NO₂ gas mixed-potential sensor based on positive temperature coefficient ceramics self-operated thermostatic controller

Abstract

For a proper operation, conventional gas sensors based on solid electrolytes usually require complex heating elements and temperature control systems to ensure the transfer of ions inside a solid electrolyte substrate. In this study, a positive temperature coefficient (PTC) ceramic was used for the first time as a heating source to successfully compose a self-thermostatic potential NO₂ gas sensor. Powered by a 12-V multi-batteries, the PTC ceramic can be quickly heated to and stabilised at 250°C to provide the necessary working temperature to the sensor. It was proved that this self-thermostatic sensor displays a high NO₂ sensitivity (84.60 mV/decade) toward 5–150 ppm NO₂ at different ambient temperatures. Meanwhile, it exhibits a high NO₂ selectivity, along with excellent repeatability and stability. This simple and effective method is a solution to the significant obstruction of traditional gas sensors with burdensome heating structures, allowing a broad application to various types of on-site gas detection.