Study on liquid dielectrophoresis based on double flexibleelectrodes simulating interdigitated pattern electrodes

Dielectrophoresis affects the surface wettability by applying a non-uniform electric field to dipoles insidedielectric liquid, achieving adjustable droplet contact angle and overcoming the saturation limitation of contactangle caused by the electrowettability effect. However, it is difficult to realize useful three-dimensional tunableoptical devices because most of the driving electrodes need to be patterned. In this work, a model of doubleflexible electrodes simulating planar interdigitated pattern electrodes is proposed based on the dielectrophoresis.Double flexible electrodes, which are wrapped with an insulating dielectric layer and are not conductive to eachother are arranged at close intervals and wound along the plane substrate to form a two-dimensional planar linewall. A hydrophobic layer is used to fill the gap and increase the initial contact angle. Ultimately, the "droplet-interdigitated planar line wall" dielectrophoresis driven-droplet model is formed after the dielectric dropletshave been deposited on the line wall surface. Firstly, considering the influence of penetration depth andelectrode gap area, Young's equation is theoretically modified to adapt to this model. Then, the finite elementalgorithm simulation is used to used to comparatively analyze the potential distribution of this model and theplanar interdigitated pattern electrode model. The field strength distributions of the electrodes with differentwire diameters and insulating layer thickness values are analyzed. It can be found that with the increase of thediameter of the electrode wire and the thickness of the insulating layer, the morphology of the model changesfrom the tip electrode into the planar electrode, the surface field strength attenuates exponentially and the peakvalue decreases. This shows that the structure of this electrode in this model is superior to that of the planarelectrode. After that, the contact angle of the model is measured experimentally in a range of 58 degrees 90 degrees under0-250 Vrms voltage, which is in line with the theoretical expectation. At the same time, neither obvious contactangle lag nor saturation is observed in the experiment. Finally, the new electrophoretic driving droplet modelconstructed in this paper transforms the dielectric electrophoretic driving mode from a two-dimensional planarelectrode to a one-dimensional flexible linear electrode. Because of its flexibility and plasticity, it is convenientto form a three-dimensional cavity and can be applied to more complex device structures