A novel sandwich capacitive accelerometer with a double-sided 16-beam-mass structure

• The proof mass is suspended symmetrically by double-sided 16 straight beams.
• The highly symmetrical beam-mass structure is fabricated from a single wafer.
• The accelerometer is designed reasonably and can be fabricated easily.
• The fabricated accelerometer is measured within the range of 30 g.

A novel sandwich capacitive accelerometer with a double-sided, 16-beam-mass structure is presented. In this design, the proof mass is supported by 16 tiny beams distributed uniformly on both sides, which aims to dramatically reduce the cross-axis response. Parameters of the beam-mass structure are analyzed and optimized by analytical modeling and the finite element analysis (FEA) method. The micro-accelerometer is fabricated by bulk micromachining technology, and the proof mass and tiny beams are released by KOH anisotropic wet etching from both sides of the silicon wafer, simultaneously. The resonance frequency and the quality factor of the accelerometer are 4.34 kHz and 311, respectively, which are measured in an open-loop system. The measurement results show that the accelerometer has a full-scale (FS) range of 30 g, a close-loop sensitivity of 80 mV/g, and a nonlinearity of 0.27% of FS. The cross-axis sensitivities are 0.353% (x/z axis) and 0.045% (y/z axis), respectively. The bias stability is 0.63 mg for an hour. The accelerometer can withstand high shock of over 10,000 g.

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