Biological Dielectrophoresis

Dielectrophoretic studies of the activation of human T lymphocytes using a newly developed cell profiling system

“…As shown in Fig. 2, particular attention was given to computing the DEP crossover frequency (DEP fxo ), corresponding to where each cell exhibited a transition between negative and positive DEP [4,5,7]. …”

“…Dielectrophoresis (DEP) is a noninvasive method for determining the electrical properties of cell populations, down to the single cell level. DEP is the motion of particles caused by dielectric polarization effects in applied electric field gradients [4,5]. This effect can be quantified either in terms of the electromagnetic momentum balance via the Maxwell stress tensor [6], or in terms of the magnitude and distribution of the charges induced on and within the particle by the applied field [7,8].…”

Nonlinear electrokinetics and “superfast” electrophoresis

“…Integrating (14) with the no-slip and far-field boundary conditions and realizing from the matching conditions (9) and (10) that φ(y → ∞) = (∂ φ/∂y)(y → ∞) = 0, we obtain the desired form For a surface with a large electric field E s imposed by the surface charges, the Debye layer is at equilibrium and the potential drop across the Debye layer φ(0) in (15) is independent of position and the outer potential Φ 0 (see Fig. 1).…”

“…The dielectrophoretic velocity is proportional to the divergence of the square of the electric field intensity and is hence clearly nonlinear. The charging by the external field in dielectrophoresis are often modeled as a resistor and capacitor in parallel [9] and is sometimes known as the MaxwellWagner effect. However, detailed analysis of the actual double layer charging in dielectrophoresis is still lacking.…”

“…At sufficiently high frequencies, AC currents do not penetrate biological cells and electrontransfer or dissolution electrode reactions that produce undesirable bubbles/contaminants are also absent. One can hence profitably employ high-field AC electrokinetics in microfluidic devices more than DC electrokinetics [8][9][10].…”