Carbon dioxide is a main greenhouse gas and a gas that well-represents air quality. Therefore, it is important to monitor the CO2
concentration in air. Creating an affordable and reliable CO2
sensor is the purpose of this paper. Using a mass-sensitive acoustic sensor (FBAR) we can detect increasing CO2
concentration by a mass increase on the sensor surface. As humidity changes often interfere with these signals the selection of CO2
over humidity changes is another topic addressed in this paper.