Recent Progress on Photoacoustic Imaging Enhanced with Microelectromechanical Systems (MEMS) Technologies

Abstract

Photoacoustic imaging (PAI) is a new biomedical imaging technology currently in the spotlight providing a hybrid contrast mechanism and excellent spatial resolution in the biological tissues. It has been extensively studied for preclinical and clinical applications taking advantage of its ability to provide anatomical and functional information of live bodies noninvasively. Recently, microelectromechanical systems (MEMS) technologies, particularly actuators and sensors, have contributed to improving the PAI system performance, further expanding the research fields. This review introduces cutting-edge MEMS technologies for PAI and summarizes the recent advances of scanning mirrors and detectors in MEMS.

Characterization of a Fiber Bundle-Based Real-Time Ultrasound/Photoacoustic Imaging System and Its In Vivo Functional Imaging Applications

“…Neurophotonics has recently received significant attention in neuroscience because of its advantages of intrinsic contrast and nonionizing radiation [1]. However, pure optical imaging modalities [e.g., diffuse optical tomography (DOT)] often suffer from either insufficient spatial resolution or poor penetration depth [e.g., multiphoton microscopy, confocal microscopy, and optical coherence tomography (OCT)] due to strong light scattering.…”

“…However, pure optical imaging modalities [e.g., diffuse optical tomography (DOT)] often suffer from either insufficient spatial resolution or poor penetration depth [e.g., multiphoton microscopy, confocal microscopy, and optical coherence tomography (OCT)] due to strong light scattering. The penetration depth is extended to a few centimeters when using DOT with model-based reconstruction because DOT uses diffusive photons and is able to provide both optical scattering and absorption parameters [1]. However, poor spatial resolution (typically 1/5-th of the imaging depth) remains a problem with the DOT technique.…”

“…Potential clinical applications include breast cancer [12], sentinel lymph node (SLN) [13] and skin cancer [14] imaging. In clinical applications that require a large tomographic view, motorized stages can be used to control the position of the PA transducers in synchrony with the data acquisition sequence [1]. However, a gap in translating PA technology into a widely used technique for either preclinical or clinical imaging remains due to the extremely large size of the systems and the lack of a user-friendly interface [15], such as a truly programmable sequence in a single setting paired with a laser coupling system that can be easily set up for detection [1].…”

“…In clinical applications that require a large tomographic view, motorized stages can be used to control the position of the PA transducers in synchrony with the data acquisition sequence [1]. However, a gap in translating PA technology into a widely used technique for either preclinical or clinical imaging remains due to the extremely large size of the systems and the lack of a user-friendly interface [15], such as a truly programmable sequence in a single setting paired with a laser coupling system that can be easily set up for detection [1]. Another challenge in delivering high-energy laser pulses is that when focusing and coupling light into the fiber, the high peak power density can damage the surface of the fiber tip [16].…”

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

“…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 .…”