Dielectrophoretic manipulation of macromolecules: The electric field - art. no. 026605

The use of dielectrophoresis is fast becoming a proven technique for manipu lating particles and macromolecules in microfluidic systems. Here an analyt ic solution for the gradient in the electric field strength, del.(E.E), pro duced by a two-dimensional array of parallel electodes is derived using the method of Green's functions. The boundary condition for the potential betw een electrodes is estimated by using a linear approximation. While the, Gre en's function used here is somewhat different from Wang et al., J. Phys. D 29, 1649 (1996), the resulting analytic expression for the potential field is in exact agreement with their result. Selected results for equispaced el ectrodes with equal widths are compared with Wang et al., J. Phys. D 29, 16 49 (1996). The analytic solution is employed to study the effects of electr ode spacing and electrode width on the gradient in electric field intensity Results show that the magnitude in the gradient in the electric field inte nsity exhibited the expected dependence on the applied voltage, however, th e dependence on electrode width was found to be on the order of the electro de width squared. Results to explore the effects of electrode spacing show that as the spacing is reduced below two electrode widths the magnitude of the gradient increases exponentially.