Performance Analysis of VOCs Detection using Polyisobutylene and Chitosan Overlayed on QCM Sensor

The presence of advanced technologies had brought to the development of acoustic wave sensors. Quartz crystal microbalance (QCM), an acoustic wave sensor has provided a good sensing performance which enables it to be extensively used in numerous fields. The performance of the sensor is related to the material used as the sensing layer for the adsorption of analyte gas to occur. This work focuses on the use of polyisobutylene (PIB) and chitosan biopolymer films as the sensing layer to detect volatile organic compounds (VOCs). Acetone, isopropyl alcohol (IPA) and toluene are the selected VOCs used in this work. A QCM sensor with the corresponding sensing layer is modeled using COMSOL Multiphysics. The performance of the QCM sensor is evaluated in terms of the shift in resonance frequency. Toluene gas with greater molar mass exerted a greater shift in resonance frequency. Chitosan sensing layer exhibits greater sensitivity towards toluene detection compared to PIB sensing layer with a resonance frequency shift of -13 Hz at 1000 ppm and sensitivity of 0.0333 Hz/ppm. In comparison with acetone, and IPA detection, toluene shows a greater shift of resonance frequency of -96 Hz for QCM coated with the chitosan sensing layer. This is because toluene gas has a larger molar mass of 92.14 g/mol compared to acetone and IPA. Thus, this work emphasized the material selection for sensing material is crucial in improving the sensor performance.