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Article

Continuous-Flow Particle Separation by 3D Insulative Dielectrophoresis Using Coherently Shaped, dc-Biased, ac Electric Fields

Benjamin G. Hawkins,^† A. Ezekiel Smith,^‡ Yusef A. Syed,^§ and Brian J. Kirby*^§

Department of Biomedical Engineering, School of Applied and Engineering Physics, and Sibley School of Mechanical & Aerospace Engineering, College of Engineering, Cornell University, Ithaca, New York 14853

Anal. Chem., 2007, 79 (19), pp 7291–7300

DOI: 10.1021/ac0707277

Publication Date (Web): September 1, 2007

†

Department of Biomedical Engineering.

‡

School of Applied and Engineering Physics.

Sibley School of Mechanical & Aerospace Engineering.

To whom correspondence should be addressed. E-mail: bk88@cornell.edu; Phone: 6072554379.

Abstract

We present the development of a continuous-flow, “dielectrophoretic spectrometer” based on insulative DEP techniques and three-dimensional geometric design. Hot-embossed thermoplastic devices allow for high-throughput analysis and geometric control of electric fields via ridged microstructures patterned in a high width-to-depth aspect ratio (250:1) channel. We manipulate particles with dc-biased, ac electric fields and generate continuous-output streams of particles with a transverse outlet position specified by linear and nonlinear particle mobilities. We show, with simulation and experiment, that characteristic shape factors can be defined that capture the effects of constrictions in channel depth and that modulating the angle of these constrictions changes the resulting local DEP force. Microdevices are fabricated with an insulative constriction in channel depth, whose angle of incidence with the direction of flow varies continuously across the channel width. The resulting electric field gradients enable demonstration of a dielectrophoretic spectrometer that separates particles and controls their transverse channel position.

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