Abstract
The gas sensors market is constantly growing. This growth is driven by a wide range of applications and increasing legislative constraints on air monitoring. Moreover, gases play a vital role in many aspects of people’s life. Despite the wide variety of gas sensors, it is challenging to find the one that provides a good balance between sensitivity, selectivity, stability, compactness and cost. Furthermore, a continuously expanding market demands the development of new solutions that will result in more technological innovations.This thesis is a part of a research project which aims to develop a compact, integrated and portable gas sensor with excellent selectivity, high sensitivity (ppb) in fast and continuous response. It primarily focuses on the development of an active sensor component that is responsible for compactness and high sensitivity measurement.The sensor proposed in this thesis is based on photoacoustic gas detection. We studied and realized a silicon microelectromechanical (MEMS) resonator characterized by a well-defined resonance with high quality factor, compared to the standard microphone. Subsequently, to detect the photoacoustic wave, we used silicon with a capacitive readout mechanism, which allows avoiding any material deposition and CMOS compatibility.With a fabricated resonator, we reach a NNEA of 5.5⋅10^(-7) W⋅cm^(-1) Hz^(-1/2) under capacitive detection. Subsequently, we compared the results to a bare quartz tuning fork in on-beam configuration for which we got an NNEA of 1.3⋅10^(-7) W⋅cm^(-1) Hz^(-1/2). Thus we can claim that the fabricated resonator presents state-of-the-art performance.In this thesis, we proposed an innovative approach based on a microelectromechanical resonator which, we believe, will allow to integrate and miniaturize gas sensors while advancing the sensor’s research and market.