| Summary: | Sensitive H<sub>2</sub> sensors at low concentrations and room temperature are desired for the early warning and control of hydrogen leakage. In this paper, a resistive sensor based on Pt-doped In<sub>2</sub>O<sub>3</sub> nanoparticles was fabricated using inkjet printing process. The H<sub>2</sub> sensing performance of the sensor was evaluated at low concentrations below 1% at room temperature. It exhibited a relative high response of 42.34% to 0.6% H<sub>2</sub>. As the relative humidity of 0.5% H<sub>2</sub> decreased from 34% to 23%, the response decreased slightly from 34% to 23%. The sensing principle and the humidity effect were discussed. A dynamic current sensing model for dry H<sub>2</sub> detection was proposed based on Wolkenstein theory and experimentally verified to be able to predict the sensing behavior of the sensor. The H<sub>2</sub> concentration can be calculated within a short measurement time using the model without waiting for the saturation of the response, which significantly reduces the sensing and recovery time of the sensor. The sensor is expected to be a promising candidate for room-temperature H<sub>2</sub> detection, and the proposed model could be very helpful in promoting the application of the sensor for real-time H<sub>2</sub> leakage monitoring.
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