Electrochemical detectors prepared by electroless deposition for microfabricated electrophoresis chips

Microfabricated capillary electrophoresis (CE) chips with integrated electr ochemical detection have been developed on glass substrates. An electroless deposition procedure was used to deposit a gold film directly onto the cap illary outlet to provide high-sensitivity electrochemical detection for cat echol and several nitroaromatic explosives. Scanning electron microscopy re vealed that the electroless gold film contains nanoscopic gold aggregates ( 100-150 nm) with an average thickness of 79 mn. The electroless deposition procedure can be easily and routinely performed in any wet-chemistry labora tory, and electroless gold can be deposited onto complex and internal surfa ces. Intimate coupling of electrochemical detection and CE chips obviates t he need for a coupling mechanism or tedious alignment procedures. With nitr oaromatic compounds as a working model, microchip capillary electrophoresis equipped with electroless gold has proven to provide high sensitivity and fast response times for sensor applications. The CE microchip system was ca pable of separation and determination of explosive compounds including TNT in less than 130 s with detection limits ranging from 24 to 36 mu g/L, i.e. , 4-fold enhancements in detection efficiency in comparison to thick-film t echnology.