A room-temperature operated hydrogen leak sensor

A new chemi-resister type sensor for hydrogen leak detection is suggested. Tungsten trioxide (WO3) with Pt was used as sensing material. The sensor was fabricated by a sol–gel method. Tungstic acid sol with chloroplatinic acid was spread on a quartz plate with a spinner and calcined in atmosphere to form a WO3 film. Pt was expected to act as catalyst for hydrogen reduction of WO3. nductivity of the sensor was less than 0.001 μS in oxidizing atmosphere, and more than 106 times conductivity increase was observed upon exposure to (1% H2/99% N2) gas. Transient characteristics of the reduction process and oxidation process were not identical. The reduction process exhibited super-linear nature, whereas oxidation process may be approximated by a simple exponential decay. The sensitivity was susceptible to humidity. Not only the response was faster and more sensitive in humid environment than in dry one, it was also affected by the previous exposure history. Even in dry environment the sensitivity increases if the device was exposed to hydrogen, several times. A new detection scheme to explain these observations is suggested.