Hydrogen Gas Sensing Using a Pd-Coated Cantilever

A cantilever consisting of a thin glass plate coated with an evaporated Pd thin film can be utilized as a hydrogen gas sensor because the Pd film expands upon absorption of hydrogen, resulting in the bending of the free end of the cantilever. A comparison has been made between the response obtained experimentally from 100–1000-nm-thick Pd-coated glass plate cantilevers in the presence of 0.1–600 Torr hydrogen and the response calculated from the data of the Pd lattice expansion due to hydrogen absorption and the elasticity theory. It is shown that the Pd-coated cantilever can detect hydrogen at least from 0.1 to 10 Torr with good reproducibility. The use of a Pd–Ag alloy film instead of a pure Pd film was found to be effective both in enhancing the hydrogen sensitivity at low hydrogen pressures and in extending the hydrogen responsivity up to 600 Torr.