Scientists find breakthrough technique to separate two liquids using lasers

Scientists have found a breakthrough technique to separate two liquids from each other using a laser.

The research is something like taking the milk out of your tea after you've made it, say researchers – and just as difficult as that sounds. But scientists say the breakthrough will have far more advanced applications than making sure you get the tea round right.

Eventually the breakthrough could help make a technique used in the production of computers, phones, drugs, paints, light bulbs and solar cells far easier, potentially making them much cheaper.

All of those products rely on producing crystals to use within the technology. But it isn't possible to control that crystallisation process, making for difficult problems for people trying to manufacture them.

But the new approach uses a laser to harness fluctuations in a so-called critical point and to drive the system towards a phase separated state.

Professor Klaas Wynne, who designed and developed the technique, said: "It's a little bit like making a cup of tea, stirring in some milk, and then using a laser to suck the milk out again. It may seem really counterintuitive but it's all within the laws of physics."

Finlay Walton, who carried out the work, said: "These are the first steps towards a full understanding of the role that critical fluctuations play in crystal nucleation. Our aim is to gain full control over nucleation, including the type of crystal that is produced."

The paper, titled Control Over Phase Separation And Nucleation Using A Laser-Tweezing Potential, is published in Nature Chemistry, with the research funded by a grant from the Engineering and Physical Sciences Research Council.

Additional reporting by agencies