Simulation, Fabrication, and Characterization of a Sensitive SU-8-Based Fabry-Perot MOEMS Accelerometer

This paper presents the design, fabrication, and characterization of a SU-8 four L-shaped beams optical micro-electro-mechanical-system accelerometer based on a Fabry-Perot (FP) interferometer. An applied acceleration causes a displacement of the proof mass and changes the cavity of FP resonator. Fabrication process has been simplified such that only two photolithography steps are required and SU-8 is used for both the structural body and the sacrificial layer. To prevent the sacrificial layer from being exposed to UV light, a thin copper layer is coated by physical vapor deposition technique between the two SU-8 layers. The sensor chip consists of a proof mass which is suspended by four L-shaped springs. The movement of the proof mass in response to acceleration is detected by a FP cavity formed between the proof mass and the cleaved end of a single mode optical fiber. The fabricated sensor has a sensitivity of 12.5 mu W/g and resonant frequency of 1872 Hz in the range of +/- 1 g.