A novel ammonia sensor based on high density, small diameter polypyrrole nanowire arrays

A novel sensor based on the PPy nanowire arrays with high density, small diameter (about 50 nm) presented a significantly high surface-to-volume ratio. Conducting polypyrrole (PPy) nanowire arrays were synthesized by electropolymerization in the anodic aluminum oxide (AAO) template which was fabricated by two-step anodizing process. Then, two sides of the PPys/AAO were pasted by Si substrates and the AAO template was etched by HF acid. At last, the gold wires were attached on Si substrates, and the sensor came into being. The sensor was sensitive to ammonia at room temperature and showed relatively high response in low concentration and comparatively short response and recovery time.