介质上电润湿液滴输运、合并及振荡实验研究

利用MEMS技术制作了平板电润湿芯片,建立了可视化实验研究平台,运用高速CCD对分裂式电极施加交流电压后的液滴传输和合并过程以及相邻电极接地式芯片上液滴的交流振荡过程进行了可视化实验研究。除了对液滴形状的观测外,还重点关注了接触线的运动规律。研究发现,接触角滞后现象将导致接触线在液滴输运、合并以及振荡过程中出现停顿现象,在液滴振荡过程中,只有施加电压足够大时,才能克服这种迟滞现象。当液滴初始位置偏离电极对中心时,在一定条件下交流电作用将造成液滴形态左右摇摆、接触线非对称运动的非对称振荡现象。

Experimental Research on the Transporting,Merging and Oscillation for Electrowetting Droplets on the Dielectric

Electrowetting on dielectric(EWOD) chips with coplanar-electrodes were fabricated using MEMS techniques,and the visualization experimental setup was established to study the droplet transport and droplet merging on the divided electrodes and the droplet oscillation on the adjacent electrodes under the actuation of the AC voltage by the split electrode using a high speed CCD camera.Besides the change of the droplet shape,the focus was also put on the dynamic characteristics of the contact line.It is found that the contact angle hysteresis will lead to the contact line sticking during the transport,merging and oscillation process of the droplet.Only if the voltage is high enough,the contact line sticking in the droplet oscillation can be overcome.When the original droplet position is deviated from the centre of two adjacent electrodes,under certain conditions,an asymmetric droplet oscillation characterized by the periodical leftwards and rightwards waggling of the droplet and the asymmetric movement of the contact line could be triggered.