A theoretical model based on energy conversation is constructed to characterize the contracting behavior of the nonconductive droplet actuated by the dielectric effect in an immiscible dielectric liquid. To verify the...A theoretical model based on energy conversation is constructed to characterize the contracting behavior of the nonconductive droplet actuated by the dielectric effect in an immiscible dielectric liquid. To verify the theory, COMSOL is employed to simulate the evolution of the droplet based on dielectrowetting, and a measurement platform is established to monitor the change process of the droplet profile. The contact angle and the height of the droplet increase linearly up to 48° and 2.03 mm respectively when U ranges from 55 V to 160 V, while the droplet remained stationary when U < 55 V.The relative experimental results coincide with the prediction of theory and the simulation analysis.展开更多
We report on the dielectrowetting of sessile droplets of two common liquid crystals,4-cyano-4′-pentylbiphenyl(5CB)and 4-cyano-4′-n-octylbiphenyl(8CB),deposited on interdigitated electrodes that were treated to induc...We report on the dielectrowetting of sessile droplets of two common liquid crystals,4-cyano-4′-pentylbiphenyl(5CB)and 4-cyano-4′-n-octylbiphenyl(8CB),deposited on interdigitated electrodes that were treated to induce homeotropic anchoring.We found a pronounced hysteretic response of the contact angle to the applied voltage caused by the pinning and depinning of the droplet contact line.Depinning occurred as the voltage exceeded a threshold value that increased from the nematic to the isotropic phase,whereas the smectic phase showed an intermediate value.Above the threshold,the contact angle decreased linearly and rapidly as a function of the voltage square,as expected from the dielectrowetting equation originally formulated for dielectric and isotropic liquids,with a slope larger in the anisotropic liquid crystal phases than in the isotropic phase.Observation between crossed polarizers showed that the molecular director realigned along the applied field in the anisotropic phase near the surface between the electrodes,thereby increasing the effective dielectric constant and strengthening the dielectrophoretic force compared to the isotropic phase.Director realignment involved the nucleation of topological defects in the nematic phase and was inhibited by large energy barriers in the smectic phase,which weakened the dielectrowetting response.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61775102)the Youth Program of the National Natural Science Foundation of China(Grant No.61905117).
文摘A theoretical model based on energy conversation is constructed to characterize the contracting behavior of the nonconductive droplet actuated by the dielectric effect in an immiscible dielectric liquid. To verify the theory, COMSOL is employed to simulate the evolution of the droplet based on dielectrowetting, and a measurement platform is established to monitor the change process of the droplet profile. The contact angle and the height of the droplet increase linearly up to 48° and 2.03 mm respectively when U ranges from 55 V to 160 V, while the droplet remained stationary when U < 55 V.The relative experimental results coincide with the prediction of theory and the simulation analysis.
文摘We report on the dielectrowetting of sessile droplets of two common liquid crystals,4-cyano-4′-pentylbiphenyl(5CB)and 4-cyano-4′-n-octylbiphenyl(8CB),deposited on interdigitated electrodes that were treated to induce homeotropic anchoring.We found a pronounced hysteretic response of the contact angle to the applied voltage caused by the pinning and depinning of the droplet contact line.Depinning occurred as the voltage exceeded a threshold value that increased from the nematic to the isotropic phase,whereas the smectic phase showed an intermediate value.Above the threshold,the contact angle decreased linearly and rapidly as a function of the voltage square,as expected from the dielectrowetting equation originally formulated for dielectric and isotropic liquids,with a slope larger in the anisotropic liquid crystal phases than in the isotropic phase.Observation between crossed polarizers showed that the molecular director realigned along the applied field in the anisotropic phase near the surface between the electrodes,thereby increasing the effective dielectric constant and strengthening the dielectrophoretic force compared to the isotropic phase.Director realignment involved the nucleation of topological defects in the nematic phase and was inhibited by large energy barriers in the smectic phase,which weakened the dielectrowetting response.
