Design and fabrication of MEMS-based micropropulsion devices at JPL

The development and fabrication of microfabricated propulsion components at the Jet Propulsion Laboratory (JPL) is reviewed. These include a vaporizing liquid micro-thruster (VLM), which vaporizes propellant to produce thrust. Thrust performances of 32 μN for an input power of 0.8 W were measured. Miniature solenoid and latch valves are being developed by Moog, Inc. in collaboration with JPL. Although metal-based, these valves employ batch fabrication approaches in their design. A valve prototype 1 cm³ in size and weighing 7 gram was recently manufactured by Moog. This valve has a power requirement (holding power) of 0.7 W, a 5-V operating voltage, and response times of 1.5 ms (open) and 0.5 ms (close). In a lifetest at Moog this valve reached 1,000,000 cycles. A piezoelectrically actuated microvalve is being developed at JPL. The device is still in early development, however, initial testing showed leak rates as low as 0.001 sccm N₂ at pressures between 10-100 psig. A micro-isolation valve being developed at JPL is aimed at isolating propulsion systems prior to their use. This one-time opening valve can be actuated with 0.01 J within 0.1 ms. This valve, fabricated entirely from silicon and Pyrex, reaches burst pressures as high as 3,000 psia.