Patent ID: 8877512

Claim:
A method of forming a bubble in a droplet actuator, the method comprising: (a) providing a droplet actuator comprising: (i) one or more substrates configured to form a droplet operations gap, the one or more substrates comprising electrodes arranged for conducting droplet operations in the droplet operations gap; and (ii) a physical or chemical feature provided at a predetermined locus within or exposed to the droplet operations gap and configured to retain a bubble in position within the droplet operations gap; and (b) dispensing an oil filler fluid, which fluid is sufficiently immiscible with a droplet phase to render the droplet phase subject to electrode-mediated droplet operations, into the droplet operations gap at a rate and volume sufficient to fill the fluid reservoir and to form a gaseous bubble at the physical or chemical feature, wherein the gaseous bubble is at least partially surrounded by the oil filler fluid.