Smallest steam engine

A team of physicists and engineers under the leadership of Jeff Sniegowski at Sandia National Laboratories in Albuquerque, New Mexico, USA, invented a microscopic steam engine with a rectangular piston 6 microns wide (roughly a tenth of the width of a human hair, or the diameter of a human red blood cell) by 2 microns high in 1993. Perched on a silicon wafer, it was made in much the same way as a computer chip. Despite the engine's tiny size, its makers believe is powerful enough to do useful work in all manner of microtools and might be particularly suitable in liquid ambient such as tweezers and scalpels used in eye or brain surgery. The minute piston of the engine is encased in a silicon sleeve and is pushed outward by steam, created when electrical current is applied to a tiny water droplet. Because the engine is manufactured in the same way as high-density computer microchips but is a much simpler design, it can potentially be manufactured in high volumes at very low cost.