Development of Surface Acoustic Wave Sensors Using Nanostructured Palladium for Hydrogen Detection

This thesis addresses the development of new gas sensor using surface acoustic wave (SAW) technology. SAW sensors detect the change in mass, modulus, and conductivity of a sensing layer material via absorption or adsorption of an analyte. The advantage of SAW sensor includes low cost, small size, high sensitivity. We investigated the use of nano-crystalline palladium film for sensing hydrogen gas. We also investigated SAW fabrication for radio frequency (RF) range operation where high signal-to-noise ratios can be achieved. A test-bed consisting of a gas dilution system, a temperature-controlled test cell, a network analyzer, and computer-based measurement system was used for evaluating the performance of SAW gas sensors at very low concentrations. Both single and dual delay line SAW devices were fabricated by means of photolithography on a lithium niobate substrate. Tests are carried to determine response speed, resolution, reproducibility, and linear characteristics, over a range of analyte concentrations