Selective Microfabrication of Silver Electrodes inside a Microchannel by Multiphase Laminar Flow with Density Difference

Abstract

In this paper, we propose a selective microfabrication technique of metal electrodes in a microchannel. The technique is based on the chemical deposition and the interface rotation of laminar flows among three multiphase fluids. Silver electrodes were patterned by electroless silver deposition only on the wall of the microchannel where the interface between a silver electroless plating solution and a reducer solution makes contact with the wall. A third fluid having a lower (or higher) density compared to the two solutions was introduced into the microchannel at the same time. The density difference between the two solutions and the third fluid induced the stable rotations of the interfaces between two among the three fluids. The third fluid having a different density, therefore, enabled us to selectively position the interfaces between the electroless plating and reducer solutions on the wall of the microchannel. We have demonstrated the fabrication of a single electrode and double electrodes on the bottom walls of microchannels based on the suggested microfabrication technique by changing number of streams, injection locations, flow rates, and flow duration time. (C) 2009 Elsevier B.V. All rights reserved.