Comparative study of novel micromachined accelerometers employing MIDOS

This paper reports on the fabrication and characterization of a novel implementation of micromachined accelerometers. The accelerometers employ a new sensing technique, the modulated integrative differential optical sensing (MIDOS), to sense the output displacements of their proof-mass. The fabrication process of the hybrid device is presented. The device consists of a bulk micromachined mechanical part attached by indium bumps to a CMOS chip containing photodetectors and readout electronics. Several prototypes were fabricated and characterized. The differences between the prototypes are discussed in detail as well as the comparison between their measured characteristics (noise equivalent acceleration (NEA), bandwidth and linearity). The prototypes have demonstrated NEA ranging from 70 (μg/√Hz) to 1 (mg/√Hz) with bandwidth of 1 KHz to 4 KHz.

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