Patent ID: 8591830

Claim:
A droplet actuator comprising: (a) a base substrate comprising electrodes configured for conducting droplet transport operations on a droplet operations surface thereof and a top substrate arranged parallel to the droplet operations surface to form a droplet operations gap, wherein the droplet operations gap comprises an oil filler fluid; (b) a funnel-shaped reservoir in the top substrate comprising a narrow opening situated in proximity to the base substrate the reservoir comprising a liquid sample comprising beads; (c) a magnetic field source situated sufficiently near the funnel-shaped reservoir to attract magnetic beads from the funnel-shaped reservoir onto the droplet operations surface; wherein the base substrate and the funnel-shaped reservoir are arranged such that a portion of the sample comprising the beads loaded in the funnel is in contact with the droplet operations surface, and wherein the portion of the sample in contact with the droplet operations surface comprises a substantial amount of the beads.