High-Quality-Factor Quartz Crystal Microbalance Ammonia Sensor Based on Self-Assembled Film

The quality (Q) factor is an important parameter for the high-performance quartz crystal microbalance (QCM) sensor. We propose a high Q factor QCM ammonia sensor based on a sandwich sensing structure with reduced graphene oxide film (rGO) and a layer-by-layer (LBL) self-assembled film. Due to the high elastic modulus of the rGO isolation layer, the surface energy loss of QCM is suppressed. The larger the Q factor, the greater the measuring range of the sensor. The self-assembled monolayers contain a large number of free carboxyl groups and a large specific surface area, and have high adsorption and selectivity for ammonia. Experimental results show that the Q factor of QCM with the rGO isolation layer is approximately twice that of QCM without the rGO isolation layer over the entire detection range. These data show the great potential of sandwich QCM sensors to detect gases with a wider measurement range and higher sensitivity.