Fabrication of gold microelectrodes on polystyrene sheets by UV-directed electroless plating and its application in electrochemical detection

A novel method for the fabrication of micro gold electrodes on polystyrene (PS) sheets by UV-directed electroless plating was developed. The microelectrode pattern was transferred onto the surface of PS sheets by exposure of the surface to UV-lights emitted from a low-pressure mercury lamp through a photo-mask. The carboxyl moieties photo-chemically generated on the UV-exposed region were used as the scaffold for further surface modifications. After amination of the carboxyl groups with ethylenediamine, adsorption of Au(III) ions by the tethered free amine groups, and reduction of the adsorbed Au(III) with NaBH4, a layer of gold nano-particles that served as seeds to catalyze the electroless plating was formed on the UV-exposed region (so-called being activated). Gold microelectrodes were then selectively plated onto the activated area by using an electroless gold plating bath. Water contact angle, attenuated total reflection fourier transformation infrared (ATR-FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and chemical mapping were employed to trace the surface changes during the activation process. The prepared microelectrodes showed strong adhesion to the substrates, good stability in strong acidic and alkaline solutions, and good electrochemical properties similar to standard gold-disk electrodes. The fabricated gold microelectrodes were used as the electrode bases of the three-electrode system for amperometric detection in a full PS micro electrophoresis chip, which was demonstrated for separation and detection of model analytes of dopamine (DA) and catechol (CA). (c) 2009 Elsevier B.V. All rights reserved.