The Maximum Electrowetting Force on Droplets

The maximum force that electrowetting can generate on a droplet depends on the complex interaction between electric fields and surface energies of liquid and solid. To understand what limits this force we developed a new setup that directly measures the horizontal droplet force, contact angles and shape while minimally interfering with the droplet.For the first time we measured electrowetting force for voltages beyond 150 V and up to 2 kV, near the breakdown limit of our dielectric. We found that the force saturation observed at 150 V exists up to 2 kV. By using a high surface tension liquid (mercury), we measured the highest reported EWOD force by a factor of 2.