New research could help control liquids at micro and nano scales

The project, using super-sized atoms to reveal the behaviour of liquids in microscopic channels, could mean more targeted drug delivery

The study, being led by Dr Rodrigo Ledesma-Aguilar, a senior lecturer in the Department of Physics and Electrical Engineering in Northumbria University, is a collaborative effort between Oxford University, the University of Barcelona and UT Malaysia.

The study revolves around the established lab-on-a-chip concept, in which complex laboratory functions are performed in a minute space. By getting micron-sized particles known as colloids to act as over-sized atoms, the team has been able to show how fluids behave under extreme confinement.

Atoms are tiny and cannot be seen under a microscope. This is not the same for colloidal particles, however, which makes it possible for scientists to understand the behaviour of fluids — such as water — at extremely small scales.

The team used a colloidal mix to figure out how fluids behave in micron-sized channels. Using a technique called ‘confocal microscopy,’ they managed to observe in detail, for the first time, the flow of a two-phase mixture (very similar to separating oil from water).

The new research shows how simple changes in the channel size can be used to create very small structures, including droplets and jets. This ability to control fluid structures at such small scales can potentially be used to devise new ways that improve the delivery and the effectiveness of drugs, and to assist the assembly of more complex structures such as micro-robots that can travel, for example, around the bloodstream to deliver lifesaving drugs.

Dr Ledesma-Aguilar said: ‘We have revealed the next piece of a puzzle that, with time, could lead to the controlled tailoring of liquids at extremely small scales. This knowledge opens the door to developing new devices that target other liquids, such as water-based solutions, to tailor the formation of drops, jets and streams measuring just a few nanometres.’

Prof. Ignacio Pagonabarraga from the University of Barcelona said: ‘The ability to control drops can also be used to guide the assembly of micro-robots or to act as microscopic beakers for chemical reactions for the development of smart materials such as clever sensors.’

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