Research Of MOEMS Accelerometer Based On Talbot Effect

Accelerometer is an important part of inertial measurement system,which is widely used in seismic monitoring,resource exploration and other fields.MEMS accelerometer has become the mainstream development direction due to its advantages of small size,light weight,low cost,low power consumption,easy integration and high sensitivity.However,the dynamic range of the silicon capacitive MEMS accelerometers currently used is limited,and the capacitive type is also susceptible to electromagnetic interference and parasitic capacitance,so it is difficult to remove noise.Therefore,it is urgent to explore a new type of high performance MEMS accelerometer.MOEMS accelerometer is a new type of MEMS accelerometer with high precision and anti-electromagnetic interference,which combines optical detection effect with MEMS accelerometer.In this paper,a MOEMS accelerometer based on grating Talbot effect is proposed.Firstly,the theoretical feasibility of grating acceleration detection is verified based on the theory of grating near-field Talbot effect,and a double-layer grating out-of-plane detection model is established on the theoretical basis.Secondly,through the mechanical model of the accelerometer sensitive structure,the relationship between displacement and acceleration was established,and four cantilever beam-mass block accelerometer sensor structures were designed.The sensitivity of the structure was 0.66μm/g and the cross-axis sensitivity was 3.03%（at 1g acceleration）under 50 g dynamic range by COMSOL finite element simulation.Then,a simulation model was established based on the transmission detection of double-layer grating,the grating parameters were optimized and the linear region was fitted,the optical effect sensitivity of the double-layer grating was 12.05%/μm.Next,the manufacturing process of double grating MOEMS accelerometer is designed,and the device processing of the accelerometer is completed according to the fabrication steps.Finally,the quality and morphology of the machined accelerometer chip were characterized,and the average shear strength of the anodic bonding was 19.5 MPa.The static mechanical test of MOEMS in atmospheric environment shows that its acceleration sensitivity is 3.1V/g,the resolution is 484 μg,and bias stability is 0.15 mg.