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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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(a) Photograph of the mouse ear showing blood vessels. (b) In vivo noninvasive PA MAP image of the mouse ear. (c) The enlarged region of the white line box in (b). White arrows indicate individual red blood cells.
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f4: (a) Photograph of the mouse ear showing blood vessels. (b) In vivo noninvasive PA MAP image of the mouse ear. (c) The enlarged region of the white line box in (b). White arrows indicate individual red blood cells.

Mentions: Finally, we conducted in vivo noninvasive PA imaging of microvasculatures in a mouse ear. The laser pulse energy on the mouse skin was less than 9 mJ/cm2, which is below the American National Standard Institute (ANSI) safety limit, 20 mJ/cm2 at 532 nm. It took 100 seconds to acquire one volumetric PA image with 1,000 × 500 pixels along the X and Y axes, respectively. A step size was determined using scanning ranges divided by number of pixels. We used an acoustic lens with a focal length of 27 mm to provide a large field of view (FOV, 9 × 4 mm2 along the X and Y axes, respectively). Fig. 4(a) is the photograph of the mouse ear, and Fig. 4(b) is the corresponding in vivo PA MAP image. By comparing both Figs. 4(a) and (b), not only large blood vessels but also small capillaries were clearly shown in the PA image. Additionally, Fig. 4(c) is an enlarged region of the white line box in Fig. 4(b). Individual red blood cells (RBCs) along the capillaries were clearly visualized.


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)

(a) Photograph of the mouse ear showing blood vessels. (b) In vivo noninvasive PA MAP image of the mouse ear. (c) The enlarged region of the white line box in (b). White arrows indicate individual red blood cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: (a) Photograph of the mouse ear showing blood vessels. (b) In vivo noninvasive PA MAP image of the mouse ear. (c) The enlarged region of the white line box in (b). White arrows indicate individual red blood cells.
Mentions: Finally, we conducted in vivo noninvasive PA imaging of microvasculatures in a mouse ear. The laser pulse energy on the mouse skin was less than 9 mJ/cm2, which is below the American National Standard Institute (ANSI) safety limit, 20 mJ/cm2 at 532 nm. It took 100 seconds to acquire one volumetric PA image with 1,000 × 500 pixels along the X and Y axes, respectively. A step size was determined using scanning ranges divided by number of pixels. We used an acoustic lens with a focal length of 27 mm to provide a large field of view (FOV, 9 × 4 mm2 along the X and Y axes, respectively). Fig. 4(a) is the photograph of the mouse ear, and Fig. 4(b) is the corresponding in vivo PA MAP image. By comparing both Figs. 4(a) and (b), not only large blood vessels but also small capillaries were clearly shown in the PA image. Additionally, Fig. 4(c) is an enlarged region of the white line box in Fig. 4(b). Individual red blood cells (RBCs) along the capillaries were clearly visualized.

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