jin, Dayang; Yang, Fen; Chen, Zhongjiang; Yang, Sihua; Xing, Da

    2017-09-01

    The combination of phase-sensitive photoacoustic (PA) imaging of tissue viscoelasticity with the esophagus-adaptive PA endoscope (PAE) technique allows the characterization of the biomechanical and morphological changes in the early stage of esophageal disease with high accuracy. In this system, the tissue biomechanics and morphology are obtained by detecting the PA phase and PA amplitude information, respectively. The PAE has a transverse resolution of approximately 37 μm and an outer diameter of 1.2 mm, which is suitable for detecting rabbit esophagus. Here, an in-situ biomechanical and morphological study of normal and diseased rabbit esophagus (tumors of esophagus and reflux esophagitis) was performed. The in-situ findings were highly consistent with those observed by histology. In summary, we demonstrated the potential application of PAE for early clinical detection of esophageal diseases.

  8. Development of Modified Titanium Nitride Nanoparticles as Potential Contrast Material for Photoacoustic Imaging

    Science.gov (United States)

    2014-05-10

    to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data...needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection...based on modified fullerenes , carbon nanotubes and gold nanoparticles (including nanocages and nanorods) were very recently reported.4 Nevertheless, this

  9. Joseph F. Keithley Award For Advances in Measurement Science Lecture: Thermophotonic and Photoacoustic Radar Imaging Methods for Biomedical and Dental Imaging

    Science.gov (United States)

    Mandelis, Andreas

    2012-02-01

    In the first part of this presentation I will introduce thermophotonic radar imaging principles and techniques using chirped or binary-phase-coded modulation, methods which can break through the maximum detection depth/depth resolution limitations of conventional photothermal waves. Using matched-filter principles, a methodology enabling parabolic diffusion-wave energy fields to exhibit energy localization akin to propagating hyperbolic wave-fields has been developed. It allows for deconvolution of individual responses of superposed axially discrete sources, opening a new field: depth-resolved thermal coherence tomography. Several examples from dental enamel caries diagnostic imaging to metal subsurface defect thermographic imaging will be discussed. The second part will introduce the field of photoacoustic radar (or sonar) biomedical imaging. I will report the development of a novel biomedical imaging system that utilizes a continuous-wave laser source with a custom intensity modulation pattern, ultrasonic phased array for signal detection and processing coupled with a beamforming algorithm for reconstruction of photoacoustic correlation images. Utilization of specific chirped modulation waveforms (``waveform engineering'') achieves dramatic signal-to-noise-ratio increase and improved axial resolution over pulsed laser photoacoustics. The talk will conclude with aspects of instrumental sensitivity of the PA Radar to optical contrast using cancerous breast tissue-mimicking phantoms, super paramagnetic iron oxide nanoparticles as contrast enhancement agents and in-vivo tissue samples.

  10. Photoacoustic active ultrasound element for catheter tracking

    Science.gov (United States)

    Guo, Xiaoyu; Tavakoli, Behnoosh; Kang, Hyun-Jae; Kang, Jin U.; Etienne-Cummings, Ralph; Boctor, Emad M.

    2014-03-01

    In recent years, various methods have been developed to improve ultrasound based interventional tool tracking. However, none of them has yet provided a solution that effectively solves the tool visualization and mid-plane localization accuracy problem and fully meets the clinical requirements. Our previous work has demonstrated a new active ultrasound pattern injection system (AUSPIS), which integrates active ultrasound transducers with the interventional tool, actively monitors the beacon signals and transmits ultrasound pulses back to the US probe with the correct timing. Ex vivo and in vivo experiments have proved that AUSPIS greatly improved tool visualization, and provided tool-tip localization accuracy of less than 300 μm. In the previous work, the active elements were made of piezoelectric materials. However, in some applications the high driving voltage of the piezoelectric element raises safety concerns. In addition, the metallic electrical wires connecting the piezoelectric element may also cause artifacts in CT and MR imaging. This work explicitly focuses on an all-optical active ultrasound element approach to overcome these problems. In this approach, the active ultrasound element is composed of two optical fibers - one for transmission and one for reception. The transmission fiber delivers a laser beam from a pulsed laser diode and excites a photoacoustic target to generate ultrasound pulses. The reception fiber is a Fabry-Pérot hydrophone. We have made a prototype catheter and performed phantom experiments. Catheter tip localization, mid-plan detection and arbitrary pattern injection functions have been demonstrated using the all-optical AUSPIS.

  11. Photoacoustic spectroscopic studies of polycyclic aromatic hydrocarbons

    Science.gov (United States)

    Zaidi, Zahid H.; Kumar, Pardeep; Garg, R. K.

    1999-02-01

    Because of their involvement in environmental pollutants, in carcinogenic activity, plastics, pharmaceuticals, synthesis of some laser dyes and presence in interstellar space etc., Polycyclic aromatic hydrocarbons (PAHs) are important. As their structure and properties can be varied systematically, they form a beautiful class of molecules for experimental and quantum chemical investigations. These molecules are being studied for last several years by using conventional spectroscopy. In recent years, Photoacoustic (PA) spectroscopy has emerged as a new non-destructive technique with unique capability and sensitivity. The PA effect is the process of generation of acoustic waves in a sample resulting from the absorption of photons. This technique not only reveals non- radiative transitions but also provides information about forbidden singlet-triplet transitions which are not observed normally by the conventional spectroscopy. The present paper deals with the spectroscopic studies of some PAH molecules by PA spectroscopy in the region 250 - 400 nm. The CNDO/S-CI method is used to calculate the electronic transitions with the optimized geometries. A good agreement is found between the experimental and calculated results.

  12. Photoacoustic and ultrasound characterization of bone composition

    Science.gov (United States)

    Lashkari, Bahman; Yang, Lifeng; Liu, Lixian; Tan, Joel W. Y.; Mandelis, Andreas

    2015-02-01

    This study examines the sensitivity and specificity of backscattered ultrasound (US) and backscattering photoacoustic (PA) signals for bone composition variation assessment. The conventional approach in the evaluation of bone health relies on measurement of bone mineral density (BMD). Although, a crucial and probably the most important parameter, BMD is not the only factor defining the bone health. New trends in osteoporosis research, also pursue the changes in collagen content and cross-links with bone diseases and aging. Therefore, any non-invasive method that can assess any of these parameters can improve the diagnostic tools and also can help with the biomedical studies on the diseases themselves. Our previous studies show that both US and PA are responsive to changes in the BMD, PA is, in addition, sensitive to changes in the collagen content of the bone. Measurements were performed on bone samples before and after mild demineralization and decollagenization at the exact same points. Results show that combining both modalities can enhance the sensitivity and specificity of diagnostic tool.

  13. Intracavity quartz-enhanced photoacoustic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Borri, S., E-mail: simone.borri@ino.it; Galli, I.; Mazzotti, D.; Giusfredi, G.; De Natale, P. [CNR-INO UOS Sesto Fiorentino and LENS, via Carrara 1, 50019 Sesto Fiorentino FI (Italy); Patimisco, P.; Scamarcio, G.; Spagnolo, V. [CNR-IFN UOS Bari and Dipartimento Interateneo di Fisica, Università degli Studi di Bari e Politecnico di Bari, via Amendola 173, 70126 Bari BA (Italy); Akikusa, N. [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan); Yamanishi, M. [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)

    2014-03-03

    We report on a spectroscopic technique named intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) employed for sensitive trace-gas detection in the mid-infrared spectral region. It is based on a combination of QEPAS with a buildup optical cavity. The sensor includes a distributed feedback quantum cascade laser emitting at 4.33 μm. We achieved a laser optical power buildup factor of ∼500, which corresponds to an intracavity laser power of ∼0.75 W. CO{sub 2} has been selected as the target molecule for the I-QEPAS demonstration. We achieved a detection sensitivity of 300 parts per trillion for 4 s integration time, corresponding to a noise equivalent absorption coefficient of 1.4 × 10{sup −8} cm{sup −1} and a normalized noise-equivalent absorption of 3.2 × 10{sup −10} W cm{sup −1} Hz{sup −1/2}.

  14. Photoacoustic Tomography Imaging of the Adult Zebrafish by Using Unfocused and Focused High-Frequency Ultrasound Transducers

    Directory of Open Access Journals (Sweden)

    Yubin Liu

    2016-11-01

    Full Text Available The zebrafish model provides an essential platform for the study of human diseases or disorders due to the possession of about 87% homologous genes with human. However, it is still very challenging to noninvasively visualize the structure and function of adult zebrafish based on available optical imaging techniques. In this study, photoacoustic tomography (PAT was utilized for high-resolution imaging of adult zebrafish by using focused and unfocused high-frequency (10 MHz ultrasound transducers. We examined and compared the imaging results from the two categories of transducers with in vivo experimental tests, in which we discovered that the unfocused transducer is able to identify the inner organs of adult zebrafish with higher contrast but limited regional resolution, whereas the findings from the focused transducer were with high resolution but limited regional contrast for the recovered inner organs.

  15. The effect of Se content on defect levels in CuInSe{sub 2} single crystals detected by photoacoustic spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zegadi, A.; Yakushev, M.V.; Ahmed, E.; Hill, A.E.; Tomlinson, R.D. [Salford Univ. (United Kingdom). Dept. of Electronic and Electrical Engineering; Slifkin, M.A. [Jerusalem Coll. of Technology (Israel). Dept. of Electrical Engineering

    1994-12-31

    The objective of this paper is to investigate the impact of changes in the selenium content of CuInSe{sub 2} single crystals on their optical properties in the subgap region of the infrared spectrum. A high resolution near-infrared photoacoustic spectrometer of the gas-microphone type is used for room temperature analysis of non-radiative defect states in as-grown n and p-type CIS crystals. Samples with an excess and a deficiency of Se (5% off the stoichiometric composition), were grown from the melt by the vertical Bridgman technique. The absorption coefficient has been derived from photoacoustic spectra in order to establish activation energies for several defect-related energy levels.

  16. Titanium alloys for aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    Peters, M.; Leyens, C. [DLR-German Aerospace Center, D-51170 Koeln (Germany); Kumpfert, J. [Airbus Industrie, F-31707 Blagnac (France); Ward, C.H. [US Air Force Research Laboratory, London NW1 5TH (United Kingdom)

    2003-06-01

    There is probably no other material more closely related to aerospace than titanium and its alloys. With a density of 4.5 g/cm{sup 3}, titanium alloys are only about half as heavy as steel or Ni-based superalloys, yielding an excellent strength-to-weight ratio. Furthermore, they have exceptional corrosion resistance. The use of titanium alloys in the aerospace sector will be highlighted including airframe, engine, helicopter, and space applications. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  17. Titanium: light, strong, and white

    Science.gov (United States)

    Woodruff, Laurel; Bedinger, George

    2013-01-01

    Titanium (Ti) is a strong silver-gray metal that is highly resistant to corrosion and is chemically inert. It is as strong as steel but 45 percent lighter, and it is twice as strong as aluminum but only 60 percent heavier. Titanium dioxide (TiO2) has a very high refractive index, which means that it has high light-scattering ability. As a result, TiO2 imparts whiteness, opacity, and brightness to many products. ...Because of the unique physical properties of titanium metal and the whiteness provided by TiO2, titanium is now used widely in modern industrial societies.

  18. Initial results of finger imaging using photoacoustic computed tomography

    NARCIS (Netherlands)

    van Es, Peter; Biswas, Samir Kumar; Bernelot Moens, Hein J.; Steenbergen, Wiendelt; Manohar, Srirang

    2014-01-01

    We present a photoacoustic computed tomography investigation on a healthy human finger, to image blood vessels with a focus on vascularity across the interphalangeal joints. The cross-sectional images were acquired using an imager specifically developed for this purpose. The images show rich detail

  19. Photoacoustic monitoring of life cycles of Leishmania Mexicana

    Science.gov (United States)

    Arguello, C.; Acosta-Avalos, D.; Alvarado-Gil, J. J.; Vargas, H.

    1999-03-01

    Photoacoustic spectroscopy is used to monitor in situ, the difference between the two forms of the protozoan Leishmania Mexicana. Differences are the result of changes in the respiratory chain and could be attributed, according to our results, to the presence of cytochrome b in promastigotes and cytochrome c in amastigotes.

  20. Multispectral photoacoustic bioimaging using low power continuous wave lasers

    Science.gov (United States)

    Sathiyamoorthy, K.; Strohm, Eric M.; Kolios, Michael C.

    2017-03-01

    We have developed a low-cost, non-contact, multispectral photoacoustic microscope system to study the functional parameters of cellular choromophores. The system uses low power continuous wave lasers and a photoacoustic sensor made of a kHz microphone coupled to a resonant chamber. Methemoglobin has relatively high optical absorption at 500 nm and 630 nm. Moreover, it has an almost the same optical absorption as hemoglobin at the isosbestic point of 525 nm. Photoacoustic data collected from methemoglobin using our system at wavelengths of 473 nm, 533 nm, and 633 nm show the similar trends as the methemoglobin optical absorption spectrum. The PA amplitude at 473 nm is about 1.03 times greater than at 533 nm and about 2.4 times greater than at 633 nm. Similarly, it possesses optical absorption of about 1.08 greater than at 533 nm and 1.34 times greater than at 633 nm. The developed system can be used as a differential photoacoustic microscope.

  1. Photoacoustic elastic bending in thin film—Substrate system

    Energy Technology Data Exchange (ETDEWEB)

    Todorović, D. M., E-mail: dmtodor@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, P.O. Box 33, 11030 Belgrade (Serbia); Rabasović, M. D.; Markushev, D. D. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade-Zemun (Serbia)

    2013-12-07

    Theoretical model for optically excited two-layer elastic plate, which includes plasmaelastic, thermoelastic, and thermodiffusion mechanisms, is given in order to study the dependence of the photoacoustic (PA) elastic bending signal on the optical, thermal, and elastic properties of thin film—substrate system. Thin film-semiconductor sample (in our case Silicon) is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Multireflection effects in thin film are included in theoretical model and analyzed. Relations for the amplitude and phase of electronic and thermal elastic bending in the optically excited two-layer mechanically-supported circular plate are derived. Theoretical analysis of the thermodiffusion, plasmaelastic, and thermoelastic effects in a sample-gas-microphone photoacoustic detection configuration is given. Two normalization procedures of the photoacoustic elastic bending signal in function of the modulation frequency of the optical excitation are established. Given theoretical model can be used for various photoacoustic detection configurations, for example, in the study of optical, thermal, and elastic properties of the dielectric-semiconductor or metal-semiconductor structure, etc., Theoretical analysis shows that it is possible to develop new noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 μm.

  2. Applications of infrared photo-acoustic spectroscopy for wood samples

    Science.gov (United States)

    Mon-Lin Kuo; John F. McClelland; Siquan Luo; Po-Liang Chien; R.D. Walker; Chung-Yun Hse

    1988-01-01

    Various infrared (IR) spectroscopic techniques for the analysis of wood samples are briefly discussed. Theories and instrumentation of the newly developed photoacoustic spectroscopic (PAS) technique for measuring absorbance spectra of solids are presented. Some important applications of the PAS technique in wood science research are discussed. The application of the...

  3. Photoacoustic measurements of photokinetics in single optically trapped aerosol droplets

    Science.gov (United States)

    Covert, Paul; Cremer, Johannes; Signorell, Ruth; Thaler, Klemens; Haisch, Christoph

    2017-04-01

    It is well established that interaction of light with atmospheric aerosols has a large impact on the Earth's climate. However, uncertainties in the magnitude of this impact remain large, due in part to broad distributions of aerosol size, composition, and chemical reactivity. In this context, photoacoustic spectroscopy is commonly used to measure light absorption by aerosols. Here, we present photoacoustic measurements of single, optically-trapped nanodroplets to reveal droplet size-depencies of photochemical and physical processes. Theoretical considerations have pointed to a size-dependence in the magnitude and phase of the photoacoustic response from aerosol droplets. This dependence is thought to originate from heat transfer processes that are slow compared to the acoustic excitation frequency. In the case of a model aerosol, our measurements of single particle absorption cross-section versus droplet size confirm these theoretical predictions. In a related study, using the same model aerosol, we also demonstrate a droplet size-dependence of photochemical reaction rates [1]. Within sub-micron sized particles, photolysis rates were observed to be an order of magnitude greater than those observed in larger droplets. [1] J. W. Cremer, K. M. Thaler, C. Haisch, and R. Signorell. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics. Nat. Commun., 7:10941, 2016.

  4. Ultrasound-transmission parameter imaging in a photoacoustic imager

    NARCIS (Netherlands)

    Jose, J.; Jose, J.; Willemink, Rene; Resink, Steffen; Maalderink, T.; van Hespen, Johannes C.G.; van Leeuwen, Ton; Manohar, Srirang; Depeursinge, Christian D.; Vitkin, I. Alex

    2009-01-01

    We present a 'hybrid' imaging system, which can image both optical absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography photoacoustic imager. The ultrasound transmission measurement method uses a strong absorber of light which

  5. Photoacoustic trace gas sensing : application to fruit and insects

    NARCIS (Netherlands)

    Persijn, Stefan Timotheüs

    2001-01-01

    A novel photoacoustic spectrometer has been applied to study trace gas emissions by fruit and insects. The spectrometer is based on a newly designed CO laser that can operate on 400 laser lines between 5.1-8.0 and 2.8-4.1 micrometer (delta v=1 and 2 mode, respectively). The spectrometer is equipped

  6. Photoacoustic emission from Au nanoparticles arrayed on thermal insulation layer.

    Science.gov (United States)

    Namura, Kyoko; Suzuki, Motofumi; Nakajima, Kaoru; Kimura, Kenji

    2013-04-08

    Efficient photoacoustic emission from Au nanoparticles on a porous SiO(2) layer was investigated experimentally and theoretically. The Au nanoparticle arrays/porous SiO(2)/SiO(2)/Ag mirror sandwiches, namely, local plasmon resonators, were prepared by dynamic oblique deposition (DOD). Photoacoustic measurements were performed on the local plasmon resonators, whose optical absorption was varied from 0.03 (3%) to 0.95 by varying the thickness of the dielectric SiO(2) layer. The sample with high absorption (0.95) emitted a sound that was eight times stronger than that emitted by graphite (0.94) and three times stronger than that emitted by the sample without the porous SiO(2) layer (0.93). The contribution of the porous SiO(2) layer to the efficient photoacoustic emission was analyzed by means of a numerical method based on a one-dimensional heat transfer model. The result suggested that the low thermal conductivity of the underlying porous layer reduces the amount of heat escaping from the substrate and contributes to the efficient photoacoustic emission from Au nanoparticle arrays. Because both the thermal conductivity and the spatial distribution of the heat generation can be controlled by DOD, the local plasmon resonators produced by DOD are suitable for the spatio-temporal modulation of the local temperature.

  7. An algorithm for total variation regularized photoacoustic imaging

    DEFF Research Database (Denmark)

    Dong, Yiqiu; Görner, Torsten; Kunis, Stefan

    2014-01-01

    Recovery of image data from photoacoustic measurements asks for the inversion of the spherical mean value operator. In contrast to direct inversion methods for specific geometries, we consider a semismooth Newton scheme to solve a total variation regularized least squares problem. During the iter...

  8. Identification and elimination of reflection artifacts in biomedical photoacoustic imaging

    NARCIS (Netherlands)

    Kuniyil Ajith Singh, M.

    2016-01-01

    Photoacoustic (PA) or optoacoustic imaging is a hybrid imaging modality that acoustically detects optical absorption contrast via the PA effect, a physical phenomenon that converts absorbed optical energy into acoustic energy. PA imaging is one of the fastest growing fields in biomedical optics, and

  9. A simple photoacoustic detector for highly corrosive gases

    Czech Academy of Sciences Publication Activity Database

    Rakovský, Jozef; Votava, Ondřej

    2017-01-01

    Roč. 88, č. 1 (2017), č. článku 013103. ISSN 0034-6748 R&D Projects: GA ČR GA13-11635S Institutional support: RVO:61388955 Keywords : photoacoustic spectroscopy * biosensors * laser sensors Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.515, year: 2016

  10. Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

    NARCIS (Netherlands)

    Xia, W.; Piras, D.; Heijblom, M.; Steenbergen, Wiendelt; van Leeuwen, Ton; Manohar, Srirang

    2011-01-01

    A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F–T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where

  11. Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

    NARCIS (Netherlands)

    Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G.; Manohar, Srirang

    2011-01-01

    A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where

  12. Image reconstruction in a passive element enriched photoacoustic tomography setup

    NARCIS (Netherlands)

    Willemink, Rene

    2010-01-01

    Photoacoustic imaging is a relatively new imaging technology, in which an object is illuminated with optical energy and where in return measurements are taken in the acoustical domain, in order to image the optical absorption distribution inside the object. In this thesis we focus on an experimental

  13. Endobronchial Photoacoustic Microscopy for Staging of Lung Cancer

    Science.gov (United States)

    2016-08-01

    properly manage the treatment of patients, the staging of lung cancer needs to be accurately performed. Surgical resection is mostly preferred when the...integrate the photoacoustic imaging modality into endoscopy through trachea is the limited room for the implementation of scanning. We have identified...disciplinary research team involving researchers in imaging, molecular targeting, tunable focusing, cancer biology, and surgical oncology

  14. Endobronchial Photoacoustic Microscopy for Staging of Lung Cancer

    Science.gov (United States)

    2015-06-01

    ORGANIZATION REPORT NUMBER Department of Biomedical Engineering, University of Florida JG56 BMS building 1275 center Dr. Gainesville FL 32601 xx 9... nanoparticle /dye for lymph node imaging have also been tested. 15. SUBJECT TERMS Endoscopic photoacoustic imaging, lung cancer, tumor staging, tunable...cancer. This technology focused application has put together a truly multi-disciplinary research team involving researchers in imaging, molecular

  15. Wavelength-stabilization-based photoacoustic spectroscopy for methane detection

    Science.gov (United States)

    Wang, Qiang; Wang, Zhen; Ren, Wei

    2017-06-01

    A compact and portable photoacoustic gas sensor was developed for sensitive methane (CH4) detection at 1.6 µm using a software-based wavelength stabilization scheme. A transmission-type photoacoustic cell was connected in series with a reference gas cell to measure the photoacoustic signal and the reference gas absorption for wavelength stabilization simultaneously. The central wavelength of the diode laser was locked to the target CH4 line with a fluctuation of less than 10.6 MHz using a digital proportional-integral-derivative controller. The CH4 sensor was designed to be insensitive to the incoherent external acoustic noise by the cumulative average of the demodulated photoacoustic signal by a digital lock-in amplifier. With an incident laser power of 6 mW, our CH4 sensor achieved a minimum detection limit of 11.5 ppm at 10 s response time and an excellent linearity (R 2  =  0.9999) in the concentration range of 400-6300 ppm.

  16. Coherent fiber bundle based integrated photoacoustic, ultrasound and fluorescence imaging (PAUSFI) for endoscopy and diagnostic bio-imaging applications

    Science.gov (United States)

    James, Joseph; Murukeshan, V. M.; Sathiyamoorthy, K.; Woh, Lye Sun

    2014-08-01

    Recent research in diagnostic imaging and sensing focuses on deriving complementary information from the diagnosed site. From that perspective it is imperative to devise new imaging platforms where multiple distinct modalities are used either simultaneously or sequentially. Increased efforts have been devoted towards establishing such multi-modal imaging systems, which house and operate more than two imaging modalities within a single instrumentation set-up. In this context, we propose a novel multi-modal imaging platform using non-ionizing radiation that has been successfully conceptualized, established and experimentally demonstrated. This proposed GRIN lensed fiber-optic microscope and linear array transducer based PAUSFI (photoacoustic, ultrasound and fluorescence imaging) system makes use of non-ionizing radiation sources to map optical and acoustic heterogeneities (complementary information) along the depth of the tissue at multi-scale resolution (microscopic to mesoscopic). The fiber-optic assembly enables the system to perform minimally invasive remote light delivery and high resolution fluorescence and photoacoustic imaging of inaccessible areas of intact tissues or intra body cavities. It is expected that the proposed multi-modal imaging system could open up niches in bio-imaging research in the near future.

  17. Characterizing intraocular tumors with photoacoustic imaging

    Science.gov (United States)

    Xu, Guan; Xue, Yafang; Gursel, Zeynep; Slimani, Naziha; Wang, Xueding; Demirci, Hakan

    2016-03-01

    Intraocular tumors are life-threatening conditions. Long-term mortality from uveal melanoma, which accounts for 80% of primary intraocular tumors, could be as high as 25% depending on the size, ciliary body involvement and extraocular extension. The treatments of intraocular tumors include eye-sparing approaches such as radiotherapy and thermotherapy, and the more aggressive enucleation. The accurate diagnosis of intraocular tumors is thereby critical in the management and follow-up of the patients. The diagnosis of intraocular tumors is usually based on clinical examination with acoustic backscattering based ultrasonography. By analyzing the high frequency fluctuations within the ultrasound (US) signals, microarchitecture information inside the tumor can be characterized. However, US cannot interrogate the histochemical components formulating the microarchitecture. One representative example is the inability of US imaging (and other contemporary imaging modalities as well) in differentiating nevoid and melanoma cells as the two types of cells possesses similar acoustic backscattering properties. Combining optical and US imaging, photoacoustic (PA) measurements encode both the microarchitecture and histochemical component information in biological tissue. This study attempts to characterize ocular tumors by analyzing the high frequency signal components in the multispectral PA images. Ex vivo human eye globes with melanoma and retinoblastoma tumors were scanned using less than 6 mJ per square centimeters laser energy with tunable range of 600-1700 nm. A PA-US parallel imaging system with US probes CL15-7 and L22-14 were used to acquire the high frequency PA signals in real time. Preliminary results show that the proposed method can identify uveal melanoma against retinoblastoma tumors.

