- The device measures only a few micrometres
- It's based on the classical heat engine, developed in 1824
- The scientists are working to refine their creation
Two German scientists from the University of Stuttgart have developed the world's smallest steam engine, a creation they say could spark more micromechanical machines in the coming years.
Their development is based on the description of classical heat engines by French physicist Sadi Carnot in 1824.
"Instead of pistons that were common at that time, we use laser beams," one of the scientists, Clemens Bechinger, said Tuesday.
The result: Bechinger needs a microscope to take a look at his experiment, since it is only several micrometres large. A micrometre is one-millionth of a meter.
Even though it's tiny, his invention is of scientific relevance, Bechinger said.
"For the first time, we have build a steam engine out of laser beams that is as effective as classical ones," he explained.
According to Bechinger, the conversion of heat into mechanical work is essential for almost every industrial process.
He and his colleague Valentin Blickle have been working on the device for one year. On December 11, their results were published by "Nature Physics," a monthly magazine that features scientific developments.
Their version of a steam engine is hugely simplified -- but its basic functions remain intact.
Reducing the intensity of the laser beams also compresses the gas particles -- comparable to putting pressure on a device. Increasing its intensity decreases the pressure.
"If we change the temperature in the right rhythm, we operate like a large steam engine," Bechinger said.
"Our experiments offer a rare insight into the conversion of thermal to mechanical energy on a microscopic level, and pave the way for the design of future micromechanical machines."
But according to the two other scientists, the device is unstable.
"And we are lacking a device to make the produced energy usable," Bechinger said. He and his colleague are now trying to enhance its effectiveness.
"Unfortunately this steam engine is not going to solve the world's energy problems," he said.