Ultralow-voltage electrothermal MEMS based fiber-optic scanning probe for forward-viewing endoscopic OCT

We report an ultralow-voltage, electrothermal (ET) micro-electro-mechanical system (MEMS) based probe for forward-viewing endoscopic optical coherence tomography (OCT) imaging. The fully assembled probe has a diameter of 5.5 mm and a length of 55 mm, including the imaging optics and a 40 mm long fiber-optic cantilever attached on a micro-platform of the bimorph ET MEMS actuator. The ET MEMS actuator provides a sufficient mechanical actuation force as well as a large vertical displacement, achieving up to a 3 mm optical scanning range with only a 3 V drive voltage with a 1.5 V offset. The imaging probe was integrated with a swept-source OCT system of a 100 kHz A-scan rate, and its performance was successfully demonstrated with cross-sectional imaging of biological tissues ex vivo and in vivo at a speed up to 200 frames per second.