  18. Chemical changes of titanium and titanium dioxide under electron bombardment

    Directory of Open Access Journals (Sweden)

    Romins Brasca

    2007-09-01

    Full Text Available The electron induced effect on the first stages of the titanium (Ti0 oxidation and titanium dioxide (Ti4+ chemical reduction processes has been studied by means of Auger electron spectroscopy. Using factor analysis we found that both processes are characterized by the appearance of an intermediate Ti oxidation state, Ti2O3 (Ti3+.

  19. Spatially Fourier-encoded photoacoustic microscopy using a digital micromirror device

    OpenAIRE

    Liang, Jinyang; Gao, Liang; Li, Chiye; Wang, Lihong V.

    2014-01-01

    We have developed spatially Fourier-encoded photoacoustic microscopy using a digital micromirror device. The spatial intensity distribution of laser pulses is Fourier-encoded, and a series of such encoded photoacoustic measurements allows one to decode the spatial distribution of optical absorption. The throughput and Fellgett advantages were demonstrated by imaging a chromium target. By using 63 spatial elements, the signal-to-noise ratio in the recovered photoacoustic signal was enhanced by...

  20. Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy

    OpenAIRE

    Andreas Pohlkötter; Michael Köhring; Ulrike Willer; Wolfgang Schade

    2010-01-01

    Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS). With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sa...

  1. Recent advances toward preclinical and clinical translation of photoacoustic tomography: a review

    Science.gov (United States)

    Upputuri, Paul Kumar; Pramanik, Manojit

    2017-04-01

    Photoacoustic imaging is an emerging hybrid imaging modality that can provide multicontrast, multiscale imaging of biological features ranging from organelles to organs. The three major embodiments of photoacoustic imaging are microscopy, endoscopy, and computed tomography. Photoacoustic tomography (PAT) or photoacoustic computed tomography allows deep-tissue imaging, and hence it is more suitable for whole body preclinical/clinical imaging applications. Due to fast-growing laser technology and ultrasound detector technology, PAT is evolving rapidly, leading to a quicker translation into clinical trials. We review the recent developments of PAT systems and their applications in preclinical and clinical practices.

  2. Multiparametric spectroscopic photoacoustic imaging of breast cancer development in a transgenic mouse model

    National Research Council Canada - National Science Library

    Wilson, Katheryne E; Bachawal, Sunitha V; Tian, Lu; Willmann, Jürgen K

    2014-01-01

    To evaluate the potential of multiparametric spectroscopic photoacoustic imaging using oxygen saturation, total hemoglobin, and lipid content to differentiate among four different breast histologies...

  3. Stimulated Raman rotational photoacoustic spectroscopy using a quartz tuning fork and femtosecond excitation

    Science.gov (United States)

    Schippers, W.; Gershnabel, E.; Burgmeier, J.; Katz, O.; Willer, U.; Averbukh, I. S.; Silberberg, Y.; Schade, W.

    2011-11-01

    Molecular alignment of linear molecules (O2, N2, CO2 and CO) is measured photoacoustically in the gas phase. The rotational excitation is accomplished using a simple femtosecond stimulated Raman excitation scheme, employing two femtosecond pulses with variable delay between the pulses. Molecular alignment is determined directly by measuring the energy dumped into the gas by quartz-enhanced photoacoustic spectroscopy (QEPAS), utilizing a quartz tuning fork as a sensitive photoacoustic transducer. The experimental results demonstrate for the first time the use of a tuning fork for resonant photoacoustic detection of Raman spectra excited by femtosecond double pulses and match both simulation and literature values.

  4. In vivo oral imaging with integrated portable photoacoustic microscopy and optical coherence tomography

    Science.gov (United States)

    Qin, Wei; Qi, Weizhi; Jin, Tian; Guo, Heng; Xi, Lei

    2017-12-01

    Oral diseases, especially oral cancers, are becoming serious health problems in humans. To image vasculatures and structures simultaneously in the human oral cavity which are tightly associated with various oral diseases, we develop a dual-modality portable optical resolution photoacoustic microscopy (ORPAM) and optical coherence tomography (OCT) system. This system utilizes a new rotary scanning mechanism and a compact design of the imaging head, making it portable and free of translation of the imaging interface or samples. Through the phantom experiments, both modalities yield high lateral resolutions of 8.1 μm (ORPAM) and 8.56 μm (OCT), respectively. The axial resolutions are measured to be 116.5 μm for ORPAM and 6.1 μm for OCT. In vivo imaging of a mouse ear was carried out to evaluate the performance of the system in biological tissues. In addition, in vivo oral imaging of a healthy human lip and monitoring recovery progress of a lip ulcer demonstrate the clinical potential of this system.

  5. Water-Immersible MEMS scanning mirror designed for wide-field fast-scanning photoacoustic microscopy

    Science.gov (United States)

    Yao, Junjie; Huang, Chih-Hsien; Martel, Catherine; Maslov, Konstantin I.; Wang, Lidai; Yang, Joon-Mo; Gao, Liang; Randolph, Gwendalyn; Zou, Jun; Wang, Lihong V.

    2013-03-01

    By offering images with high spatial resolution and unique optical absorption contrast, optical-resolution photoacoustic microscopy (OR-PAM) has gained increasing attention in biomedical research. Recent developments in OR-PAM have improved its imaging speed, but have sacrificed either the detection sensitivity or field of view or both. We have developed a wide-field fast-scanning OR-PAM by using a water-immersible MEMS scanning mirror (MEMS-ORPAM). Made of silicon with a gold coating, the MEMS mirror plate can reflect both optical and acoustic beams. Because it uses an electromagnetic driving force, the whole MEMS scanning system can be submerged in water. In MEMS-ORPAM, the optical and acoustic beams are confocally configured and simultaneously steered, which ensures uniform detection sensitivity. A B-scan imaging speed as high as 400 Hz can be achieved over a 3 mm scanning range. A diffraction-limited lateral resolution of 2.4 μm in water and a maximum imaging depth of 1.1 mm in soft tissue have been experimentally determined. Using the system, we imaged the flow dynamics of both red blood cells and carbon particles in a mouse ear in vivo. By using Evans blue dye as the contrast agent, we also imaged the flow dynamics of lymphatic vessels in a mouse tail in vivo. The results show that MEMS-OR-PAM could be a powerful tool for studying highly dynamic and time-sensitive biological phenomena.

  6. Resting-state functional connectivity imaging of the mouse brain using photoacoustic tomography

    Science.gov (United States)

    Nasiriavanaki, Mohammadreza; Xia, Jun; Wan, Hanlin; Bauer, Adam Q.; Culver, Joseph P.; Wang, Lihong V.

    2014-03-01

    Resting-state functional connectivity (RSFC) imaging is an emerging neuroimaging approach that aims to identify spontaneous cerebral hemodynamic fluctuations and their associated functional connections. Clinical studies have demonstrated that RSFC is altered in brain disorders such as stroke, Alzheimer's, autism, and epilepsy. However, conventional neuroimaging modalities cannot easily be applied to mice, the most widely used model species for human brain disease studies. For instance, functional magnetic resonance imaging (fMRI) of mice requires a very high magnetic field to obtain a sufficient signal-to-noise ratio and spatial resolution. Functional connectivity mapping with optical intrinsic signal imaging (fcOIS) is an alternative method. Due to the diffusion of light in tissue, the spatial resolution of fcOIS is limited, and experiments have been performed using an exposed skull preparation. In this study, we show for the first time, the use of photoacoustic computed tomography (PACT) to noninvasively image resting-state functional connectivity in the mouse brain, with a large field of view and a high spatial resolution. Bilateral correlations were observed in eight regions, as well as several subregions. These findings agreed well with the Paxinos mouse brain atlas. This study showed that PACT is a promising, non-invasive modality for small-animal functional brain imaging.

  7. Compaction of Titanium Powders

    Energy Technology Data Exchange (ETDEWEB)

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 μm, <75 μm, and < 45 μm; two different sizes of a hydride-dehydride [HDH] <75 μm and < 45 μm; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  8. Compaction of Titanium Powders

    Energy Technology Data Exchange (ETDEWEB)

    Gerdemann, Stephen,J; Jablonski, Paul, J

    2011-05-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines<150 {micro}m,<75 {micro}m, and<45 {micro}m; two different sizes of a hydride-dehydride [HDH]<75 {micro}m and<45 {micro}m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  9. Research and Development on Titanium Alloys

    Science.gov (United States)

    1949-08-31

    61 No. 733 LWE: ec/mk/ma September 14, 1949 13ATTK- LLE MESMORIAL INSTITUTE DEPARTMENT OF THE AIR FORCE HEADOUARTERS AERONAUTICAL SYSTEMS CENTER (AFMC...period reported, titanium binary alloys of germanium and nickel vere studied, as venl as tltanium-molybdenum and titanium- manganese ternary alloys. Carbon...September 18, 1949, titanium binary alloys of germanium and nickel were studied. Also investigated were titanium-molybdenum and titanium-manganese ternary

  10. Photoacoustic imaging in both soft and hard biological tissue

    Energy Technology Data Exchange (ETDEWEB)

    Li, T; Dewhurst, R J, E-mail: richard.dewhurst@manchester.ac.u [Photon Science Institute, University of Manchester, Alan Turing Building, Oxford road, Manchester, M13 9PL (United Kingdom)

    2010-03-01

    To date, most Photoacoustic (PA) imaging results have been from soft biotissues. In this study, a PA imaging system with a near-infrared pulsed laser source has been applied to obtain 2-D and 3-D images from both soft tissue and post-mortem dental samples. Imaging results showed that the PA technique has the potential to image human oral disease, such as early-stage teeth decay. For non-invasive photoacoustic imaging, the induced temperature and pressure rises within biotissues should not cause physical damage to the tissue. Several simulations based on the thermoelastic effect have been applied to predict initial temperature and pressure fields within a tooth sample. Predicted initial temperature and pressure rises are below corresponding safety limits.

  11. Sensitive Detection: Photoacoustics, Thermography, and Optical Radiation Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, Gerald J. [Brown Univ., Providence, RI (United States)

    2017-04-21

    Research during the granting period has been carried out in several areas concerned with sensitive detection. An infrared pyrometer based on the photoacoustic effect has been developed. The sensitivity of this instrument to temperature differentials has been shown to be 50 mK. An investigation of transients that accompany photoacoustic waves generated by pulsed lasers has been carried out. Experiments have shown the existence of the transients, and a theory based on rapid heat diffusion has been developed. The photoacoustic effect in one dimension is known to increase without bound (in the linear acoustics regime) when an optical beam moves in a fluid at the sound speed. A solution to the wave equation for pressure has been found that describes the photoacoustic effect in a cell where an infrared optical grating moves at the sound speed. It was shown that the amplification effect exists along with a cavity resonance that can be used to great advantage in trace gas detection. The theory of the photoacoustic effect in a structure where the acoustic properties periodically vary in a one-dimensional based has been formulated based on solutions to a Mathieu equation. It was found that it is possible to excite photoacoustic waves within the band gaps to produce large amplitude acoustic waves. The idea of self-oscillation in a photoacoustic cell using a continuous laser has been investigated. A theory has been completed showing that in a compressive wave, the absorption increases as a result of the density increase leading to further absorption and hence an increased amplitude photoacoustic effect with the result that in a resonator, self-oscillation can place. Experiments have been carried out where irradiation of a suspension of absorbing carbon particles with a high power laser has been shown to result in cavitation luminescence. That is, following generation of CO and H2 from the carbon particles through the carbon-steam reaction, an expanding gas bubble is

  12. Iterative methods for photoacoustic tomography in attenuating acoustic media

    Science.gov (United States)

    Haltmeier, Markus; Kowar, Richard; Nguyen, Linh V.

    2017-11-01

    The development of efficient and accurate reconstruction methods is an important aspect of tomographic imaging. In this article, we address this issue for photoacoustic tomography. To this aim, we use models for acoustic wave propagation accounting for frequency dependent attenuation according to a wide class of attenuation laws that may include memory. We formulate the inverse problem of photoacoustic tomography in attenuating medium as an ill-posed operator equation in a Hilbert space framework that is tackled by iterative regularization methods. Our approach comes with a clear convergence analysis. For that purpose we derive explicit expressions for the adjoint problem that can efficiently be implemented. In contrast to time reversal, the employed adjoint wave equation is again damping and, thus has a stable solution. This stability property can be clearly seen in our numerical results. Moreover, the presented numerical results clearly demonstrate the efficiency and accuracy of the derived iterative reconstruction algorithms in various situations including the limited view case.

  13. Investigation of zinc stannate synthesis using photoacoustic spectroscopy

    Directory of Open Access Journals (Sweden)

    Ivetić T.

    2007-01-01

    Full Text Available Mixtures of ZnO and SnO2 powders, with molar ratio of 2:1, were mechanically activated for 40, 80 and 160 minutes in a planetary ball mill. The resulting powders were compacted into pellets and non-isothermally sintered up to 1200°C with a heating rate of 5°C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained a correlation between thermal diffusivity and experimental conditions as well the samples microstructure characteristics was discussed. .

  14. Optical pyrometer based on the gas phase photoacoustic effect.

    Science.gov (United States)

    Meng, Xiangling; Diebold, Gerald J

    2016-05-15

    A photoacoustic cell containing an infrared active gas and equipped with a pair of infrared transmitting windows that alternately views two bodies at different temperatures through a pair of chopping wheels acts as a differential detector of the radiation emitted by the two bodies. A theory for the photoacoustic signal shows that the device acts to monitor the difference in the incidances between the two bodies integrated over the absorptions of the gas in the cell. Experiments are reported showing that the response of the pyrometer depends on the relative temperatures of heated bodies, the absorption coefficient of the gas in the cell, and the modulation frequency of the chopping wheels. The instrument is shown to be a sensitive detector of a null in the integrated incidance of the two bodies.

  15. Photoacoustic spectroscopy of standard explosives in the MIR region

    Energy Technology Data Exchange (ETDEWEB)

    Giubileo, Gianfranco, E-mail: gianfranco.giubileo@enea.i [ENEA, Via E. Fermi 45, Frascati 00044 (Italy); Puiu, Adriana [Tor Vergata University of Rome, Faculty of Engineering, Via del Politecnico 1, 00133 Rome (Italy)

    2010-11-11

    An emerging and important topic of interest in the field of homeland security is the identification and quantification of explosives. This paper brings new elements in the Laser Photoacoustic Spectroscopy (LPAS) based characterisation of some classical explosives (2,4-DNT; 2,6-DNT; HMX; TATP; PETN) in solid phase at CO{sub 2} laser wavelengths, not yet reported in the literature to our knowledge. Moreover, we report our LPAS analysis of TNT and RDX, already previously studied with the same technique in the same spectral interval by different authors. The reported photoacoustic signals from standard commercial samples of the classical explosive substances were recorded in the 9-11 {mu}m region, by a CO{sub 2} laser based homemade optical apparatus. The underlying experimental activity was performed in the molecular spectroscopy laboratory of the ENEA Research Centre in Frascati.

  16. Photoacoustic spectroscopy of standard explosives in the MIR region

    Science.gov (United States)

    Giubileo, Gianfranco; Puiu, Adriana

    2010-11-01

    An emerging and important topic of interest in the field of homeland security is the identification and quantification of explosives. This paper brings new elements in the Laser Photoacoustic Spectroscopy (LPAS) based characterisation of some classical explosives (2,4-DNT; 2,6-DNT; HMX; TATP; PETN) in solid phase at CO 2 laser wavelengths, not yet reported in the literature to our knowledge. Moreover, we report our LPAS analysis of TNT and RDX, already previously studied with the same technique in the same spectral interval by different authors. The reported photoacoustic signals from standard commercial samples of the classical explosive substances were recorded in the 9-11 μm region, by a CO 2 laser based homemade optical apparatus. The underlying experimental activity was performed in the molecular spectroscopy laboratory of the ENEA Research Centre in Frascati.

  17. Non-destructive photoacoustic imaging of metal surface defects

    Science.gov (United States)

    Jeon, Seungwan; Kim, Jeesu; Yun, Jong Pil; Kim, Chulhong

    2016-11-01

    The detection of metal surface defects is important in achieving the goals of product quality enhancement and manufacturing cost reduction. Identifying the defects with visual inspection is difficult, inaccurate, and time-consuming. Thus, several inspection methods using line cameras, magnetic field, and ultrasound have been proposed. However, identifying small defects on metal surfaces remains a challenge. To deal with this problem, we propose the use of photoacoustic imaging (PAI) as a new non-destructive imaging tool to detect metal surface defects. We successfully visualized two types of cracks (i.e., unclassified and seam cracks) in metal plate samples using PAI. In addition, we successfully extracted cracked edges from height-encoded photoacoustic maximum amplitude projection images using the Laplacian of Gaussian filtering method, and then, quantified the detected edges for a statistical analysis. We concluded that PAI can be useful in detecting metal surface defects reducing the defect rate and manufacturing cost during metal production.

  18. Double Stage Delay Multiply and Sum Beamforming Algorithm: Application to Linear-Array Photoacoustic Imaging.

    Science.gov (United States)

    Mozaffarzadeh, Moein; Mahloojifar, Ali; Orooji, Mahdi; Adabi, Saba; Nasiriavanaki, Mohammadreza

    2017-04-05

    Photoacoustic imaging (PAI) is an emerging medical imaging modality capable of providing high spatial resolution of Ultrasound (US) imaging and high contrast of optical imaging. Delay-and-Sum (DAS) is the most common beamforming algorithm in PAI. However, using DAS beamformer leads to low resolution images and considerable contribution of offaxis signals. A new paradigm namely Delay-Multiply-and-Sum (DMAS), which was originally used as a reconstruction algorithm in confocal microwave imaging, was introduced to overcome the challenges in DAS. DMAS was used in PAI systems and it was shown that this algorithm results in resolution improvement and sidelobe degrading. However, DMAS is still sensitive to high levels of noise, and resolution improvement is not satisfying. Here, we propose a novel algorithm based on DAS algebra inside DMAS formula expansion, Double Stage DMAS (DSDMAS), which improves the image resolution and levels of sidelobe, and is much less sensitive to high level of noise compared to DMAS. The performance of DS-DMAS algorithm is evaluated numerically and experimentally. The resulted images are evaluated qualitatively and quantitatively using established quality metrics including signal-to-noise ratio (SNR), full-widthhalf- maximum (FWHM) and contrast ratio (CR). It is shown that DS-DMAS outperforms DAS and DMAS at the expense of higher computational load. DS-DMAS reduces the lateral valley for about 15 dB and improves the SNR and FWHM better than 13% and 30%, respectively. Moreover, the levels of sidelobe are reduced for about 10 dB in comparison with those in DMAS.

  19. Antibacterial coatings on titanium implants.

    Science.gov (United States)

    Zhao, Lingzhou; Chu, Paul K; Zhang, Yumei; Wu, Zhifen

    2009-10-01

    Titanium and titanium alloys are key biomedical materials because of their good biocompatibility and mechanical properties. Nevertheless, infection on and around titanium implants still remains a problem which is usually difficult to treat and may lead to eventual implant removal. As a result, preventive measures are necessary to mitigate implant-frelated infection. One important strategy is to render the implant surface antibacterial by impeding the formation of a biofilm. A number of approaches have been proposed for this purpose and they are reviewed in this article. (c) 2009 Wiley Periodicals, Inc.

  20. Local context encoding enables machine learning-based quantitative photoacoustics

    OpenAIRE

    Kirchner, Thomas; Gröhl, Janek; Maier-Hein, Lena

    2017-01-01

    Real-time monitoring of functional tissue parameters, such as local blood oxygenation, based on optical imaging could provide groundbreaking advances in the diagnosis and interventional therapy of various diseases. While photoacoustic (PA) imaging is a novel imaging concept with great potential to measure optical absorption deep inside tissue, quantification of the measurements remains a major challenge to be addressed. In this paper, we introduce the first machine learning-based approach to ...

  1. Deep Learning for Photoacoustic Tomography from Sparse Data

    OpenAIRE

    Antholzer, Stephan; Haltmeier, Markus; Schwab, Johannes

    2017-01-01

    The development of fast and accurate image reconstruction algorithms is a central aspect of computed tomography. In this paper we investigate this issue for the sparse data problem in photoacoustic tomography (PAT). We develop a direct and highly efficient reconstruction algorithm based on deep learning. In our approach image reconstruction is performed with a deep convolutional neural network (CNN), whose weights are adjusted prior to the actual image reconstruction based on a set of trainin...

  2. Cement hardening investigation by method of piezoelectric photoacoustics

    Science.gov (United States)

    Gorsky, Mykhaylo P.; Maksimyak, Peter P.

    2018-01-01

    Piezoelectric photoacoustics application possibility for concrete hydration stages determination has been analyzed. Cement sample placed on a transparent base was irradiated by laser beam. The acoustic signal from base transformed by piezoelectric converter into electric signal and through the amplifier moved in recorder device. The accent was on research and transient modelling with a pulse laser irradiation. Accent has been made to thermal conductivity measurement of cement during hydration process and its connection with hydration stages.

  3. Orthogonal Fabry-Pérot sensors for photoacoustic tomography

    Science.gov (United States)

    Ellwood, R.; Ogunlade, O.; Zhang, E. Z.; Beard, P. C.; Cox, B. T.

    2016-03-01

    Fabry-Pérot (FP) sensors have been used to produce in-vivo photoacoustic images of exquisite quality. However, for simplicity of construction FP sensors are produced in a planar form. Planar sensors suffer from a limited detection aperture, due to their planarity. We present a novel sensor geometry that allowed a greater field of view by placing a second sensor orthogonal to the first. This captured data from the deeper lying regions of interest and mitigated the limited view.

  4. Spatial interference encoding patterns based super resolved photoacoustic microscopy

    Science.gov (United States)

    Meiri, Amihai; Strohm, Eric M.; Kolios, Michael C.; Zalevsky, Zeev

    2017-03-01

    Single sensor (pixel) signals require scanning of the sample in order to obtain spatial information. In this paper we show that using interference, optically induced signals can be reconstructed when recorded using interference pattern excitation, rather than a point illumination. This method reduces the need for dense scanning and requires a small number of scans, or can eliminate the need for scanning in some cases. It is shown that this method can be used in particular in photo-acoustic imaging.

  5. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy

    OpenAIRE

    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S.; Beere, Harvey E.; Ritchie, David A.; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2016-01-01

    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH3OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a ...

  6. Quantitative photoacoustic tomography by stochastic search, direct recovery of the optical absorption field

    NARCIS (Netherlands)

    Venugopal, M.; van Es, Peter; Manohar, Srirang; Roy, D.; Vasu, R.M.

    2016-01-01

    We present, perhaps for the first time, a stochastic search algorithm in quantitative photoacoustic tomography (QPAT) for a one-step recovery of the optical absorption map from time-resolved photoacoustic signals. Such a direct recovery is free of the numerical inaccuracies inherent in conventional

  7. Effect of flow velocity on the photoacoustic detection for glucose aqueous solutions

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Ding, Yu; Yao, Qingkai

    2018-01-01

    The blood glucose non-invasive detection has become the research hot-spot. The photoacoustic spectroscopy is a well-promising, high-efficient and noninvasive detection method because it combines the advantages of the pure optic and pure ultrasonic. In practice, the photoacoustic detection of blood glucose is impacted by many factors because the human body is a complicated bio-system. To study the effect of flow velocity in the blood vessel on the photoacoustic detection of blood glucose, a photoacoustic detection system based on optical parameter oscillator (OPO) pulsed laser induced ultrasonic was established. In this system, a 532nm pumped Nd: YAG OPO pulsed laser was used as the excitation source, and the photoacoustic signals of glucose were captured by ultrasonic transducer. Moreover, a set of blood circulation system was built to simulate the real blood flow situation in the human body. The experiments of the photoacoustic detection of glucose aqueous solutions with different concentrations at different flow velocities were experimentally investigated. Experimental results show that the photoacoustic peak-to-peak value linearly increases with the glucose concentration, but it decreases with the increase of the flow velocity although the profiles of photoacoustic signals don't change.

  8. Determination of glucose concentration based on pulsed laser induced photoacoustic technique and least square fitting algorithm

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2015-08-01

    In this paper, a noninvasive glucose concentration monitoring setup based on the photoacoustic technique was established. In this setup, a 532nm pumped Q switched Nd: YAG tunable pulsed laser with repetition rate of 20Hz was used as the photoacoustic excitation light source, and a ultrasonic transducer with central response frequency of 9.55MHz was used as the detector of the photoacoustic signal of glucose. As the preliminary exploration of the blood glucose concentration, a series of in vitro photoacoustic monitoring of glucose aqueous solutions by using the established photoacoustic setup were performed. The photoacoustic peak-to-peak values of different concentrations of glucose aqueous solutions induced by the pulsed laser with output wavelength of 1300nm to 2300nm in interval of 10nm were obtained with the average times of 512. The differential spectral and the first order derivative spectral method were used to get the characteristic wavelengths. For the characteristic wavelengths of glucose, the least square fitting algorithm was used to establish the relationship between the glucose concentrations and photoacoustic peak-to-peak values. The characteristic wavelengths and the predicted concentrations of glucose solution were obtained. Experimental results demonstrated that the prediction effect of characteristic wavelengths of 1410nm and 1510nm were better than others, and this photoacoustic setup and analysis method had a certain potential value in the monitoring of the blood glucose concentration.

