title: Isomotive dielectrophoresis for parallel analysis of individual particles.
abstract: Two dielectrophoresis systems are introduced where the induced dielectrophoretic force is constant throughout the experimental region, resulting in uniform (isomotive) microparticle translation. Isomotive dielectrophoresis (isoDEP) is accomplished through a unique geometry where the gradient of the field-squared (∇Erms2) is constant, a characteristic that is otherwise highly nonuniform in traditional DEP platforms. The governing isoDEP equations were derived herein and applied to two different isoDEP prototypes: (i) one fabricated from deep reactive ion etching (DRIE) of a conductive silicon wafer (1-10 Ω-cm) whose patterned features served as electrodes and microchannel sidewalls simultaneously; (ii) a second where the electric field is applied lengthwise through a PDMS microchannel whose geometry follows a specific curvature. Both positive and negative dielectrophoresis was demonstrated with the isoDEP devices using silver-coated hollow glass spheres and polystyrene particles, respectively. Particle tracking was used to compare particle trajectory with the expected dielectrophoretic response; further, particle velocity was used to measure the Clausius-Mossotti factor of individual polystyrene particles (18-24.9 μm) in both devices with a value of -0.40 ± 0.063 (n = 110) and -0.48 ± 0.055 (n = 18) for the DRIE and PDMS isoDEP platforms, respectively. The isoDEP platform is capable of analyzing multiple particles simultaneously, providing greater throughput than traditional electrorotation platforms.
authors.affiliation: Department of Mechanical Engineering, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Allen
authors.affiliation: Department of Biological Systems Engineering, Virginia Polytechnic Institute, Blacksburg, Virginia, USA.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Accolla
authors.affiliation: Department of Mechanical Engineering, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Williams
mesh_terms: D003198:Computer Simulation; D053841:Electroosmosis; D046209:Electrophoresis, Microchip / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design / Q000295:instrumentation / Q000379:methods; D008839:Microelectrodes; D008962:Models, Theoretical; D010316:Particle Size; D011137:Polystyrenes
chemical_list: D011137:Polystyrenes
keywords: Dielectric spectroscopy; Dielectrophoresis; Microfluidics; Particle tracking velocimetry