Electrohydrodynamic lift-off from the electrode of a colloidal particle suspended in a non-polar fluid

A charge-neutral colloid is electrostatically attracted by a nearby electrode. However, electrohydrodynamic (EHD) flows can induce lift and particle detachment from the electrode. In aqueous electrolyte solutions, an ICEO-type flow due to action of the electric filed (perturbed by the particle) on the charge in the polarization layer near the electrode can cause the colloid lift-off. In this talk, we show that in a non-polar fluid the Onsager effect (field-dependent rate of ion pair dissociation) can give rise to a non-uniform conductivity and a bulk electric charge. The resulting EHD flow scales with the cube of the magnitude of the applied field. Under the assumption of zero Reynolds number, the lift force on the particle is calculated using the Lorentz reciprocal theorem. The results indicate that the lift decays as the inverse square of the distance between the particle and the electrode, much slower than the EHD lift in aqueous solutions.