Micro-droplet driven digital mirofluidic device with crescent electrode

According to the high driving potential of existing digital microfluidic devices, a novel crescent electrode was designed to reduce the driving potential based on traditional electrode structure. First, based upon the theory of electrowetting-on-dielectric (EWOD), the relation between the driving force exerted on a micro-droplet and the chord length of an effective Triple Contact Line (TCL)of the contact circle of the micro-droplet was analyzed. Then, the chord lengths of the effective TCLs from a square electrode, a jagged electrode and the crescent electrode were analyzed. It shows that the chord length of TCL from the crescent electrode is the maximal, so the driving force exerted on the droplet in the digital microfluicic device with the crescent electrode was the maximal. Finally, the droplet driving effect was tested via three kinds of electrode devices. The experimental results show that the minimum driving potential on the device with the crescent electrode can reduce approximately 37% and 67% as compared with those of the square and jagged electrode devices. Furthermore, when the driving potential is 60 V_RMS, a 2 μL droplet can be driven at a velocity of 10 cm/s, which is triple and double the velocity of the same droplet on the square and jagged electrode devices. The obtained experimental results validate the feasibility of reducing the driving potential of digital microfluidic device with the crescent electrode.