Pristine ZnO and SnO₂ films for sensing of volatile organic compounds

Volatile organic compounds can cause severe health problems if inhaled in concentrations more than the permissible threshold. This paper presents the experimental sensing study of three different volatile organic compounds (VOCs) viz. ethanol (C₂H₅OH), propanol (C₃H₇OH) and benzene (C₆H₆). Sensing experiments are performed on undoped, reactively sputtered films (ZnO/SnO₂) integrated with micro-heater and interdigitated electrodes. Process integration is carried out using standard MEMS unit processes. A comprehensive experimental study is carried out to analyze the operating temperature and sensing behavior of the above mentioned volatile organic compounds on SnO₂ and ZnO sensing films. The operating temperature is optimized for maximum sensitivity. Fast response (<40 s) and recovery times (<55 s) are achieved and sensor response for VOCs (C₂H₅OH, C₃H₇OH and C₆H₆) concentrations as low as 25 PPM is recorded.