Mercury detection at microfabricated pyrolyzed photoresist film (PPF) disk electrodes

This work describes a method to passivate pyrolized photoresist films (PPF) to microfabricate electrodes suitable for electrochemical applications. The work describes the passivation process in detail, which entails pre-treating the PPF structures with mild ammonia plasma followed by silanization with SiH4 to promote the adhesion of the passivation layer. The working condition of these electrodes is demonstrated by the detection of mercury in aqueous solutions (pH = 1.5) down to 2 ppb. We discuss possible ways to improve the passivation of PPF that will lead to more complex structures and devices made in this material. The dynamic range of the method described here is already analytically useful, but we suggest ways to shorten the time of analysis and push the detection limit below 1 ppb using PPF electrodes.