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.