Potentiometric Sensor Array with Multi-Nernstian Slope

The sensitivity of potentiometric sensors functioning in equilibrium mode is limited by the value predicted according to the Nernst equation and inversely proportional to the charge in the analyte ion. Therefore, an increased ion charge results in a dramatic decrease in the sensor sensitivity. We propose an approach to allow one to increase the sensitivity of the potentiometric measurements by using a combined electrochemical cell composed of several identical ion-selective electrodes immersed into separate sample solutions of equal composition. The combination of n electrodes, demonstrating individually a Nernstian slope in one electrochemical cell allows to amplify the signal and associated response slope by n times. The proposed approach is shown to provide a double and triple Nernstian slope for potassium-, calcium-, nitrate-, and carbonate-selective electrodes by combining two or three identical electrodes, correspondingly. Each ion-selective electrode functions in an equilibrium mode, hence, ensuring response stability and reproducibility.