New twist on a fibre-optic spanner

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Researchers have created what they are calling the fibre-optic equivalent of the world's smallest spanner, harnessing laser light's ability to gently push and pull microscopic particles.

This virtual tool can precisely twist and turn tiny particles, from living cells and DNA to microscopic motors and dynamos used in biological and physical research.

This development by physicists at The University of Texas at Arlington will give scientists the ability to manipulate single cells for cancer research, twist and untwist individual strands of DNA, and perform other functions where microscopic precision is essential.

The authors describe their new technique, which they dub a fibre-optic spanner, in a paper published in the Optical Society's (OSA) journal Optics Letters.

The innovation that distinguishes this technique from other optical tools is that it can spin or twist microscale objects in any direction and along any axis without moving any optical component.

It’s able to do this because it uses flexible optical fibres, rather than stationary lasers, to do the work. This has the added benefit that the optical fibres can be positioned inside the human body, where they can manipulate and help study specific cells or potentially guide neurons in the spinal cord.

The fibre-optic spanner is created when two beams of laser light – emitted by a pair of optical fibres – strike opposite sides of the microscopic object. Individual photons impart a virtually imperceptible bit of force when they strike an object, but an intense beam of laser light can create just enough power to gently rotate microscopic particles.