A pair of tweezers has been created which are so small they can grab, hold and move a single molecule in any direction.

As more developments and discoveries are being made on the nano scale it will be important to have better tools to work in the space of a few micrometres, and the ‘plasmonic nanotweezers’ are the latest utility in the nanoengineer’s miniscule toolbox.

Researchers have demonstrated for the first time the ability to use near-field optical tweezers to trap a nano size object and manipulate it in 3 dimensions.

The work was undertaken in collaboration between teams from he Institute of Photonic Sciences (ICFO) in Spain and Australian authorities from the ARC Centre for Engineered Quantum Systems at Macquarie University.

The tweezers have been designed to help move individual objects wherever they need to be but importantly exert almost no actual force on the object they are moving, as it is pinned down by a beam of light.

The device is made from an optical fibre coated in metal with a bowtie-shaped gold-plated aperture at its tip. It suspends an object in the centre of the aperture by focussing an intense amount of light at one point, not dissimilar to the tractor beams of science fiction folklore.

Similar optical tweezers have been able to grip and manipulate certain nano scale substances of some time, but the newly developed device makes them look crude by comparison.

Where previous versions used light focused though a lens directly onto the object being moved, the latest design traps objects in a plasmonic field.

By basing new nanotweezers on plasmonics, they have become capable of trapping nano scale objects such as proteins or nanoparticles without overheating and damaging the specimen.

A few years ago, ICFO researchers demonstrated that, by focusing light on a very small gold nano-structure lying on a glass surface which acts as a nano-lens, one can trap a specimen at the vicinity of the metal where the light is concentrated. Now researchers have taken this a crucial step further by implementing the concept of plasmonic nano-tweezers at the extremity of a mobile optical fibre, nano-engineered with a bowtie-like gold aperture.

Using this approach, they have demonstrated trapping and 3D displacement of specimens as small as a few tens of nanometers using an extremely small, non-invasive laser intensity.

The potential of this new technique is difficult to overstate. Because it can both trap and monitor the trapped specimen through the optical fibre, researchers can perform the manipulation of nano-objects in a simple and manageable way outside of the physics research lab.

The tool has plenty of possible uses, and could prompt avenues for research which have previous been impossible. Nanotweezers could assist the field of medicine as a tool to further understand the biological mechanisms behind the development of diseases. Similarly, it holds promise in the nanotech world for assembling future miniature devices.

More information is available in the complete report, now published in Nature Nanotechnology.