BALL SURFACE ACOUSTIC WAVE HYDROGEN SENSOR WITH WIDEST SENSING RANGE AND FAST RESPONSE

摘要

SAW(surface acoustic wave) excited on a spherical surface under a specific condition is naturally collimated, realizing ultra-multiple roundtrips along an equator of the sphere. The ball SAW hydrogen gas sensor is based on this newly discovered phenomenon, and uses a very thin Pd-Ni alloy sensitive film. The detection range for hydrogen gas was 10ppm to 100% and the response time was less than 1s for 3.0% hydrogen concentration in nitrogen gas, evaluated by using a newly developed digital quadrature detector (DQD).