Development of metal-based microelectrode sensor platforms by chemical vapor deposition

A novel approach to the fabrication of metal mircoelectrodes is described t hat employs chemical vapor deposition (CVD) techniques and electrode modifi cation strategies. Two specific examples for the fabrication of copper and silver microelectrodes are described, which utilize a combination of CVD co ating, electroetching and electroplating. Initially, a 25 mum diameter tung sten wire is concentrically coated with an insulating layer of silica with excellent adhesion between the two surfaces. Tungsten metal is then readily removed by electrochemical etching in hydroxide solution to afford a well- defined microcavity at the electrode tip. For the purpose of demonstrating the concept of introducing specific selectivity into the device as well as fabricating well-defined metal microelectrodes, copper and silver were elec trodeposited into the microcavity from aqueous solutions of the respective cations. Both modified electrodes were characterized by electrochemistry an d microscopy, and subsequently used as electrochemical sensors for the dete ction of glucose and chloride ions. This methodology offers a facile approa ch to the development of highly selective microsensors with well-defined el ectrode sensing elements.