By Mark Prigg
Tiny machines that could do everything from carry drugs through the body to keep our clothes clean have been a staple of science fiction for decades.
However, researchers have now made a major breakthrough in mass producing them - by creating tiny 3D structures that 'bloom' like a flower, bending themselves into shape.
Researchers say the technique could now be used to mass produce tiny self-assembling nanomachines.
'The fabrication of many objects, machines, and devices around us rely on the controlled deformation of metals by industrial processes such as bending, shearing, and stamping,' the researchers from Aalto University in Finland and the University of Washington in the US wrote.
'Is this technology transferrable to nanoscale? Can we build similarly complex devices and machines with very small dimensions?'
By combining etching and nanolithography they have managed to create complex three-dimensional structures at nanoscale that can 'fold' - after being inspired by a dandelion.
In nature, similar geometrical effects take place in self-organization directly observable to the human eye,' the team wrote.
'When dandelion flowers bloom, one may try cutting the flower stem into small strips; put them in water, and the strips will fold with observable width-dependent curvatures due to differences in the water absorption between the inside and outside parts of the stem.
'Our idea was to find a way to adapt these natural processes to nanofabrication.
'This led us to an incidental finding that a focused ion beam can locally induce bending with nanoscale resolution.
The team also noticed that thin metals were curling up, which made them think that a manufacturing technique could be developed.
'We were puzzled by the strong-width-dependent curvatures in the metallic strips. Usually initially-strained bilayer metals do not curl up this way,' said Khattiya Chalapat from Aalto University.
The technology has various applications in the fabrication of nanoscale devices, the team says.
The structures are surprisingly resilient: the team found them to be quite sturdy and robust under a variety of adverse conditions, such as electrostatic discharge and heating.
'As for applications, we have demonstrated so far that these structures can capture and retain particles with dimensions of the order of a micrometer.
'However, we believe that we are just scratching the tip of the iceberg: a comprehensive theory of ion-assisted self-assembly processes is yet to be reached, they said.
The research has been recently published in the Early View edition of Advanced Materials.