Room-temperature hydrogen sensor based on optimized interdigitated palladium nanofilm: Structure and performance

The detection of trace level hydrogen in energy systems is of significant importance. This study presents a performance optimization strategy for palladium nanofilm hydrogen sensors through geometric design of interdigital electrodes, departing from conventional material modification. Sensors with identical areas but different finger widths/spacings (S3/S10/S50: 3/10/50 μm) were fabricated via photolithography and magnetron sputtering. The optimized S3 sensor exhibits a 96.7 % higher response toward 5000 ppm H₂, a detection limit of 20 ppm, and accelerated response kinetics at room-temperature. It also demonstrates excellent selectivity, long-term stability (<2.63 % signal fluctuation over 30 days), and reliable operation across 25–85 °C and 20–80 % RH. Multi-scale analysis reveals that the enhanced performance originates from the synergistic effect between the improved Pd crystallinity and the denser, more efficient current paths enabled by the fine IDE structure, providing a design foundation for high-performance hydrogen sensors.