All-Solid-State Potentiometric Sensors for Potassium Ion Detection with Enhanced Stability By Interlayer Incorporation

Solid state potassium ion selective electrode (K+ ISE) has been the epitome of the most studied chemical sensors in recent years due to its practical importance in biomedical applications. In fact, potassium monitoring in food and serum, urine, and potentially in brain has been carried out in the clinical and medical fields to reveal physical conditions of the patients such as renal diseases, hypopotassemia, alkalosis, cirrhosis of liver, etc. In this report, we developed an electrochemical sensing unit which working, counter and reference electrodes are integrated in a single plane as all-solid-state form. Here, a polyaniline intermediate layer and salt-saturated polyvinylebutyral top coating are introduced in the working and reference electrodes, respectively, in order to mitigate the output potential drift problem that prevented widespread use of solid-state K+ ISE. Morphological and electrochemical properties of K+ ISE are studied by using a scanning electron microscope (SEM) and a potentiostat, respectively. Various measurement modes of electrochemical measurements, including cyclic voltammetry (CV), chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS), are implemented. The K+ ISE show desirable properties including high sensitivity (60.5 mV/decade), low concentration for the limit of detection (10-5.8 M), and large range of linear detection (10-5 – 1 M). Selectivity of our of K+ ISE against NH4 + , Na+ , Mg2+ , Ca2+ , and Fe3+ was studied. With its high potential to be miniaturized, we foresee that our solid-state K+ ISE will find future applications in microdevices for clinical analysis, agricultural and, environmental applications.