| Summary: | A novel hydrogen sensor based on a negative temperature coefficient (NTC) thermistor with Pt-loaded WO<sub>3</sub>/SiO<sub>2</sub> coating is proposed and demonstrated experimentally. When the Pt-loaded WO<sub>3</sub>/SiO<sub>2</sub> film is exposed to the mixture of air and H<sub>2</sub>, the exothermic reactions caused by hydrogen and WO<sub>3</sub> with the cooperation of the Pt catalyst raise the local temperature of the NTC thermistor and lower its resistance. Hence, hydrogen concentration can be measured by monitoring the voltage across the NTC thermistor in a series circuit. The proposed device has a rapid response time, high sensitivity, and excellent repeatability to hydrogen as well as immunity to humidity, a compact size, a low manufacturing cost, and is easy to use.
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