Effects of Electrode Switching Sequence on EWOD Droplet Manipulation: A Simulation Study

Electrowetting-on-dielectric (EWOD) is a new method for handling droplets on the microfluidic chips. By applying electrical potential, the interfacial energy of liquid-solid interface changes, results altering of droplet contact lines. To increase the flow rate of such a digital microfluidic system one way is to raise the droplet velocity. One important factor for enhancing droplet velocity in EWOD systems is the proper switching the electrodes or “switching sequence”. To examine the effect of switching in EWOD, the EDEW 1.0 simulation tool is used in this paper. By simulating the motion of a 1μL water droplet in a 1D electrode array, the resultant surface energy curves during the motion of droplet in different electrode switching sequences are obtained. The results show proper electrode switching has a remarkable effect on increasing of droplet velocity. To enhance the droplet velocity, the electrode, which is placed next to the droplet at forward direction, should be powered after droplet passed over it. In addition, it would be more efficient to first turn on the next electrode, and then turn off the previous one.