Static and Dynamic Performance Evaluation of a Piezoresistive Silicon MEMS Strain Sensor

Static and dynamic characterization was performed on a prototype piezoresistive silicon MEMS strain sensor. Static tests showed the MEMS sensor's gauge factor ranged from 10-13, which is higher than a foil gauge's gauge factor. Power measurements at -20 °C, 24 °C, and 80 °C showed that the average sensor power decreases as temperature increases. A dramatic decrease in the sensor voltage settling time was observed at a temperature of -20 °C. Sensor dynamic outputs measured at 10 Hz, 63 Hz and 175 Hz revealed noise in the signal and were processed using a digital low pass filter. Rainflow counting on the resulting strain histories revealed that the filtered MEMS sensor signal gives a conservative fatigue life estimate while the unfiltered MEMS signal overestimates the number of loading cycles. Extended vibration testing results showed that the sensor lifetime is 2.70 million cycles at an equivalent strain range of 1261 muepsilon.