Highly precision carbon dioxide acoustic wave sensor with minimized humidity interference

Extensive applications of carbon dioxide (CO2) in various fields, such as food industry, agricultural production, medical and pharmacological industries, have caused a great demand for high-performance CO2 sensors. However, most existing sensors suffer from poor performance wet environment often cannot work accurately high humidity condition. In this study, quartz crystal resonator (QCR) coated with uniform layer reduced graphene oxide (RGO) is proposed to detect both the concentrations water molecules simultaneously, which can be used significantly minimize interference. Unlike other common gas sensors, RGO-based QCR sensor operated different levels concentration quantified precisely effectively. Moreover, it has fast response (?0.4 s), also suitable respiration monitoring. Our results showed that before after volunteer did low-intensity exercise, could differences exhaled breath (i.e., 4.50 % 5.15 %, respectively).