Patent ID: 8613889

Claim:
A method of providing a droplet comprising beads with a reduced concentration of a substance, the method comprising: (a) providing the droplet comprising the beads, the droplet further comprising a starting concentration and starting quantity of the substance and having a starting volume; (b) conducting one or more droplet operations to merge a wash droplet with the droplet provided in step (a) to yield a combined droplet; and (c) conducting one or more droplet operations, white retaining the beads on a first electrode using magnetic or physical means, to divide the combined droplet to yield a set of droplets comprising: (i) a first daughter droplet on the first electrode comprising at least about 99% of the beads and having a decreased concentration of the substance relative to the starting concentration; and (ii) a second daughter droplet on a second electrode; wherein the droplet operations of steps 1(b) and 1(c) are effected on a droplet microactuator and are electrowetting-mediated.