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254 MEMS and Microstructures in Aerospace Applications

FIGURE 11.16 VLM thruster (T-shape). (Source: NASA.)

contain thin-film deposited gold heaters, spaced apart by a third spacer-chip. The
chips are joined via a gold thermal compression bond, using a gold layer deposited
in the same fabrication step as the heaters. Several chips were tested recently at JPL
on a microthrust stand and yielded a thrust of 32 mN for a power level of 0.8 W,
corresponding to a thrust-to-power ratio of 40 mN/W.
As indicated earlier valve fabrication is challenging. A new valve had to be
developed to prevent leakage. The so-called microisolation valve (MIV) consists of
two chips, one made from silicon and the other from Pyrex, anodically bonded
together. The silicon chip features the flow channel, which can be blocked by a

FIGURE 11.17 Triple chip assembly. (Source: NASA.)

© 2006 by Taylor & Francis Group, LLC