Research On Low-g Piezoresistive Triaxial Acceleration Senso

According to the application requirement of low g value acceleration sensor in automobile stability control system,this paper shows basic structure of a piezoresistive three-axis acceleration sensor,which is composed of support body,two mass blocks,four double L-shaped beams and middle double beams.To measure low g acceleration value,stress calculation models of beams were constructed,the stress concentration problem of beam root was studied with material mechanics.Based on the piezoresistive effect,the change of 12 piezoresistors at beam root with acceleration is analyzed.The theoretical calculation shows sensor can realize measurement of external acceleration(a_x,a_yand a_z).The COMSOL software was build low g value three-axis acceleration sensor structure model.On the surface of mass blocks,the symmetrical mass block structure was compensated(vertically and horizontally).The surface stress of beam was analyzed when acceleration was applied in three directions(x,y,z).Influence of size of elastic element on output voltage is studied.Process of sensor chip was made by MEMS technology,compensated mass block was integrated with sensor chip by combination packaging method,test chip sample was packaged by pressure welding technology.The characteristic frequency,sensitivity and cross interference characteristics of chip samples were analyzed by vibration table,multimeter and others.The experimental results show that at room temperature,when the power supply voltage is 5.0 V and the frequency range is 0～20000 Hz,the x,y and z sensitivity of the low g value acceleration sensor compensated vertical mass block are 12.81 m V/g,22.36 m V/g and 24.73 m V/g.In the range of 0～2 g,the sensitivity of sensor is improved effectively,the acceleration measurement in the range of low g value is realized.