Vaporizing liquid microthruster

MEMS technology is expanding into increasingly diverse applications. As part of a micropropulsion system, microthruster attitude controls have been micromachined in silicon. This paper presents the microthruster design, fabrication, and test results. Fluid injected into a microchamber is vaporized by resistive silicon heaters. The exiting vapor generates the thruster force as it exits a silicon micro-nozzle. The vaporization chamber, inlet and exit nozzles were fabricated using anisotropic wet etching of silicon. With a 5 W heater input, injected water could be vaporized for input flow rates up to a maximum of 0.09 cc/s. Experimental testing produced thruster force magnitudes ranging from 0.15 mN to a maximum force output of 0.46 mN depending on fabrication parameters: chamber length, nozzle geometries, heater power, and liquid flow rates.

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