  9. Simultaneous imaging of ultrasound attenuation, speed of sound and optical absorption in a photoacoustic setup

    NARCIS (Netherlands)

    Willemink, Rene; Manohar, Srirang; Jose, J.; Jose, Jithin; Slump, Cornelis H.; van der Heijden, Ferdinand; van Leeuwen, Ton; McAleavey, Stephen A.; D'hooge, Jan

    2009-01-01

    Photoacoustic imaging is a relatively new medical imaging modality. In principle it can be used to image the optical absorption distribution of an object by measurements of optically induced acoustic signals. Recently we have developed a modified photoacoustic measurement system which can be used to

  10. Photoacoustic imaging of blood vessels with a double-ring sensor featuring a narrow angular aperture

    NARCIS (Netherlands)

    Kolkman, R.G.M.; Hondebrink, Erwin; Steenbergen, Wiendelt; van Leeuwen, Ton; de Mul, F.F.M.

    2004-01-01

    A photoacoustic double-ring sensor, featuring a narrow angular aperture, is developed for laser-induced photoacoustic imaging of blood vessels. An integrated optical fiber enables reflection-mode detection of ultrasonic waves. By using the cross-correlation between the signals detected by the two

  11. Photoacoustic and Ultrasonic Image-Guided Needle Biopsy of the Prostate

    Science.gov (United States)

    2015-10-01

    Homan K, Kim S, Chen Y-S, Wang B, Mallidi S, Emelianov S. Prospects of molecular photoacoustic imaging at 1064 nm wavelength. Optics letters 2010;35...Photoacoustic imaging of prostate brachytherapy seeds. Biomedical Optics Express 2011;2(8):2243–54. [8] Mitcham T, Homan K, Frey W, Chen Y-S

  12. Quantum cascade laser-based photoacoustic sulfuryl fluoride sensing

    Science.gov (United States)

    Minini, Kariza Mayra Silva; Bueno, Sâmylla Cristina Espécie; da Silva, Marcelo Gomes; Sthel, Marcelo Silva; Vargas, Helion; Angster, Judit; Miklós, András

    2017-02-01

    Although sulfuryl fluoride (SO2F2) is an efficient fumigant that does not react with the surface of indoor materials and does not reduce the stratospheric ozone shield, there are some concerns about its use. It is a toxic gas that attacks the central nervous system, and its global warming potential (GWP) value is 4780 for 100 years' time. Therefore, it is a clear necessity of implementing detection methods for tracing such a molecule. In this work a sensitive photoacoustic setup was built to detect SO2F2 at concentrations of parts per billion by volume (ppbv). The symmetric S-O stretching mode was excited by a continuous-wave quantum cascade laser with radiation wavenumber ranging from 1275.7 to 1269.3 cm-1. The photoacoustic signal was generated by modulating the laser wavenumber at the first longitudinal mode of the photoacoustic cell with amplitude depth of 5 × 10-3 cm-1. The detection of a minimum SO2F2 concentration of 20 ppbv was achieved.

  13. Advanced titanium processing

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, Alan D.; Gerdemann, Stephen J.; Schrems, Karol K.; Holcomb, Gordon R.; Argetsinger, Edward R.; Hansen, Jeffrey S.; Paige, Jack I.; Turner, Paul C.

    2001-01-01

    The Albany Research Center of the U.S. Department of Energy has been investigating a means to form useful wrought products by direct and continuous casting of titanium bars using cold-wall induction melting rather than current batch practices such as vacuum arc remelting. Continuous ingots produced by cold-wall induction melting, utilizing a bottomless water-cooled copper crucible, without slag (CaF2) additions had minor defects in the surface such as ''hot tears''. Slag additions as low as 0.5 weight percent were used to improve the surface finish. Therefore, a slag melted experimental Ti-6Al-4V alloy ingot was compared to a commercial Ti-6Al-4V alloy ingot in the areas of physical, chemical, mechanical, and corrosion attributes to address the question, ''Are any detrimental effects caused by slag addition''?

  14. Plasmonic amplification of photoacoustic waves detected using piezotransistive GaN microcantilevers

    Science.gov (United States)

    Khan, Digangana; Bayram, Ferhat; Gajula, Durga; Talukdar, Abdul; Li, Hongmei; Koley, Goutam

    2017-08-01

    Strong enhancement in a photoacoustic signal due to plasmonic absorption in Au nanostructures was measured using piezotransistive GaN microcantilevers. A pulsed 790 nm laser focused on the Au metallization of the piezotransistor resulted in a much larger photoacoustic signal compared to the non-metallized areas. Upon deposition of a 5 nm Au layer, the photoacoustic signal increased significantly for both previously metallized and non-metallized areas, while 2 nm Ni deposition decreased the photoacoustic signal, confirming the role of Au nanostructures in facilitating plasmonic absorption. Infrared microscopy images covering the boundary of Au metallized and non-metallized surfaces indicated a much larger rise in temperature of the former region with laser exposure, explaining the generation of photoacoustic signals through plasmonic absorption.

  15. Photoacoustic imaging: a potential new platform for assessment of bone health

    Science.gov (United States)

    Feng, Ting; Kozloff, Kenneth M.; Hsiao, Yi-Sing; Xu, Guan; Du, Sidan; Yuan, Jie; Deng, Cheri X.; Wang, Xueding

    2015-02-01

    The ultimate goal of this work is to develop a novel photoacoustic (QPA) platform for highly-sensitive and quantitative assessment of bone health. First, the feasibility to perform 3D photoacoustic imaging (PAI) of bone was investigated. Then another two techniques, including thermal photoacoustic measurement (TPAM) and photoacoustic spectral analysis (PASA), both being able to achieve quantitative results were investigated for bone characterization. TPAM, by evaluating the dependence of photoacoustic signal amplitude on the sample temperature, is sensitive to the chemical constituents in tissue and holds promise for assessment of bone mineral density (BMD). PASA characterizes micron size physical features in tissue, and has shown feasibility for objective assessment of bone microarchitecture (BMA). This integrated QPA platform can assess both bone mass and microstructure simultaneously without involving invasive biopsy or ionizing radiation. Since QPA is non-ionizing, non-invasive, and has sufficient penetration in both soft tissue and bone, it has unique advantages for clinical translation.

  16. Optical Drug Monitoring: Photoacoustic Imaging of Nanosensors to Monitor Therapeutic Lithium In Vivo

    Science.gov (United States)

    Cash, Kevin J.; Li, Chiye; Xia, Jun; Wang, Lihong V.; Clark, Heather A.

    2015-01-01

    Personalized medicine could revolutionize how primary care physicians treat chronic disease and how researchers study fundamental biological questions. To realize this goal we need to develop more robust, modular tools and imaging approaches for in vivo monitoring of analytes. In this report, we demonstrate that synthetic nanosensors can measure physiologic parameters with photoacoustic contrast, and we apply that platform to continuously track lithium levels in vivo. Photoacoustic imaging achieves imaging depths that are unattainable with fluorescence or multiphoton microscopy. We validated the photoacoustic results that illustrate the superior imaging depth and quality of photoacoustic imaging with optical measurements. This powerful combination of techniques will unlock the ability to measure analyte changes in deep tissue and will open up photoacoustic imaging as a diagnostic tool for continuous physiological tracking of a wide range of analytes. PMID:25588028

  17. In vivo ultrasound and photoacoustic monitoring of mesenchymal stem cells labeled with gold nanotracers.

    Science.gov (United States)

    Nam, Seung Yun; Ricles, Laura M; Suggs, Laura J; Emelianov, Stanislav Y

    2012-01-01

    Longitudinal monitoring of cells is required in order to understand the role of delivered stem cells in therapeutic neovascularization. However, there is not an imaging technique that is capable of quantitative, longitudinal assessment of stem cell behaviors with high spatial resolution and sufficient penetration depth. In this study, in vivo and in vitro experiments were performed to demonstrate the efficacy of ultrasound-guided photoacoustic (US/PA) imaging to monitor mesenchymal stem cells (MSCs) labeled with gold nanotracers (Au NTs). The Au NT labeled MSCs, injected intramuscularly in the lower limb of the Lewis rat, were detected and spatially resolved. Furthermore, our quantitative in vitro cell studies indicate that US/PA imaging is capable of high detection sensitivity (1×10⁴ cells/mL) of the Au NT labeled MSCs. Finally, Au NT labeled MSCs captured in the PEGylated fibrin gel system were imaged in vivo, as well as in vitro, over a one week time period, suggesting that longitudinal cell tracking using US/PA imaging is possible. Overall, Au NT labeling of MSCs and US/PA imaging can be an alternative approach in stem cell imaging capable of noninvasive, sensitive, quantitative, longitudinal assessment of stem cell behaviors with high spatial and temporal resolutions at sufficient depths.

  18. In vivo ultrasound and photoacoustic monitoring of mesenchymal stem cells labeled with gold nanotracers.

    Directory of Open Access Journals (Sweden)

    Seung Yun Nam

    Full Text Available Longitudinal monitoring of cells is required in order to understand the role of delivered stem cells in therapeutic neovascularization. However, there is not an imaging technique that is capable of quantitative, longitudinal assessment of stem cell behaviors with high spatial resolution and sufficient penetration depth. In this study, in vivo and in vitro experiments were performed to demonstrate the efficacy of ultrasound-guided photoacoustic (US/PA imaging to monitor mesenchymal stem cells (MSCs labeled with gold nanotracers (Au NTs. The Au NT labeled MSCs, injected intramuscularly in the lower limb of the Lewis rat, were detected and spatially resolved. Furthermore, our quantitative in vitro cell studies indicate that US/PA imaging is capable of high detection sensitivity (1×10⁴ cells/mL of the Au NT labeled MSCs. Finally, Au NT labeled MSCs captured in the PEGylated fibrin gel system were imaged in vivo, as well as in vitro, over a one week time period, suggesting that longitudinal cell tracking using US/PA imaging is possible. Overall, Au NT labeling of MSCs and US/PA imaging can be an alternative approach in stem cell imaging capable of noninvasive, sensitive, quantitative, longitudinal assessment of stem cell behaviors with high spatial and temporal resolutions at sufficient depths.

  19. Brazing titanium to stainless steel

    Science.gov (United States)

    Batista, R. I.

    1980-01-01

    Titanium and stainless-steel members are usually joined mechanically for lack of any other effective method. New approach using different brazing alloy and plating steel member with nickel resolves problem. Process must be carried out in inert atmosphere.

  20. Amplified photoacoustic performance and enhanced photothermal stability of reduced graphene oxide coated gold nanorods for sensitive photoacoustic imaging.

    Science.gov (United States)

    Moon, Hyungwon; Kumar, Dinesh; Kim, Haemin; Sim, Changbeom; Chang, Jin-Ho; Kim, Jung-Mu; Kim, Hyuncheol; Lim, Dong-Kwon

    2015-03-24

    We report a strongly amplified photoacoustic (PA) performance of the new functional hybrid material composed of reduced graphene oxide and gold nanorods. Due to the excellent NIR light absorption properties of the reduced graphene oxide coated gold nanorods (r-GO-AuNRs) and highly efficient heat transfer process through the reduced graphene oxide layer, r-GO-AuNRs exhibit excellent photothermal stability and significantly higher photoacoustic amplitudes than those of bare-AuNRs, nonreduced graphene oxide coated AuNRs (GO-AuNRs), or silica-coated AuNR, as demonstrated in both in vitro and in vivo systems. The linear response of PA amplitude from reduced state controlled GO on AuNR indicates the critical role of GO for a strong photothermal effect of r-GO-AuNRs. Theoretical studies with finite-element-method lab-based simulation reveal that a 4 times higher magnitude of the enhanced electromagnetic field around r-GO-AuNRs can be generated compared with bare AuNRs or GO-AuNRs. Furthermore, the r-GO-AuNRs are expected to be a promising deep-tissue imaging probe because of extraordinarily high PA amplitudes in the 4-11 MHz operating frequency of an ultrasound transducer. Therefore, the r-GO-AuNRs can be a useful imaging probe for highly sensitive photoacoustic images and NIR sensitive therapeutics based on a strong photothermal effect.

  1. Quartz-Enhanced Photoacoustic Detection for Aerosol Optical Characterization

    Science.gov (United States)

    Hollinger, M.; Black, N.; Mazzoleni, C.

    2010-12-01

    Particulate matter emitted by anthropogenic and natural sources strongly affect the radiative budget of the Earth. Non-absorbing aerosols have a negative radiative forcing effect, acting to cool the planet and thereby masking the warming caused by greenhouse gases. Absorbing aerosols including black carbon, dust and brown carbon can provide positive radiative forcing at the top of the atmosphere depending on their optical properties. Due to its short atmospheric lifetime, black carbon can have a strong regional effect (e.g. in Himalaya and in the Arctic, where surface albedo is high). How much aerosols affect the Earth’s climate however remains highly uncertain. Providing accurate, widespread and unbiased measurements of aerosol optical properties is important for understanding how aerosols will affect the future climate system. However, in depth studies on aerosol optical properties, and in particular absorption, are still lacking. Photoacoustic spectrometry has been recently employed to measure aerosol absorption. The technique is more fundamental and unbiased then traditional filter-based techniques. This type of spectrometry exploits the photoacoustic effect, which is the production of an acoustic wave from the excitation of a particle absorbing a photon. Currently available commercial spectrometers are very useful for laboratory and field experiments, but due to their typical size, they are unpractical for studies employing small payload aircrafts (e.g. unmanned aircrafts) or balloons. A recent development in photoacoustic spectrometry reported by Kosterev et al. in 2002 is the use of a quartz tuning fork for the detection, termed Quartz-Enhanced Photoacoustic Spectrometry (QEPAS). Due to the high resonance frequency (~32 KHz) of the tuning fork, QEPAS has good potential for the miniaturization of a photoacoustic spectrometry system. The quartz tuning fork is piezoelectric, and a signal is generated only when the tines of the tuning fork move in opposite

  2. Low cost titanium--myth or reality

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Paul C.; Hartman, Alan D.; Hansen, Jeffrey S.; Gerdemann, Stephen J.

    2001-01-01

    In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium, and titanium cost has prevented its use in non-aerospace applications including the automotive and heavy vehicle industries.

  3. India Ink Incorporated Multifunctional Phase-transition Nanodroplets for Photoacoustic/Ultrasound Dual-modality Imaging and Photoacoustic Effect Based Tumor Therapy

    OpenAIRE

    Jian, Jia; Liu, Chengbo; Gong, Yuping; Su, Lei; Zhang, Bin; Wang, Zhigang; wang, Dong; Zhou, Yu; Xu, Fenfen; Li, Pan; Zheng, Yuanyi; Song, Liang; Zhou, Xiyuan

    2014-01-01

    The in vivo applications of gas-core microbubbles have been limited by gas diffusion, rapid body clearance, and poor vascular permeability. To overcome these limitations, using a modified three-step emulsion process, we have developed a first-of-its-kind India ink incorporated optically-triggerable phase-transition perfluorocarbon nanodroplets (INDs) that can provide not only three types of contrast mechanisms—conventional/thermoelastic photoacoustic, phase-transition/nonlinear photoacoustic,...

  4. India ink incorporated multifunctional phase-transition nanodroplets for photoacoustic/ultrasound dual-modality imaging and photoacoustic effect based tumor therapy.

    Science.gov (United States)

    Jian, Jia; Liu, Chengbo; Gong, Yuping; Su, Lei; Zhang, Bin; Wang, Zhigang; Wang, Dong; Zhou, Yu; Xu, Fenfen; Li, Pan; Zheng, Yuanyi; Song, Liang; Zhou, Xiyuan

    2014-01-01

    The in vivo applications of gas-core microbubbles have been limited by gas diffusion, rapid body clearance, and poor vascular permeability. To overcome these limitations, using a modified three-step emulsion process, we have developed a first-of-its-kind India ink incorporated optically-triggerable phase-transition perfluorocarbon nanodroplets (INDs) that can provide not only three types of contrast mechanisms-conventional/thermoelastic photoacoustic, phase-transition/nonlinear photoacoustic, and ultrasound imaging contrasts, but also a new avenue for photoacoustic effect mediated tumor therapy. Upon pulsed laser illumination above a relatively low energy threshold, liquid-gas phase transition of the INDs has been demonstrated both in vitro and in vivo, offering excellent contrasts for photoacoustic and ultrasound dual-modality imaging. With further increased laser energy, the nanodroplets have been shown to be capable of destructing cancer cells in vivo, presumably due to the photoacoustic effect induced shock-wave generation from the carbon particles of the incorporated India ink. The demonstrated results suggest that the developed multifunctional phase-transition nanodroplets have a great potential for many theranostic biomedical applications, including photoacoustic/ultrasound dual-modality molecular imaging and targeted, localized cancer therapy.

  5. Hydrogen content in titanium and a titanium–zirconium alloy after acid etching

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Matthias J.; Walter, Martin S. [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway); Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, 85748 Garching (Germany); Lyngstadaas, S. Petter [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway); Wintermantel, Erich [Institute of Medical and Polymer Engineering, Chair of Medical Engineering, Technische Universität München, Boltzmannstrasse 15, 85748 Garching (Germany); Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no [Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, P.O. Box 1109, Blindern, NO-0317 Oslo (Norway)

    2013-04-01

    Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium–zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (p < 0.01) on the titanium–zirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium. - Highlights: ► TiZr alloy showed increased hydrogen levels over Ti. ► The alloying element Zr appeared to catalyze hydrogen absorption in Ti. ► Surface roughness was significantly increased for the TiZr alloy over Ti. ► TiZr alloy revealed nanostructures not observed for Ti.

  6. Titanium nanostructures for biomedical applications

    Science.gov (United States)

    Kulkarni, M.; Mazare, A.; Gongadze, E.; Perutkova, Š.; Kralj-Iglič, V.; Milošev, I.; Schmuki, P.; Iglič, A.; Mozetič, M.

    2015-02-01

    Titanium and titanium alloys exhibit a unique combination of strength and biocompatibility, which enables their use in medical applications and accounts for their extensive use as implant materials in the last 50 years. Currently, a large amount of research is being carried out in order to determine the optimal surface topography for use in bioapplications, and thus the emphasis is on nanotechnology for biomedical applications. It was recently shown that titanium implants with rough surface topography and free energy increase osteoblast adhesion, maturation and subsequent bone formation. Furthermore, the adhesion of different cell lines to the surface of titanium implants is influenced by the surface characteristics of titanium; namely topography, charge distribution and chemistry. The present review article focuses on the specific nanotopography of titanium, i.e. titanium dioxide (TiO2) nanotubes, using a simple electrochemical anodisation method of the metallic substrate and other processes such as the hydrothermal or sol-gel template. One key advantage of using TiO2 nanotubes in cell interactions is based on the fact that TiO2 nanotube morphology is correlated with cell adhesion, spreading, growth and differentiation of mesenchymal stem cells, which were shown to be maximally induced on smaller diameter nanotubes (15 nm), but hindered on larger diameter (100 nm) tubes, leading to cell death and apoptosis. Research has supported the significance of nanotopography (TiO2 nanotube diameter) in cell adhesion and cell growth, and suggests that the mechanics of focal adhesion formation are similar among different cell types. As such, the present review will focus on perhaps the most spectacular and surprising one-dimensional structures and their unique biomedical applications for increased osseointegration, protein interaction and antibacterial properties.

  7. Photoacoustic Image Analysis for Cancer Detection and Building a Novel Ultrasound Imaging System

    Science.gov (United States)

    Sinha, Saugata

    Photoacoustic (PA) imaging is a rapidly emerging non-invasive soft tissue imaging modality which has the potential to detect tissue abnormality at early stage. Photoacoustic images map the spatially varying optical absorption property of tissue. In multiwavelength photoacoustic imaging, the soft tissue is imaged with different wavelengths, tuned to the absorption peaks of the specific light absorbing tissue constituents or chromophores to obtain images with different contrasts of the same tissue sample. From those images, spatially varying concentration of the chromophores can be recovered. As multiwavelength PA images can provide important physiological information related to function and molecular composition of the tissue, so they can be used for diagnosis of cancer lesions and differentiation of malignant tumors from benign tumors. In this research, a number of parameters have been extracted from multiwavelength 3D PA images of freshly excised human prostate and thyroid specimens, imaged at five different wavelengths. Using marked histology slides as ground truths, region of interests (ROI) corresponding to cancer, benign and normal regions have been identified in the PA images. The extracted parameters belong to different categories namely chromophore concentration, frequency parameters and PA image pixels and they represent different physiological and optical properties of the tissue specimens. Statistical analysis has been performed to test whether the extracted parameters are significantly different between cancer, benign and normal regions. A multidimensional [29 dimensional] feature set, built with the extracted parameters from the 3D PA images, has been divided randomly into training and testing sets. The training set has been used to train support vector machine (SVM) and neural network (NN) classifiers while the performance of the classifiers in differentiating different tissue pathologies have been determined by the testing dataset. Using the NN

  8. Rapid and noncontact photoacoustic tomography imaging system using an interferometer with high-speed phase modulation technique

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun [School of Physics and Telecom Engineering, South China Normal University, Guangzhou 510006 (China); Tang, Zhilie; Wu, Yongbo [School of Physics and Telecom Engineering, South China Normal University, Guangzhou 510006 (China); GuangDong Province Key Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, IMOT, Guangzhou 510006 (China); Wang, Yi [School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China)

    2015-04-15

    We designed, fabricated, and tested a rapid and noncontact photoacoustic tomography (PAT) imaging system using a low-coherence interferometer with high-speed phase modulation technique. Such a rapid and noncontact probing system can greatly decrease the time of imaging. The proposed PAT imaging system is experimentally verified by capturing images of a simulated tissue sample and the blood vessels within the ear flap of a mouse (pinna) in vivo. The axial and lateral resolutions of the system are evaluated at 45 and ∼15 μm, respectively. The imaging depth of the system is 1 mm in a special phantom. Our results show that the proposed system opens a promising way to realize noncontact, real-time PAT.

  9. Optical biopsy approach to basal cell carcinoma and melanoma based on all-optically integrated photoacoustic and optical coherence tomography.

    Science.gov (United States)

    Zhou, Wangting; Chen, Zhongjiang; Yang, Sihua; Xing, Da

    2017-06-01

    Basal cell carcinoma (BCC) and melanoma (MM), with the highest morbidity and mortality, respectively, are considered as two skin cancers of concern in dermatology. Histological studies have demonstrated that vascular patterns and collagenous stroma serve as key parameters for BCC and MM classification. In this Letter, we sought to identify BCC and MM based on the dual parameters of vascular patterns and scattering structures provided by all-optically integrated photoacoustic and optical coherence tomography (AOPA/OCT). The imaging capability of the AOPA/OCT was verified by the mimic phantoms. Furthermore, in vivo characterization of vasculatures and tissue structures from BCC and MM mice were successfully achieved with high resolution. Results prove the feasibility of AOPA/OCT as a novel method to dedicate to the in vivo biopsy of skin cancers which shows new insights into the study of skin diseases in early stages.

  10. Off-axis quartz-enhanced photoacoustic spectroscopy using a pulsed nanosecond mid-infrared optical parametric oscillator.

    Science.gov (United States)

    Lassen, Mikael; Lamard, Laurent; Feng, Yuyang; Peremans, Andre; Petersen, Jan C

    2016-09-01

    A trace-gas sensor, based on quartz-enhanced photoacoustic spectroscopy (QEPAS), consisting of two acoustically coupled micro-resonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF) is demonstrated. The complete acoustically coupled mR system is optimized based on finite-element simulations and is experimentally verified. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator. The sensor is used for spectroscopic measurements on methane in the 3.1-3.5 μm wavelength region with a resolution bandwidth of 1  cm-1 and a detection limit of 0.8 ppm. An Allan deviation analysis shows that the detection limit at the optimum integration time for the QEPAS sensor is 32 ppbv at 190 s, and that the background noise is due solely to the thermal noise of the QTF.

  11. Piezoelectric line detector array for photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Guenther Paltauf

    2017-12-01

    The tomograph exhibits a spatial resolution on the order of 200 to 250 μm. In a phantom experiment, the steps from acquisition of a single, 2D projection image to a full 3D image are demonstrated. Finally, in vivo projection images of a human finger are shown, revealing the near real-time imaging capability of the device in 2D.

  12. An experimental and theoretical approach to the study of the photoacoustic signal produced by cancer cells

    Directory of Open Access Journals (Sweden)

    Rafael Pérez Solano

    2012-03-01

    Full Text Available The distinctive spectral absorption characteristics of cancer cells make photoacoustic techniques useful for detection in vitro and in vivo. Here we report on our evaluation of the photoacoustic signal produced by a series of monolayers of different cell lines in vitro. Only the melanoma cell line HS936 produced a detectable photoacoustic signal in which amplitude was dependent on the number of cells. This finding appears to be related to the amount of melanin available in these cells. Other cell lines (i.e. HL60, SK-Mel-1, T47D, Hela, HT29 and PC12 exhibited values similar to a precursor of melanin (tyrosinase, but failed to produce sufficient melanin to generate a photoacoustic signal that could be distinguished from background noise. To better understand this phenomenon, we determined a formula for the time-domain photoacoustic wave equation for a monolayer of cells in a non-viscous fluid on the thermoelastic regime. The theoretical results showed that the amplitude and profile of the photoacoustic signal generated by a cell monolayer depended upon the number and distribution of the cells and the location of the point of detection. These findings help to provide a better understanding of the factors involved in the generation of a photoacoustic signal produced by different cells in vitro and in vivo.

