A portable paper-based sensor for simultaneous determination of sodium and potassium ions in the human plasma matrix

Accurate determination of sodium and potassium ions in biological fluids is crucial for managing various health conditions, as these electrolytes play a vital role in regulating physiological processes and maintaining overall well-being. A low-cost portable paper-based sensor has been developed for the simultaneous determination of sodium and potassium in the human plasma matrix. It comprises three electrodes on a single paper substrate: a solid-state polyvinyl butyral reference electrode, a sodium selective electrode and a potassium selective electrode. The sensor utilizes conductive functionalized multi-walled carbon nanotubes, selective ionophores and dyes to enhance sensing capabilities. It demonstrates high selectivity for sodium and potassium ions, with a linear range of 10⁻⁶ to 10⁻² M and a Nernstian response (slopes of 59.08 ± 0.32 and 59.15 ± 0.28 mV per decade for sodium and potassium, respectively). The sensor provides a reproducible stable potential over 180 days and a dynamic response time of 10 s. The described paper-based sensor is an excellent tool for point-of-care analysis of sodium and potassium imbalances due to its simplicity, cost-effectiveness and disposability. It provides fast and reliable determination of sodium and potassium ions in the human plasma matrix, making it a valuable tool for managing their imbalances in clinical settings.