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

This paper presents a 5-axis motion sensor which can detect 3-axis acceleration and 2-axis angular rate using resonant electrostatic driving and non-resonant capacitive detection mode. This sensor is fabricated by silicon on insulator (SOI) bulk-micromachining, and is vacuum sealed by anodic bonding and activation of the non-evaporated getters (NEG). The sensor chip size is 5.0 × 5.0 × 1.7 mm3. By applying electrostatic reference vibration of a proof mass along Z-axis at resonant frequency of 3.42 kHz, 3-axis acceleration and 2-axis angular rate can be detected capacitively at non-resonant detection mode. Measured acceleration sensitivities along X-, Y- and Z-axis are 1.9, 1.1 and 4.7 V/G, respectively. Angular rate sensitivities around X- and Y-axis are 6.7 and 12 mV/(° s), respectively.