An optical MEMS acoustic sensor based on grating interferometer

Mengying Zhang, Gaomi Wu, Dipeng Ren, Ran Gao, Zhi Mei Qi*, Xingdong Liang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Acoustic detection is of great significance because of its wide applications. This paper reports a Micro-Electro-Mechanical System (MEMS) acoustic sensor based on grating interferometer. In the MEMS structure, a diaphragm and a micro-grating made up the interference cavity. A short-cavity structure was designed and fabricated to reduce the impact of temperature on the cavity length in order to improve its stability against environment temperature variations. Besides this, through holes were designed in the substrate of the grating to reduce the air damping of the short-cavity structure. A silicon diaphragm with a 16.919 µm deep cavity and 2.4 µm period grating were fabricated by an improved MEMS process. The fabricated sensor chip was packaged on a conditioning circuit with a laser diode and a photodetector for acoustic detection. The output voltage signal in response to an acoustic wave is of high quality. The sensitivity of the acoustic sensor is up to -15.14 dB re 1 V/Pa @ 1 kHz. The output signal of the high-stability acoustic sensor almost unchanged as the environment temperature ranged from 5 °C to 55 °C.

Original languageEnglish
Article number1503
JournalSensors
Volume19
Issue number7
DOIs
Publication statusPublished - 1 Apr 2019
Externally publishedYes

Keywords

  • Acoustic sensors
  • Grating
  • Interferometry
  • MEMS
  • Stability

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