Nonlinear dynamics of MEMS resonators: numerical modelling and experiments

Numerical modelling of MicroElectroMechanical Systems (MEMS) resonators is attracting increasing interest from the sensors community especially when the nonlinear regime is activated by challenging applications of the device. Here, the dynamic response of a double-ended tuning fork MEMS resonator is studied both in the linear and nonlinear regime. A one Degree Of Freedom (1 dof) model able to predict the frequency response of the device is proposed. Geometric and electrostatic nonlinearities are simulated through a Finite Element Method (FEM) and a Boundary Element Method (BEM) code, respectively. The total damping of the resonator is computed by taking into account both the thermoelastic and the nonlinear fluid contributions. Experimental measurements performed on a resonator fabricated in polysilicon through a commercial surface micromachining process, validate the proposed model showing a very good agreement with theoretical predictions.