Pulsed excitation enhances low-temperature H ₂ Sensing in Pt-In ₂ O ₃ sensors: a performance and humidity tolerance study against DC bias

In metal-oxide resistive gas sensors, conventional DC excitation often induces signal drift due to overheating, compromising long-term stability for hydrogen monitoring, particularly in humid environments. To overcome the inherent limitations of the DC mode, this study adopts pulsed excitation instead of DC excitation and applies it to a low-cost, screen-printed resistive sensor based on a platinum-modified indium oxide (Pt-In2O3) thin film for hydrogen detection at 50°C. The Pt concentration and pulse duty cycle were optimized, and the dry and humid hydrogen sensing characteristics under both DC and pulsed excitation were systematically evaluated. Under pulsed excitation, the sensor achieved a detection limit of 2.63 ppm and exhibited a response to 0.1% hydrogen approximately twice that under DC conditions across a broad relative humidity range of 30% to 70%. Moreover, the pulsed excitation effectively mitigated the detrimental effect of humidity on recovery kinetics. This phenomenon was explained by a proton current-dominated mechanism. This study establishes pulsed excitation as a simple yet powerful strategy to enhance the sensitivity, humidity tolerance, and stability of metal oxide semiconductor resistive hydrogen sensors, paving the way for their more reliable application in real-world conditions.