Sensing via Voltammetric Ion-Transfer at an Aqueous-Organogel Micro-Interface Array

Abstract

Ion-transfer across micro-interfaces between aqueous electrolyte and gellified organic electrolyte phases formed at micropores in a micromachined silicon membrane was studied. The membrane used had 30 pores of ca. 11 μm radius, with pore-pore separation of ca. 20-times the radius. Near-steady-state voltammetry was obtained on the forward (aqueous to organogel transfer) sweep and peak-shaped voltammetry on the reverse (organogel to aqueous transfer) sweep, consistent with the dominance of radial diffusion and linear diffusion transport processes during the forward and reverse sweeps, respectively. Computational simulation of voltammetry also produced these responses. Differential pulse stripping voltammetry at these micro-interface arrays showed that the stripping current saturated at a preconcetration time of 30 s, attributed to the rapid diffusion from the aqueous phase to the micro-interfaces and the slow diffusion within the organic phase. The results provide the basis for chemical or biochemical sensing based on ion-transfer voltammetry at micro-interface arrays formed at micromachined membranes.