A Miniaturized Electrothermal-MEMS-Based Optical Coherence Tomography (OCT) Handheld Microscope

Swept-source optical coherence tomography (SS-OCT), benefiting from its high sensitivity, relatively large penetration depth, and non-contact and non-invasive imaging capability, is ideal for human skin imaging. However, limited by the size and performance of the reported optical galvanometer scanners, existing portable/handheld OCT probes are still bulky, which makes continuously handheld imaging difficult. Here, we reported a miniaturized electrothermal-MEMS-based SS-OCT microscope that only weighs about 25 g and has a cylinder with a diameter of 15 mm and a length of 40 mm. This MEMS-based handheld imaging probe can achieve a lateral resolution of 25 μm, a 3D imaging time of 5 s, a penetration depth of up to 3.3 mm, and an effective imaging field of view (FOV) of 3 × 3 mm². We have carried out both calibration plate and biological tissue imaging experiments to test the imaging performance of this microscope. OCT imaging of leaves, dragonfly, and human skin has been successfully obtained, showing the imaging performance and potential applications of this probe on human skin in the future.