US Patent 7694694 Phase-change valve apparatuses

A valve apparatus includes a substrate, a main flow channel formed in the substrate, a control channel formed in the substrate such that the main flow channel and the control channel meet at a junction, a bi-phase material within the control channel, a heating element adjacent the control channel and the junction, the heating element being controllable to generate sufficient energy to cause the bi-phase material to transition from a solid phase to a liquid phase, and a pumping mechanism for forcing the bi-phase material either into or out of the junction when the bi-phase material is in the liquid phase.