Cordless solid-state hydrogen sensor using proton-conductor thick film

Potentiometric as well as amperometric solid-state gas sensors using a thick film (≈ 10 μm) of proton-conductor have been developed for detecting small amounts of hydrogen in air at room temperature. The sensor elements are composed of the following electrochemical cell: reference (or counter) electrode (Au or Pt) | proton-conductor thick film | sensing electrode (Pt). The thick film is formed on an alumina substrate by applying a paste of antimonic acid-polyvinyl alcohol mixture, mainly by means of a spin-coating method. The electromotive force of the potentiometric sensor varies logarithmically with H₂ concentration, while the short-circuit current of the amperometric sensor is found to be proportional to H₂ concentration. Both give a 90% response time of about 10 s at 30 °C.