Frequency-controlled dielectrophoresis-driven wetting of nematic liquid crystals

We show that surface-localized dielectrophoresis-driven wetting of anisotropic nematic liquid crystal sessile droplets obeys the same relationship, cos [ θ ( V o ) ] = cos [ θ Y ] − β V o 2 , which has previously been found for isotropic liquid droplets, even though the nematic liquid crystal phase possesses a uniaxial dielectric permittivity tensor. We also demonstrate that the dielectrowetting coefficient β , which determines the magnitude of the reduction in the contact angle, from θ Y to θ V o , through the action of a potential difference V o , can be controlled by the frequency of the applied voltage between interdigitated electrodes beneath a droplet of highly dispersive nematic liquid crystal. Our Q-tensor modelling of the electric field-induced 2-dimensional n -director distortions within a nematic droplet elucidates how this linear relationship holds for voltages when θ V o − θ Y exceeds 3°–4°.