A Study on SF6 Gas Sensor on MEMS

This paper aims to realize miniaturized, highly sensitive passive gas sensors. The basic operation principle of the sensor is illustrated below. Light is coupled from the source into the on-chip waveguide and attenuated at selected wavelengths due to evanescent wave interactions with surrounding molecules. Such wavelength-specific absorption can be used to identify and quantify gas molecules in the environment. According to the Lambert-Beer Law, optical absorption scales with the gas concentration as well as the optical path length. This dependence forms the basis for quantitative gas analysis using optical absorption spectroscopy. The main technical challenges for this sensor design include: 1) realizing low-loss on-chip optical waveguides in the long-wave infrared (LWIR, 8-14 um); and 2) optical packaging of LWIR sensor chip. Both challenges are beyond the capabilities of existing technologies, and therefore we will need to pioneer new innovative solutions above and beyond the current state-of-the-art. Successful completion of the project will likely involve not-yet-invented technologies and thus represent a major technical triumph in the field of infrared integrated photonics. It will also have broad impacts on application arenas including environmental monitoring, industrial process control, as well as security and defense.