A PDMS-Based 2-Axis Waterproof Scanner for Photoacoustic Microscopy

Lee

et al. 2017

Self Cite

122

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.

Section: Introductionmentioning

confidence: 99%

Handheld Photoacoustic Microscopy Probe

Park

Lee

et al. 2017

Self Cite

122

“…We developed a water-proofed MEMS scanner to steer acoustic paths rapidly for real-time B-mode US imaging. The fabrication process is detailed in previous studies [11][12][13] . Briefly, the MEMS scanner has a mirror assembly and body assembly.…”

Section: Fabrication Of a Water-proofed Mems Scannermentioning

confidence: 99%

“…Thus, unlike mechanical sector scanning, the mirror scanning does not highly depend on the physical dimensions and weight of the single-element transducer. To steer the acoustic path, we employed a water-proofed microelectromechanical system (MEMS), a design which has been recently employed in photoacoustic microscopy and optical coherent tomography [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] . Some studies have been performed US imaging on phantoms in vitro, but not in vivo 25,26 .…”

mentioning

confidence: 99%

Versatile Single-Element Ultrasound Imaging Platform using a Water-Proofed MEMS Scanner for Animals and Humans

Choi

Lim

et al. 2020

Self Cite

Single-element transducer based ultrasound (US) imaging offers a compact and affordable solution for high-frequency preclinical and clinical imaging because of its low cost, low complexity, and high spatial resolution compared to array-based US imaging. To achieve B-mode imaging, conventional approaches adapt mechanical linear or sector scanning methods. However, due to its low scanning speed, mechanical linear scanning cannot achieve acceptable temporal resolution for real-time imaging, and the sector scanning method requires specialized low-load transducers that are small and lightweight. Here, we present a novel single-element US imaging system based on an acoustic mirror scanning method. Instead of physically moving the US transducer, the acoustic path is quickly steered by a waterproofed microelectromechanical (MEMS) scanner, achieving real-time imaging. Taking advantage of the low-cost and compact MEMS scanner, we implemented both a tabletop system for in vivo small animal imaging and a handheld system for in vivo human imaging. Notably, in combination with mechanical raster scanning, we could acquire the volumetric US images in live animals. This versatile US imaging system can be potentially used for various preclinical and clinical applications, including echocardiography, ophthalmic imaging, and ultrasound-guided catheterization.

“…Recently, a compact waterproof microelectromechnical system (MEMS) scanner was applied in an OR-PAM system with an opto-ultrasound combiner. With the target immersed in water, the waterproof MEMS scanner provided simultaneous angular scanning of the laser and ultrasound, achieving fast real-time PA imaging of brain activity 19 and flowing carbon particles 20 21 . By scanning the laser and ultrasound directly instead of with the use of heavy instruments, the waterproof MEMS system attained its potential maximum imaging speed.…”

mentioning

confidence: 99%

High-speed and high-SNR photoacoustic microscopy based on a galvanometer mirror in non-conducting liquid

Lee

Park

et al. 2016

Self Cite

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.