A Capacitive Force Transducer Structure with Improved Linearity

In MEMS capacitive force transducers,force is transformed to the variation of capacitance,then the capacitance variation is read out by circuits.Because of the nonlinearity between the displacement of polar plate and the capacitance,the output of the transducer has sever nonlinear relation with the force been measured in large measurement range.A structure with nonlinear force-to-displacement relation,which can counteract the displacement-to-capacitance nonlinearity was introduced.Rayleigh-Ritz method was adopted to analysis the force-to-displacement relation of the hardening spring in the structure.Test result indicated that the nonlinearity of the sensor was reduced by 1/3 in the test range.