Intercalation Compounds as Inner Reference Electrodes for Reproducible and Robust Solid‐Contact Ion‐Selective Electrodes |
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Authors: | Yu Ishige Dr Stefan Klink Prof?Dr Wolfgang Schuhmann |
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Institution: | 1. Center for Technology Innovation, Healthcare, Research & Development Group, Hitachi Ltd., Kokubunji-shi, Tokyo, 185-8601, Japan;2. Analytical Chemistry, Center for Electrochemical Sciences, Ruhr-University Bochum, Bochum, Germany |
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Abstract: | With billions of assays performed every year, ion‐selective electrodes (ISEs) provide a simple and fast technique for clinical analysis of blood electrolytes. The development of cheap, miniaturized solid‐contact (SC‐)ISEs for integrated systems, however, remains a difficult balancing act between size, robustness, and reproducibility, because the defined interface potentials between the ion‐selective membrane and the inner reference electrode (iRE) are often compromised. We demonstrate that target cation‐sensitive intercalation compounds, such as partially charged lithium iron phosphate (LFP), can be applied as iREs of the quasi‐first kind for ISEs. The symmetrical response of the interface potentials towards target cations ultimately results in ISEs with high robustness towards the inner filling (ca. 5 mV dec?1 conc.) as well as robust and miniaturized SC‐ISEs. They have a predictable and stable potential derived from the LiFePO4/FePO4 redox couple (97.0±1.5 mV after 42 days). |
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Keywords: | cation intercalation compounds inner reference electrode ion-selective electrodes lithium iron phosphate solid contact |
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