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Microfluidic-based ion-selective thermoplastic electrode array for point-of-care detection of potassium and sodium ions

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Abstract

A microfluidic paper-based thermoplastic electrode (TPE) array has been developed for point-of-care detection of Na+ and K+ ions using a custom-made portable potentiometer. TPEs were fabricated using polystyrene as the binder and two different types of graphite to compare the electrode performance. The newly designed TPE array embedded in a polymethyl methacrylate chip consists of two working electrodes modified with carbon black nanomaterial and an ion-selective membrane, and an all-solid-state reference electrode modified with Ag/AgCl ink and poly(butyl methacrylate-co-methyl methacrylate) membrane via drop-casting. Ion-selective membrane compositions and conditioning steps were optimized. Under optimized conditions, ion-selective TPEs demonstrated fast response time (4 s) and good stability. The TPE array demonstrated a Nernstian behavior for K+ with a sensitivity of 59.2 ± 0.2 mV decade−1 and near-Nernstian response for Na+ with a sensitivity of 54.0 ± 1.1 mV decade−1 in the range 10−1 – 10−4 M and 1 –  10−3 M, respectively. The detection limits were 1 × 10−5 M and 1 × 10−4 M for K+ and Na+, respectively. In addition, a K+ and Na+ selective microfluidic paper-based analytical device (µPAD) was applied to artificial serum analysis and found in good agreement with average recoveries of 101.3% and 99.7%, respectively, suggesting that the developed ISE array is suitable for detection of sodium and potassium in complex matrix.

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Acknowledgements

The authors would like to thank Dr. Ismail Agir for providing the custom-made potentiometer with its software for potentiometric measurements.

Funding

This work was financially supported by the National Science Foundation (CHE-1710222). Additional support was provided by Colorado State University.

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Authors and Affiliations

  1. Faculty of Chemical-Metallurgical Engineering, Department of Bioengineering, Yildiz Technical University, Istanbul, 34220, Turkey

    Tugba Ozer

  2. Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA

    Tugba Ozer & Charles S. Henry

  3. School of Biomedical Engineering, Colorado State University, Fort Collins, CO, 80523, USA

    Charles S. Henry

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  1. Tugba Ozer
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Correspondence to Charles S. Henry.

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Ozer, T., Henry, C.S. Microfluidic-based ion-selective thermoplastic electrode array for point-of-care detection of potassium and sodium ions. Microchim Acta 189, 152 (2022). https://doi.org/10.1007/s00604-022-05264-y

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