Combined detection of AC‐electrokinetic effects: Experiments with three‐axial chicken red blood cells

Abstract

Dielectrophoresis (DEP), electrorotation (ROT), and electro-orientation were used for the dielectric spectroscopy of nucleated three-axial chicken red blood cells (CRBCs). Because the different AC-electrokinetic effects are not mutually independent, their DEP and ROT spectra were combined in ranges separated by the reorientation of the CRBCs in the inhomogeneous linear DEP and circular ROT fields. This behavior can be qualitatively described by a single-shell ellipsoidal model. Whereas in linear fields, the maximum of the Clausius-Mossotti factor along the three axes determines the orientated axis, in circular fields, the minimum of the factor determines the axis perpendicularly orientated to the field plane. Quantitatively, it has not been possible to find a consistent parameter set for fitting the DEP and ROT spectra, as well as the reorientation frequencies. Our ellipsoidal CRBC standard model had semiaxes of a = 7.7 μm, b = 4.0 μm, and c = 1.85 μm, a relative permittivity of 35 to 45 and conductivity of 0.36 to 0.04 S/m for the cytoplasm, combined with a specific capacitance of 10 to 14 mF/m and a conductivity of 3500 S/m for the cell membrane. The fits in different external conductivity ranges between external conductivities of 0.015 and 1.0 S/m were improved when the membrane capacitance was changed between 4 to 25 mF/m depending on the method used. A similar transition was reflected in the effective properties of a three-shell spherical model containing an internal membranous sphere with the geometry of the CRBC nucleus. Our findings suggest that the simultaneous interpretation of various AC-electrokinetic spectra is a step toward the dielectric fingerprinting of biological cells.

Dielectrophoresis from the System’s Point of View: A Tale of Inhomogeneous Object Polarization, Mirror Charges, High Repelling and Snap-to-Surface Forces and Complex Trajectories Featuring Bifurcation Points and Watersheds

“…However, there are at least two arguments against this assumption. First, in 3D, the 2D-pointed electrode corresponds to a 1 m vertical blade, and second, a voxel ratio of electrode to object of 1:39 ( Figure 1 ) is similar to the size ratio of 110 nm-thick glass-chip electrodes and 4 µm cells [ 32 ].…”

Dielectrophoresis: From Molecular to Micrometer-Scale Analytes

“…Very recently, Frusawa et al 171 reported frequency-modulated wave DEP for pDEPand nDEP-based manipulation of RBCs and vesicles in the range near the crossover frequencies. Gimsa et al 172 used single-shell ellipsoidal and triple-shell spherical theoretical models for studying the DEP, electro-rotation, and electroorientation characteristics of chicken RBCs. The authors concluded that the single-shell ellipsoidal model qualitatively reflects the experimentally observed electrokinetic properties of chicken RBCs.…”

Biofluid pumping and mixing by an AC electrothermal micropump embedded with a spiral microelectrode pair in a cylindrical microchannel

“…and Gimsa et al. . The interaction of nonuniform electric field by the smeared spatial charges can drive an effective medium flow, and the induced ACET pumping force depends on the temperature and field gradients, as well as on the frequency of AC electric field.…”

“…Generally, the ACEO effect diminishes at the high‐conductivity medium ( ) and high‐frequency AC signal ( kHz) . The main reasons are that the electric double layer can be neglected because of the capacitive bridging at high frequency , and the thickness of double layer decreases as the concentration of ions increases in the fluid , making ACEO ineffective with high conductivity. The pumping capacity of a spiral ACET micropump can be evaluated by the average value of the horizontal fluidic velocity component u at the periodic outlet cross‐section, written as .…”