Monitoring of NH3 gas by LB polypyrrole-based SAW sensor

Surface acoustic wave (SAW) devices have been fabricated and tested as sensors of NH, in gaseous phase. Polypyrrole films, prepared by Langmuir-Blodgett (LB) technique, have been deposited onto the surface of SAW devices as gas absorbent layers. Simultaneous measurements of SAW phase velocity and attenuation have been carried out in order to investigate the sensing mechanisms. The sensor response shows high sensitivity towards NH, gas and excellent selectivity with respect to main interfering gases (CO, CH4, H-2, O-2), at room temperature. The low cross-sensitivity permits the recognition of NH3 gas as one component of a mixture of interfering gases.