Hydrophilic redox buffers for textile-based potentiometric sensors

Abstract

One of the barriers to the more widespread use of ion-selective electrodes (ISEs) in resource-limited areas is the need for frequent recalibration of such devices. The incorporation of a redox buffer to minimize the effect of redox-active impurities in the system has previously been shown to significantly improve reproducibility. To date, however, there have been no examples of redox buffers compatible with anion-sensing polymeric sensing membranes that can be incorporated into the inner filling solution of an ISE. Here, we introduce a novel hydrophilic redox buffer, cobalt(II/III) bis(terpyridine), and show the improvement of the standard deviation of E0 of chloride sensors from 2.7 to 0.3 mV upon introduction of the redox buffer into the inner filing solution of conventional, rod-shaped electrodes. The redox buffer is also compatible with a textile-based sensing platform, which was shown by incorporation into a textile-based platform with embedded ion-sensing and reference membranes. As only a surprisingly small number of hydrophilic redox buffers have been reported in the literature, the cobalt(II/III) bis(terpyridine) redox buffer may also find applications outside of the field of ISEs.