Patent ID: 8492168

Claim:
A method of detecting a target analyte in a sample, the method comprising: (a) executing electrowetting-mediated droplet operations using droplets on a droplet microactuator to effect an immunoassay, wherein the electrowetting-mediated droplet operations are selected to: (i) combine one or more immunoassay reagent droplets comprising an antibody immobilized on one or more magnetically-responsive beads disposed in a droplet with a sample droplet potentially comprising the target analyte to yield a combined droplet, wherein the one or more immunoassay reagent droplets, the sample droplet, and the combined droplet are each: (1) arranged on the droplet microactuator; and (2) subject to the electrowetting-mediated droplet operations; and (ii) effect a droplet-based washing protocol on the droplet microactuator using a droplet comprising the magnetically responsive beads, wherein the washing protocol comprises conducting droplet operations selected to: (1) merge one or more wash buffer droplets with a droplet comprising the magnetically responsive beads; and (2) split the droplet comprising the magnetically responsive beads, while using a magnet to retain the magnetically responsive beads, thereby removing a sub-droplet comprising unbound substances from a sub-droplet comprising the beads; and (b) generating and detecting a signal which corresponds to the presence, absence and/or quantity of the analyte in the sample.