QCM Sensors Based on PEI Films for CO_2 Detection

In this paper, quartz crystal microbalance（QCM） gas sensors coated with polyehtyleneimine（PEI）was utilized for carbon dioxide（CO2） detection. The sensing mechanism is based on the availability of reversible acid-base reactions between CO2 molecules and PEI at room temperature. The experimental results revealed that the PEI/starch sensor exhibited much higher sensitivity than that of pure PEI, and showed approximate linearity over a concentration region ranging from 500 ppm to 8000 ppm. The influence of humidity had also been investigated. Furthermore, the response and recovery time deceased as the operation temperatures increased. Finally, sensitivity loss after conservation for several days and reversibility of the sensors had been discussed.