Highly integrated MEMS resonators for CO2 gas sensing

Abstract

Gas sensors are a technology widely used for many applications and purposes. Notably, the current climate crisis is a motivation for the development of sensors to measure greenhouse gases, mainly CO2. With the development of new microfabrication processes it has been possible to produce micro-resonators for multiple applications, such as gas sensors, offering multiple advantages over commercial sensors, thanks to the fact that they use less energy, are smaller, and are more economical to produce. While the different parts of an integrated micro-resonator sensor have been researched for years, the possibility of creating a fully integrated gas sensor using a microresonator has not been sufficiently explored. This has created the need to examine whether it is possible to create a fully integrated microelectromechanical system (MEMS) CO2 sensor based on micro-resonators, which is functional and competitive with the current gas sensor market. This master’s thesis is focused on the creation of a fully functional CO2 MEMS sensor prototype whose measurement variable is the variation of the resonance frequency of the integrated micro-resonator in the presence of a CO2 concentration in air. For this purpose, multiple adsorbance coatings based on polymeric amines are characterized. Afterward, a fully integrated MEMS CO2 sensor is implemented, including both electronics and micro-resonator with its adsorbent coating. It is shown that the sensor can be competitive with commercial optical CO2 sensors. However, due to the impact of external variables such as pressure, temperature and humidity on the performance of the sensor, it is necessary to perform compensation to guarantee the reliability and accuracy of the measurements.

Date	15 Jun 2020
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Nabki (Supervisor)