Transport mechanism by which droplets on electrowetting-on-dielectric devices

Digital microfluidics technology based on the electrowetting-on-dielectric (EWOD) effect is a popular emerging technology whose objects of manipulation are individual droplets on the micro-liter or even nano-liter scales. It has the unique advantages such as rapid reaction, low reagent consumption, and high integration, which have drawn extensive attention and application in the fields of biology, medicine, and chemistry. However, there has been no a complete mechanism by which the droplets transition from stillness to motion in EWOD chip, leaving the proper mechanism for droplet movement uncertain. At this point in time, we studied the EWOD theory and polarization mechanism underlying solid-liquid interface, thus building upon previous research. The theoretical derivation and numerical analyses of EWOD driving force were presented. Then, the process and mechanism of droplet movement from stillness to motion was comprehensively analyzed, the results obtained from the simulation and discussion were in agreement with experimental results. It is our hope that this work will inspire new research into less understood EWOD regimes and help design useful EWOD devices.