Spiral swimmers

Harvard researchers have created a new type of microscopic swimmer: a magnetised spiral that corkscrews through liquids.

Though other researchers have created similar devices in the past, Peer Fischer, a junior fellow at the Rowland Institute at Harvard, said the new nano-robot is the only swimmer that can be precisely controlled in solution.

At just two microns long and 200 to 300 nanometres wide, the corkscrew swimmer is about the size of a bacterial cell.

Fischer and Rowland Institute postdoctoral research associate Ambarish Ghosh were able to control the tiny device well enough to push a five micron bead - which had a volume more than 1,000 times that of the swimmer - and were also able to control two of the swimmers at the same time.

Fischer said the strength of his and Ghosh’s work is not just the swimmer’s performance but also its manufacturing method, which allows many swimmers to be created simultaneously.