A low-cost microplasma generation unit allowing for the on-site processing of ZnO-based gas sensors
In this study, a low-cost gas-sensing device that integrates a zinc-oxide (ZnO)-based gas sensor with a microplasma generation unit is presented. By the proper connection of different sets of electrodes to the desired power sources or the measurement circuit, the device can be operated in the microplasma mode (MPM) or the gas-sensing mode (GSM), respectively. Due to the device design, microplasma can be generated at the same location where the precursor for the sensing materials, namely Zn(NO3)2 solution, is coated. Such an arrangement allows for low temperature and the on-site conversion of the precursor materials to ZnO particles upon microplasma treatment under MPM. GSM can be used to detect ethanol vapor with a concentration between 100 and 18 000 ppm at room temperature. We observed that the sensor can be operated under a wide range of ethanol concentrations with stable sensing behavior for over 80 test cycles.