Vertical-plate-type microaccelerometer with high linearity and low cross-axis sensitivity

This paper reports the development of a microaccelerometer with high performance in linearity and cross-axis sensitivity. The accelerometer consisted of a vertical, double-ended flexural beam, a proof mass integrated at the middle section of the beam, and four suspended piezoresistors fixed at the mass block and across the trenches to the anchor pads. The mass block had maximum displacements of the dynamic structure which would activate the sensors to deliver maximal output. The sensing chip was fabricated on a silicon-on-insulator wafer through MEMS processes. The accelerometer was placed on a rate table that provided stable centrifugal acceleration up to approximately 3000 × G for testing. The output voltage of the accelerometer was digitized and radio-frequency transmitted for remote data acquisition. The correlations for the individual runs showed that the accelerometer had a sensitivity of 3.0015 μV/Vexc/G with extraordinary performance. The linearity of the sensing output was only 0.11% of full scale output (FS, or 59 dB), as deduced from the average standard deviation of all test runs. The average of the maximum reading deviations from the corresponding correlated curves was approximately 0.26% FS. Moreover, the cross-axis sensitivity for the two orthogonal directions nearly vanished in the test range. With the high rigidity of the microstructure, the accelerometer exhibited an ultra high performance factor of 25.8 × 106 MHz2. The accelerometer possessed exceptional sensitivity, linearity, and repeatability, and extremely low cross-axis interference and noise.