Poly(3-methylthiophene) (PMeT) thin films were electrochemically deposited on quartz crystal microbalance QCM transducers to investigate their volatile organic compound (VOC) sensing properties depending on ambient conditions. Twelve different VOCs including alcohols, ketones, chlorinated compounds, amines, and the organosphosphate dimethyl methylphosphonate (DMMP) were used as analytes. The responses of the chemical sensors against DMMP were the highest among the tested analytes; thus, fabricated chemical sensors based on PMeT can be evaluated as potential candidates for selectively detecting DMMP. Generally, detection limits in the low ppm range could be achieved. The gas sensing measurements were recorded at various humid air conditions to investigate the effects of the humidity on the gas sensing properties. The sensing performance of the chemical sensors was slightly reduced in the presence of humidity in ambient conditions. While a decrease in sensitivity was observed for humidity levels up to 50% r.h., the sensitivity was nearly unaffected for higher humidity levels and a reliable detection of the VOCs and DMMP was possible with detection limits in the low ppm range.

ZnO nanorods were synthesized directly on the mass sensitive transducer elements, namely the quartz crystal microbalance (QCM), by electrochemical deposition techniques. Besides, vanadium pentaoxide (V 2 O 5 ) thin films were evaporated on the ZnO nanorods using a thermal evaporation system. The fabricated chemical gas sensors were exposed to different levels of various volatile organic compounds (VOCs). The VOCs sensing measurements were realized at room temperature. The application of an additional V 2 O 5 layer on the ZnO nanorods was found to improve the sensing performance of the nanorods. The highest responses were obtained for the analyte DMMP and the DMMP sensitivities of the sensors are at least three times higher than the sensitivities for the other tested VOCs. ZnO nanorods are considered excellent sensing materials on the QCM allowing selective detection of DMMP and other analytes at room temperature.

No abstract