DC Dielectrophoresis in Lab-on-a-Chip Devices

Abstract

Definition Direct current (DC) dielectrophoresis (DEP) is an efficient means to move and thus separate particles or cells with the force of a stationary electric field. This is accomplished with a spatially nonuniform electric field shaped around insulative objects as obstacles in the path of the DC field. DC-DEP is then the induced motion of polarizable, dielectric objects of micron and smaller size, in a DC electric field that is modified by lab-on-a-chip geometry (or other means) to be spatially nonuniform. Overview Dielectrophoresis (DEP) is the motion observed of a dielectric particle polarized in a nonuniform electric field [1]. The dielectrophoretic phenomenon has a number of advantages over linear electrophoresis, which can only discern particles with a narrow range of properties (significant surface charge, electrically conductive, measurably dense, or with discernable radius). However, nonlinear DEP enables precise manipulation of particles with widely varying electrical properties (particle need only be polarizable) and morphologies while still interfacing with electronically controllable, microfluidics-based platforms. Dielectrophoresis can also directly manipulate native, unmodified cells, thus eliminating the expense, labor, and time of labeling and tagging, as well as the development and validation of such labels and tags. The same basic DEP method has the capability of separating, concentrating, and analyzing a wide range of particle types (polymer microparticles, metallic particles, cells, bacteria, viruses, DNA, and proteins) using one basic procedure. The field of dielectrophoresis is relatively recent. Herbert Pohl did dielectrophoretic research in the 1950s although this area did not gain wide visibility until his groundbreaking book Dielectrophoresis: The behavior of neutral matter in nonuniform electric fields was published in 1978 [1]. In this book, the two main components of the electric field in alternating current (AC) dielectrophoresis were extensively discussed, namely, (i) a spatially nonuniform electric field and (ii) an alternating current electric field, both of which contribute to the nonlinear DEP force. Within the last 10 years,