Contamination-Free Reference Electrode Using Prussian Blue for Small Oxygen Sensors

Area of Science:

• Electrochemistry
• Materials Science
• Biomedical Engineering

Background:

• Point-of-care testing (POCT) devices are crucial for efficient patient care.
• Electrochemical sensing, common in POCTs like blood oxygen sensors, often relies on Ag/AgCl reference electrodes.
• Ag/AgCl electrodes can contaminate working electrodes with silver ions, leading to device degradation.

Purpose of the Study:

• To develop a stable and reliable reference electrode for small electrochemical POCT devices.
• To address the limitations of conventional Ag/AgCl reference electrodes in POCT applications.

Main Methods:

• Fabrication of a novel reference electrode using graphene-coated porous silica spheres (G/PSS) embedded with Prussian blue (PB), termed PB/G/PSS.
• Dispersion of PB within a conductive G/PSS matrix to ensure electrolyte contact.
• Screen printing of the PB/G/PSS electrode for POCT device fabrication.

Main Results:

• The PB/G/PSS electrode demonstrated stable open-circuit potential within 30 mV for 31 days.
• Oxygen sensors utilizing the PB/G/PSS electrode showed stable operation for several days.
• Sensors with Ag/AgCl electrodes exhibited rapid deterioration within a day.

Conclusions:

• The PB/G/PSS reference electrode offers significantly improved stability compared to Ag/AgCl electrodes.
• This novel electrode is a promising alternative for small electrochemical-based POCT devices.
• The screen-printable, stable PB/G/PSS electrode facilitates the development of next-generation POCTs.