Dielectrophoresis

An induced dipole links the cell’s electrical response to the spatial pattern of the applied field. The nonuniform field creates unequal electrical interactions across the cell, producing a net force rather than merely orienting the cell. Depending on the direction of that force relative to the gradient, cells move toward stronger or weaker regions.

Positive dielectrophoresis directs a polarizable cell toward a stronger portion of the electric field, whereas negative dielectrophoresis directs it toward a weaker portion. This distinction matters because the same general electrical approach can create different spatial outcomes. In a microfluidic device, those opposing responses provide a basis for positioning or separating cells according to their electrical behavior.

Cell size, membrane structure, and electrical conductivity are key properties identified for dielectrophoretic characterization and separation. These features influence how readily a cell becomes polarized and how it interacts with the field gradient. Because biological cells can differ in these properties, the technique can distinguish populations without relying on a net charge or an added label.

Instead of requiring a net charge or an attached marker, the approach uses the cell’s own polarizability and electrical characteristics. That makes movement, trapping, or concentration responsive to intrinsic properties such as membrane structure and conductivity. In biology, this label-free basis is useful when researchers want to examine cells while sorting or characterizing them through their physical electrical behavior.

Within a microfluidic system, cells experience a nonuniform alternating electric field, become polarized, and move according to the resulting dielectrophoretic force. The device can be configured to produce movement toward stronger or weaker field regions, enabling several operations. Depending on the intended outcome, those operations include concentrating cells, trapping them, separating populations, or supporting their analysis.

Researchers may choose this technique when they need label-free control or characterization of biological cells. Its reported uses include cell sorting, concentration, trapping, and analysis, so it can address both cell-handling and characterization tasks. The method is especially relevant to diagnostics, cancer biology, cell therapy, and single-cell studies, where differences among cells are scientifically important.