Platinum Interdigitated Electrode Arrays for Reagent-Free Detection of Copper

Water is a precious resource that is under threat from a number of pressures, including release of toxic compounds that can have damaging effect on ecology and human health. The current methods of water quality monitoring are based on sample collection and analysis at dedicated laboratories. This can provide an incomplete picture of the status of the water body as pollution events can be missed. Recently, electrochemical based methods have attracted a lot of attention for environmental sensing owing to their versatility, sensitivity and compatible integration with cost effective, smart and portable readout systems. In the present work, we report on the fabrication and characterization of platinum interdigitated microband electrodes arrays, and their application for trace detection of copper. Using square wave voltammetry after acidification with mineral acids, a limit of detection of 0.8 μg/L was achieved. Copper detection was also under taken on river water samples and compared with standard analytical techniques. The possibility of controlling the pH at the surface of the sensors – thereby avoiding the necessity to add mineral acids – was investigated. By applying potentials driving the water splitting reaction at one comb on the sensors electrode (the protonator), it was possible to lower the pH in the vicinity of the sensing electrode. Detection of standard copper solutions down to 5 μg/L using this technique is reported. This reagent free method of detection opens the way for autonomous, in situ monitoring of pollutants in water bodies.