Authors: M.N. Kozicki, P. Maroufkhani and M. Mitkova
Affilation: Arizona State University, United States
Pages: 716 - 719
Keywords: microfluidics, valve, electrodeposition, electrolyte
We have recently developed a reliable and inexpensive way to electrically regulate flow through microchannels via a structure that can be made using readily available microfabrication techniques. We use an electrical signal to stimulate silver deposition on a thin Ag-Ge-Se solid electrolyte layer in a small region of a microchannel. The electrodeposit can extend for several hundred microns if the electrolyte is fed with silver from the anode, the ions in the electrolyte being reduced by electrons from the cathode. The electrodeposited silver, which is a high surface area fractal structure less than 1 micron high, changes the fluid-surface interaction, increasing the contact angle for water by at least 20 degrees over that measured on solid electrolyte alone. Since fluid flow in a microchannel is dominated by the nature of the channel surface, this increase in effective hydrophobicity can be used to control the movement of the fluid. In this paper we show the latest results from the use of this technique in a microfluidic testbed.