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.