数字微流控芯片半月形驱动电极的设计

Design of crescent driving electrodes for digital electrowetting-on-dielectric devices

为了降低数字微流控芯片的驱动电压,将传统的方形驱动电极结构设计为半月形,并研究了不同参数的半月形驱动电极降低驱动电压的效果。首先,根据介电湿润的基本原理分析了不同驱动电极形状对降低驱动电压的影响。然后,通过流体体积法(VOF)对液滴的运动过程进行建模和数值仿真;根据数值仿真结果对比分析了不同结构参数的半月形驱动电极随驱动时间的运动过程。最后,设计了4种不同结构参数的半月形驱动电极芯片,并对其驱动液滴的效果进行了试验验证。结果表明:研制的4种半月形驱动电极微流控芯片中,电极圆弧直径等于电极长度结构的芯片其驱动电压比其他3种电极结构的芯片的驱动电压至少降低了15.6%,而且可以在16V的驱动电压下使1μL去离子水液滴的运动速度达到1.6cm/s,是设计为半月形驱动电极中的最优设计。实验数据证明了电极圆弧直径等于电极长度的半月形驱动电极结构可有效降低微流控芯片的驱动电压。

To reduce the driving voltage of the digital microfluidic device, the traditional square elec- trode structure was designed to crescent shapes, and the driving effects of crescent shape electrode structures with different parameters were investigated. First, the effect of different electrode shapes on reducing the driving voltage was analyzed based upon the theory of electrowetting-on-dielectric. Then, the moving process was numerically simulated by means of Volume of Fluid （VOF）. Based up- on simulation results, the moving process of the same droplet in different electrode structures was an- alyzed. Finally, four electrodes with different crescent shapes was designed and their driving effects for the same droplet were verified. The experimental results show that the crescent electrode device with the arc diameter equal to the length of the electrode is able to reduce the driving voltage by 15.6% more than those of other three crescent shape electrode devices. Besides, the 1 μL droplet on this electrode structure device can be driven successfully with the velocity of 1.6 cm/s when the driv- ing voltage is just 16 V, accordingly, which shows that this configuration design is the optimal struc- ture among various crescent electrode structures. In conclusion, the obtained experimental results val- idate the feasibility that the crescent electrode with the arc diameter equal to electrode length can re- duce the driving voltage effectively.