Facile fabrication of tailorable Ag/AgCl reference electrodes for planar devices

Abstract

• Ag/AgCl planar reference electrodes were fabricated using a facile process. • Planar reference electrodes show an open circuit potential of ∼15 mV vs a commercial. • The reference electrodes showed 70 h of stability in a chloride solution. • Planar reference electrodes were used for electrodeposition and glucose sensing. We report the fabrication of tailorable and planar silver-silver chloride (Ag/AgCl) solid-state reference electrodes (SSREs) deposited onto a flexible acetate. A silver layer was thermally evaporated and then was chlorinated in an iron (III) chloride solution. The solid salt reservoir composite consisted of salt crystals embedded in a pre-cured poly(dimethylsiloxane) matrix solution. We performed cyclic voltammetry to study the suitability of the fabricated SSREs in a three-electrode system and showed a negligible difference in the voltammograms obtained by the redox reaction of Fe 3+ /Fe 2+ compared to a commercial Ag/AgCl reference electrode, showing the reduction and oxidation peaks very slight potential shifts. Also, we used the planar SSRE in a glucose reactive strip sensor and for electroplating deposition of four different metals. These planar SSREs have a lifetime of at least 70 h of continuous monitoring at open-circuit potential, a result that makes possible the use of these electrodes in disposable devices. The principal advantage of this system is that the SSREs can be tailored to any desired form to fabricate planar devices that require reference electrodes, like most of chemical and biological sensors, and could be used where access to a laboratory is difficult.