Micromachined electrowetting microfluidic valve

A microfluidic valve comprising:

• a microfluidic channel comprising an interior surface;
• two or more hydrophobic patches disposed along the microfluidic channel;
• a first conductive region underlying the patches with the patches between the first conductive region and the channel interior;
• and,
• a second conductive region disposed along the microfluidic channel at positions between the two or more hydrophobic patches;
• wherein an aqueous fluid in the channel will not flow past the hydrophobic patches in the presence of a first voltage potential between the first and second conductive regions, and wherein the fluid will flow past the hydrophobic patches in the presence of a second voltage potential between the first and second conductive regions, which second voltage potential is greater than the first voltage potential.

A method of controlling a flow of a fluid in a channel, which method comprises:

• providing a channel comprising an internal surface and a hydrophobic patch disposed upon the surface;
• providing a first electrically conductive region exposed on the internal surface of the channel;
• flowing a fluid from the first electrically conductive region along the channel toward the hydrophobic patch;
• electrolytically generating a bubble in the channel by applying a first voltage to the first electrically conductive region,
• whereby the bubble is forced by the fluid flow onto the hydrophobic patch forming an interface with adequate surface tension to stop the fluid flow;
• and providing a second electrically conducting region adjacent to the hydrophobic patch with the patch between the conducting region and the channel interior;
• and, applying a second voltage to the second electrically conducting region;
• wherein said application of the second voltage produces an electric field that reduces a contact angle of the fluid at the hydrophobic patch bubble, thus reducing resistance to the flow and allowing the fluid to flow over the hydrophobic patch.