Surface Acousic Wave Sensor for Hydrogen Detection with a Two-Layered Structure

Result concerning a hydrogen sensor based on a two-layer structure in a Surface Acousic Wave dual-delay line sustem are presented. The sensor material consist of two layeds performed in two different vapor deposition processes. The first one is a 720nm CuPc (or 110nm H2Pc) layer, the other one - a 20 nm thin palladium film. This structure was formed in a one of the dual-delay line system on a LiNbO3 Y-cut Z-propagation substrate. In such a multilayer structure can detect hydrogen in a medium concentration range (from 0.25% to 3% in nitrogen), even at room temperature. The sensor has a very good sensitivity, stability and is entirely reversible. The responce and recovery times are very short (-200s 0 800s), which is very important from the practical point fo view.