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Spotted: Researchers at the University of Washington have developed a more efficient way to power miniature robots. The researchers use electrohydrodynamic (EHD) thrust, which requires no moving mechanical parts. EHD is similar to ion propulsion used in solar-powered spacecrafts. 

Ion propulsion systems work by bombarding xenon atoms with electrons, which gives them a positive charge (an ion is an atom or molecule with a net electrical charge). The ions are then passed through a negatively-charged grid, which accelerates them and expels them into space, creating thrust. The thrust created is small, but in the vacuum of space it is enough to propel a spacecraft. On Earth, however, a slightly different system is used which takes advantage of the ready supply of air molecules.

The team, led by mechanical engineer Igor Novosselov, directed electricity to flow through a tiny, pointed ‘comb’ made of a conductive metal. Each point of the comb gave off ions, which were accelerated by a carbon fibre “collector” plate underneath. The ions transfer their momentum to neutral air molecules as they hit the collector, creating thrust. 

Although this system is not new and requires a lot of power, it has improved upon previous systems. Earlier thrusters were formed through the expensive and time-consuming ion etching process. Instead, Novosselov’s team developed a fabrication process based on laser micromachining, which takes less than 25 minutes.