Intercalation Compounds as Inner Reference Electrodes for Reproducible and Robust Solid-Contact Ion-Selective...

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Ion-selective electrodes (ISEs) are crucial for clinical blood electrolyte analysis.
• Developing miniaturized solid-contact ISEs (SC-ISEs) faces challenges in maintaining interface potential stability, impacting robustness and reproducibility.

Purpose of the Study:

• To investigate lithium iron phosphate (LFP) as a novel inner reference electrode (iRE) for SC-ISEs.
• To improve the robustness and miniaturization of SC-ISEs for reliable clinical applications.

Main Methods:

• Utilized partially charged lithium iron phosphate (LFP) as a cation-sensitive intercalation compound for iREs.
• Characterized the interface potential stability and response of the developed SC-ISEs.

Main Results:

• Demonstrated that LFP functions as an effective iRE of the quasi-first kind.
• Achieved ISEs with high robustness towards inner filling variations (5 mV/dec concentration).
• Developed stable and predictable potentials from the LiFePO4/FePO4 redox couple (97.0±1.5 mV after 42 days).

Conclusions:

• Lithium iron phosphate (LFP) offers a viable solution for robust and miniaturized SC-ISEs.
• The symmetrical response of LFP-based iREs significantly enhances electrode performance and stability.
• This advancement paves the way for more reliable integrated systems for clinical electrolyte monitoring.