Researchers develop new technique that could pave the way for the next generation of optical tweezers

Scientists have developed an innovative new technique that could pave the way for the next generation of optical tweezers.

A team of researchers from the Universities of Glasgow, Bristol and Exeter has created a new method of moving microscopic objects using micro-robotics.

Currently, optical forceps – used to study proteins, biological molecular motors, DNA and internal cell life – use light to keep objects as small as a single nanoparticle in the same place.

They use the unusual optical forces created by tightly focused laser beams to trap and manipulate particles, essentially acting as "microscopic hands" for scientists.

The first optical tweezers were developed in the 1970s by Dr. Arthur Ashkin. Since then, a series of breakthroughs have allowed scientists to manipulate complex objects such as viruses and cells. Dr. Ashkin, now 90, recently received the Nobel Prize in Physics in 2018 for his pioneering work.

However, this existing technique has limitations: the high light intensities required by optical tweezers can damage living biological specimens and also restrict the type of objects that can be held.

The research team has developed a new technique that allows optical trapping without focusing laser light on trapped particles.

To do this, they have developed optically trapped micro rotors, which are placed in the liquid surrounding the particle and used to manipulate its motion with the aid of a fluid flow.

When rotating micro-rotors, they create a wave in the liquid that exerts a force on the particle – in the same way that a jet of water in a jacuzzi can repel anything that floats.

By controlling the directions of each micro-rotor, scientists can move the particle to a specific location or store it at a specific location, which can be used to sort or image high resolution particles.

Crucially, this new technique allows scientists to use the flow to locate one particle at a time without affecting others nearby.

The search is published in the reference journal Nature Communications.

Dr. Phillips, a member of the Department of Physics at Exeter University, and lead author of the study, said, "This research expands the applications of optical tweezers to trap particles of any material in a liquid environment, without risk of photo-damage, and adds to the panoply of techniques that allow us to develop new nanotechnologies ".