Multi-flexure piezoresistive accelerometer for vibration detection

To meet the requirements for vibration detection sensor in intelligent manufacturing and overcome shortcomings in the existing accelerometers including unsatisfactory performances, higher cost and bulky volume, a multi-flexure piezoresistive accelerometer is developed based on micro-electro-mechanical system (MEMS) technology. The proposed accelerometer introduces two tiny beams into the conventional quad-beam structure, which enhances the accelerometer's natural frequency without decreasing the sensitivity. The product of natural frequency and sensitivity is regarded as the evaluation factor to determine the sensor structural dimensions, considering the constraints form analytical optimization and manufacturing process. The sensor chip is fabricated by silicon etching, boron implantation, Al sputtering and anodic bonding. The experimental results show that the developed accelerometer possesses a sensitivity of 0.544 mV per gravity acceleration, a full scale accuracy of 1.76% and natural frequency of 13.61 kHz, and can accurately acquire the acceleration signal with different frequencies. Compared with the conventional quad-beam sensor, the comprehensive property of the proposed multi-flexure accelerometer is improved by 85%.