  13. Detection of Melanoma Metastases in Resected Human Lymph Nodes by Noninvasive Multispectral Photoacoustic Imaging

    Directory of Open Access Journals (Sweden)

    Gerrit Cornelis Langhout

    2014-01-01

    Full Text Available Objective. Sentinel node biopsy in patients with cutaneous melanoma improves staging, provides prognostic information, and leads to an increased survival in node-positive patients. However, frozen section analysis of the sentinel node is not reliable and definitive histopathology evaluation requires days, preventing intraoperative decision-making and immediate therapy. Photoacoustic imaging can evaluate intact lymph nodes, but specificity can be hampered by other absorbers such as hemoglobin. Near infrared multispectral photoacoustic imaging is a new approach that has the potential to selectively detect melanin. The purpose of the present study is to examine the potential of multispectral photoacoustic imaging to identify melanoma metastasis in human lymph nodes. Methods. Three metastatic and nine benign lymph nodes from eight melanoma patients were scanned ex vivo using a Vevo LAZR© multispectral photoacoustic imager and were spectrally analyzed per pixel. The results were compared to histopathology as gold standard. Results. The nodal volume could be scanned within 20 minutes. An unmixing procedure was proposed to identify melanoma metastases with multispectral photoacoustic imaging. Ultrasound overlay enabled anatomical correlation. The penetration depth of the photoacoustic signal was up to 2 cm. Conclusion. Multispectral three-dimensional photoacoustic imaging allowed for selective identification of melanoma metastases in human lymph nodes.

  14. Photoacoustic imaging of gene expression using tyrosinase as a reporter gene

    Science.gov (United States)

    Paproski, Robert J.; Forbrich, Alexander; Harrison, Tyler; Hitt, Mary; Zemp, Roger J.

    2011-03-01

    Optical reporter genes, such as green fluorescence protein, are powerful research tools that allow visualization of gene expression. We have successfully used tyrosinase as a reporter gene for photoacoustic imaging. Tyrosinase is the key regulatory enzyme in the production of melanin which has a broad optical absorption spectrum. MCF-7 cells were stably transfected with tyrosinase under the control of an inducible promoter. For photoacoustic experiments, MCF-7 cells were resuspended at 108 cells/mL and injected in 700 μm (inner diameter) plastic tubing. Photoacoustic signal of MCF-7 cells expressing tyrosinase were >20-fold greater than those of untransfected MCF-7 cells. Photoacoustic signal of tyrosinaseexpressing MCF-7 cells were approximately 2-fold lesser and greater than those of blood at 576 and 650 nm, respectively, suggesting that photoacoustic signal from blood and tyrosinase-expressing cells can be separated by dualwavelength analysis. Photoacoustic signal from tyrosinase-expressing MCF-7 cells covered by chicken tissue could even be detected at a laser penetration depth of 4 cm, suggesting that tyrosinase can be used to image gene expression in relatively deep tissues. The current data suggests that tyrosinase is a strong reporter gene for photoacoustic imaging.

  15. Photoacoustic tomography of human hepatic malignancies using intraoperative indocyanine green fluorescence imaging.

    Directory of Open Access Journals (Sweden)

    Akinori Miyata

    Full Text Available Recently, fluorescence imaging following the preoperative intravenous injection of indocyanine green has been used in clinical settings to identify hepatic malignancies during surgery. The aim of this study was to evaluate the ability of photoacoustic tomography using indocyanine green as a contrast agent to produce representative fluorescence images of hepatic tumors by visualizing the spatial distribution of indocyanine green on ultrasonographic images. Indocyanine green (0.5 mg/kg, intravenous was preoperatively administered to 9 patients undergoing hepatectomy. Intraoperatively, photoacoustic tomography was performed on the surface of the resected hepatic specimens (n = 10 under excitation with an 800 nm pulse laser. In 4 hepatocellular carcinoma nodules, photoacoustic imaging identified indocyanine green accumulation in the cancerous tissue. In contrast, in one hepatocellular carcinoma nodule and five adenocarcinoma foci (one intrahepatic cholangiocarcinoma and 4 colorectal liver metastases, photoacoustic imaging delineated indocyanine green accumulation not in the cancerous tissue but rather in the peri-cancerous hepatic parenchyma. Although photoacoustic tomography enabled to visualize spatial distribution of ICG on ultrasonographic images, which was consistent with fluorescence images on cut surfaces of the resected specimens, photoacoustic signals of ICG-containing tissues decreased approximately by 40% even at 4 mm depth from liver surfaces. Photoacoustic tomography using indocyanine green also failed to identify any hepatocellular carcinoma nodules from the body surface of model mice with non-alcoholic steatohepatitis. In conclusion, photoacoustic tomography has a potential to enhance cancer detectability and differential diagnosis by ultrasonographic examinations and intraoperative fluorescence imaging through visualization of stasis of bile-excreting imaging agents in and/or around hepatic tumors. However, further technical

  16. Detection of algae and bacterial biofilms formed on titanium surfaces using micro-Raman analysis

    Science.gov (United States)

    Ramya, S.; George, R. P.; Rao, R. V. Subba; Dayal, R. K.

    2010-06-01

    Biofouling is one of the major impediments in the use of titanium in sea-water cooled condensers of power plants, which is otherwise an excellent material with respect to corrosion resistance. Raman microscopic experiments were carried out on biofilms grown on titanium surfaces to find out the chemical composition of complex extracellular polymeric substances (EPS) in the biofilm. Though the spectral resolution of normal Raman experiments on these systems was very poor, it was improved when micro-SERS experiments were carried out using mono and bimetallic Ag and Cu colloids. It was observed that spatial distribution of polysaccharides was higher than that of proteins in algae biofilms formed on titanium matrix. Similar experiments were performed on laboratory cultured bacterial films of Pseudomonas aeruginosa. It was evidenced that algal and bacterial biofilms on titanium can be clearly distinguished with the help of Raman mapping coupled with SERS technique using bimetallic Ag/Cu colloids.

  17. Plasmonic titanium nitride nanostructures for perfect absorbers

    DEFF Research Database (Denmark)

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  18. Plasmonic Titanium Nitride Nanostructures via Nitridation of Nanopatterned Titanium Dioxide

    DEFF Research Database (Denmark)

    Guler, Urcan; Zemlyanov, Dmitry; Kim, Jongbum

    2017-01-01

    Plasmonic titanium nitride nanostructures are obtained via nitridation of titanium dioxide. Nanoparticles acquired a cubic shape with sharper edges following the rock-salt crystalline structure of TiN. Lattice constant of the resulting TiN nanoparticles matched well with the tabulated data. Energy-filtered...... TEM images and XPS results showed that oxygen was replaced by nitrogen. In contrast to nanoscale processing challenges of refractory TiN, well-understood material synthesis of TiO2 provides an attractive route to large-scale fabrication of refractory plasmonic materials with complex designs...

  19. Speckle-based off-axis holographic detection for non-contact photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Buj C.

    2015-09-01

    Full Text Available A very fast innovative holographic off-axis non-contact detection method for Photoacoustic Tomography (PAT is introduced. It overcomes the main problems of most state-of-the-art photoacoustic imaging approaches that are long acquisition times and the requirement of acoustic contact. In order to increase the acquisition speed significantly, the surface displacements of the object, caused by the photoacoustic pressure waves, are measured interferometrically in two dimensions. Phase alterations in the observed speckle field are used to identify changes in the object’s topography. A sampling rate of up to 80 MHz is feasible, which reduces the occurrence of motion artefacts.

  20. Laser photoacoustic detection of the essential oil vapors of thyme, mint, and anise

    Science.gov (United States)

    El-Kahlout, A. M.; Al-Jourani, M. M.; Abu-Taha, M. I.; Laine, Derek C.

    1998-07-01

    Photoacoustic studies of the vapors of the essential oils of thyme, mint and anise have been made using a line-tunable waveguide CO2 laser in conjunction with a heat-pipe type of photoacoustic vapor sample cell operated over the temperature range 20 - 180 degree(s)C. Identifying spectral fingerprint features are found in the 9 - 10 micrometers spectral region for each of the three essential oils investigated. The principal features of the photoacoustic spectrum of each essential oil are associated with the dominant chemicals present i.e. thymol in thyme oil, menthol in mint and anethole in anise.

  1. Sensitivity improvement of optical fiber acoustic probe for all-optical photoacoustic imaging system

    Science.gov (United States)

    Seki, Atsushi; Iwai, Katsumasa; Katagiri, Takashi; Matsuura, Yuji

    2017-07-01

    An acoustic probe based on a Fabry-Perot interferometer composed of a polymer film attached to the end of an optical fiber was designed and fabricated for an endoscopic, all-optical photoacoustic imaging system. The finesse of the interferometer was improved by forming a half-mirror at the end of the fiber and a partial reflection mirror on the outer surface of the polymer film. A photoacoustic imaging system was constructed by combining the fiber-optic acoustic probe with a bundle of hollow optical fibers used for the excitation of the photoacoustic wave, and an image of blood capillaries in a fish ovarian membrane was successfully obtained.

  2. Upconversion nanoparticles as a contrast agent for photoacoustic imaging in live mice.

    Science.gov (United States)

    Maji, Swarup Kumar; Sreejith, Sivaramapanicker; Joseph, James; Lin, Manjing; He, Tingchao; Tong, Yan; Sun, Handong; Yu, Sidney Wing-Kwong; Zhao, Yanli

    2014-08-27

    An inclusion complex of NaYF4 :Yb(3+) ,Er(3+) upconversion nanoparticles with α-cyclodextrin in aqueous conditions exhibits luminescence quenching when excited at 980 nm. This non-radiative relaxation leads to an unprecedented photoacoustic signal enhancement. In vivo localization of α-cyclodextrin-covered NaYF4 :Yb(3+) ,Er(3+) is demonstrated using photoacoustic tomography in live mice, showing its high capability for photoacoustic imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Trace-Gas Detection with Off-Beam Quartz Enhanced Photoacoustic Spectroscopy

    Science.gov (United States)

    Liu, Kun; Wang, Lei; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-06-01

    Trace-gas sensors have a wide range of potential applications such as environmental monitoring, climate research, agriculture, workplace safety, medical diagnostics, and industrial process control. A recently introduced technique called quartz-enhanced photoacoustic spectroscopy (QEPAS) is described. QEPAS use a quartz tuning fork as an acoustic transducer for a photoacoustic signal induced in an absorbing gas by modulated optical radiation. Advantages of the QEPAS compared to conventional photoacoustic spectroscopy include immunity to environmental acoustic noise and ultra-small sample volume. Trace gases of , and were monitored with a novel off-beam QEPAS approach and are described in detail.

  4. Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy

    Directory of Open Access Journals (Sweden)

    Andreas Pohlkötter

    2010-09-01

    Full Text Available Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS. With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sample gas that promote the radiationless de-excitation of the oxygen molecules.

  5. Detection of molecular oxygen at low concentrations using quartz enhanced photoacoustic spectroscopy.

    Science.gov (United States)

    Pohlkötter, Andreas; Köhring, Michael; Willer, Ulrike; Schade, Wolfgang

    2010-01-01

    Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS). With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sample gas that promote the radiationless de-excitation of the oxygen molecules.

  6. Anodic growth of titanium dioxide nanostructures

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

  7. Taking advantage of acoustic inhomogeneities in photoacoustic measurements

    Science.gov (United States)

    Da Silva, Anabela; Handschin, Charles; Metwally, Khaled; Garci, Houssem; Riedinger, Christophe; Mensah, Serge; Akhouayri, Hassan

    2017-04-01

    This paper proposes a method for improving the localization and the quantification of the optical parameters in photoacoustic (PA) tomography of biological tissues that are intrinsically heterogeneous in both optical and acoustic properties. It is based on the exploitation of both the PA signal, generated by the heterogeneous optical structures, and the secondary acoustic echoes due to the interaction between a primary PA wave generated near the tissue surface and the heterogeneous acoustic structures. These secondary echoes can also be collected through proper measurements of the PA signals. The experimental procedure is presented along with the method to filter the signal and the reconstruction algorithm that includes the account of the acoustic information.

  8. Photoacoustic in-vivo spectra of recent stromatolites

    Science.gov (United States)

    Schubert, W.; Giani, D.; Rongen, P.; Krumbein, W. E.; Schmidt, W.

    1980-03-01

    In-vivo photoacoustic spectra (PAS) of pure cultures of cyanobacteria and photosynthetic bacteria ( Chromatiaceae) which usually occur in stromatolitic microbial mats were measured. The PA spectra of the pure cultures were compared to PA spectra measured directly on different layers of microbial mats from Mellum (North Sea). The advantages of PAS of opaque, solid samples (e.g., sediment, rock), and of particle suspensions (e.g., light-scattering cell cultures with interference by sulfur globules) over conventional spectroscopy using classical in-vivo or extraction photometry are discussed.

  9. Photoacoustic microbeam-oscillator with tunable resonance direction and amplitude

    Science.gov (United States)

    Wu, Qingjun; Li, Fanghao; Wang, Bo; Yi, Futing; Jiang, J. Z.; Zhang, Dongxian

    2018-01-01

    We successfully design one photoacoustic microbeam-oscillator actuated by nanosecond laser, which exhibits tunable resonance direction and amplitude. The mechanism of laser induced oscillation is systematically analyzed. Both simulation and experimental results reveal that the laser induced acoustic wave propagates in a multi-reflected mode, resulting in resonance in the oscillator. This newly-fabricated micrometer-sized beam-oscillator has an excellent actuation function, i.e., by tuning the laser frequency, the direction and amplitude of actuation can be efficiently altered, which will have potential industrial applications.

  10. Photoacoustic cavitation for theranostics: mechanism, current progress and applications

    Science.gov (United States)

    Feng, Y.; Qin, D.; Wan, M.

    2015-12-01

    As an emerging cavitation technology, photoacoustic cavitation (PAC) means the formation of bubbles in liquids using focused laser and pre-established ultrasound synchronously. Its significant advantages include the decreased threshold of each modality and the precise location of cavitation determined by the focused laser. In this paper, a brief review of PAC is presented, including the physical mechanism description, the classic experimental technology, the representative results in variety of media, and its applications in biomedical imaging and therapy. Moreover, some preliminary results of PAC in perfluoropentane (PFP) liquid and PFP droplets investigated by passive cavitation detection (PCD) in our group are also presented.

  11. New polymer-based phantom for photoacoustic imaging

    Science.gov (United States)

    Kawaguchi, Yasushi; Iwazaki, Hideaki; Ida, Taiichiro; Nishi, Taiji; Tanikawa, Yukari; Nitta, Naotaka

    2014-03-01

    We will report newly developed polymer-based phantom for photoacoustic (PA) imaging systems. Phantoms are important for performance evaluation and calibration of new modalities; however, there is no established method for making phantoms with no long-term change. We have developed skin mimicking phantoms simulating both optical and acoustic properties (i.e. optical scattering and absorption coefficients, and sound velocity). Furthermore, the phantoms are able to give accurate simulation of blood vessels by Inkjet-printing. Newly developed phantoms are consisted of castor oil included acrylic block copolymer and we can fabricate 0.8mm or less thick sheets and pile them using their self-adhesiveness.

  12. Photoacoustic tomography using orthogonal Fabry-Pérot sensors.

    Science.gov (United States)

    Ellwood, Robert; Ogunlade, Olumide; Zhang, Edward; Beard, Paul; Cox, Ben

    2017-04-01

    Fabry–Pérot sensors have been used to produce in-vivo photoacoustic images of exquisite quality. However, for ease of construction and interrogation, they are produced in a planar form. Planar arrays suffer from a limited detection aperture, which leads to artifacts in the reconstruction of the initial pressure distribution. Here, an L-shaped detection geometry is described that allows a greater field of view by placing a second planar array orthogonal to the first. This captures data from the deeper lying regions of interest and mitigates the limited view, thus reducing artifacts in the reconstructed initial pressure distribution.

  13. Photoacoustic tomography using orthogonal Fabry-Pérot sensors

    Science.gov (United States)

    Ellwood, Robert; Ogunlade, Olumide; Zhang, Edward; Beard, Paul; Cox, Ben

    2017-04-01

    Fabry-Pérot sensors have been used to produce in-vivo photoacoustic images of exquisite quality. However, for ease of construction and interrogation, they are produced in a planar form. Planar arrays suffer from a limited detection aperture, which leads to artifacts in the reconstruction of the initial pressure distribution. Here, an L-shaped detection geometry is described that allows a greater field of view by placing a second planar array orthogonal to the first. This captures data from the deeper lying regions of interest and mitigates the limited view, thus reducing artifacts in the reconstructed initial pressure distribution.

  14. Study of nanodispersed aluminum and iron alcosols by photoacoustic spectroscopy

    Science.gov (United States)

    An, Vladimir; de Izarra, Charles; Saveliev, Gennady

    2011-06-01

    Nanodispersed aluminum and iron alcosols were prepared by ultrasonic dispersion of nanodispersed aluminum and iron powders in absolute ethanol. The photoacoustic signal (PAS) produced in modulated CO2 laser irradiation (1.026 and 1.096 kHz) of alcosols depends on the nature and method of nanoparticle fabrication and does not depend on their concentration in ethanol (within 1-5 g/l). Chemical interaction between metal nanoparticles and ethanol activated by laser irradiation or/and ultrasound is considered as the cause of the PAS.

  15. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism

    OpenAIRE

    Yongning Liu; Jun Chang; Jie Lian; Zhaojun Liu; Qiang Wang; Zengguang Qin

    2016-01-01

    A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS) system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 co...

  16. Double acoustic microresonator quartz-enhanced photoacoustic spectroscopy.

    Science.gov (United States)

    Dong, Lei; Wu, Hongpeng; Zheng, Huadan; Liu, Yanyan; Liu, Xiaoli; Jiang, Wenzhe; Zhang, Lei; Ma, Weiguang; Ren, Wei; Yin, Wangbao; Jia, Suotang; Tittel, Frank K

    2014-04-15

    Quartz-enhanced photoacoustic spectroscopy (QEPAS) based on double acoustic microresonators (AmRs) is developed and experimentally investigated. The double AmR spectrophone configuration exhibits a strong acoustic coupling between the AmR and the quartz tuning fork, which results in a ∼5  ms fast response time. Moreover, the double AmRs provide two independent detection channels that allow optical signal addition or cancellation from different optical wavelengths and facilitate rapid multigas sensing measurements, thereby avoiding laser beam combination.

  17. Quartz enhanced photoacoustic leak sensor for mechatronic components

    Science.gov (United States)

    Sampaolo, A.; Patimisco, P.; Giglio, M.; Calabrese, P. P.; Chieco, L.; Scamarcio, G.; Tittel, F. K.; Spagnolo, V.

    2016-02-01

    We report the first demonstration of a leak sensor based on a mid-IR quartz-enhanced photoacoustic (QEPAS) spectroscopic technique. A QEPAS sensor was integrated in a vacuum seal test station for mechatronic components. The laser source is a quantum cascade laser emitting at 10.56 μm, resonant with a strong absorption band of sulfur hexafluoride (SF6), which was selected as target gas for leak detection. The minimum detectable concentration of the QEPAS sensor is 6.9 ppb with an integration time of 1 s. This detection sensitivity allowed to measure SF6 leak flows as low as 3x10-5 standard cm3.

  18. 21 CFR 73.2575 - Titanium dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the requirements...

  19. 21 CFR 73.575 - Titanium dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.575 Section 73.575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.575 Titanium dioxide. (a) Identity. (1) The color additive titanium dioxide is synthetically prepared TiO2, free from admixture with other substances. (2) Color...

  20. 21 CFR 73.1575 - Titanium dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the requirements...

  1. 21 CFR 73.3126 - Titanium dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891, shall...

  2. 40 CFR 180.1195 - Titanium dioxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or on...

  3. Adaptive mesh refinement in titanium

    Energy Technology Data Exchange (ETDEWEB)

    Colella, Phillip; Wen, Tong

    2005-01-21

    In this paper, we evaluate Titanium's usability as a high-level parallel programming language through a case study, where we implement a subset of Chombo's functionality in Titanium. Chombo is a software package applying the Adaptive Mesh Refinement methodology to numerical Partial Differential Equations at the production level. In Chombo, the library approach is used to parallel programming (C++ and Fortran, with MPI), whereas Titanium is a Java dialect designed for high-performance scientific computing. The performance of our implementation is studied and compared with that of Chombo in solving Poisson's equation based on two grid configurations from a real application. Also provided are the counts of lines of code from both sides.

  4. Photoacoustic imaging of intestinal strictures: microscopic and macroscopic assessment in vivo (Conference Presentation)

    Science.gov (United States)

    Xu, Guan; Lei, Hao; Johnson, Laura A.; Moons, David S.; Ma, Teng; Zhou, Qifa; Rice, Michael D.; Ni, Jun; Wang, Xueding; Higgins, Peter D. R.

    2017-03-01

    The pathology of Crohn's disease (CD) is characterized by obstructing intestinal strictures because of inflammation (with high levels of hemoglobin), fibrosis (high levels of collagen), or a combination of both. Inflammatory strictures are medically treated. Fibrotic strictures have to be removed surgically. The accurate characterization of the strictures is therefore critical for the management of CD. Currently the comprehensive assessment of a stricture is difficult, as the standard diagnostic procedure, endoscopic biopsy, is superficial and with limited locations as well as depth. In our previous studies, photoacoustic imaging (PAI) has recovered the layered architectures and the relative content of the molecular components in human and animal tissues ex vivo. This study will investigate the capability of multispectral PAI in resolving the architecture and the molecular components of intestinal strictures in rats in vivo. PA images at 532, 1210 and 1310 nm targeting the strong optical absorption of hemoglobin, lipid and collagen were acquired using two approaches. A compact linear array, CL15-7, was used to transcutaneously acquire PA signals generated by the a fiber optics diffuser positioned within the inner lumen of the strictures. Another approach was to use an endoscopic capsule probe for acoustic resolution PA microscopy. The capsule probe is designed for human and therefore cannot fit into rat colon. The inner surface of the intestinal stricture was exposed and the probe was attached to the diseased location for imaging. The findings in PA images were confirmed by histology results.

  5. Photoacoustic microscopy of cerebral hemodynamic and oxygen-metabolic responses to anesthetics

    Science.gov (United States)

    Cao, Rui; Li, Jun; Ning, Bo; Sun, Naidi; Wang, Tianxiong; Zuo, Zhiyi; Hu, Song

    2017-02-01

    General anesthetics are known to have profound effects on cerebral hemodynamics and neuronal activities. However, it remains a challenge to directly assess anesthetics-induced hemodynamic and oxygen-metabolic changes from the true baseline under wakefulness at the microscopic level, due to the lack of an enabling technology for high-resolution functional imaging of the awake mouse brain. To address this challenge, we have developed head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin (CHb and sO2), and blood flow in awake mice. From these hemodynamic measurements, two important metabolic parameters, oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2), can be derived. Side-by-side comparison of the mouse brain under wakefulness and anesthesia revealed multifaceted cerebral responses to isoflurane, a volatile anesthetic widely used in preclinical research and clinical practice. Key observations include elevated cerebral blood flow (CBF) and reduced oxygen extraction and metabolism.

  6. Photoacoustic Sentinel Lymph Node Imaging with Self-Assembled Copper Neodecanoate Nanoparticles

    Science.gov (United States)

    Pan, Dipanjan; Cai, Xin; Yalaz, Ceren; Senpan, Angana; Omanakuttan, Karthik; Wickline, Samuel A.; Wang, Lihong V.; Lanza, Gregory M.

