Microfluidic mixing and reaction systems for high efficiency screening

A microfluidic device comprising:

• a rigid base layer;
• an elastomeric layer on the base layer, wherein the elastomeric layer comprises at least part of:
• (i) a fluid channel for transporting a liquid reagent, and (ii) a vent channel that accepts gas diffusing through the elastomeric-layer from the fluid channel and vents it out of the elastomeric layer;
• a rigid plastic layer on the elastomeric layer;
• a mixing chamber at least partially formed within the elastomeric layer or rigid plastic layer, the mixing chamber being fluidly connected to the fluid channel;
• and
• a control channel overlapping with a deflectable membrane that defines a portion of the fluid channel, wherein the control channel is operable to change a rate at which the liquid reagent flows through the fluid channel;
• wherein the vent channel is separated from the fluid channel by a gas permeable membrane.