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

Kim JY, Lee C, Park K, Lim G, Kim C - Sci Rep (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea.

ABSTRACT
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 mm(2) 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 mm(3). 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.

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In vitro PA monitoring of the flow of carbon particles in a silicone tube.The measured flow speed of the carbon particles' solution was 0.04 mm/s. 189 (a), 210 (b), and 252 (c) seconds after injecting carbon particles. CPL, carbon particles lump. (Supplementary Video S1).
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f3: In vitro PA monitoring of the flow of carbon particles in a silicone tube.The measured flow speed of the carbon particles' solution was 0.04 mm/s. 189 (a), 210 (b), and 252 (c) seconds after injecting carbon particles. CPL, carbon particles lump. (Supplementary Video S1).

Mentions: The scanning speed of the MEMS scanner is from DC to 200 Hz. In this range, the imaging speed of the 2A-WP-MEMS-OR-PAM system is determined by the laser repetition rate and the total number of imaging pixels in one volumetric image. The current PA A-line imaging speed is 5,000 A-lines per second with a laser repetition rate of 10 kHz because we only acquire the PA signals during the one-way travel of the MEMS scanner. To test the imaging speed, we monitored the flow of an aqueous solution of carbon particles in a silicone tube. We obtained 100 × 200 pixels along the Y and X axes, respectively. Thus, the B-scan image acquisition rate along the Y direction was 50 Hz, which is at least 50 times faster than that of the OR-PAM system using mechanical stages. The volumetric 3D PA image acquisition was 0.25 Hz, but the actual display rate including image processing was 0.14 Hz. As shown in Fig. 3, we have successfully monitored the flow of aggregated carbon particles using the 2A-WP-MEMS-OR-PAM system. The measured flow speed was 0.04 mm/s, much lower than the preset value of 1.7 mm/s because of a large density of carbon particles.


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

Kim JY, Lee C, Park K, Lim G, Kim C - Sci Rep (2015)

In vitro PA monitoring of the flow of carbon particles in a silicone tube.The measured flow speed of the carbon particles' solution was 0.04 mm/s. 189 (a), 210 (b), and 252 (c) seconds after injecting carbon particles. CPL, carbon particles lump. (Supplementary Video S1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300456&req=5

f3: In vitro PA monitoring of the flow of carbon particles in a silicone tube.The measured flow speed of the carbon particles' solution was 0.04 mm/s. 189 (a), 210 (b), and 252 (c) seconds after injecting carbon particles. CPL, carbon particles lump. (Supplementary Video S1).
Mentions: The scanning speed of the MEMS scanner is from DC to 200 Hz. In this range, the imaging speed of the 2A-WP-MEMS-OR-PAM system is determined by the laser repetition rate and the total number of imaging pixels in one volumetric image. The current PA A-line imaging speed is 5,000 A-lines per second with a laser repetition rate of 10 kHz because we only acquire the PA signals during the one-way travel of the MEMS scanner. To test the imaging speed, we monitored the flow of an aqueous solution of carbon particles in a silicone tube. We obtained 100 × 200 pixels along the Y and X axes, respectively. Thus, the B-scan image acquisition rate along the Y direction was 50 Hz, which is at least 50 times faster than that of the OR-PAM system using mechanical stages. The volumetric 3D PA image acquisition was 0.25 Hz, but the actual display rate including image processing was 0.14 Hz. As shown in Fig. 3, we have successfully monitored the flow of aggregated carbon particles using the 2A-WP-MEMS-OR-PAM system. The measured flow speed was 0.04 mm/s, much lower than the preset value of 1.7 mm/s because of a large density of carbon particles.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea.

ABSTRACT
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 mm(2) 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 mm(3). 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.

Show MeSH