US Patent 7328979 System for manipulation of a body of fluid

A system for manipulation of a body of fluid, in particular a fluid droplet comprises several control electrodes to which an adjustable voltage is applied to control displacement of the droplet on the basis of the electrowetting effect. There is a counter electrode having a fixed voltage between the body of fluid and one of the control electrodes. Further, as the counter electrode and the control electrodes are located at the same side of the fluid droplet, the fluid droplet is freely accessible at its side remote from the counter electrode and the control electrodes. Hence, the fluid droplet can be employed as an object carrier and a pay-load can be placed on the droplet from the freely accessible side.