Study of droplets motion on a chip driven by thermal gradient

In this paper a microfluidic device for actuation of liquid droplets on a solid surface was designed, fabricated and tested. The digital microfluidic chip with Ti as micro-heater, Au film as pad, PECVD SiO₂ as dielectric layer on glass substrate, is fabricated by the silicon bulk process. Test results show that deionized (DI) water and silicon oil can be transported on device surface smoothly under voltage of 7V. We have also drawn out that the speed of droplet is a function of applied thermal gradient, droplet size and liquid material parameters. In this study we demonstrate that the thermocapillary actuation droplet can be tunable.