Oxygen and Humidity Sensing Property of a Limiting Current-Type Thin-Film YSZ-Based Sensor on a Micro-Hotplate

In this study, we fabricated a limiting current-type microelectromechanical system (MEMS) sensor and evaluated its sensing performance of oxygen and humidity concentration. The MEMS oxygen and humidity sensor consisted of a thin-film YSZ-based sensing element on a cantilever-shaped micro-hotplate. The thin-film YSZ layer was electrically heated by a Pt heater of the cantilever-shaped micro-hotplate. The limiting current characteristics were observed above 575°C. We confirmed the limiting current proportionally increased with oxygen concentration. In contrast, the limiting current increased with humidity at a higher bias voltage. These results indicate that both of oxygen and humidity concentration can be separately measured by selecting the bias voltage to the YSZ thin film.