Ammonia detection mechanism with polyacrylic acid sensitive layers: Field effect transduction

The origin of work-function (WF) changes induced in polyacrylic acid (PAA) layers deposited on metallic electrodes upon ammonia exposure is examined. The changes are recorded in experiments performed in Kelvin Probe (KP) set-ups. To understand and explain the origin of the signals, data gathered in gravimetric (QMB), morphology, direct current (dc) conductance, 4 MHz conductance and 4 MHz capacitance investigations are also used. The origin of the measured KP effects seems to be the polymer-electrode interface enriched in target gas molecules by the absorption in the PAA film. In this context, the complex role of the polymer and background humidity is addressed.