Layered SAW gas sensor based on CSA synthesized polyaniline nanofiber on AlN on 64° YX LiNbO3 for H2 sensing

A 64° YX LiNbO3 surface acoustic wave (SAW) transducer was fabricated and then aluminium nitride (AlN) layer was deposited on the active area of the device as acoustic wave guiding layer. Structural studies revealed that the deposited AlN thin films have strong preferential c-axis orientation. Morphological analysis showed that the AlN layer is compact with grain dimensions of less than 80 nm. Polyaniline nanofibers were polymerized from the reactions in which an oxidant was rapidly mixed with the aniline monomer in an acidic environment. The polymer was synthesized in camphor sulfonic acid (CSA) to obtain 50 nm average diameter polyaniline nanofibers. These nanofibers were deposited on the layered SAW device and were tested towards hydrogen (H2) gas while operating at room temperature. The device demonstrated a large and reproducible response to different concentrations of the H2 gas making it an ideal candidate for H2 sensing at room temperature.