Plate-Type Solid-State Ag/AgCl Reference Electrode Modified With KCl Agar–PVA and PDMS Composites

Aiming to address the issues associated with traditional Ag/AgCl reference electrodes, such as the risk of leakage and contamination of the liquid electrolyte solution, as well as fragility, a plate-type solid-state Ag/AgCl reference electrode was developed. This electrode is modified with a KCl agar-polyvinyl alcohol (PVA) gel as the electrolyte layer and cured polydimethylsiloxane (PDMS) as the liquid junction layer. The bare Ag/AgCl reference electrodes were prepared separately, along with the Ag/AgCl reference electrode containing the KCl agar-PVA gel single electrolyte layer and the Ag/AgCl reference electrode containing the KCl crystal-PDMS composite layer, for comparative performance analysis. Dense KCl agar-PVA gel particles with a uniformly covered PDMS liquid junction layer were observed through physical characterization of the electrode surface. In the pH buffer solution, this reference electrode exhibited the lowest sensitivity to chloride concentration and the best chloride insensitivity. It exhibited the best output potential stability and the smallest standard deviation. During the reversibility test, the output potential of the reference electrode was restored to a stable value. In the cyclic voltammetry tests, this reference electrode exhibited stable peaks and minimal drift, and its electrochemical performance was stable and reliable. The pH sensor was constructed using a commercial antimony working electrode, demonstrating excellent sensitivity and accuracy in both pH calibration and real-time detection of the culture substrate. The results indicate that the developed composite-modified plate-type solid-state Ag/AgCl reference electrode can provide a stable reference potential and exhibits good adaptability for the online detection of culture substrate pH.