A Compact MEMS-Based Infrared Spectrometer for Multi-Gases Measurement

A microspectrometer based on a middle-infrared (Mid-IR) linear variable optical filters (LVOF) and a MEMS-based infrared thermopile detector array has been developed for multi-gases sensing in the indoor and industrial environments. The designs, fabrications, and characterizations of LVOF and thermopile detector are presented. Experimentally, the LVOF exhibits a mean FWHM of ~ 400 nm and mean peak transmittance of ~ 70% at the central wavelength of the operating spectrum of 2.5 ~ 5 μm. The thermopile detectors used p- and n-polysilicon/Al metal as thermocouple materials, exhibiting a resistance temperature coefficient of 0.08%/°C and a responsivity of 112 V/W. The LVOF can be regarded as a narrow-band filter array that is installed above the thermopile detector array to form a portable and inexpensive Mid-IR spectrometer for multi-gases sensing.