Patent ID: 8304253

Claim:
A method for extracting a droplet from fluid within a microfluidic column or channel, comprising the steps of: (a) providing a microfluidic device comprising: (i) a substrate comprising a channel comprising a liquid column and bounded by: (1) channel walls; or (2) surface property differences that constrain and direct the liquid column; (ii) an extraction point in the channel comprising an extraction opening and a refill opening opposite the extraction opening; and (iii) electrowetting electrodes on the substrate arranged for extracting a droplet from the liquid column at the extraction point; (b) separating particles or solute molecules of the liquid column into bands or zones; and (c) extracting, by use of the electrowetting electrodes, a first droplet comprising a band or zone of particles or solute molecules from the liquid column via the extraction opening while supplying a refill droplet into the liquid column via the refill opening.