Diamond like carbon films for enzyme electrodes; characterisation of novel overlying permselective barriers

Diamond like carbon (DLC) coated microporous polycarbonate membranes have been studied for use as novel composite permselective barriers membranes for a glucose enzyme electrode. Permeability coefficients, P, for key electrochemically active interferents across uncoated and DLC coated polycarbonate membranes has been compared. Interferent responses have then been assessed for sensors incorporating such membranes, and their relationship to differing DLC depositions assessed. Membranes with smaller pore sizes (0.03 and 0.01 μm) and extended DLC depositions (up to 7 min coating), while imparting some enhanced selectivity towards glucose, failed to show major discrimination for glucose over interferents as shown by P values: maximum glucose-to-interferent P ratios being 1.36 and 1.25 for ascorbate and urate, respectively. The implications of these findings are discussed.