title: A simple mechanism for reliable particle sorting in a microdevice with combined electroosmotic and pressure-driven flow.
abstract: Selective transport and sorting of particles in microfluidic devices by electroosmosis is complicated due to superposition of uncontrolled hydrodynamic pressure contributions on the electroosmotic force. In this paper, we present a microfluidic concept for the reliable and simple separation and sorting of particles in a microchip by electroosmosis combined with pressure-driven flow. The presented device allows fluid quantities to be switched and particles to be sorted within a channel manifold using only a single power supply with fixed voltage and an electric switch. Consequently, chip operation and fluid switching procedure are greatly simplified compared to a situation, in which several independent power sources are used for flow balancing, as is the common procedure. With the triple-T channel design presented, backpressure flow disturbing the electrokinetic fluid and particle separation process is eliminated by introducing controlled opposed hydrodynamic flow of buffer from side channels. This pressure-driven flow is generated on-chip by setting up differences in the reservoir pressures in a defined manner. A detailed flow analysis based on the equivalence of fluid flow and electric current is performed and the conditions for reliable chip function are worked out.
authors.affiliation: Swiss Federal Institute of Technology, EPFL, STI-LMIS, Lausanne, Switzerland. robert.johann@epfl.ch
authors.forename: Robert
authors.initials: R
authors.lastname: Johann
authors.forename: Philippe
authors.initials: P
authors.lastname: Renaud
mesh_terms: D002469:Cell Separation / Q000295:instrumentation / Q000379:methods*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D008962:Models, Theoretical; D015003:Yeasts / Q000166:cytology