A 35-μm pitch IR thermo-mechanical MEMS sensor with AC-coupled optical readout

Ulas Adiyan, Fehmi Çivitçi, Onur Ferhanoʇlu, Hamdi Torun, Hakan Urey

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

A thermo-mechanical MEMS detector with 35-μm pixel pitch is designed, fabricated, and characterized. This fabricated design has one of the smallest pixel sizes among the IR thermo-mechanical MEMS sensors in the literature. The working principle of the MEMS detector is based on the bimaterial effect that creates a deflection when exposed to IR radiation in the 8-12-μm waveband. The nanometer level out of plane mechanical motion is observed in response to IR heating of the pixel, which is detected by a diffraction grating-based optical readout. Performance of MEMS sensor arrays with optical readout have been limited by a large DC bias that accompanies a small AC signal. We developed a novel optical setup to reduce the DC term and the related noise using an AC-coupled detection scheme. Detailed noise characterization of the pixel and the readout system is reported in this paper. The noise equivalent temperature difference of our detector is measured as 216 mK using f/0.86 lens with the AC-coupled optical readout. Finally, we obtained a thermal image using a single MEMS pixel combined with a scanning configuration. Despite the reduced pixel size, the measured noise levels are comparable to the state-of-the-art thermo-mechanical IR sensors.

Original languageEnglish (US)
Pages (from-to)87-92
Number of pages6
JournalIEEE Journal of Selected Topics in Quantum Electronics
Volume21
Issue number4
DOIs
StatePublished - Jul 1 2015
Externally publishedYes

Keywords

  • Diffraction Grating
  • IR Imaging
  • Optical Readout
  • Thermo-Mechanical MEMS

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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