Solid-state ion sensor for on-chip determination of potassium ion in body fluid

Abstract

This article describes a synthetic route for the fabrication of all-solid-state potentiometric ion-sensing device for on-chip determination of potassium ion in body fluid. The sensing electrodes comprised of (a) a solid-state reference electrode made from a Ag/AgCl-printed electrode covered with a solid-electrolyte-embedded membrane made from siloxane polymer and (b) solid-state ion-selective electrode as working electrode made by assembling ionophore-impregnated PVC membrane casting solution over a ion exchanger-impregnated membrane. The ion exchanger-impregnated membrane is cast by assembling siloxane–polyindole nanodispersion over working electrode of screen-printed electrode to yield constant dipolar potential. The screen-printed electrodes comprising of all-solid-state reference and working electrode can be operated under zero current flow to monitor potassium ion in given sample. The configuration of the printed electrodes is designed to fix a microneedle assembly over the working portion of both reference and working electrodes for transdermal ion sensing. The functional alkoxysilanes derived from nanodispersion allow to make solid-state reference electrode avoiding the use of internal filling solution providing innovation in designing potentiometric sensor. In one aspect, a potentiometric device for detecting analyte in biological fluid that can include a array of hollowed microneedle in which each needle acts as protruded needle structure including an exterior wall forming a hollow interior covering both solid-state working and reference electrode with an opening at terminal end in such that one microneedle is converted into a potassium ion-selective electrode.