    2012-01-01

    Photoacoustic tomography (PAT) is emerging as a novel, hybrid, and non ionizing imaging modality, because of its satisfactory spatial resolution and high soft tissue contrast. PAT combines the advantages of both optical and ultrasonic imaging methods. It opens up the possibilities for non-invasive staging of breast cancer and may replace sentinel lymph node (SLN) biopsy in clinic in the near future. In this work, we demonstrate for the first time that Copper can be used as a contrast metal for near infrared detection of SLN using PAT. A unique strategy is adopted to encapsulate multiple copies of Cu as organically soluble small molecule complexes within a phospholipids-entrapped nanoparticle. The nanoparticles assumed a size of 80–90nm, which is the optimum hydrodynamic diameter for its distribution throughout the lymphatic systems. These particles provided at least six times higher signal sensitivity in comparison to blood, which is a natural absorber of light. We also demonstrated that high SLN detection sensitivity with PAT can be achieved in rodent model. This work clearly demonstrates for the first time, the potential use of copper as an optical contrast agent. PMID:22229462

  7. Limitations of quantitative photoacoustic measurements of blood oxygenation in small vessels

    Energy Technology Data Exchange (ETDEWEB)

    Sivaramakrishnan, Mathangi [Optical Imaging Laboratory, Department of Biomedical Engineering, Texas A and M University 3120 TAMU, College Station, TX 77843-3120 (United States); Maslov, Konstantin [Optical Imaging Laboratory, Department of Biomedical Engineering, Texas A and M University 3120 TAMU, College Station, TX 77843-3120 (United States); Zhang, Hao F [Optical Imaging Laboratory, Department of Biomedical Engineering, Texas A and M University 3120 TAMU, College Station, TX 77843-3120 (United States); Stoica, George [Department of Pathobiology, Texas A and M University, College Station, TX 77843-5547 (United States); Wang, Lihong V [Optical Imaging Laboratory, Department of Biomedical Engineering, Texas A and M University 3120 TAMU, College Station, TX 77843-3120 (United States)

    2007-03-07

    We investigate the feasibility of obtaining accurate quantitative information, such as local blood oxygenation level (sO{sub 2}), with a spatial resolution of about 50 {mu}m from spectral photoacoustic (PA) measurements. The optical wavelength dependence of the peak values of the PA signals is utilized to obtain the local blood oxygenation level. In our in vitro experimental models, the PA signal amplitude is found to be linearly proportional to the blood optical absorption coefficient when using ultrasonic transducers with central frequencies high enough such that the ultrasonic wavelengths are shorter than the light penetration depth into the blood vessels. For an optical wavelength in the 578-596 nm region, with a transducer central frequency that is above 25 MHz, the sensitivity and accuracy of sO{sub 2} inversion is shown to be better than 4%. The effect of the transducer focal position on the accuracy of quantifying blood oxygenation is found to be negligible. In vivo oxygenation measurements of rat skin microvasculature yield results consistent with those from in vitro studies, although factors specific to in vivo measurements, such as the spectral dependence of tissue optical attenuation, dramatically affect the accuracy of sO{sub 2} quantification in vivo.

  8. Photoacoustic bio-quantification of graphene based nanomaterials at a single cell level (Conference Presentation)

    Science.gov (United States)

    Nedosekin, Dmitry A.; Nolan, Jacqueline; Biris, Alexandru S.; Zharov, Vladimir P.

    2017-03-01

    Arkansas Nanomedicine Center at the University of Arkansas for Medical Sciences in collaboration with other Arkansas Universities and the FDA-based National Center of Toxicological Research in Jefferson, AR is developing novel techniques for rapid quantification of graphene-based nanomaterials (GBNs) in various biological samples. All-carbon GBNs have wide range of potential applications in industry, agriculture, food processing and medicine; however, quantification of GBNs is difficult in carbon reach biological tissues. The accurate quantification of GBNs is essential for research on material toxicity and the development of GBNs-based drug delivery platforms. We have developed microscopy and cytometry platforms for detection and quantification of GBNs in single cells, tissue and blood samples using photoacoustic contrast of GBNs. We demonstrated PA quantification of individual graphene uptake by single cells. High-resolution PA microscopy provided mapping of GBN distribution within live cells to establish correlation with intracellular toxic phenomena using apoptotic and necrotic assays. This new methodology and corresponding technical platform provide the insight on possible toxicological risks of GBNs at singe cells levels. In addition, in vivo PA image flow cytometry demonstrated the capability to monitor of GBNs pharmacokinetics in mouse model and to map the resulting biodistribution of GBNs in mouse tissues. The integrated PA platform provided an unprecedented sensitivity toward GBNs and allowed to enhance conventional toxicology research by providing a direct correlation between uptake of GBNs at a single cell level and cell viability status.

  9. Phantom-based image quality test methods for photoacoustic imaging systems

    Science.gov (United States)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, T. Joshua

    2017-09-01

    As photoacoustic imaging (PAI) technologies advance and applications arise, there is increasing need for standardized approaches to provide objective, quantitative performance assessment at various stages of the product development and clinical translation process. We have developed a set of performance test methods for PAI systems based on breast-mimicking tissue phantoms containing embedded inclusions. Performance standards for mature imaging modalities [magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound] were used to guide selection of critical PAI image quality characteristics and experimental methods. Specifically, the tests were designed to address axial, lateral, and elevational spatial resolution, signal uniformity, penetration depth, sensitivity, spatial measurement accuracy, and PAI-ultrasound coregistration. As an initial demonstration of the utility of these test methods, we characterized the performance of a modular, bimodal PAI-ultrasound system using four clinical ultrasound transducers with varying design specifications. Results helped to inform optimization of acquisition and data processing procedures while providing quantitative elucidation of transducer-dependent differences in image quality. Comparison of solid, tissue-mimicking polymer phantoms with those based on Intralipid indicated the superiority of the former approach in simulating real-world conditions for PAI. This work provides a critical foundation for the establishment of well-validated test methods that will facilitate the maturation of PAI as a medical imaging technology.

  10. Photoacoustic Spectroscopy for the Determination of Lung Cancer Biomarkers—A Preliminary Investigation

    Directory of Open Access Journals (Sweden)

    Yannick Saalberg

    2017-01-01

    Full Text Available With 1.6 million deaths per year, lung cancer is one of the leading causes of death worldwide. One reason for this high number is the absence of a preventive medical examination method. Many diagnoses occur in a late cancer stage with a low survival rate. An early detection could significantly decrease the mortality. In recent decades, certain substances in human breath have been linked to certain diseases. Different studies show that it is possible to distinguish between lung cancer patients and a healthy control group by analyzing the volatile organic compounds (VOCs in their breath. We developed a sensor based on photoacoustic spectroscopy for six of the most relevant VOCs linked to lung cancer. As a radiation source, the sensor uses an optical-parametric oscillator (OPO in a wavelength region from 3.2 µm to 3.5 µm. The limits of detection for a single substance range between 5 ppb and 142 ppb. We also measured high resolution absorption spectra of the biomarkers compared to the data currently available from the National Institute of Standards and Technology (NIST database, which is the basis of any selective spectroscopic detection. Future lung cancer screening devices could be based on the further development of this sensor.

  11. Photoacoustic Spectroscopy for the Determination of Lung Cancer Biomarkers—A Preliminary Investigation

    Science.gov (United States)

    Saalberg, Yannick; Bruhns, Henry; Wolff, Marcus

    2017-01-01

    With 1.6 million deaths per year, lung cancer is one of the leading causes of death worldwide. One reason for this high number is the absence of a preventive medical examination method. Many diagnoses occur in a late cancer stage with a low survival rate. An early detection could significantly decrease the mortality. In recent decades, certain substances in human breath have been linked to certain diseases. Different studies show that it is possible to distinguish between lung cancer patients and a healthy control group by analyzing the volatile organic compounds (VOCs) in their breath. We developed a sensor based on photoacoustic spectroscopy for six of the most relevant VOCs linked to lung cancer. As a radiation source, the sensor uses an optical-parametric oscillator (OPO) in a wavelength region from 3.2 µm to 3.5 µm. The limits of detection for a single substance range between 5 ppb and 142 ppb. We also measured high resolution absorption spectra of the biomarkers compared to the data currently available from the National Institute of Standards and Technology (NIST) database, which is the basis of any selective spectroscopic detection. Future lung cancer screening devices could be based on the further development of this sensor. PMID:28117732

  12. In vivo rat deep brain imaging using photoacoustic computed tomography (Conference Presentation)

    Science.gov (United States)

    Lin, Li; Li, Lei; Zhu, Liren; Hu, Peng; Wang, Lihong V.

    2017-03-01

    The brain has been likened to a great stretch of unknown territory consisting of a number of unexplored continents. Small animal brain imaging plays an important role charting that territory. By using 1064 nm illumination from the side, we imaged the full coronal depth of rat brains in vivo. The experiment was performed using a real-time full-ring-array photoacoustic computed tomography (PACT) imaging system, which achieved an imaging depth of 11 mm and a 100 μm radial resolution. Because of the fast imaging speed of the full-ring-array PACT system, no animal motion artifact was induced. The frame rate of the system was limited by the laser repetition rate (50 Hz). In addition to anatomical imaging of the blood vessels in the brain, we continuously monitored correlations between the two brain hemispheres in one of the coronal planes. The resting states in the coronal plane were measured before and after stroke ligation surgery at a neck artery.

  13. In vivo tumor detection with combined MR–Photoacoustic-Thermoacoustic imaging

    Directory of Open Access Journals (Sweden)

    Lin Huang

    2016-09-01

    Full Text Available Here, we report a new method using combined magnetic resonance (MR–Photoacoustic (PA–Thermoacoustic (TA imaging techniques, and demonstrate its unique ability for in vivo cancer detection using tumor-bearing mice. Circular scanning TA and PA imaging systems were used to recover the dielectric and optical property distributions of three colon carcinoma bearing mice While a 7.0-T magnetic resonance imaging (MRI unit with a mouse body volume coil was utilized for high resolution structural imaging of the same mice. Three plastic tubes filled with soybean sauce were used as fiducial markers for the co-registration of MR, PA and TA images. The resulting fused images provided both enhanced tumor margin and contrast relative to the surrounding normal tissues. In particular, some finger-like protrusions extending into the surrounding tissues were revealed in the MR/TA infused images. These results show that the tissue functional optical and dielectric properties provided by PA and TA images along with the anatomical structure by MRI in one picture make accurate tumor identification easier. This combined MR–PA–TA-imaging strategy has the potential to offer a clinically useful triple-modality tool for accurate cancer detection and for intraoperative surgical navigation.

  14. Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer

    Science.gov (United States)

    Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.

    2011-03-01

    A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.

  15. A novel two-axis micromechanical scanning transducer for handheld 3D ultrasound and photoacoustic imaging

    Science.gov (United States)

    Huang, Chih-Hsien; Zou, Jun

    2016-03-01

    This paper reports the development of a new two-axis micromechanical scanning transducer for handheld 3D ultrasound imaging. It consists of a miniaturized single-element ultrasound transducer driven by a unique 2-axis liquid-immersible electromagnetic microactuator. With a mechanical scanning frequency of 19.532 Hz and an ultrasound pulse repetition rate of 5 kHz, the scanning transducer was scanned along 60 concentric paths with 256 detection points on each to simulate a physical 2D ultrasound transducer array of 60 × 256 elements. Using the scanning transducer, 3D pulse-echo ultrasound imaging of two silicon discs immersed in water as the imaging target was successfully conducted. The lateral resolution of the 3D ultrasound image was further improved with the synthetic aperture focusing technique (SAFT). The new two-axis micromechanical scanning transducer doesn't require complex and expensive multi-channel data acquisition (DAQ) electronics. Therefore, it could provide a new approach to achieve compact and low-cost 3D ultrasound and photoacoustic imaging systems, especially for handheld operations.

  16. Experimental titanium alloys for dental applications.

    Science.gov (United States)

    Faria, Adriana C L; Rodrigues, Renata C S; Rosa, Adalberto L; Ribeiro, Ricardo F

    2014-12-01

    Although the use of titanium has increased, casting difficulties limit routine use. The purpose of the present study was to compare the mechanical properties and biocompatibility of the experimental titanium alloys titanium-5-zirconium, titanium-5-tantalum, and titanium-5-tantalum-5-zirconium (in wt%) with those of commercially pure titanium. Specimens of titanium alloys and commercially pure titanium were cast by using plasma. Their modulus of elasticity and ultimate tensile strength were determined in a universal testing machine. Biocompatibility was evaluated with SCC9 cells. In periods of 1, 4, 7, 10, and 14 days, cell proliferation was evaluated by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, and cell viability was evaluated in the 7-day period. Cell morphology was evaluated at 2, 12, and 24 hours. Modulus of elasticity, ultimate tensile strength, and cell viability were analyzed by 1-way ANOVA and the Bonferroni test; cell proliferation data were compared by 2-way ANOVA (alloy versus time) and by the Bonferroni test; and the cell morphology data were analyzed by split-plot design. All statistical tests were performed at the 95% confidence level (Ptantalum presented the lowest modulus of elasticity and ultimate tensile strength, whereas titanium-5-zirconium and titanium-5-tantalum-5-zirconium were statistically similar to commercially pure titanium. Cell proliferation and viability were not affected by any alloy being similar to those observed for commercially pure titanium. No noticeably differences were found in the morphology of cells cultured on any alloy and commercially pure titanium. Experimental alloys, especially titanium-5-zirconium and titanium-5-tantalum-5-zirconium, presented promising mechanical results for future studies and clinical applications. In addition, these alloys, evaluated by cell proliferation, viability, and morphology, were found to be biocompatible in vitro. Copyright © 2014

  17. Effect of whitening toothpaste on titanium and titanium alloy surfaces.

    Science.gov (United States)

    Faria, Adriana Cláudia Lapria; Bordin, Angelo Rafael de Vito; Pedrazzi, Vinícius; Rodrigues, Renata Cristina Silveira; Ribeiro, Ricardo Faria

    2012-01-01

    Dental implants have increased the use of titanium and titanium alloys in prosthetic applications. Whitening toothpastes with peroxides are available for patients with high aesthetic requirements, but the effect of whitening toothpastes on titanium surfaces is not yet known, although titanium is prone to fluoride ion attack. Thus, the aim of the present study was to compare Ti-5Ta alloy to cp Ti after toothbrushing with whitening and conventional toothpastes. Ti-5Ta (%wt) alloy was melted in an arc melting furnace and compared with cp Ti. Disks and toothbrush heads were embedded in PVC rings to be mounted onto a toothbrushing test apparatus. A total of 260,000 cycles were carried out at 250 cycles/minute under a load of 5 N on samples immersed in toothpaste slurries. Surface roughness and Vickers microhardness were evaluated before and after toothbrushing. One sample of each material/toothpaste was analyzed by Scanning Electron Microscopy (SEM) and compared with a sample that had not been submitted to toothbrushing. Surface roughness increased significantly after toothbrushing, but no differences were noted after toothbrushing with different toothpastes. Toothbrushing did not significantly affect sample microhardness. The results suggest that toothpastes that contain and those that do not contain peroxides in their composition have different effects on cp Ti and Ti-5Ta surfaces. Although no significant difference was noted in the microhardness and roughness of the surfaces brushed with different toothpastes, both toothpastes increased roughness after toothbrushing.

  18. Effect of whitening toothpaste on titanium and titanium alloy surfaces

    Directory of Open Access Journals (Sweden)

    Adriana Cláudia Lapria Faria

    2012-12-01

    Full Text Available Dental implants have increased the use of titanium and titanium alloys in prosthetic applications. Whitening toothpastes with peroxides are available for patients with high aesthetic requirements, but the effect of whitening toothpastes on titanium surfaces is not yet known, although titanium is prone to fluoride ion attack. Thus, the aim of the present study was to compare Ti-5Ta alloy to cp Ti after toothbrushing with whitening and conventional toothpastes. Ti-5Ta (%wt alloy was melted in an arc melting furnace and compared with cp Ti. Disks and toothbrush heads were embedded in PVC rings to be mounted onto a toothbrushing test apparatus. A total of 260,000 cycles were carried out at 250 cycles/minute under a load of 5 N on samples immersed in toothpaste slurries. Surface roughness and Vickers microhardness were evaluated before and after toothbrushing. One sample of each material/toothpaste was analyzed by Scanning Electron Microscopy (SEM and compared with a sample that had not been submitted to toothbrushing. Surface roughness increased significantly after toothbrushing, but no differences were noted after toothbrushing with different toothpastes. Toothbrushing did not significantly affect sample microhardness. The results suggest that toothpastes that contain and those that do not contain peroxides in their composition have different effects on cp Ti and Ti-5Ta surfaces. Although no significant difference was noted in the microhardness and roughness of the surfaces brushed with different toothpastes, both toothpastes increased roughness after toothbrushing.

  19. Method of making multilayered titanium ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, George T., II; Hansen; Jeffrey S.; Oden; Laurance L.; Turner; Paul C.; Ochs; Thomas L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  20. Prospects of Passive Element enRiched PhotoAcoustic Computed Tomography (PER-PACT)

    NARCIS (Netherlands)

    Jose, J.

    2012-01-01

    This thesis describes the design and development of a hybrid photoacoustic-ultrasound transmission tomographic imager optimised for small animal imaging (mice). The system allows imaging of ultrasound transmission properties (speed of sound (SOS) and acoustic attenuation (AA) ) simultaneously with

  1. Mobile laser spectrometer with novel resonant multipass photoacoustic cell for trace-gas sensing

    Science.gov (United States)

    Nägele, M.; Sigrist, M. W.

    The development and application of a mobile laser-photoacoustic spectrometer for in situ multicomponent monitoring of trace gases in different environments is reported. Sub-ppbV (fruit storage chamber.

  2. Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber

    Science.gov (United States)

    Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui

    2017-09-01

    Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.

  3. Discrimination of prostate cancer cells by reflection mode FTIR photoacoustic spectroscopy.

    Science.gov (United States)

    Harvey, Tim J; Henderson, Alex; Gazi, Ehsan; Clarke, Noel W; Brown, Mick; Faria, Elsa Correia; Snook, Richard D; Gardner, Peter

    2007-04-01

    In this communication reflection mode Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) is used to obtain IR spectra of four prostate and prostate cancer cell line types (CaP) allowing their differentiation by principal components analysis.

  4. Imaging breast lesions using the Twente Photoacoustic Mammoscope: ongoing clinical experience

    NARCIS (Netherlands)

    Heijblom, M.; Piras, D.; Xia, W.; van Hespen, Johannes C.G.; Klaase, J.M.; van den Engh, F.M.; van Leeuwen, Ton; Steenbergen, Wiendelt; Manohar, Srirang

    2012-01-01

    Current imaging modalities are often not able to detect early stages of breast cancer with high imaging contrast. Visualizing malignancy-associated increased hemoglobin concentrations might improve breast cancer diagnosis. Photoacoustic imaging can visualize hemoglobin in tissue with optical

  5. Silica-coated gold nanoplates as stable photoacoustic contrast agents for sentinel lymph node imaging

    Science.gov (United States)

    Luke, Geoffrey P.; Bashyam, Ashvin; Homan, Kimberly A.; Makhija, Suraj; Chen, Yun-Sheng; Emelianov, Stanislav Y.

    2013-11-01

    A biopsy of the first lymph node to which a tumor drains—the sentinel lymph node (SLN)—is commonly performed to identify micrometastases. Image guidance of the SLN biopsy procedure has the potential to improve its accuracy and decrease its morbidity. We have developed a new stable contrast agent for photoacoustic image-guided SLN biopsy: silica-coated gold nanoplates (Si-AuNPs). The Si-AuNPs exhibit high photothermal stability when exposed to pulsed and continuous wave laser irradiation. This makes them well suited for in vivo photoacoustic imaging. Furthermore, Si-AuNPs are shown to have low cytotoxicity. We tested the Si-AuNPs for SLN mapping in a mouse model where they exhibited a strong, sustained photoacoustic signal. Real-time ultrasound and photoacoustic imaging revealed that the Si-AuNPs quickly drain to the SLN, gradually spreading throughout a large portion of the node.

  6. Spectral power density of the random excitation for the photoacoustic wave equation

    Directory of Open Access Journals (Sweden)

    Hakan Erkol

    2014-09-01

    Full Text Available The superposition of the Green's function and its time reversal can be extracted from the photoacoustic point sources applying the representation theorems of the convolution and correlation type. It is shown that photoacoustic pressure waves at locations of random point sources can be calculated with the solution of the photoacoustic wave equation and utilization of the continuity and the discontinuity conditions of the pressure waves in the frequency domain although the pressure waves cannot be measured at these locations directly. Therefore, with the calculated pressure waves at the positions of the sources, the spectral power density can be obtained for any system consisting of two random point sources. The methodology presented here can also be generalized to any finite number of point like sources. The physical application of this study includes the utilization of the cross-correlation of photoacoustic waves to extract functional information associated with the flow dynamics inside the tissue.

  7. Methodology of Pulsed Photoacoustics and Its Application to Probe Photosystems and Receptors

    Directory of Open Access Journals (Sweden)

    Harvey J.M. Hou

    2010-06-01

    Full Text Available We review recent advances in the methodology of pulsed time-resolved photoacoustics and its application to studies of photosynthetic reaction centers and membrane receptors such as the G protein-coupled receptor rhodopsin. The experimental parameters accessible to photoacoustics include molecular volume change and photoreaction enthalpy change. Light-driven volume change secondary to protein conformational changes or electrostriction is directly related to the photoreaction and thus can be a useful measurement of activity and function. The enthalpy changes of the photochemical reactions observed can be measured directly by photoacoustics. With the measurement of enthalpy change, the reaction entropy can also be calculated when free energy is known. Dissecting the free energy of a photoreaction into enthalpic and entropic components may provide critical information about photoactivation mechanisms of photosystems and photoreceptors. The potential limitations and future applications of time-resolved photoacoustics are also discussed.

  8. CONTRAST-ENHANCED PHOTOACOUSTIC IMAGING USING INDOCYANINE GREEN-CONTAINING NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    JUNPING ZHONG

    2014-01-01

    Full Text Available Contrast agents are attracting a great deal of attention in photoacoustic imaging. Here we introduce an exogenous contrast agent that provides high photoacoustic signal amplitude at the near-infrared wavelength. Our agents consist of Indocyanine green (ICG and phospholipid–polyethylene glycol (PL–PEG, entitled ICG–PL–PEG nanoparticles. These nanoparticles have overcome numerous limitations of ICG, such as poor aqueous stability, concentration-dependent aggregation and lack of target specificity. ICG–PL–PEG nanoparticles are biocompatible and relatively nontoxic. All the components of ICG–PL–PEG nanoparticles have been approved for human use. Upon pulsed laser irradiation, the nanoparticles are more efficient in producing photoacoustic waves than ICG alone. The results showed that ICG–PL–PEG nanoparticles act as good contrast agents for photoacoustic imaging. These unique ICG–PL–PEG nanoparticles have great potential in clinical applications.

  9. Photoacoustic imaging to detect rat brain activation after cocaine hydrochloride injection

    Science.gov (United States)

    Jo, Janggun; Yang, Xinmai

    2011-03-01

    Photoacoustic imaging (PAI) was employed to detect small animal brain activation after the administration of cocaine hydrochloride. Sprague Dawley rats were injected with different concentrations (2.5, 3.0, and 5.0 mg per kg body) of cocaine hydrochloride in saline solution through tail veins. The brain functional response to the injection was monitored by photoacoustic tomography (PAT) system with horizontal scanning of cerebral cortex of rat brain. Photoacoustic microscopy (PAM) was also used for coronal view images. The modified PAT system used multiple ultrasonic detectors to reduce the scanning time and maintain a good signal-to-noise ratio (SNR). The measured photoacoustic signal changes confirmed that cocaine hydrochloride injection excited high blood volume in brain. This result shows PAI can be used to monitor drug abuse-induced brain activation.

  10. All-optical Photoacoustic and laser-ultrasound imaging of fixed arterial tissue (Conference Presentation)

    Science.gov (United States)

    Johnson, Jami L.; van Wijk, Kasper; Merrilees, Mervyn

    2017-03-01

    Arterial tissue imaging and characterization is important for disease diagnosis, treatment planning and monitoring, and research into disease processes. The high optical contrast of photoacoustic imaging can distinguish molecules with unique optical spectra from surrounding arterial tissue, while ultrasound is sensitive to variations in acoustic properties. Combining photoacoustics with ultrasonics provides more comprehensive diagnostic information by extracting molecular information from photoacoustics and structural information from ultrasound. Furthermore, ultrasound may be able to distinguish molecules with indistinct optical spectra but strong acoustic properties, such as calcification. In this work we will present our results applying our recently developed all-optical, multi-channel photoacoustic and laser-ultrasound imaging techniques to arterial tissue ex-vivo. We first apply redatuming techniques to remove reverberation artifacts, and subsequently image with time-reversal.

  11. Photoacoustic image-guided navigation system for surgery (Conference Presentation)

    Science.gov (United States)

    Park, Sara; Jang, Jongseong; Kim, Jeesu; Kim, Young Soo; Kim, Chulhong

    2017-03-01

    Identifying and delineating invisible anatomical and pathological details during surgery guides surgical procedures in real time. Various intraoperative imaging modalities have been increasingly employed to minimize such surgical risks as anatomical changes, damage to normal tissues, and human error. However, current methods provide only structural information, which cannot identify critical structures such as blood vessels. The logical next step is an intraoperative imaging modality that can provide functional information. Here, we have successfully developed a photoacoustic (PA) image-guided navigation system for surgery by integrating a position tracking system and a real-time clinical photoacoustic/ultrasound (PA/US) imaging system. PA/US images were acquired in real time and overlaid on pre-acquired cross-sectional magnetic resonance (MR) images. In the overlaid images, PA images represent the optical absorption characteristics of the surgical field, while US and MR images represent the morphological structure of surrounding tissues. To test the feasibility of the system, we prepared a tissue mimicking phantom which contained two samples, methylene blue as a contrast agent and water as a control. We acquired real-time overlaid PA/US/MR images of the phantom, which were well-matched with the optical and morphological properties of the samples. The developed system is the first approach to a novel intraoperative imaging technology based on PA imaging, and we believe that the system can be utilized in various surgical environments in the near future, improving the efficacy of surgical guidance.

  12. Quantitative photoacoustic elastography of Young's modulus in humans

    Science.gov (United States)

    Hai, Pengfei; Zhou, Yong; Gong, Lei; Wang, Lihong V.

