A MEMS Fluid Density Sensor Based on Trapezoidal Cantilever

摘要

A kind of fluid density sensor based on MEMS (Micro-Electro-Mechanical-System) technology was introduced with trapezoidal cantilever structure. The Ti-Pt-Au coil was sputtered on the surface of the sensitive chip. The alternating current,whose frequency could be variable, was supplied to the Ti-Pt-Au coil. When the chip was placed in uniform magnetic field, the cantilever then began to vibrate. The Wheatstone bridge in the chip could transform the vibration signal output into voltage signal output which could be observed by lock-in amplifier. The input AC frequency, corresponding to the maximum output of Wheatstone bridge, was the resonant frequency of trapezoidal cantilever in the measured fluid. The fluid density then could be determined by the equation with the resonant frequency of trapezoidal cantilever. The rectangular cantilever and trapezoidal cantilever, based on the same parameters, were analyzed. The results show that the sensitivity of trapezoidal cantilever is higher than that of rectangular cantilever. Four different sizes of trapezoidal cantilever were analyzed by modal and harmonic simulation with ANSYS software, the optimum solution would be obtained from simulation results.