US Patent 7373819 - MEMS humidity sensor

http://www.freepatentsonline.com/7373819.html

For proper operation of fuel cells the humidity should be monitored to determine the rate of supplying feed gases. This patent from Honeywell teaches a MEMS based humidity monitor which may allow for miniaturization of fuel cell technology. Claim 1 reads:

1. A humidity sensing apparatus, comprising:

a substrate; and

a MEMS structure supported by said substrate, wherein said MEMS structure comprises a humidity-sensitive material in association with a mechanical movable member such that when said humidity-sensitive material changes with humidity, said MEMS structure moves said mechanical movable member, thereby providing an indication of humidity based on a stress within said MEMS structure.