    2017-03-01

    Elastography can noninvasively map the elasticity distribution of biological tissue, which is often altered in pathological states. In this work, we report quantitative photoacoustic elastography (QPAE), capable of measuring Young's modulus of human tissue in vivo. By combining photoacoustic elastography with a stress sensor having known stress-strain behavior, QPAE can simultaneously measure strain and stress, from which Young's modulus is calculated. We first applied QPAE to quantify the Young's modulus of tissue-mimicking agar phantoms with different concentrations. The measured values fitted well with both the empirical expectations based on the agar concentrations and those measured in independent standard compression tests. We then demonstrated the feasibility of QPAE by measuring the Young's modulus of human skeletal muscle in vivo. The data showed a linear relationship between muscle stiffness and loading. The results proved that QPAE can noninvasively quantify the absolute elasticity of biological tissue, thus enabling longitudinal imaging of tissue elasticity. QPAE can be exploited for both preclinical biomechanics studies and clinical applications.

  13. Adaptive photoacoustic imaging quality optimization with EMD and reconstruction

    Science.gov (United States)

    Guo, Chengwen; Ding, Yao; Yuan, Jie; Xu, Guan; Wang, Xueding; Carson, Paul L.

    2016-10-01

    Biomedical photoacoustic (PA) signal is characterized with extremely low signal to noise ratio which will yield significant artifacts in photoacoustic tomography (PAT) images. Since PA signals acquired by ultrasound transducers are non-linear and non-stationary, traditional data analysis methods such as Fourier and wavelet method cannot give useful information for further research. In this paper, we introduce an adaptive method to improve the quality of PA imaging based on empirical mode decomposition (EMD) and reconstruction. Data acquired by ultrasound transducers are adaptively decomposed into several intrinsic mode functions (IMFs) after a sifting pre-process. Since noise is randomly distributed in different IMFs, depressing IMFs with more noise while enhancing IMFs with less noise can effectively enhance the quality of reconstructed PAT images. However, searching optimal parameters by means of brute force searching algorithms will cost too much time, which prevent this method from practical use. To find parameters within reasonable time, heuristic algorithms, which are designed for finding good solutions more efficiently when traditional methods are too slow, are adopted in our method. Two of the heuristic algorithms, Simulated Annealing Algorithm, a probabilistic method to approximate the global optimal solution, and Artificial Bee Colony Algorithm, an optimization method inspired by the foraging behavior of bee swarm, are selected to search optimal parameters of IMFs in this paper. The effectiveness of our proposed method is proved both on simulated data and PA signals from real biomedical tissue, which might bear the potential for future clinical PA imaging de-noising.

  14. Quinone-fused porphyrins as contrast agents for photoacoustic imaging

    KAUST Repository

    Banala, Srinivas

    2017-06-27

    Photoacoustic (PA) imaging is an emerging non-invasive diagnostic modality with many potential clinical applications in oncology, rheumatology and the cardiovascular field. For this purpose, there is a high demand for exogenous contrast agents with high absorption coefficients in the optical window for tissue imaging, i.e. the near infrared (NIR) range between 680 and 950 nm. We herein report the photoacoustic properties of quinone-fused porphyrins inserted with different transition metals as new highly promising candidates. These dyes exhibit intense NIR absorption, a lack of fluorescence emission, and PA sensitivity in concentrations below 3 nmol mL. In this context, the highest PA signal was obtained with a Zn(ii) inserted dye. Furthermore, this dye was stable in blood serum and free thiol solution and exhibited negligible cell toxicity. Additionally, the Zn(ii) probe could be detected with an up to 3.2 fold higher PA intensity compared to the clinically most commonly used PA agent, ICG. Thus, further exploration of the \\'quinone-fusing\\' approach to other chromophores may be an efficient way to generate highly potent PA agents that do not fluoresce and shift their absorption into the NIR range.

  15. Theoretical and experimental investigation of multispectral photoacoustic osteoporosis detection method

    Science.gov (United States)

    Steinberg, Idan; Hershkovich, Hadas Sara; Gannot, Israel; Eyal, Avishay

    2014-03-01

    Osteoporosis is a widespread disorder, which has a catastrophic impact on patients lives and overwhelming related to healthcare costs. Recently, we proposed a multispectral photoacoustic technique for early detection of osteoporosis. Such technique has great advantages over pure ultrasonic or optical methods as it allows the deduction of both bone functionality from the bone absorption spectrum and bone resistance to fracture from the characteristics of the ultrasound propagation. We demonstrated the propagation of multiple acoustic modes in animal bones in-vitro. To further investigate the effects of multiple wavelength excitations and of induced osteoporosis on the PA signal a multispectral photoacoustic system is presented. The experimental investigation is based on measuring the interference of multiple acoustic modes. The performance of the system is evaluated and a simple two mode theoretical model is fitted to the measured phase signals. The results show that such PA technique is accurate and repeatable. Then a multiple wavelength excitation is tested. It is shown that the PA response due to different excitation wavelengths revels that absorption by the different bone constitutes has a profound effect on the mode generation. The PA response is measured in single wavelength before and after induced osteoporosis. Results show that induced osteoporosis alters the measured amplitude and phase in a consistent manner which allows the detection of the onset of osteoporosis. These results suggest that a complete characterization of the bone over a region of both acoustic and optical frequencies might be used as a powerful tool for in-vivo bone evaluation.

  16. Portable multiwavelength laser diode source for handheld photoacoustic devices

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2016-04-01

    The ageing population faces today an increase of chronic diseases such as rheumatism/arthritis, cancer and cardio vascular diseases for which appropriate treatments based on a diagnosis at an early-stage of the disease are required. Some imaging techniques are already available in order to get structural information. Within the non-invasive group, ultrasound images are common in these fields of medicine. However, there is a need for a point-of-care device for imaging smaller structures such as blood vessels that cannot be observed with purely ultrasound based devices. Photoacoustics proved to be an attractive candidate. This novel imaging technique combines pulsed laser light for excitation of tissues and an ultrasound transducer as a receptor. Introduction of this technique into the clinic requires to drastically shrink the size and cost of the expensive and bulky nanosecond lasers generally used for light emission. In that context, demonstration of ultra-short pulse emission with highly efficient laser diodes in the near-infrared range has been performed by Quantel, France. A multi-wavelength laser source as small as a hand emitted more than 1 mJ per wavelength with four different wavelengths available in pulses of about 90 ns. Such a laser source can be integrated into high sensitivity photoacoustic handheld systems due to their outstanding electrical-to-optical efficiency of about 25 %. Further work continues to decrease the pulse length as low as 40 ns while increasing the pulse energy to 2 mJ.

  17. Optimizing light delivery for a photoacoustic surgical system

    Science.gov (United States)

    Eddins, Blackberrie; Lediju Bell, Muyinatu A.

    2017-03-01

    This work explores light delivery optimization for a photoacoustic surgical system previously proposed to provide real-time, intraoperative visualization of the internal carotid arteries hidden by bone during minimally invasive neurosurgeries. Monte Carlo simulations were employed to study 3D light propagation in tissue. For a 2.4 mm diameter drill shaft and 2.9 mm spherical drill tip, the optimal fiber distance from the drill shaft was 2 mm, determined from the maximum normalized fluence seen by the artery. A single fiber was insufficient to deliver light to arteries separated by a minimum of 8 mm. Using similar drill geometry and the optimal 2 mm fiber-to-drill shaft distance, Zemax ray tracing simulations were employed to propagate a 950 nm wavelength Gaussian beam through one or more 600 μm core diameter optical fibers, and the resulting optical beam profile was detected on the representative bone surface. For equally spaced fibers, a single merged optical profile formed with 7 or more fibers, determined by thresholding the resulting light profile images at 1/e times the maximum intensity. The corresponding spot size was larger than that of a single fiber transmitting the same input energy, thus reducing the fluence delivered to the sphenoid bone and enabling higher energies within safety limits. A prototype was designed and built based on these optimization parameters. The methodology we used to optimize our light delivery system to surround surgical tools is generalizable to multiple interventional photoacoustic applications.

  18. Photoacoustic-Based-Close-Loop Temperature Control for Nanoparticle Hyperthermia.

    Science.gov (United States)

    Xiaohua, Feng; Fei, Gao; Yuanjin, Zheng

    2015-07-01

    Hyperthermia therapy requires tight temperature control to achieve selective killing of cancerous tissue with minimal damage on surrounding healthy tissues. To this end, accurate temperature monitoring and subsequent heating control are critical. However, an economic, portable, and real-time temperature control solution is currently lacking. To bridge this gap, we present a novel portable close-loop system for hyperthermia temperature control, in which photoacoustic technique is proposed for noninvasive real-time temperature measurement. Exploiting the high sensitivity of photoacoustics, the temperature is monitored with an accuracy of around 0.18 °C and then fed back to a controller implemented on field programmable gate array (FPGA) for temperature control. Dubbed as portable hyperthermia feedback controller (pHFC), it stabilizes the temperature at preset values by regulating the hyperthermia power with a proportional-integral-derivative (PID) algorithm; and to facilitate digital implementation, the pHFC further converts the PID output into switching values (0 and 1) with the pulse width modulation (PWM) algorithm. Proof-of-concept hyperthermia experiments demonstrate that the pHFC system is able to bring the temperature from baseline to predetermined value with an accuracy of 0.3° and a negligible temperature overshoot. The pHFC can potentially be translated to clinical applications with customized hyperthermia system design. This paper can facilitate future efforts in seamless integration of close-loop temperature control solution and various clinical hyperthermia systems.

  19. Theoretical analysis of a quartz-enhanced photoacoustic spectroscopy sensor

    Science.gov (United States)

    Petra, N.; Zweck, J.; Kosterev, A. A.; Minkoff, S. E.; Thomazy, D.

    2009-03-01

    Quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors are based on a recent approach to photoacoustic detection which employs a quartz tuning fork as an acoustic transducer. These sensors enable detection of trace gases for air quality monitoring, industrial process control, and medical diagnostics. To detect a trace gas, modulated laser radiation is directed between the tines of a tuning fork. The optical energy absorbed by the gas results in a periodic thermal expansion which gives rise to a weak acoustic pressure wave. This pressure wave excites a resonant vibration of the tuning fork thereby generating an electrical signal via the piezoelectric effect. This paper describes a theoretical model of a QEPAS sensor. By deriving analytical solutions for the partial differential equations in the model, we obtain a formula for the piezoelectric current in terms of the optical, mechanical, and electrical parameters of the system. We use the model to calculate the optimal position of the laser beam with respect to the tuning fork and the phase of the piezoelectric current. We also show that a QEPAS transducer with a particular 32.8 kHz tuning fork is 2-3 times as sensitive as one with a 4.25 kHz tuning fork. These simulation results closely match experimental data.

  20. A strategy to measure electrophysiological changes with photoacoustic imaging (Conference Presentation)

    Science.gov (United States)

    Sepela, Rebecka J.; Sherlock, Benjamin E.; Tian, Lin; Marcu, Laura; Sack, Jon

    2017-03-01

    Photoacoustic imaging is an emerging technology capable of both functional and structural biological imaging. Absorption and scattering in tissue limit the penetration depth of conventional microscopy techniques to live cell imaging. This technology could permit photoacoustic imaging of electrophysiological dynamics in deep tissue, such as the brain. Further optimization of this technology could lead to concurrent imaging of neural activity and hemodynamic responses, a crucial step towards understanding neurovascular coupling in the brain.

  1. Investigation of Plant-Pathogen Interaction by Laser-Based Photoacoustic Spectroscopy

    Science.gov (United States)

    Puiu, A.; Giubileo, G.; Lai, A.

    2014-12-01

    The laser-based photoacoustic spectroscopy apparatus, constructed at ENEA Frascati (Italy), was applied to monitor trace amounts of ethylene emitted by plants in a stress condition. More specifically, in the present work, the biotic stress response of tomato mutant plants after inoculation with Phthorimaea operculella larvae ( Lepidoptera: Gelechiidae) was investigated. The principle of the method, the photoacoustic setup, the experimental work, and the results are being reported.

  2. Photoacoustic and nephelometric spectroscopy of aerosol optical properties with a supercontinuum light source

    OpenAIRE

    Sharma, N; I. J. Arnold; H. Moosmüller; W. P. Arnott; Mazzoleni, C.

    2013-01-01

    A novel multi-wavelength photoacoustic-nephelometer spectrometer (SC-PNS) has been developed for the optical characterization of atmospheric aerosol particles. This instrument integrates a white light supercontinuum laser with photoacoustic and nephelometric spectroscopy to measure aerosol absorption and scattering coefficients at five wavelength bands (centered at 417, 475, 542, 607, and 675 nm). These wavelength bands were selected from the continuous spectrum of the laser (ranging f...

  3. Photoacoustic and nephelometric spectroscopy of aerosol optical properties with a supercontinuum light source

    OpenAIRE

    Sharma, N; I. J. Arnold; H. Moosmüller; W. P. Arnott; Mazzoleni, C.

    2013-01-01

    A novel multi-wavelength photoacoustic-nephelometer spectrometer (SC-PNS) has been developed for the optical characterization of atmospheric aerosol particles. This instrument integrates a white light supercontinuum laser with photoacoustic and nephelometric spectroscopy to measure aerosol absorption and scattering coefficients at five wavelength bands (centered at 417, 475, 542, 607, and 675 nm). These wavelength bands are selected from the continuous spectrum of the laser ...

  4. Application of time-resolved glucose concentration photoacoustic signals based on an improved wavelet denoising

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2014-10-01

    Real-time monitoring of blood glucose concentration (BGC) is a great important procedure in controlling diabetes mellitus and preventing the complication for diabetic patients. Noninvasive measurement of BGC has already become a research hotspot because it can overcome the physical and psychological harm. Photoacoustic spectroscopy is a well-established, hybrid and alternative technique used to determine the BGC. According to the theory of photoacoustic technique, the blood is irradiated by plused laser with nano-second repeation time and micro-joule power, the photoacoustic singals contained the information of BGC are generated due to the thermal-elastic mechanism, then the BGC level can be interpreted from photoacoustic signal via the data analysis. But in practice, the time-resolved photoacoustic signals of BGC are polluted by the varities of noises, e.g., the interference of background sounds and multi-component of blood. The quality of photoacoustic signal of BGC directly impacts the precision of BGC measurement. So, an improved wavelet denoising method was proposed to eliminate the noises contained in BGC photoacoustic signals. To overcome the shortcoming of traditional wavelet threshold denoising, an improved dual-threshold wavelet function was proposed in this paper. Simulation experimental results illustrated that the denoising result of this improved wavelet method was better than that of traditional soft and hard threshold function. To varify the feasibility of this improved function, the actual photoacoustic BGC signals were test, the test reslut demonstrated that the signal-to-noises ratio(SNR) of the improved function increases about 40-80%, and its root-mean-square error (RMSE) decreases about 38.7-52.8%.

  5. Study of photoacoustic measurement of bone health based on clinically relevant models

    Science.gov (United States)

    Feng, Ting; Kozloff, Ken; Cao, Meng; Cheng, Qian; Yuan, Jie; Wang, Xueding

    2016-02-01

    Photoacoustic (PA) technique involving both ultrasound and light has been explored for potential application in the assessment of bone health. The optical and ultrasound penetration in bone have been studied. The feasibility of conducting 3D PA imaging of bone, and performing quantitative evaluation of bone microstructures by using photoacoustic spectrum analysis (PASA) has also been investigated. The findings from the experiments demonstrate that PA measurement could offer information of bone mineral density and bone microstructure, both relevant to bone health.

  6. Volumetric photoacoustic endoscopy of internal organs: a phantom and in situ study

    Science.gov (United States)

    Yang, Joon-Mo; Maslov, Konstantin; Chen, Ruimin; Yang, Hao-Chung; Zhou, Qifa; Shung, K. Kirk; Wang, Lihong V.

    2010-02-01

    In this study, we further developed our photoacoustic endoscopic system to produce three-dimensional images of internal organs by performing pullback C-scans. Employing the side-scanning photoacoustic endoscopic probe discussed in the Optical Society of America's journal Optics Letters, we could acquire successive B-scan images by pulling back the probe with a motorized linear stage. We demonstrate the endoscopic system's volumetric imaging ability through imaging of a metal wire phantom and an in situ rat rectum.

  7. Photoacoustic imaging of early gastric cancer diagnosis based on long focal area ultrasound transducer

    Science.gov (United States)

    Wu, Huaqin; Li, Zuoran; Liu, Lantian; Li, Zhifang; Wu, Shulian; Li, Hui

    2017-06-01

    We illustrated a novel imaging method to diagnose gastric neoplasms via photoacoustic tomography (PAT). Depending on the structural characteristics of gastric cavity, we used column diffusion fiber to irradiate the stomach tissue through the esophagus, and the externally placed telecentric focus ultrasonic transducer detected photoacoustic signals from the gastric tissue. We reconstructed the distribution of light energy deposition of the simulated gastric tumor, and obtained the location and size information of gastric tumor.

  8. Practical Analysis of materials with depth varying compositions using FT-IR photoacoustic spectroscopy (PAS)

    Energy Technology Data Exchange (ETDEWEB)

    J.F. McClelland; R.W. Jones; Siquan Luo

    2004-09-30

    FT-IR photoacoustic spectroscopy (PAS) is discussed as a nondestructive method to probe the molecular composition of materials versus depth on the basis of the analysis of layers of experimentally controllable thickness, which are measured from the sample surface to depths of some tens of micrometers, depending on optical and thermal properties. Computational methods are described to process photoacoustic amplitude and phase spectra for both semi-quantitative and quantitative depth analyses. These methods are demonstrated on layered and gradient samples.

  9. Aerosol source apportionment based on multi-wavelength photoacoustic light absorption measurements: a simulation method for system's optimisation

    Science.gov (United States)

    Simon, Károly; Ajtai, Tibor; Kiss-Albert, Gergely; Utry, Noémi; Pintér, Máté; Szabó, Gábor; Bozóki, Zoltán

    2017-04-01

    Aerosol source apportionment is currently one of the outstanding challenges for environmental monitoring. In most cases atmospheric aerosol is a heterogeneous mixture as it typically originates from various sources. Consequently, each aerosol type has distinct chemical and physical properties. Contrary to chemical properties, optical absorption and size distribution of airborne particles can be measured in real time with high time resolution i.e. their measurement facilitates real time source apportionment (Favez et al (2009), Ajtai et al (2011), Favez et al (2010)). The wavelength dependency of the optical absorption coefficient (OAC) is usually characterised by the Absorption Angström Exponent (AAE). So far, the selection of light sources (lasers) into a photoacoustic aerosol measuring system was based on rule of thumb type estimations only. Recently, we proposed a simulation method that can be used to estimate the accuracy of aerosol source apportionment in case of a dual wavelength photoacoustic system (Simon et al., (2017)). This simulation is based on the assumption that the atmospheric aerosol load is dominated by two distinct sources and each of them is strongly light absorbing with specific AAE values. This is a typical scenario e.g. for urban measurements under wintry conditions when dominating aerosol sources are fossil fuel and wood burning with characteristic AAE 1 and 2, respectively. The wavelength pair of 405 and 1064 nm was found to be optimal for source apportionment in this case. In the presented study we investigated the situation when there are aerosol components with only slightly different AAE values and searched for a photoacoustic system which is optimal for distinguishing these components. Ajtai, T.; Filep, Á.; Utry, N.; Schnaiter, M.; Linke, C.; Bozóki, Z.; Szabó, G. and Leisner T. (2011) Journal of Aerosol Science 42, 859-866. Favez, O.; Cachier, H.; Sciare, J.; Sarda-Estève, R. and Martinon, L. (2009) Atmospheric Environment 43

  10. Multifunctional photoacoustic signals detected by P(VDF/TrFE) film sensor with a wide range of frequency

    Science.gov (United States)

    Ishihara, M.; Hirasawa, T.; Tsujita, K.; Kitagaki, M.; Bansaku, I.; Fujita, M.; Kikuchi, M.

    2011-03-01

    Photoacoustics has been widely studied as a combined imaging modality of both optical and acoustical methods. The merits of the photoacoustic imaging are realizing the full potentials of pulsed laser-tissue interaction. As the photoacoustic waves can be induced at chromophores by pulsed lased irradiation through a thermoelastic process, it covers a wide range of frequency. In order to take advantages of the wide range frequency characteristics, we employed not PZT, but piezoelectronic copolymer film, P(VDF/TrFE) film, with various thickness ranging from 20 to 100 μm as photoacoustic transducers. Because blood vessels play a key role in homeostasis, we experimentally demonstrated blood vessels phantom using second harmonic generation of Q-switched Nd:YAG laser and Ti:sapphire nanosecond laser pulses through optical fiber transmission. The detected photoacoustic waveforms showed distinctive time-of-flight signals. The photoacoustic signals were sensitive to temperature, absorption coefficients of chromophores, and diameters of the phantom vessels. Hemoglobin oxygen saturation could be easily derived from the multi wavelength photoacoustic signals using differential optical absorption characteristics. These results proved the functional quantitative photoacoustic imaging using the signal characteristics. A multivariate photoacoustic imaging approach must be promising to convenient diagnosis.

  11. Discrimination of the glucose and the white sugar based on the pulsed laser-induced photoacoustic technique

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong

    2017-08-01

    In this study, to discriminate the glucose and the white sugar gradient in the food, a noninvasive optical detection system based on pulsed laser-induced photoacoustic technique was developed. Meanwhile, the Nd: YAG 532nm pumped OPO pulsed laser was used as the excitation light source to generate of the photoacoustic signals of the glucose and white sugar. The focused ultrasonic transducer with central detection frequency of 1MHz was used to capture the photoacoustic signals. In experiments, the real-time photoacoustic signals of the glucose and the white sugar aqueous solutions were gotten and compared with each other. In addition, to discriminate the difference of the characteristic photoacoustic signals between both of them, the difference spectrum and the first order derivative technique between the peak-to-peak photoacoustic signals of the water and that of the glucose and white sugar were employed. The difference characteristic photoacoustic wavelengths between the glucose and the white sugar were found based on the established photoacoustic detection system. This study provides the potential possibility for the discrimination of the glucose and the white sugar by using the photoacoustic detection method.

  12. Cell Attachment Following Instrumentation with Titanium and Plastic Instruments, Diode Laser, and Titanium Brush on Titanium, Titanium-Zirconium, and Zirconia Surfaces.

    Science.gov (United States)

    Lang, Melissa S; Cerutis, D Roselyn; Miyamoto, Takanari; Nunn, Martha E

    2016-01-01

    The aim of this study was to evaluate the surface characteristics and gingival fibroblast adhesion of disks composed of implant and abutment materials following brief and repeated instrumentation with instruments commonly used in procedures for implant maintenance, stage-two implant surgery, and periimplantitis treatment. One hundred twenty disks (40 titanium, 40 titaniumzirconium, 40 zirconia) were grouped into treatment categories of instrumentation by plastic curette, titanium curette, diode microlaser, rotary titanium brush, and no treatment. Twenty strokes were applied to half of the disks in the plastic and titanium curette treatment categories, while half of the disks received 100 strokes each to simulate implant maintenance occurring on a repetitive basis. Following analysis of the disks by optical laser profilometry, disks were cultured with human gingival fibroblasts. Cell counts were conducted from scanning electron microscopy (SEM) images. Differences in surface roughness across all instruments tested for zirconia disks were negligible, while both titanium disks and titaniumzirconium disks showed large differences in surface roughness across the spectrum of instruments tested. The rotary titanium brush and the titanium curette yielded the greatest overall mean surface roughness, while the plastic curette yielded the lowest mean surface roughness. The greatest mean cell counts for each disk type were as follows: titanium disks with plastic curettes, titanium-zirconium disks with titanium curettes, and zirconia disks with the diode microlaser. Repeated instrumentation did not result in cumulative changes in surface roughness of implant materials made of titanium, titanium-zirconium, or zirconia. Instrumentation with plastic implant curettes on titanium and zirconia surfaces appeared to be more favorable than titanium implant curettes in terms of gingival fibroblast attachment on these surfaces.

  13. Photoacoustic Doppler flowmetry of carbon particles flow using an autocorrelation method

    Science.gov (United States)

    Lu, Tao

    2014-11-01

    In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler (PAD) frequency shift is calculated based on a series of individual A scans using an autocorrelation method. A 532 nm pulsed laser with repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused piezoelectric (PZT) ultrasound transducer with central frequency of 5 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by the Hilbert transformation from time-domain photoacoustic signal, and then it is autocorrelated to calculate the Doppler frequency shift. The photoacoustic Doppler frequency shift is calculated by averaging the autocorrelation results of some individual A scans. The advantage of the autocorrelation method is that the time delay in autocorrelation can be defined by user, and the requirement of high pulse repetition rate is avoided. The feasibility of the proposed autocorrelation method is preliminarily demonstrated by quantifying the motion of a carbon particle suspension with flow velocity from 5 mm/s to 60 mm/s. The experimental results show that there is an approximately linear relation between the autocorrelation result and the setting velocity.

  14. Ultrasound-Mediated Biophotonic Imaging: A Review of Acousto-Optical Tomography and Photo-Acoustic Tomography

    Directory of Open Access Journals (Sweden)

    Lihong V. Wang

    2004-01-01

    Full Text Available This article reviews two types of ultrasound-mediated biophotonic imaging–acousto-optical tomography (AOT, also called ultrasound-modulated optical tomography and photo-acoustic tomography (PAT, also called opto-acoustic or thermo-acoustic tomography–both of which are based on non-ionizing optical and ultrasonic waves. The goal of these technologies is to combine the contrast advantage of the optical properties and the resolution advantage of ultrasound. In these two technologies, the imaging contrast is based primarily on the optical properties of biological tissues, and the imaging resolution is based primarily on the ultrasonic waves that either are provided externally or produced internally, within the biological tissues. In fact, ultrasonic mediation overcomes both the resolution disadvantage of pure optical imaging in thick tissues and the contrast and speckle disadvantages of pure ultrasonic imaging. In our discussion of AOT, the relationship between modulation depth and acoustic amplitude is clarified. Potential clinical applications of ultrasound-mediated biophotonic imaging include early cancer detection, functional imaging, and molecular imaging.

