SOI micromachined 5-axis motion sensor using resonant electrostatic drive and non-resonant capacitive detection mode

The paper presents a 5-axis motion sensor which can detect 3-axis acceleration and 2-axis angular rate capacitively. The sensor is fabricated by SOI bulk-micromachining, and is vacuum scaled by anodic bonding and activation of the non-evaporated getters. The sensor chip size is 5.0×5.0×1.7 mm³. By applying a Z-axis reference vibration to a proof mass with an electrostatic force at resonant frequency, 5-axis motions can be detected capacitively in a non-resonant detection mode. Measured sensitivities of X-, Y- and Z-axis acceleration were 1.9, 1.1 and 4.7 V/G, respectively. X-and Y-axis angular rate sensitivities were 6.7 and 12 mV/(deg/s), respectively.