Comparison of Different Commercial Conducting Materials as Ion-to-Electron Transducer Layers in Low-Cost Selective Solid-Contact Electrodes

Simple, robust, sensitive and low-cost all-solid-state ion-selective electrodes (SCISEs) are of interest in different fields, such as medicine, veterinary, water treatment, food control, environmental and pollution monitoring, security, etc. as a replacement for traditional ion-selective electrodes with liquid inner contact. In spite of their potential advantages, SCISEs remain mainly in the research laboratories. With the motivation of developing simple and low-cost SCISEs with possible commercial applications, we report a comparison study of six different commercial conducting materials, namely, polypyrrole-block-polycaprolactone (PPy-b-PCaprol), graphene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) ink, poly(3,4-ethylenedioxythiophene):polyethylenglycol (PEDOT:PEG), high conductivity PEDOT:PSS, polyethylenimine (PEI) with PEDOT:PSS for their possible use as ion-to-electron transducer in polyurethane based pH-SCISEs. Among all studied pH-SCISES, PEDOT:PEG based electrodes exhibited the best results in terms of sensitivity, reproducibility and lifetime. Finally, these sensors were tested in different real samples showing good accuracy.