title: Microfluidic dielectrophoretic sorter using gel vertical electrodes.
abstract: We report the development and results of a two-step method for sorting cells and small particles in a microfluidic device. This approach uses a single microfluidic channel that has (1) a microfabricated sieve which efficiently focuses particles into a thin stream, followed by (2) a dielectrophoresis (DEP) section consisting of electrodes along the channel walls for efficient continuous sorting based on dielectric properties of the particles. For our demonstration, the device was constructed of polydimethylsiloxane, bonded to a glass surface, and conductive agarose gel electrodes. Gold traces were used to make electrical connections to the conductive gel. The device had several novel features that aided performance of the sorting. These included a sieving structure that performed continuous displacement of particles into a single stream within the microfluidic channel (improving the performance of downstream DEP, and avoiding the need for additional focusing flow inlets), and DEP electrodes that were the full height of the microfluidic walls ("vertical electrodes"), allowing for improved formation and control of electric field gradients in the microfluidic device. The device was used to sort polymer particles and HeLa cells, demonstrating that this unique combination provides improved capability for continuous DEP sorting of particles in a microfluidic device.
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, California 92697, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Luo
authors.affiliation: Department of Medicine, Institute for Immunology, University of California, Irvine, California 92697, USA.
authors.forename: Edward L
authors.initials: EL
authors.lastname: Nelson
authors.affiliation: Department of Electrical Engineering and Computer Science, University of California, Irvine, California 92697, USA.
authors.forename: G P
authors.initials: GP
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, University of California, Irvine, California 92697, USA ; Department of Electrical Engineering and Computer Science, University of California, Irvine, California 92697, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Bachman