Magnetic-Actuated Stainless Steel Scanner for Two-Photon Hyperspectral Fluorescence Microscope

We present a fluorescence two-photon laser scanning microscope that uses a soft-magnetic stainless steel microscanner to generate a 2-D Lissajous scanning pattern. The wide-scanning low-voltage driven gimbaled torsional stainless steel microelectromechanical systems (MEMSs) scanner is designed and then fabricated using electrical discharge machining. This technology offers unique advantages by allowing larger mirror surface areas (4 mm (times5) mm) to enhance the fluorescence collection efficiency at low incoming signal level, and providing a rapid prototyping and low-cost alternative to silicon-based MEMS devices, particularly when large displacements and large field of view are required. A maximum total optical scan angle (TOSA) of 20.6° at 112 Hz for a drive power of 200 mW is required for the slow-scan movement, whereas the fast-scan movement occurs at the resonance frequency of 1268 Hz and has a TOSA of 26.6° using a drive power of 400 mW. The soft-magnetic microscanner incorporated in the two-photon hyperspectral fluorescence microscope demonstrates its applicability in two-photon hyperspectral imaging of circulating cancer cells, stem cells, and biological tissue with extrinsic fluorophores.