Spatially variant red blood cell crenation in alternating current non-uniform fields

Area of Science:

• Biophysics
• Electrokinetics
• Cell Biology

Background:

• Alternating-current (AC) electrokinetics describes particle and cell behavior influenced by electric fields.
• Dielectrophoretic applications rely on charge interactions between cells and their medium.
• Spatially uniform medium concentrations are typically assumed in theoretical and experimental models.

Purpose of the Study:

• Investigate red blood cell (RBC) crenation in non-uniform AC electric fields.
• Determine the influence of frequency and potential on RBC volume changes.
• Elucidate the physical mechanisms driving RBC crenation under these conditions.

Main Methods:

• RBCs were subjected to AC electric fields with varying frequencies (250 kHz–1 MHz) and potentials (10–17.5 Vpp).
• Experiments utilized perpendicular electrode gaps of 100 μm.
• Control experiments examined factors like AC electroporation, temperature, pH, and fluid flow.

Main Results:

• RBCs exhibited significant crenation (shrinkage) over 10-minute experiments.
• Higher potentials and lower frequencies resulted in greater cell volume loss, up to 20%.
• AC electroporation, temperature changes, pH, electrode reactions, convection, and AC electrothermal flows did not explain the observed crenation.

Conclusions:

• RBC crenation in non-uniform AC electric fields is not caused by electroporation, thermal effects, or fluid flow.
• The observed cell deformation is attributed to medium hypertonicity.
• Ion concentration gradients induced by the non-uniform AC electric fields are the primary cause of hypertonicity and subsequent RBC crenation.