Researchers build world's smallest steam engine that could

Wanna create your very own microscopic steam engine? Just take a colloid particle, put it in water, and add a laser. That's a CliffsNotes version of what a group of German researchers recently did to create the world's smallest steam engine. To pull it off, engineers from the University of Stuttgart and Max Planck Institute for Intelligent Systems tweaked the traditional approach introduced by Robert Stirling nearly 200 years ago. In Stirling's model, gas within a cylindrical tube is alternately heated and cooled, allowing it to expand and push an attached piston. Professor Clemens Bechinger and his team, however, decided to downsize this system by replacing the piston with a laser beam, and the cylinder's working gas with a single colloid bead that floats in water and measures just three thousandths of a millimeter in size. The laser's optical field limits the bead's range of motion, which can be easily observed with a microscope, since the plastic particle is about 10,000 times larger than an atom. Because the beam varies in intensity, it effectively acts upon the particle in the same way that heat compresses and expands gas molecules in Stirling's model. The bead, in turn, does work on the optical field, with its effects balanced by an outside heat source. The system's architects admit that their engine tends to "sputter" at times, but insist that its mere development shows that "there are no thermodynamic obstacles" to production. Read more about the invention and its potential implications in the full press release, after the break.