一种提高电容式力传感器线性度的结构设计

在MEMS电容式力传感器中,力被变换为电容的变化,再用电路检测电容的变化以反映力的信号。这种力-电容变换方式的一个缺点是在大量程下,由于电容变化量与极板位移之间的非线性,检测输出与被检测的力之间具有较为严重的非线性关系。本文提出一种用力-极板位移之间的非线性抵消极板位移-电容变化量之间的非线性的结构方式,用瑞利-里兹法计算了结构中具有"硬弹簧"特性的梁的受力与变形之间的非线性关系。实验结果表明,采用这种设计的结构非线性降低了约1/3。

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.