Abstract: A method of maintaining at least one component in an aqueous microdroplet dispersed in conditioned oil to form an emulsion is provided.

Abstract: A device for dispensing one or more microdroplets is provided. The device comprising a microfluidic chip having an oEWOD structure configured to create an optically-mediated electrowetting (oEWOD) force, the microfluidic chip includes a first region and a second region, wherein said first and second regions are separated by a constriction; wherein the first region is adapted to receive and manipulate one or more microdroplets dispersed in a carrier fluid at first flow rate; and wherein the second region is configured to receive the microdroplet via the constriction from the first region and transfer said microdroplet to an outlet port of the microfluidic chip in a second flow rate; wherein the second region is configured to receive said microdroplet via the constriction from the first region by application of an optically -mediated electrowetting (oEWOD) force; and wherein the second flow rate in the second region is higher than the first flow rate in the first flow region.

Abstract: The present invention provides methods and apparatus for manipulating and interrogating the contents of large numbers of microdroplets in parallel on a surface of a microfluidic chip. According to one aspect of the invention a method is provided for manipulating and inspecting microdroplets on a microfluidic chip by optically- mediated electrowetting (oEWOD), the method comprising forming, using a first optical assembly, a plurality of oEWOD traps on a surface of the chip and forming, using a second optical assembly, a second array of oEWOD traps on the surface of the chip, and making an adjustment to the first optical assembly whilst one or more of the microdroplets are held in place by second array of oEWOD traps. Apparatus comprising a microfluidic chip and first and second optical assemblies is also provided.