Micro-pump with no moving parts

A pump can propel liquids along millimetre-sized channels at high speeds with no mechanical parts.

The pump, designed by Khashayar Khoshmanesh at the Royal Melbourne Institute of Technology University in Australia and his colleagues, is a droplet of metal — an alloy of gallium, indium and tin — that is held loosely in a spherical chamber in the middle of a Plexiglas channel. A slow chemical reaction in the metal droplet results in gallate anions diffusing to the droplet's surface. When a low-power electric field is applied, the rearrangement of charges at the droplet's surface causes it to shift in its constrained space in such a way that the surrounding solution flows past it (pictured).

Credit: Phred Petersen/Shiyang Tang/RMIT

The pump might be useful in microscopic machines, the researchers say.

Proc. Natl Acad. Sci. USA 111, 3304–3309 (2014)