A Solid-Contact Reference Electrode Based on Silver/Silver Organic Insoluble Salt for Potentiometric Ion Sensing

Area of Science:

• Electrochemistry
• Wearable Biotechnology
• Materials Science

Background:

• Solid-contact ion-selective electrodes (SC-ISEs) are crucial for miniaturized wearable sensors.
• Existing solid-contact reference electrodes (SC-REs) often use Ag/AgCl with solid electrolytes, risking leakage.
• There is a need for more stable and reliable SC-REs in wearable potentiometric sensors.

Purpose of the Study:

• To develop a novel, stable, and leakage-free solid-contact reference electrode (SC-RE).
• To investigate the performance of a silver/silver tetraphenylborate (Ag/AgTPB) based SC-RE.
• To integrate the developed SC-RE into a wearable sensor for real-time sweat ion monitoring.

Main Methods:

• Fabrication of an Ag/AgTPB solid contact using silver/silver tetraphenylborate.
• Construction of the SC-RE with a plasticized poly(vinyl chloride) (PVC) membrane containing tetrabutylammonium tetraphenylborate (TBATPB).
• Potentiometric measurements to evaluate standard potential reproducibility and long-term stability.
• Integration of the SC-RE onto a flexible substrate for wearable sensor fabrication.

Main Results:

• The Ag/AgTPB/PVC-TBATPB SC-RE demonstrated reproducible standard potentials across various electrolytes.
• The developed SC-RE exhibited high long-term stability, addressing leakage issues of previous designs.
• The flexible SC-RE was successfully integrated into an all-solid-state wearable sensor.

Conclusions:

• The novel Ag/AgTPB based SC-RE offers a stable and reliable reference potential for potentiometric sensors.
• This SC-RE design overcomes the electrolyte leakage limitations of traditional Ag/AgCl reference electrodes.
• The developed wearable sensor is suitable for non-invasive, real-time sweat chloride monitoring.