Abstract

Liquid-junction-free reference electrodes were prepared on screen printed substrates using poly-3,4-ethylenedioxythiophene (PEDOT) as solid-contact and novel ionogels as capping membrane. The chemico-physical properties of the PEDOT layer were tuned by changing the electropolymerization media and electrodeposition technique. Particularly, electrodepositing PEDOT films potentiostatically or potentiodynamically impacted on the traces of the potential of the electrodes during the conditioning step. In addition, the choice of the capping membrane formulation, e.g., acrylate monomers, ionic liquid, cross-linkers and photo-initiators, was adjusted to obtain electrodes with properties almost equivalent of a standard reference electrode. Thus, calibration plots of Na+ ion-selective electrodes against the optimized solid-contact ionogel reference electrodes (SCI-REs) or against a double-liquid junction Ag/AgCl electrode did not present any significant difference. Such SCI-REs may provide an effective route to the generation of future low-cost components for potentiometric sensing strips.