  15. Clinical Report on the First Prototype of a Photoacoustic Tomography System with Dual Illumination for Breast Cancer Imaging.

    Directory of Open Access Journals (Sweden)

    Elham Fakhrejahani

    Full Text Available Photoacoustic tomography is a recently developed imaging modality that can provide high spatial-resolution images of hemoglobin distribution in tissues such as the breast. Because breast cancer is an angiogenesis-dependent type of malignancy, we evaluated the clinical acceptability of breast tissue images produced using our first prototype photoacoustic mammography (PAM system in patients with known cancer. Post-excisionally, histological sections of the tumors were stained immunohistochemically (IHC for CD31 (an endothelial marker and carbonic anhydrase IX (CAIX (a marker of hypoxia. Whole-slide scanning and image analyses were used to evaluate the tumor microvessel distribution pattern and to calculate the total vascular perimeter (TVP/area for each lesion. In this clinical study, 42 lesions were primarily scanned using PAM preoperatively, three of which were reported to be benign and were excluded from statistical analysis. Images were produced for 29 out of 39 cancers (visibility rate = 74.4% at the median depth of 26.5 (3.25-51.2 mm. Age, menopausal status, body mass index, history of neoadjuvant treatment, clinical stage and histological tumor angiogenesis markers did not seem to affect the visibility. The oxygen saturation level in all of the measured lesions was lower than in the subcutaneous counterpart vessels (Wilcoxon test, p value<0.001, as well as in the counterpart contralateral normal breast region of interest (ROI (Wilcoxon test, p value = 0.001. Although the oxygen saturation level was not statistically significant between CAIX-positive vs. -negative cases, lesional TVP/area showed a positive correlation with the oxygen saturation level only in the group that had received therapy before PAM. In conclusion, the vascular and oxygenation data obtained by PAM have great potential for identifying functional features of breast tumors.

  16. Process for production of titanium dioxide from titaniferrous ore

    Energy Technology Data Exchange (ETDEWEB)

    Rado, T.A.

    1984-07-17

    Titanium tetrachloride is produced from titanium ore and reductant suspended in molten salt by the passage of chlorine therethrough. The titanium tetrachloride is scrubbed by passage through at least one scrubber of molten salt and oxidized to produce titanium oxide and chlorine. Chlorine is recaptured as a solute in cold titanium tetrachloride and then liberated and recycled.

  17. Titanium-Oxygen Reactivity Study

    Science.gov (United States)

    Chafey, J. E.; Scheck, W. G.; Witzell, W. E.

    1962-01-01

    A program has been conducted at Astronautics to investigate the likelihood of occurrence of the catastrophic oxidation of titanium alloy sheet under conditions which simulate certain cases of accidental failure of the metal while it is in contact with liquid or gaseous oxygen. Three methods of fracturing the metal were used; they consisted of mechanical puncture, tensile fracture of welded joints, and perforation by very high velocity particles. The results of the tests which have been conducted provide further evidence of the reactivity of titanium with liquid and gaseous oxygen. The evidence indicates that the rapid fracturing of titanium sheet while it is in contact with oxygen initiates the catastrophic oxidation reaction. Initiation occurred when the speed of the fracture was some few feet per second, as in both the drop-weight puncture tests and the static tensile fracture tests of welded joints, as well as when the speed was several thousand feet per second, as in the simulated micrometeoroid penetration tests. The slow propagation of a crack, however, did not initiate the reaction. It may logically be concluded that the localized frictional heat of rapid fracture and/or spontaneous oxidation (exothermic) of minute particles emanating from the fracture cause initiation of the reaction. Under conditions of slow fracture, however, the small heat generated may be adequately dissipated and the reaction is not initiated. A portion of the study conducted consisted of investigating various means by which the reaction might be retarded or prevented. Providing a "barrier" at the titanium-oxygen interface consisting of either aluminum metal or a coating of a petroleum base corrosion inhibitor appeared to be only partially effective in retarding the reaction. The accidental puncturing or similar rupturing of thin-walled pressurized oxygen tanks on missiles and space vehicle will usually constitute loss of function, and may sometimes cause their catastrophic destruction

  18. Synthesis and physicochemical characterization of titanium oxide and sulfated titanium oxide obtained by thermal hydrolysis of titanium tetrachloride

    OpenAIRE

    Esteban Benito,H.; Del Ángel Sánchez, T.; R. García Alamilla; Hernández Enríquez, J. M.; Sandoval Robles,G.; F. Paraguay Delgado

    2014-01-01

    This work reports the synthesis of titanium oxide (TiO2) and sulfated titanium oxide (TiO2-SO4(2-)) obtained by thermal hydrolysis of titanium tetrachloride. Titanium hydroxide synthesized by this method was impregnated with a 1 N H2SO4 solution, to give amounts of sulfate ions (SO4(2-)) of 3 and 7 wt%. The synthesized samples were dried at 120 °C during 24 h and then calcined for 3 h at 400 °C. Thermal analyses, X-ray diffraction, nitrogen physisorption, infrared spectroscopy, potentiometric...

  19. Anodisation Increases Integration of Unloaded Titanium Implants in Sheep Mandible

    Directory of Open Access Journals (Sweden)

    Warwick J. Duncan

    2015-01-01

    Full Text Available Spark discharge anodic oxidation forms porous TiO2 films on titanium implant surfaces. This increases surface roughness and concentration of calcium and phosphate ions and may enhance early osseointegration. To test this, forty 3.75 mm × 13 mm titanium implants (Megagen, Korea were placed into healed mandibular postextraction ridges of 10 sheep. There were 10 implants per group: RBM surface (control, RBM + anodised, RBM + anodised + fluoride, and titanium alloy + anodised surface. Resonant frequency analysis (RFA was measured in implant stability quotient (ISQ at surgery and at sacrifice after 1-month unloaded healing. Mean bone-implant contact (% BIC was measured in undemineralised ground sections for the best three consecutive threads. One of 40 implants showed evidence of failure. RFA differed between groups at surgery but not after 1 month. RFA values increased nonsignificantly for all implants after 1 month, except for controls. There was a marked difference in BIC after 1-month healing, with higher values for alloy implants, followed by anodised + fluoride and anodised implants. Anodisation increased early osseointegration of rough-surfaced implants by 50–80%. RFA testing lacked sufficient resolution to detect this improvement. Whether this gain in early bone-implant contact is clinically significant is the subject of future experiments.

  20. Photoacoustic imaging driven by an interstitial irradiation source

    Directory of Open Access Journals (Sweden)

    Trevor Mitcham

    2015-06-01

    Full Text Available Photoacoustic (PA imaging has shown tremendous promise in providing valuable diagnostic and therapy-monitoring information in select clinical procedures. Many of these pursued applications, however, have been relatively superficial due to difficulties with delivering light deep into tissue. To address this limitation, this work investigates generating a PA image using an interstitial irradiation source with a clinical ultrasound (US system, which was shown to yield improved PA signal quality at distances beyond 13 mm and to provide improved spectral fidelity. Additionally, interstitially driven multi-wavelength PA imaging was able to provide accurate spectra of gold nanoshells and deoxyhemoglobin in excised prostate and liver tissue, respectively, and allowed for clear visualization of a wire at 7 cm in excised liver. This work demonstrates the potential of using a local irradiation source to extend the depth capabilities of future PA imaging techniques for minimally invasive interventional radiology procedures.

  1. Efficient regularization with wavelet sparsity constraints in photoacoustic tomography

    Science.gov (United States)

    Frikel, Jürgen; Haltmeier, Markus

    2018-02-01

    In this paper, we consider the reconstruction problem of photoacoustic tomography (PAT) with a flat observation surface. We develop a direct reconstruction method that employs regularization with wavelet sparsity constraints. To that end, we derive a wavelet-vaguelette decomposition (WVD) for the PAT forward operator and a corresponding explicit reconstruction formula in the case of exact data. In the case of noisy data, we combine the WVD reconstruction formula with soft-thresholding, which yields a spatially adaptive estimation method. We demonstrate that our method is statistically optimal for white random noise if the unknown function is assumed to lie in any Besov-ball. We present generalizations of this approach and, in particular, we discuss the combination of PAT-vaguelette soft-thresholding with a total variation (TV) prior. We also provide an efficient implementation of the PAT-vaguelette transform that leads to fast image reconstruction algorithms supported by numerical results.

  2. Photoacoustic Doppler measurement of flow using tone burst excitation.

    Science.gov (United States)

    Sheinfeld, Adi; Gilead, Sharon; Eyal, Avishay

    2010-03-01

    In this paper a novel technique for flow measurement which is based on the photoacoustic (PA) Doppler effect is described. A significant feature of the proposed approach is that it can be implemented using tone burst optical excitation thus enabling simultaneous measurement of both velocity and position. The technique, which is based on external modulation and heterodyne detection, was experimentally demonstrated by measurement of the flow of a suspension of carbon particles in a silicon tube and successfully determined the particles mean velocity up to values of 130 mm/sec, which is about 10 times higher than previously reported PA Doppler set-ups. In the theoretical part a rigorous derivation of the PA response of a flowing medium is described and some important simplifying approximations are highlighted.

  3. A wide spectral range photoacoustic aerosol absorption spectrometer.

    Science.gov (United States)

    Haisch, C; Menzenbach, P; Bladt, H; Niessner, R

    2012-11-06

    A photoacoustic spectrometer for the measurement of aerosol absorption spectra, based on the excitation of a pulsed nanosecond optical parametrical oscillator (OPO), will be introduced. This spectrometer is working at ambient pressure and can be used to detect and characterize different classes of aerosols. The spectrometer features a spectral range of 410 to 2500 nm and a sensitivity of 2.5 × 10(-7) m(-1) at 550 nm. A full characterization of the system in the visible spectral range is demonstrated, and the potential of the system for near IR measurement is discussed. In the example of different kinds of soot particles, the performance of the spectrometer was assessed. As we demonstrate, it is possible to determine a specific optical absorption per particle by a combination of the new spectrometer with an aerosol particle counter.

  4. Recording membrane potential changes through photoacoustic voltage sensitive dye

    DEFF Research Database (Denmark)

    Zhang, Haichong K.; Kang, Jeeun; Yan, Ping

    2017-01-01

    systems for external detection. In contrast, photoacoustic (PA) imaging, an emerging modality, is capable of deep tissue, noninvasive imaging by combining near infrared light excitation and ultrasound detection. In this work, we develop the theoretical concept whereby the voltage-dependent quenching......Monitoring of the membrane potential is possible using voltage sensitive dyes (VSD), where fluorescence intensity changes in response to neuronal electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in vivo...... the experimental PA intensity change depends on fluorescence and absorbance properties of the dye. These results not only demonstrate the voltage sensing capability of the dye, but also indicate the necessity of considering both fluorescence and absorbance spectral sensitivities in order to optimize...

  5. The derivative-free Fourier shell identity for photoacoustics.

    Science.gov (United States)

    Baddour, Natalie

    2016-01-01

    In X-ray tomography, the Fourier slice theorem provides a relationship between the Fourier components of the object being imaged and the measured projection data. The Fourier slice theorem is the basis for X-ray Fourier-based tomographic inversion techniques. A similar relationship, referred to as the 'Fourier shell identity' has been previously derived for photoacoustic applications. However, this identity relates the pressure wavefield data function and its normal derivative measured on an arbitrary enclosing aperture to the three-dimensional Fourier transform of the enclosed object evaluated on a sphere. Since the normal derivative of pressure is not normally measured, the applicability of the formulation is limited in this form. In this paper, alternative derivations of the Fourier shell identity in 1D, 2D polar and 3D spherical polar coordinates are presented. The presented formulations do not require the normal derivative of pressure, thereby lending the formulas directly adaptable for Fourier based absorber reconstructions.

  6. Photoacoustic molecular imaging of ferritin as a reporter gene

    Science.gov (United States)

    Ha, S.; Carson, A.; Kim, K.

    2012-02-01

    Spectral analysis of photoacoustic (PA) molecular imaging (PMI) of ferritin expressed in human melanoma cells (SK-24) was performed in vitro. Ferritin is a ubiquitously expressed protein which stores iron that can be detected by PA imaging, allowing ferritin to act as a reporter gene. To over-express ferritin, SK-24 cells were co-transfected with plasmid expressing Heavy chain ferritin (H-FT) and plasmid expressing enhanced green fluorescent protein (pEGFP-C1) using LipofectamineTM 2000. Non-transfected SK-24 cells served as a negative control. Fluorescent imaging of EGFP confirmed transfection and transgene expression in co-transfected cells. To detect iron accumulation in SK-24 cells, a focused high frequency ultrasonic transducer (60 MHz, f/1.5), synchronized to a pulsed laser (molecular imaging and basic science research.

  7. Photoacoustic imaging: a potential new tool for arthritis

    Science.gov (United States)

    Wang, Xueding

    2012-12-01

    The potential application of photoacoustic imaging (PAI) technology to diagnostic imaging and therapeutic monitoring of inflammatory arthritis has been explored. The feasibility of our bench-top joint imaging systems in delineating soft articular tissue structures in a noninvasive manner was validated first on rat models and then on human peripheral joints. Based on the study on commonly used arthritis rat models, the capability of PAI to differentiate arthritic joints from the normal was also examined. With sufficient imaging depth, PAI can realize tomographic imaging of a human peripheral joint or a small-animal joint as a whole organ noninvasively. By presenting additional optical contrast and tissue functional information such as blood volume and blood oxygen saturation, PAI may provide an opportunity for early diagnosis of inflammatory joint disorders, e.g. rheumatoid arthritis, and for monitoring of therapeutic outcomes with improved sensitivity and accuracy.

  8. A cost-efficient frequency-domain photoacoustic imaging system

    Science.gov (United States)

    LeBoulluec, Peter; Liu, Hanli; Yuan, Baohong

    2013-09-01

    Photoacoustic (PA) imaging techniques have recently attracted much attention and can be used for noninvasive imaging of biological tissues. Most PA imaging systems in research laboratories use the time domain method with expensive nanosecond pulsed lasers that are not affordable for most educational laboratories. Using an intensity modulated light source to excite PA signals is an alternative technique, known as the frequency domain method, with a much lower cost. In this paper, we describe a simple frequency domain PA system and demonstrate its imaging capability. The system provides opportunities not only to observe PA signals in tissue phantoms but also to acquire hands-on skills in PA signal detection. It also provides opportunities to explore the underlying mechanisms of the PA effect.

  9. Contributed review: quantum cascade laser based photoacoustic detection of explosives.

    Science.gov (United States)

    Li, J S; Yu, B; Fischer, H; Chen, W; Yalin, A P

    2015-03-01

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

  10. New developments in THz quartz enhanced photoacoustic spectroscopy

    Science.gov (United States)

    Spagnolo, Vincenzo; Patimisco, Pietro; Sampaolo, Angelo; Giglio, Marilena; Vitiello, Miriam S.; Scamarcio, Gaetano; Tittel, Frank K.

    2016-09-01

    We will report on new developments of quartz-enhanced photo-acoustic (QEPAS) sensor employing THz quantum cascade laser (QCLs). The extension of the QEPAS technique in the THz range was made possible by the realization of custom made QTFs. With the aim to improve the QTF acousto-electric transduction efficiency, we designed and realized new QTF designs. A detailed analysis of the quality factor, the resonance frequency and the electrical resistance of custom quartz tuning forks (QTFs) with different geometrical parameters is reported. The custom QTFs were employed in QEPAS sensors using THz QCLs as the laser excitation sources and targeting CH3OH and H2S. Minimum detection limits of a few tens of ppb and normalized noise equivalent absorption factors down to 3.75×10-11 cm-1W/Hz½ were achieved.

  11. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy.

    Science.gov (United States)

    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S; Beere, Harvey E; Ritchie, David A; Scamarcio, Gaetano; Tittel, Frank K; Spagnolo, Vincenzo

    2016-03-25

    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH₃OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a 3.93 THz quantum cascade laser as the excitation source in resonance with a CH₃OH rotational absorption line located at 131.054 cm(-1). A minimum detection limit of 160 ppb in 30 s integration time, corresponding to a normalized noise equivalent absorption NNEA = 3.75 × 10(-11) cm(-1)W/Hz(½), was achieved, representing a nearly one-order-of-magnitude improvement with respect to previous reports.

  12. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism.

    Science.gov (United States)

    Liu, Yongning; Chang, Jun; Lian, Jie; Liu, Zhaojun; Wang, Qiang; Qin, Zengguang

    2016-02-06

    A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS) system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 compared with the original signal, which was acquired without resonators or a prism. In addition, the system noise was reduced a little with double resonators due to the Q factor decrease. The signal-to-noise ratio (SNR) was greatly improved. Additionally, a normalized noise equivalent absorption coefficient (NNEA) of 5.8 × 10(-8) W·cm(-1)·Hz(-1/2) was achieved for water vapor detection in the atmosphere.

  13. Quartz-enhanced photoacoustic spectroscopy exploiting tuning fork overtone modes

    Science.gov (United States)

    Sampaolo, A.; Patimisco, P.; Dong, L.; Geras, A.; Scamarcio, G.; Starecki, T.; Tittel, F. K.; Spagnolo, V.

    2015-12-01

    We report on a quartz-enhanced photoacoustic sensor (QEPAS) based on a custom-made quartz tuning fork (QTF) to operate in both the fundamental and the first overtone vibrational mode resonances. The QTF fundamental mode resonance falls at ˜3 kHz and the first overtone at ˜18 kHz. Electrical tests showed that the first overtone provides a higher quality factor and increased piezoelectric current peak values, with respect to the fundamental flexural mode. To evaluate the QTF acousto-electric energy conversion efficiency, we operated the QEPAS in the near-IR and selected water vapor as the target gas. The first overtone resonance provides a QEPAS signal-to-noise ratio ˜5 times greater with respect to that measured for the fundamental mode. These results open the way to employing QTF overtone vibrational modes for QEPAS based trace gas sensing.

  14. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism

    Directory of Open Access Journals (Sweden)

    Yongning Liu

    2016-02-01

    Full Text Available A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 compared with the original signal, which was acquired without resonators or a prism. In addition, the system noise was reduced a little with double resonators due to the Q factor decrease. The signal-to-noise ratio (SNR was greatly improved. Additionally, a normalized noise equivalent absorption coefficient (NNEA of 5.8 × 10−8 W·cm−1·Hz−1/2 was achieved for water vapor detection in the atmosphere.

  15. Optical Detection Technique Using Quartz-Enhanced Photoacoustic Spectrum

    Science.gov (United States)

    Wu, Hongpeng; Zhang, Dongdong; Dong, Lei; Zheng, Huadan; Liu, Yanyan; Yin, Wangbao; Ma, Weiguang; Zhang, Lei; Jia, Suotang

    2015-06-01

    A new optical detection approach based on quartz-enhanced photoacoustic spectroscopy (QEPAS) to detect gases is developed. The new method not only employs a modulated laser to excite acoustic wave, as the general QEPAS does, but also adds an extra laser beam without modulation as the detection source to transform the prong vibration into a laser intensity change. Due to the mechanical vibration of the prongs, the intensity of the reflection laser beam is modulated. Thus, the information of the target gas (composition, concentration, etc.) is obtained by demodulating the reflected light. The achieved sensitivity of is inter-compared to the sensitivity of the conventional QEPAS. Further developments of the new optical detection approach are also discussed in detail.

  16. Investigation of standoff explosives detection via photothermal/photoacoustic interferometry

    Science.gov (United States)

    Cho, Pak S.; Jones, Robert M.; Shuman, Timothy; Scoglietti, Daniel; Harston, Geof

    2011-05-01

    Progress in standoff detection of surface-bound explosives residue using photothermal and photoacoustic (PT/PA) imaging and spectroscopy has been reported recently. Photothermal/photoacoustic interferometry (PTI), a variation of the aforementioned techniques, is a candidate for standoff detection as a result of its non-contact and non-destructive approach. In PTI, the transient PT/PA hydrodynamic response produced by impulsive infra-red laser excitation(s) are detected by an overlapping focused probe laser beam. The return back-scattered/reflected probe laser beam is collected and coupled into a single-mode optical fiber. The PT/PA-induced perturbation on the return probe laser, in the form of phase or amplitude modulation or both, is extracted interferometrically. The resulting quadrature signals are digitized and processed to recover the minute PT/PA dynamics above background noise. Characteristic spectra for materials can be obtained by quantifying the PT response as a function of excitation(s) wavelength. The CW probe laser, operating in the 1550 nm range, and the constituents of the coherent detection system are commercial off-the-shelf components. A commercially available and continuously tunable quantum cascade laser (QCL) with output pulse energies up to 50 nJ was employed to generate the PT/PA spectra in the 8.8-10.2 μm range. PTI detected absorption spectra were collected for HMX, RDX, and PETN, with the probe laser system positioned 5 meters away from the explosives targets. In addition, PTI measurements of the stimulated Raman (SR) spectra of ammonium nitrate and 2,4,6-trinitrotoluene obtained using a near-IR OPO laser are described. We believe this is the first-ever application of photothermal techniques to the measurement of the SR effect on solid explosive materials at meaningful standoff distances.

  17. Real-time sono-photoacoustic imaging of gold nanoemulsions

    Science.gov (United States)

    Arnal, Bastien; Wei, Chen-Wei; Perez, Camilo; Lombardo, Michael; Pelivanov, Ivan M.; Pozzo, Danilo; O'Donnell, Matthew

    2015-03-01

    Phase transition contrast agents were first introduced in ultrasound (US) in the form of perfluorocarbon droplets. When their size is reduced to the nanoscale, surface tension dominates their stability and high pressure is required to vaporize them using long US emissions at high frequencies. Our group recently showed that nanoemulsion beads (100-300 nm) coated with gold nanopsheres could be used as non-linear contrast agents. Beads can be vaporized with light only, inducing stronger photoacoustic signals by increasing thermal expansion. A photoacoustic cavitation threshold study (US: 1.2 MHz, Laser 750 nm and 10-ns pulse) shows that the vaporization thresholds of NEB-GNS can be greatly reduced using simultaneous light and US excitations. The resulting signal is driven only by the pressure amplitude for a fluence higher than 2.4 mJ/cm2. At diagnostic exposures, it is possible to capture very high signals from the vaporized beads at concentrations reduced to 10 pM with optical absorption smaller than 0.01 cm-1. A real-time imaging mode selectively isolating vaporization signals was implemented on a Verasonics system. A linear US probe (L74, 3 MHz) launched short US bursts before light was emitted from the laser. Vaporization of NEB-GNS resulted in a persistent 30-dB signal enhancement compared to a dye with the same absorption. Specific vaporization signals were retrieved in phantom experiments with US scatterers. This technique, called sonophotoacoustics, has great potential for targeted molecular imaging and therapy using compact nanoprobes with potentially high-penetrability into tissue.

  18. Titanium - ceramic restoration: How to improve the binding between titanium and ceramic

    Directory of Open Access Journals (Sweden)

    Harry Laksono

    2011-03-01

    Full Text Available Background: Titanium alloys has been used as an alternative to nickel-chromium alloys for metal-ceramic restorations because of its good biocompatibility and mechanical properties. This indicated that it was possible to design coping according to standards established for metal-ceramics. However, titanium is chemically reacting strongly with gaseous elements which causes problems when ceramics are fused to titanium. Purpose: To provide information about improving the bonding between titanium and ceramic. Review: Titanium has two crystal modifications, the close-packed hexagonal (α structure, up to 880° C, and above this temperature the bodycentered cubic (β structure. The principal problems is the extensive dissolution of oxygen resulting in thick, oxygen-rich titanium layers called α-case that harms the bonding of ceramic to titanium and the great mismatch in the coefficient of thermal expansion of conventional ultra-low fusing ceramic. Methods have been developed for fusing ceramic to titanium like processing methods, the used of ultra-low fusing titanium ceramic, bonding agent, and protocol for ceramic bonding to titanium. Conclusion: Titanium and titanium alloys, based on their physical and chemical properties suitable for titanium-ceramic restorations, but careful selection of processing methods, ceramic materials, laboratory skill and strict protocol for ceramic bonding to titanium are necessary to improve the bonding between titanium and ceramic.Latar Belakang: Logam campur titanium telah dipakai sebagai salah satu bahan alternatif untuk logam nikel-krom pada pembuatan restorasi keramik taut logam karena mempunyai biokompatibilitas dan sifat mekanik yang baik. Hal ini menunjukkan bahwa logam titanium dapat dipakai untuk pembuatan koping logam berdasarkan standar yang dipakai untuk pembuatan restorasi keramik taut logam. Meskipun, secara kimiawi logam titanium bereaksi dengan elemen-elemen gas yang menyebabkan masalah pada perlekatan

  19. Production of titanium from ilmenite: a review

    Energy Technology Data Exchange (ETDEWEB)

    Kohli, R.

    1981-12-01

    The general principles for beneficiation of titanium ores are reviewed and the specific processes used in individual units in various countries are discussed. This is followed by a critical evaluation of various current and potential reduction methods for the production of titanium metal from the processed concentrates. Finally, the report outlines a research program for the development of a commercially viable alternative method for the production of titanium metal.

