The World's Smallest Stirling Engine is a Single Particle, Just Three Micrometers Across | Popular Science | Science News | Scoop.it

At the University of Stuttgart and the nearby Max Planck Institute for Intelligent Systems, researchers are taking the notion of smaller, more compact engines to a micro-machinery extreme. Their new power generator is a single particle--just 3 mircrometers wide--that functions like a Stirling engine to generate actual work.
A Stirling engine essentially works by heating and cooling a fixed volume of gas inside a cylinder, using the expansion and contraction of that gas to push a piston. The 200-year-old design is extremely efficient, though it never caught on quite like the more powerful internal combustion and steam engines did (though Segway inventor and all-around smart guy Dean Kamen is a big fan).