Identification of the relationship of carbon dioxide concentration and the frequency changes of a quartz crystal microbalance (QCM) oscillation sensor as a preliminary study of a carbon dioxide gas sensor

QCM or quartz crystal microbalance is a sensor that works based on the changes in the oscillation frequency of the crystal due to changes in mass on the surface. Therefore QCM can also be used as a gas sensor because it is expected that the change in part per million (PPM) volume of the gas will change the frequency of the oscillation. This research was aimed to identify the response of oscillation frequency changes from QCM in varying carbon dioxide (CO2)concentrations. A QCM with a fundamental frequency of 10 MHz was used as the sensor connected to the oscillator and frequency counter. A TSI Q-Trak Model 7575x was used to measure carbon dioxide concentration inside an experimental chamber. The results showed that changes in carbon dioxide gas concentrations given to the QCM surface changed the oscillation frequency of the QCM. This change was evaluated under a frequency counter. The greater the concentration of carbon dioxide gas given, the smaller the change in the frequency of the QCM oscillations that were read. The response of QCM frequency due to exposure to carbon dioxide gas concentration had a very good response and was very suitable to be used as a carbon dioxide gas sensor.