Performance and Modeling of a Micro-Grating Accelerometer

We design a packaged micro-optical-electromechanical system (MOEMS) - micro-grating accelerometer - that measures the interference of light resulting from its passage through a diffraction grating and reflection from the proof mass. In the present glass-silicon-glass embodiment, the diffraction optical element made of gold and the sensing proof mass supported by eight aluminum symmetrical cantilevers are fabricated on glass and silicon, respectively. Additional system components include a semiconductor laser, photodiodes, and the necessary electronics. First, we analyze the optical model to achieve high optical sensitivity. Then we optimize the structure parameters using the finite element method. Finally, we successfully fabricated the micro-grating accelerometer and packaged it in a small surface-mount package (12 x 12 x 3.6 mm). Our experiments show that the micro-grating accelerometer has a sensitivity of 5.6 V/G in the linear operating region, a bias stability of 0.94 mu G, a resolution of 5.6 mu G, and a dynamic range of 82.5 dB. Such a MOEMS accelerometer integrates the micro-grating with the proof mass through an anodic bonding procedure with the advantages of small size and high resolution.