Resealable, ultra-low leak micro valve using liquid surface tension sealing for vacuum applications

The design, fabrication, and successful demonstration of a micro valve that uses the surface tension of molten solder to make a reversible, ultra low-leak seal are presented. The valve comprises two parts: a silicon chip with a solder-ringed flow orifice and integrated heater, and a piezoelectric translational actuator with a solder-ringed sealing plate. When the valve is open, the solder rings are separated and flow can pass through the orifice. To close the valve, the actuator brings the solder rings into contact while the heater melts the solder and seals the plate over the orifice. The closing and opening of the valve under electrical actuation are successfully demonstrated; the measured open-state flow rate (∼530 sccm) greatly exceeds the measured closed-state leak rate of 1.7×10
⁻⁴
sccm. The closed valve's leakage is similar to the 1.5×10
⁻⁴
sccm leakage for a plate with no orifice; the difference is within the range of experimental uncertainty, consistent with a leak-free seal.