Biological sorting and fluidic devices based on catalytically generated electrokinetic phenomena

It has been shown that electroosmotic fluid flow and electrophoretic forces on charged particles can be generated by the decomposition of hydrogen peroxide at silver and gold bimetallic catalytic junctions. At this junction, gold generates protons and silver consumes protons through a catalytic process, forming a charge gradient and associated electric field extending from the gold surface to the silver surface. This electric field drives electroosmotic fluid flow where the direction of the flow is a function of the surface zeta potential, and electrophoresis where the direction of motion of the particle depends on the particle charge. In this study, several new device geometries are explored. In particular, the influence of patterned regions of surface zeta potential, device geometry and size on the motility of negatively charged carboxyl-functionalized latex spheres has begun to been evaluated. Carboxyl-functionalized latex spheres were chosen in part to simulate negatively charged biomolecules. The results indicate that the geometry of the device, location of the patterned surface zeta potential and the surface areas of the catalysts have a major impact on particle location, motion and velocity. For example, devices exhibiting a circular geometry are capable of focusing particles into a defined region on the gold surface. Collectively, such devices may be useful for both microfluidics and biological molecule manipulation.