Article

# Photoacoustic imaging based on MEMS mirror scanning

(Impact Factor: 3.65). 12/2010; 1(5):1278-1283. DOI: 10.1364/BOE.1.001278
Source: PubMed

ABSTRACT A microelectromechanical systems (MEMS)-based photoacoustic imaging system is reported for
the first time. In this system, the MEMS-based light scanning subsystem and a ring-shaped
polyvinylidene fluoride (PVDF) transducer are integrated into a miniaturized probe that is
capable of three-dimensional (3D) photoacoustic imaging. It is demonstrated that the imaging
system is able to image small objects embedded in phantom materials and in chicken and to in
vivo visualize blood vessels under the skin of a human hand.

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Available from: Huikai Xie, Sep 29, 2015
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• "The recent advancement in miniaturized scanning mirrors based on microelectromechanical systems (MEMS) technology has enabled the feasibility of fabricating compact fiber-optic-based endomicroscopic probes [23] [24] [25] [26]. In our previous work, we have successfully built an all-optical MEMS-based PAM system using miniature components and achieved imaging of microvasculatures inside a canine bladder wall [27]. "
##### Article: A fiber-optic system for dual-modality photoacoustic microscopy and confocal fluorescence microscopy using miniature components
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ABSTRACT: Imaging of the cells and microvasculature simultaneously is beneficial to the study of tumor angiogenesis and microenvironments. We designed and built a fiber-optic based photoacoustic microscopy (PAM) and confocal fluorescence microscopy (CFM) dual-modality imaging system. To explore the feasibility of this all-optical device for future endoscopic applications, a microelectromechanical systems (MEMS) scanner, a miniature objective lens, and a small size optical microring resonator as an acoustic detector were employed trying to meet the requirements of miniaturization. Both the lateral resolutions of PAM and CFM were quantified to be 8.8 μm. Axial resolutions of PAM and CFM were experimentally measured to be 19 μm and 53 μm, respectively. The experiments on ex vivo animal bladder tissues demonstrate the good performance of this system in imaging not only microvasculature but also cellular structure, suggesting that this novel imaging technique holds potential for improved diagnosis and guided treatment of bladder cancer.
Photoacoustics 05/2013; 1(2):30–35. DOI:10.1016/j.pacs.2013.07.001 · 4.60 Impact Factor
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##### Article: REVIEW Biomedical photoacoustic imaging
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ABSTRACT: 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 implementation, and a range of clinical and preclinical applications are reviewed.
Interface focus: a theme supplement of Journal of the Royal Society interface 08/2011; 1(4):602-31. DOI:10.1098/rsfs.2011.0028 · 2.63 Impact Factor
• ##### Article: Split-Frame Gimbaled Two-Dimensional MEMS Scanner for Miniature Dual-Axis Confocal Microendoscopes Fabricated by FrontSide Processing
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ABSTRACT: In this paper, we introduce a 2-D microelectromechanical systems scanner for 3.2-mm-diameter dual-axis confocal microendoscopes, fabricated exclusively by front-side processing. Compared to conventional bulk micromachining that incorporates back-side etching, the front-side process is simple and thus enables high device yield. By eliminating the back-side etch window, the process yields compact and robust structures that facilitate handling and packaging. An important component of our front-side fabrication is a low-power deep reactive ion etching (DRIE) process that avoids the heating problems associated with standard DRIE. Reducing the RF etch coil power from 2400 to 1500 W leads to elimination of the spring disconnection problem caused by heat-induced aggressive local etching. In our scanner, the outer frame of the gimbal is split and noncontinuous to allow the scanner to be diced along the very edge of the scanning mirror in order to minimize the chip size (1.8 mm $\times$ 1.8 mm). The maximum optical deflection angles in static mode are $\pm 5.5^{\circ}$ and $\pm 3.8^{\circ}$ for the outer and inner axes, respectively. In dynamic operation, the optical deflection angles are $\pm 11.8^{\circ}$ at 1.18 kHz for the outer axis and $\pm 8.8^{\circ}$ at 2.76 kHz for the inner axis. $\hfill$[2011-0217]
Journal of Microelectromechanical Systems 04/2012; 21(2):308-315. DOI:10.1109/JMEMS.2011.2175368 · 1.75 Impact Factor