Non-faradaic capacitive cation sensing under flow

Abstract

The ability to continually monitor target ion species in real-time is a highly sought-after endeavour in the field of host–guest chemistry, given its direct pertinence to medical and environmental applications. Developing methodologies which support sensitive and continuous ion sensing in aqueous media, however, remains a challenge. Herein, we present a versatile and facile, proof-of-concept electrochemical sensing methodology based on non-faradaic capacitance, which can be operated continuously with high temporal resolution (≈1.4 s), in conjunction with custom-designed integrated microfluidics. The potential of this method is demonstrated for cation sensing at a chemically simple benzo-15-crown-5-based molecular film (B15C5SAM) as a representative redox-inactive, receptive interface. Detection limits as low as 4 μM are obtained for Na+ by these entirely reagentless analyses, and are additionally characterised by exceptional baseline stabilities that are able to support continuous sensing over multiple days. The platform performs well in artificial sweat across physiologically relevant spans of sodium concentration, and provides meaningful dose-dependent responses in freshwater samples. Finally, the high assay temporal resolution affords an ability to resolve both the kinetics of binding (association/dissociation) and notably characteristic fingerprints for different alkali metals which may be diagnostic of different interfacial ion binding modes.

Graphical abstract: Non-faradaic capacitive cation sensing under flow

Supplementary files

Article information

Article type
Edge Article
Submitted
06 Aug 2024
Accepted
02 Sep 2024
First published
09 Sep 2024
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2024, Advance Article

Non-faradaic capacitive cation sensing under flow

S. C. Patrick, R. Hein, P. D. Beer and J. J. Davis, Chem. Sci., 2024, Advance Article , DOI: 10.1039/D4SC05271D

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