Palladium-surface acoustic wave interaction for hydrogen detection

A hydrogen sensitive detection technique utilizing a surface acoustic wave (SAW) delay line coated with a palladium thin film is presented. The hydrogem-palladium interaction produces change in the velocity of SAW propagating on the coated substrate, which is detected as phase shift at the output of the delay line. Presently, hydrogen concentrations as small as 50 ppm in a flowing H2 + N2 mixture have been detected.