Screen-printed reference electrodes for potentiometric measurements

A convenient and reliable method for large-scale production of miniaturized, planar, all-solid-state reference electrodes is reported. All elements of the Ag/AgCl/KCl reference half-cell i.e. layer of Ag/AgCl (inner electrode), immobilized electrolyte (junction) and encapsulation are fabricated by means of screen-printing technology. The use of pastes cured in low temperature allows fabrication on low-cost, plastic, flexible foils. The developed reference electrodes exhibit good long-term stability. Continuous operation life-time exceeds one week. Storage stability is longer than 9 months. pH, chlorides as well as other halide anions, typical buffer components, alkaline and heavy metal cations, complexing ligands and redox agents, do not influence the potential of the reference electrodes. The developed reference electrodes are compatible with strip potentiometric sensors fabricated in the same format. Examples of analytical applications of the reference electrodes with various screenprinted sensors are demonstrated.