  20. Towards a new titanium sector: Aerospace

    CSIR Research Space (South Africa)

    Du Preez, W

    2012-10-01

    Full Text Available Sector: Aerospace 4th Biennial Conference Presented by: Dr Willie du Preez Director: Titanium Centre of Competence Date: 9 October 2012 Outline ? Why Titanium? ? The Opportunity for South Africa ? The SA Titanium Industry Strategy ? Primary... 3 USD/kg Ti Ti Powder 40 USD/kg Ti SA Opportunity ? Technology-led Industry Development ? CSIR 2012 Slide 9 Raw material Market 2nd largest Ti producer 3rd largest V producer Aerospace Automotive Medical Recreational Industrial Power...

  1. Cranioplasty with individual titanium implants

    Science.gov (United States)

    Mishinov, S.; Stupak, V.; Sadovoy, M.; Mamonova, E.; Koporushko, N.; Larkin, V.; Novokshonov, A.; Dolzhenko, D.; Panchenko, A.; Desyatykh, I.; Krasovsky, I.

    2017-09-01

    Cranioplasty is the second procedure in the history of neurosurgery after trepanation, and it is still relevant despite the development of civilization and progress in medicine. Each cranioplasty operation is unique because there are no two patients with identical defects of the skull bones. The development of Direct Metal Laser Sintering (DMLS) technique opened up the possibility of direct implant printing of titanium, a biocompatible metal used in medicine. This eliminates the need for producing any intermediate products to create the desired implant. We have produced 8 patient-specific titanium implants using this technique for patients who underwent different decompressive cranioectomies associated with bone tumors. Follow-up duration ranged from 6 to 12 months. We observed no implant-related reactions or complications. In all cases of reconstructive neurosurgery we achieved good clinical and aesthetic results. The analysis of the literature and our own experience in three-dimensional modeling, prototyping, and printing suggests that direct laser sintering of titanium is the optimal method to produce biocompatible surgical implants.

  2. Rapid volumetric photoacoustic tomographic imaging with a Fabry-Perot ultrasound sensor depicts peripheral arteries and microvascular vasomotor responses to thermal stimuli.

    Science.gov (United States)

    Plumb, Andrew A; Huynh, Nam Trung; Guggenheim, Jamie; Zhang, Edward; Beard, Paul

    2017-10-10

    To determine if a new photoacoustic imaging (PAI) system successfully depicts (1) peripheral arteries and (2) microvascular circulatory changes in response to thermal stimuli. Following ethical permission, 8 consenting subjects underwent PAI of the dorsalis pedis (DP) artery, and 13 completed PAI of the index fingertip. Finger images were obtained after immersion in warm (30-35 °C) or cold (10-15 °C) water to promote vasodilation or vasoconstriction. The PAI instrument used a Fabry-Perot interferometeric ultrasound sensor and a 30-Hz 750-nm pulsed excitation laser. Volumetric images were acquired through a 14 × 14 × 14-mm volume over 90 s. Images were evaluated subjectively and quantitatively to determine if PAI could depict cold-induced vasoconstriction. The full width at half maximum (FWHM) of resolvable vessels was measured. Fingertip vessels were visible in all participants, with mean FWHM of 125 μm. Two radiologists used PAI to correctly identify vasoconstricted fingertip capillary beds with 100% accuracy (95% CI 77.2-100.0%, p thermal stimuli. • Fabry-Perot interferometer-based photoacoustic imaging (PAI) generates volumetric, high-resolution images of the peripheral vasculature. • The system reliably detects thermally induced peripheral vasoconstriction (100% correct identification rate, p < 0.001). • Vessels measuring less than 100 μm in diameter can be depicted in vivo.

  3. Titanium alloys Russian aircraft and aerospace applications

    CERN Document Server

    Moiseyev, Valentin N

    2005-01-01

    This text offers previously elusive information on state-of-the-art Russian metallurgic technology of titanium alloys. It details their physical, mechanical, and technological properties, as well as treatments and applications in various branches of modern industry, particularly aircraft and aerospace construction. Titanium Alloys: Russian Aircraft and Aerospace Applications addresses all facets of titanium alloys in aerospace and aviation technology, including specific applications, fundamentals, composition, and properties of commercial alloys. It is useful for all students and researchers interested in the investigation and applications of titanium.

  4. Titanium Matrix Composite Pressure Vessel Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For over 15 years, FMW Composite Systems has developed Metal Matrix Composite manufacturing methodologies for fabricating silicon-carbide-fiber-reinforced titanium...

  5. Appcelerator Titanium patterns and best practices

    CERN Document Server

    Pollentine, Boydlee

    2013-01-01

    The book takes a step-by-step approach to help you understand CommonJS and Titanium architecture patterns, with easy to follow samples and plenty of in-depth explanations If you're an existing Titanium developer or perhaps a new developer looking to start off your Titanium applications "the right way", then this book is for you. With easy to follow examples and a full step-by-step account of architecting a sample application using CommonJS and MVC, along with chapters on new features such as ACS, you'll be implementing enterprise grade Titanium solutions in no time. You should have some JavaSc

  6. The state of the art in breast imaging using the Twente Photoacoustic Mammoscope: results from 31 measurements on malignancies.

    Science.gov (United States)

    Heijblom, Michelle; Piras, Daniele; van den Engh, Frank M; van der Schaaf, Margreet; Klaase, Joost M; Steenbergen, Wiendelt; Manohar, Srirang

    2016-11-01

    Photoacoustic mammography is potentially an ideal technique, however, the amount of patient data is limited. To further our understanding of the in vivo performance of the method and to guide further research and development, we imaged 33 breast malignancies using the research system - the Twente Photoacoustic Mammoscope (PAM). Thirty-one patients participated in this retrospective, observational study. The study and informed consent procedure were approved by the local ethics committee. PAM uses 1,064 nm light for excitation with a planar, 588-element, 1-MHz ultrasound array for detection. Photoacoustic lesion visibility and appearance were compared with conventional imaging (x-ray mammography and ultrasonography) findings, histopathology and patient demographics. Of 33 malignancies 32 were visualized with high contrast and good co-localization with conventional imaging. The contrast of the detected malignancies was independent of radiographic breast density, and size estimation was reasonably good with an average 28 % deviation from histology. However, the presence of contrast areas outside the malignant region is suggestive for low specificity of the current system. Statistical analyses did not reveal any further relationship between PAM results and patient demographics nor lesion characteristics. The results confirm the high potential of photoacoustic mammography in future breast care. • Photoacoustic breast imaging visualizes malignancies with high imaging contrast. • Photoacoustic lesion contrast is independent of the mammographically estimated breast density. • No clear relationship exists between photoacoustic characteristics and lesion type, grade, etc. • Photoacoustic specificity to breast cancer from some cases is not yet optimal.

  7. Impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data.

    Science.gov (United States)

    Li, Xiaoqi; Jiang, Huabei

    2013-02-21

    We present a study through extensive simulation that considers the impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data collected from media mimicking breast tissue. We found that while the impact of scattering heterogeneities/targets is modest on photoacoustic recovery of optical absorption coefficients, the impact of scattering contrast caused by adipose tissue, a layer of normal tissue along the boundary of the breast, is dramatic on reconstruction of optical absorption coefficients using photoacoustic data-up to 25.8% relative error in recovering the absorption coefficient is estimated in such cases. To overcome this problem, we propose a new method to enhance photoacoustic recovery of the optical absorption coefficient in heterogeneous media by considering inhomogeneous scattering coefficient distribution provided by diffuse optical tomography (DOT). Results from extensive simulations show that photoacoustic recovery of absorption coefficient maps can be improved considerably with a priori scattering information from DOT.

  8. Anatomical and metabolic small-animal whole-body imaging using ring-shaped confocal photoacoustic computed tomography

    Science.gov (United States)

    Xia, Jun; Chatni, Muhammad; Maslov, Konstantin; Wang, Lihong V.

    2013-03-01

    Due to the wide use of animals for human disease studies, small animal whole-body imaging plays an increasingly important role in biomedical research. Currently, none of the existing imaging modalities can provide both anatomical and glucose metabolic information, leading to higher costs of building dual-modality systems. Even with image coregistration, the spatial resolution of the metabolic imaging modality is not improved. We present a ring-shaped confocal photoacoustic computed tomography (RC-PACT) system that can provide both assessments in a single modality. Utilizing the novel design of confocal full-ring light delivery and ultrasound transducer array detection, RC-PACT provides full-view cross-sectional imaging with high spatial resolution. Scanning along the orthogonal direction provides three-dimensional imaging. While the mouse anatomy was imaged with endogenous hemoglobin contrast, the glucose metabolism was imaged with a near-infrared dye-labeled 2-deoxyglucose. Through mouse tumor models, we demonstrate that RC-PACT may be a paradigm shifting imaging method for preclinical research.

  9. Circulating Tumor Cell Detection and Capture by Photoacoustic Flow Cytometry in Vivo and ex Vivo

    Energy Technology Data Exchange (ETDEWEB)

    Galanzha, Ekaterina I. [Phillips Classic Laser and Nanomedicine Laboratories, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States); Zharov, Vladimir P., E-mail: zharovvladimirp@uams.edu [Phillips Classic Laser and Nanomedicine Laboratories, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States); Arkansas Nanomedicine Center, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States)

    2013-12-10

    Despite progress in detecting circulating tumor cells (CTCs), existing assays still have low sensitivity (1–10 CTC/mL) due to the small volume of blood samples (5–10 mL). Consequently, they can miss up to 10{sup 3}–10{sup 4} CTCs, resulting in the development of barely treatable metastasis. Here we analyze a new concept of in vivo CTC detection with enhanced sensitivity (up to 10{sup 2}–10{sup 3} times) by the examination of the entire blood volume in vivo (5 L in adults). We focus on in vivo photoacoustic (PA) flow cytometry (PAFC) of CTCs using label-free or targeted detection, photoswitchable nanoparticles with ultrasharp PA resonances, magnetic trapping with fiber-magnetic-PA probes, optical clearance, real-time spectral identification, nonlinear signal amplification, and the integration with PAFC in vitro. We demonstrate PAFC’s capability to detect rare leukemia, squamous carcinoma, melanoma, and bulk and stem breast CTCs and its clusters in preclinical animal models in blood, lymph, bone, and cerebrospinal fluid, as well as the release of CTCs from primary tumors triggered by palpation, biopsy or surgery, increasing the risk of metastasis. CTC lifetime as a balance between intravasation and extravasation rates was in the range of 0.5–4 h depending on a CTC metastatic potential. We introduced theranostics of CTCs as an integration of nanobubble-enhanced PA diagnosis, photothermal therapy, and feedback through CTC counting. In vivo data were verified with in vitro PAFC demonstrating a higher sensitivity (1 CTC/40 mL) and throughput (up to 10 mL/min) than conventional assays. Further developments include detection of circulating cancer-associated microparticles, and super-resolution PAFC beyond the diffraction and spectral limits.

  10. All-optical photoacoustic imaging and detection of early-stage dental caries

    Science.gov (United States)

    Sampathkumar, Ashwin; Hughes, David A.; Longbottom, Chris; Kirk, Katherine J.

    2015-02-01

    Dental caries remain one of the most common oral diseases in the world. Current detection methods, such as dental explorer and X-ray radiography, suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease because of the small size (caries. Ex-vivo teeth exhibiting early-stage, white-spot lesions were imaged using AOPAI. Experimental scans targeted each early-stage lesion and a reference healthy enamel region. Photoacoustic (PA) signals were generated in the tooth using a 532-nm pulsed laser and the light-induced broadband ultrasound signal was detected at the surface of the tooth with an optical path-stabilized Michelson interferometer operating at 532 nm. The measured time-domain signal was spatially resolved and back-projected to form 2D and 3D maps of the lesion using k-wave reconstruction methods. Experimental data collected from areas of healthy and diseased enamel indicate that the lesion generated a larger PA response compared to healthy enamel. The PA-signal amplitude alone was able to detect a lesion on the surface of the tooth. However, time- reversal reconstructions of the PA scans also quantitatively depicted the depth of the lesion. 3D PA reconstruction of the diseased tooth indicated a sub-surface lesion at a depth of 0.6 mm, in addition to the surface lesion. These results suggest that our AOPAI system is well suited for rapid clinical assessment of early-stage dental caries. An overview of the AOPAI system, fine-resolution PA and histology results of diseased and healthy teeth will be presented.

  11. Photoacoustics and fluorescence based nanoprobes towards functional and structural imaging in vivo

    Science.gov (United States)

    Ray, Aniruddha

    Imaging of chemical analytes and structural properties related to physiological activities within biological systems is of great bio-medical interest; it can contribute to the fundamental understanding of biological systems and can be applied to the diagnosis and prognosis of diseases, especially tumors. The work presented in this thesis focuses on the development and application of polymeric nanoprobe aided optical imaging of chemical analytes (Oxygen, pH) and structural properties in live cells and animal models. To this end, specific nanoprobes, based on the polyacrylamide nanoplatform, bearing both appropriate targeting functionalities, and high concentrations of sensing and contrast agents, have been developed. The nanoprobes presented here are biodegradable, biocompatible and non-toxic, rendering them safe for in vivo use. Furthermore the nanoprobes are designed to have variable optical properties that are dependent on the local concentration of the specific analyte of interest. Optical imaging techniques that are particularly suited for deep tissue applications, such as two-photon fluorescence and photoacoustics, were applied for non-invasive real-time imaging and sensing in cancer cells, tumor spheroids and animal models. Our results demonstrate that this technique enables high sensitive detection of chemical analytes with a sensitivity of method will enable morphological and functional evaluation across any tissue, with both high spatial and temporal resolution but without eliciting short- or long-term tissue damage. Currently no gold standard exists for such xii functional imaging. The approach presented here can be used for early detection and diagnosis of tumors, as well as for monitoring the progression of disease and therapy. This technique will also enable observing phenomena at the cellular level in vivo that would lead to a better understanding of the pathophysiology of diseases as well as the disease onset, progression, and response to therapy.

  12. Out-coupling of Longitudinal Photoacoustic Pulses by Mitigating the Phase Cancellation

    Science.gov (United States)

    Lee, Taehwa; Li, Qiaochu; Guo, L. Jay

    2016-01-01

    Waves of any kinds, including sound waves and light waves, can interfere constructively or destructively when they are overlapped, allowing for myriad applications. However, unlike continuous waves of a single frequency, interference of photoacoustic pulses is often overlooked because of their broadband characteristics and short pulse durations. Here, we study cancellation of two symmetric photoacoustic pulses radiated in the opposite direction from the same photoacoustic sources near a free surface. The cancellation occurs when one of the two pulses is reflected with polarity reversal from the free surface and catches up with the other. The cancellation effect, responsible for reduced signal amplitudes, is systematically examined by implementing a thin transparent matching medium of the same acoustic impedance. By changing the thickness of the transparent layer, the overlap of the two symmetric pulses is controlled. For optimized matching layers, the cancellation effect can be significantly reduced, while the resulting output waveform remains unchanged. Similar to the planar absorber, different dimensional absorbers including cylinders and spheres also exhibit the cancellation between the outward and inward waves. This work could provide further understanding of photoacoustic generation and a simple strategy for increasing photoacoustic signal amplitudes. PMID:26869360

  13. Porphyrin Nanodroplets: Sub-micrometer Ultrasound and Photoacoustic Contrast Imaging Agents.

    Science.gov (United States)

    Paproski, Robert J; Forbrich, Alexander; Huynh, Elizabeth; Chen, Juan; Lewis, John D; Zheng, Gang; Zemp, Roger J

    2016-01-20

    A novel class of all-organic nanoscale porphyrin nanodroplet agents is presented which is suitable for multimodality ultrasound and photoacoustic molecular imaging. Previous multimodality photoacoustic-ultrasound agents are either not organic, or not yet demonstrated to exhibit enhanced accumulation in leaky tumor vasculature, perhaps because of large diameters. In the current study, porphyrin nanodroplets are created with a mean diameter of 185 nm which is small enough to exhibit the enhanced permeability and retention effect. Porphyrin within the nanodroplet shell has strong optical absorption at 705 nm with an estimated molar extinction coefficient >5 × 10(9) m(-1) cm(-1) , allowing both ultrasound and photoacoustic contrast in the same nanoparticle using all organic materials. The potential of nanodroplets is that they may be phase-changed into microbubbles using high pressure ultrasound, providing ultrasound contrast with single-bubble sensitivity. Multispectral photoacoustic imaging allows visualization of nanodroplets when injected intratumorally in an HT1080 tumor in the chorioallantoic membrane of a chicken embryo. Intravital microscopy imaging of Hep3-GFP and HT1080-GFP tumors in chicken embryos determines that nanodroplets accumulated throughout or at the periphery of tumors, suggesting that porphyrin nanodroplets may be useful for enhancing the visualization of tumors with ultrasound and/or photoacoustic imaging. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Laser Fluence Recognition Using Computationally Intelligent Pulsed Photoacoustics Within the Trace Gases Analysis

    Science.gov (United States)

    Lukić, M.; Ćojbašić, Ž.; Rabasović, M. D.; Markushev, D. D.; Todorović, D. M.

    2017-11-01

    In this paper, the possibilities of computational intelligence applications for trace gas monitoring are discussed. For this, pulsed infrared photoacoustics is used to investigate SF6-Ar mixtures in a multiphoton regime, assisted by artificial neural networks. Feedforward multilayer perceptron networks are applied in order to recognize both the spatial characteristics of the laser beam and the values of laser fluence Φ from the given photoacoustic signal and prevent changes. Neural networks are trained in an offline batch training regime to simultaneously estimate four parameters from theoretical or experimental photoacoustic signals: the laser beam spatial profile R(r), vibrational-to-translational relaxation time τ _{V-T} , distance from the laser beam to the absorption molecules in the photoacoustic cell r* and laser fluence Φ . The results presented in this paper show that neural networks can estimate an unknown laser beam spatial profile and the parameters of photoacoustic signals in real time and with high precision. Real-time operation, high accuracy and the possibility of application for higher intensities of radiation for a wide range of laser fluencies are factors that classify the computational intelligence approach as efficient and powerful for the in situ measurement of atmospheric pollutants.

  15. Needle tip visualization by bevel-point ultrasound generator and prototype photoacoustic imaging system

    Science.gov (United States)

    Irisawa, Kaku; Murakoshi, Dai; Hashimoto, Atsushi; Yamamoto, Katsuya; Hayakawa, Toshiro

    2017-03-01

    Visualization of the tip of medical devices like needles or catheters under ultrasound imaging has been a continuous topic since the early 1980's. In this study, a needle tip visualization system utilizing photoacoustic effects is proposed. In order to visualize the needle tip, an optical fiber was inserted into a needle. The optical fiber tip is placed on the needle bevel and affixed with black glue. The pulsed laser light from laser diode was transferred to the optical fiber and converted to ultrasound due to laser light absorption of the black glue and the subsequent photoacoustic effect. The ultrasound is detected by transducer array and reconstructed into photoacoustic images in the ultrasound unit. The photoacoustic image is displayed with a superposed ultrasound B-mode image. As a system evaluation, the needle is punctured into bovine meat and the needle tip is observed with commercialized conventional linear transducers or convex transducers. The needle tip is visualized clearly at 7 and 12 cm depths with linear and convex probes, respectively, even with a steep needle puncture angle of around 90 degrees. Laser and acoustic outputs, and thermal rise at the needle tip, were measured and were well below the limits of the safety standards. Compared with existing needle tip visualization technologies, the photoacoustic needle tip visualization system has potential distinguishable features for clinical procedures related with needle puncture and injection.

  16. In vitro determination of glucose concentration based on photoacoustic spectroscopy and chemometrics

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2014-09-01

    Noninvasive blood glucose level (BGL) monitoring has recently become a research hotspot in the world. Photoacoustic spectroscopy is a well-established, hybrid and promising noninvasive technique, which has already drawn many researchers' attentions in recent years due to the advantage of overcoming the scattering light interference. As the preliminary exploration of photoacoustic BGL monitoring, a photoacoustic BGL monitoring set-up based on nanosecond pulsed laser with repetition rate of 20Hz and ultrasound transducer with central frequency of 9.55MHz was established in this paper. To explore the mechanism of the time resolved BGL photoacoustic signal, a series of in vitro experiments of glucose aqueous solutions were tested, the time resolved photoacoustic signals for different concentrations of glucose solutions under different output wavelengths were captured with the data average of 512 times. The peak-to-peak values of each solution were gotten at the wavelength interval of 10nm. Difference with the peak-to-peak value of pure water via subtractive spectroscopy, the characteristic wavelengths of glucose were gotten, and the optimum characteristic wavelengths were determined via data pre-processing and principle component analysis(PCA) algorithm, the calibration equation between concentration and the peak-to-peak value was gotten via multiple linear regression(MLR), and the calibration root mean square error(CRMSE) and the prediction root mean square error(PRMSE) of glucose level is all less than 10mg/dl under the correction equation.

  17. [Quartz-enhanced photoacoustic spectroscopy trace gas detection system based on the Fabry-Perot demodulation].

    Science.gov (United States)

    Lin, Cheng; Zhu, Yong; Wei, Wei; Zhang, Jie; Tian, Li; Xu, Zu-Wen

    2013-05-01

    An all-optical quartz-enhanced photoacoustic spectroscopy system, based on the F-P demodulation, for trace gas detection in the open environment was proposed. In quartz-enhanced photoacoustic spectroscopy (QEPAS), an optical fiber Fabry-Perot method was used to replace the conventional electronic demodulation method. The photoacoustic signal was obtained by demodulating the variation of the Fabry-Perot cavity between the quartz tuning fork side and the fiber face. An experimental system was setup. The experiment for detection of water vapour in the open environment was carried on. A normalized noise equivalent absorption coefficient of 2.80 x 10(-7) cm(-1) x W x Hz(-1/2) was achieved. The result demonstrated that the sensitivity of the all-optical quartz-enhanced photoacoustic spectroscopy system is about 2.6 times higher than that of the conventional QEPAS system. The all-optical quartz-enhanced photoacoustic spectroscopy system is immune to electromagnetic interference, safe in flammable and explosive gas detection, suitable for high temperature and high humidity environments and realizable for long distance, multi-point and network sensing.

  18. Three-dimensional photoacoustic imaging and inversion for accurate quantification of chromophore distributions

    Science.gov (United States)

    Fonseca, Martina; Malone, Emma; Lucka, Felix; Ellwood, Rob; An, Lu; Arridge, Simon; Beard, Paul; Cox, Ben

    2017-03-01

    Photoacoustic tomography can, in principle, provide quantitatively accurate, high-resolution, images of chromophore distributions in 3D in vivo. However, achieving this goal requires not only dealing with the optical fluence-related spatial and spectral distortion but also having access to high quality, calibrated, measurements and using image reconstruction algorithms free from inaccurate assumptions. Furthermore, accurate knowledge of experimental parameters, such as the positions of the ultrasound detectors and the illumination pattern, is necessary for the reconstruction step. A meticulous and rigorous experimental phantom study was conducted to show that highly-resolved 3D estimation of chromophore distributions can be achieved: a crucial step towards in vivo implementation. The phantom consisted of four 580 μm diameter tubes with different ratios of copper sulphate and nickel sulphate as hemoglobin analogues, submersed in a background medium of intralipid and india ink. The optical absorption, scattering, photostability, and Grüneisen parameter were characterised for all components independently. A V-shaped imaging scanner enabled 3D imaging with the high resolution, high sensitivity, and wide bandwidth characteristic of Fabry-Pérot ultrasound sensors, but without the limited-view disadvantage of single-plane scanners. The optical beam profile and position were determined experimentally. Nine wavelengths between 750 and 1110 nm were used. The images of the chromophore concentrations were obtained using a model-based, two-step, procedure, that did not require image segmentation. First, the acoustic reconstruction was solved with an iterative time-reversal algorithm to obtain images of the initial acoustic pressure at each of the nine wavelengths for an 18×17×13 mm3 volume with 50μm voxels. Then, 3D high resolution estimates of the chromophore concentrations were obtained by using a diffusion model of light transport in an iterative nonlinear optimisation

  19. Some Mechanical and Ballistic Properties of Titanium and Titanium Alloys

    Science.gov (United States)

    1950-03-07

    unalloyed, commercially pure titanium have lIdicated that this material has a high strength/weight ratio. This would make it of value to the Ordnance...SA’r f J., VE ,’SV SUVh .( A. IN VIG. 6 AFt(A NC.R;’..ING £4. V -6 1 C.-’ I ’NdC.. 𔃺 C) 𔃺 𔃽 N Alp ’:7, 7 A T A- -C.. C 4C I At LY PLqF 71

  20. Fast and Straightforward Synthesis of Luminescent Titanium(IV Dioxide Quantum Dots

    Directory of Open Access Journals (Sweden)

    Václav Štengl

    2017-01-01

    Full Text Available The nucleus of titania was prepared by reaction of solution titanium oxosulphate with hydrazine hydrate. These titania nuclei were used for titania quantum dots synthesis by a simple and fast method. The prepared titanium(IV dioxide quantum dots were characterized by measurement of X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, atomic force microscopy (AFM, high-resolution electron microscopy (HRTEM, and selected area electron diffraction (SAED. The optical properties were determined by photoluminescence (PL spectra. The prepared titanium(IV dioxide quantum dots have the narrow range of UV excitation (365–400 nm and also a close range of emission maxima (450–500 nm.