Cycling testing methodology for PEDOT: PSS RH sensors, using different binders

This paper presents a simple testing methodology for chemosensitive RH sensors, which was applied to study the response of a conductive polymer Poly3,4-EthyleneDiOxyThiophene: Polystyrene Sulfonate (PEDOT: PSS) mixed with different binders: Polyvinylpyrrolidone (PVP), Polyethylene Glycol (PEG) and Ethyl Cellulose (EC) at 11 RH levels in a cycling manner (hysteresis). These binders enhanced the adhesion of the RH-sensitive material to the substrate and contributed to characteristic linearisation and more negligible hysteresis. As a test vehicle, we used an Inter Digital Transducer (IDT) made of Polyimide (PI), having a finger/space dimension equal to 25 micro-meter and a sensitive area of 4mm x 4mm. IDTs were fabricated by photolithography on Cr/Au metalized PI substrate (in vacuum by EB). The enhanced electrical characteristics of sensors obtained by mixing PEDOT: PSS with binders were analyzed and discussed in detail.