Ion-selective organic electrochemical transistors for the determination of potassium in clinical samples

The development and optimization of a paper-based ion-selective organic electrochemical transistor (IS-OECT) with an outstanding analytical performance is presented. The combination of thick-film transistor technology with a suitable optimization of the ion-selective membrane composition and thickness allows reaching sensitivities of up to 2.50 mA/decade, which is more than one order of magnitude higher than other similar devices reported up to date. The system shows good selectivity, allowing the detection of low concentrations of potassium in high saline concentrations, and a linear range from 0.1 mM to 100 mM, which covers the relevant clinical range of K+ in blood. A calibration curve for K+ in artificial serum between 1 and 10 mM shows changes in concentrations down to 0.05 mM can be discriminated. Furthermore, the device can be made with a simple manufacturing process, such as drop casting, on low-cost substrate materials and can be operated with a gate voltage of 0 V. This IS-OCET offers promising avenues for developing ion-sensing platforms for the point of need.