Latching Miniature Valve

A tightly-sealing, non-corrosive miniature valve that can be baked and requires power only during on/off switching has many applications, especially in the semiconductor manufacturing industry.A tight seal (10e-10 SCCM) requires a large force. Ability to tolerate bake-out, corrosion resistance, and cleanliness (freedom from organic and hydrocarbon contaminants) limits suitable materials to stainless steel and similar metals.Large force, small volume, and light weight actuation are feasible using electrically-powered shape-memory alloy (SMA) devices. Incorporating a latching mechanism, so that power is required only during on/off switching, compensates for the large power requirement of SMA actuators.The proposed valve consists of a welded extensible tube containing a poppet and matching orifice. When closed, the poppet and orifice are pressed together by a bistable spring. The bistable spring latch mechanism is moved from closed to open position by a shape-memory actuator that elongates the extensible tube. A second SMA actuator reverses the latch from the open to the closed position. In Phase I, an all-metal poppet/orifice combination will be developed to give low leak rates, forceful SMA actuators will be designed and built, a suitable latching device will be designed, and proof-of-concept latching valves will be fabricated.