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.

Optical resolution photoacoustic microscopy (OR-PAM) is a non-invasive, label-free method of in vivo imaging with microscopic resolution and high optical contrast. Based on intrinsic contrasts, OR-PAM has expanded to include in vivo vessel imaging, flow cytometry, physiological parameter analysis, and single-cell characterization. However, since conventional OR-PAM systems have a fixed tabletop configuration, a large system size, and slow imaging speed, their use in preclinical and clinical studies remains limited. In this study, using microelectromechanical systems (MEMS) technology, we developed a handheld PAM probe with a high signal-to-noise ratio and image rate. To enable broader application of the OR-PAM system, we reduced its size and combined its fast scanning capabilities into a small handheld probe that uses a 2-axis waterproof MEMS scanner (2A-WP-MEMS scanner). All acoustical, optical, and mechanical components are integrated into a single probe with a diameter of 17 mm and a weight of 162 g. This study shows phantom and in vivo images of various samples acquired with the probe, including carbon fibers, electrospun microfibers, and the ear, iris, and brain of a living mouse. In particular, this study investigated the possibility of clinical applications for melanoma diagnosis by imaging the boundaries and morphology of a human mole.

A comparative study is made on the surface film formation on the high-voltage LiNi 0.5 Mn 1.5 O 4 positive electrode at elevated temperature (55 C) in two different electrolytes; LiPF 6 /organic carbonate and LiTFSI/ionic liquid (propylmethylpyrrolidinium bis(trifluoromethylsulfonyl)imide, PMPyr-TFSI). The surface film derived by a decomposition of the former electrolyte is enriched by inorganic fluorinated species, which becomes thicker with cycling to lead a continued electrode polarization and cell failure. In contrast, organic carbon species are dominant in the film derived from the latter electrolyte. This organic-rich film deposited in the earlier period of cycling seems to effectively passivate the positive electrode presumably due to uniform coverage. As a result, the film does not grow with cycling and electrode polarization is not serious to give a stable cycling behavior.

Optical-resolution photoacoustic microscopy (OR-PAM), a promising microscopic imaging technique with high ultrasound resolution and superior optical sensitivity, can provide anatomical, functional, and molecular information at scales ranging from the microvasculature to single red blood cells. In particular, real-time OR-PAM imaging with a high signal-to-noise ratio (SNR) is a prerequisite for widespread use in preclinical and clinical applications. Although several technical approaches have been pursued to simultaneously improve the imaging speed and SNR of OR-PAM, they are bulky, complex, not sensitive, and/or not actually real-time. In this paper, we demonstrate a simple and novel OR-PAM technique which is based on a typical galvanometer immersed in non-conducting liquid. Using an opto-ultrasound combiner, this OR-PAM system achieves a high SNR and fast imaging speed. It takes only 2 seconds to acquire a volumetric image with a wide field of view (FOV) of 4 × 8 mm2 along the X and Y axes, respectively. The measured lateral and axial resolutions are 6.0 and 37.7 μm, respectively. Finally, as a demonstration of the system’s capability, we successfully imaged the microvasculature in a mouse ear in vivo. Our new method will contribute substantially to the popularization and commercialization of OR-PAM in various preclinical and clinical applications.

-In this paper, a new energy harvesting technology using stray electric field of an electric power line is presented. It is found that energy can be harvested and stored in the storage capacitor that is connected to a cylindrical aluminum foil wrapped around a commercial insulated 220 V power line. The average current flowing into 47 µF storage capacitor is about 4.53 µA with 60 cm long cylindrical aluminum foil, and it is possible to operate wireless sensor node to transmit RF data every 42 seconds. The harvested average power is about 47 µW in this case. Since the energy can be harvested without removing insulating sheath, it is believed that the proposed harvesting technology can be applied to power the sensor nodes in wireless ubiquitous sensor network and smart grid system.

Optical-resolution photoacoustic microscopy (OR-PAM) is an imaging tool to provide in vivo optically sensitive images in biomedical research. To achieve a small size, fast imaging speed, wide scan range, and high signal-to-noise ratios (SNRs) in a water environment, we introduce a polydimethylsiloxane (PDMS)-based 2-axis scanner for a flexible and waterproof structure. The design, theoretical background, fabrication process and performance of the scanner are explained in details. The designed and fabricated scanner has dimensions of 15 × 15 × 15 mm along the X, Y and Z axes, respectively. The characteristics of the scanner are tested under DC and AC conditions. By pairing with electromagnetic forces, the maximum scanning angles in air and water are 18° and 13° along the X and Y axes, respectively. The measured resonance frequencies in air and water are 60 and 45 Hz along the X axis and 45 and 30 Hz along the Y axis, respectively. Finally, OR-PAM with high SNRs is demonstrated using the fabricated scanner, and the PA images of micro-patterned samples and microvasculatures of a mouse ear are successfully obtained with high-resolution and wide-field of view. OR-PAM equipped with the 2-axis PDMS based waterproof scanner has lateral and axial resolutions of 3.6 μm and 26 μm, respectively. This compact OR-PAM system could potentially and widely be used in preclinical and clinical applications.

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