Steam powered Artificial Arm

Just read an interesting story about a new artificial arm that is being developed for the military and DARPA. It will lift and grip 30 lbs. or more and is powered by steam. The scientist who has invented it says "The amount of water involved is about the same as a person would normally sweat from their arm in a warm day," and the vapor is disposed of "in as natural a fashion as possible: by venting it through a porous cover, where it evaporates like natural perspiration". Here is the link to the article from the Register.