Loughborough academic to model ‘living’ micro-machines

A researcher at Loughborough University has been awarded over £1.25m by the European Research Council to investigate “living” micro-machines that assemble themselves.

Salmonella bacteria – an example of bacteria that can swim and propel themselves to favourable environments (Image: Loughborough University)

The five-year project will combine two areas, colloidal self-assembly and active liquids, using computational simulations on Loughborough’s high-performance computers.

Dr Tyler Shendruk is a member of the interdisciplinary centre for mathematical modelling in the Mathematical Sciences department. This is a new group “applying computational physics methods to understanding different dynamic systems than physicists would usually consider,” he said.

Particles take rough with the smooth when moving in liquid suspensions

In the swim

Colloids, suspensions of tiny particles in a fluid, can act as building blocks for more complex structures but need to be brought together to “self-assemble”. In liquid crystals, fluids composed of rod-like molecules that lie in straight lines, colloids self-assemble into chains, zigzag lines and lattice structures. These are known as colloidal liquid crystals. However, they are limited to simple, static structures.

Dr Shendruk will investigate a new class of “active” liquid crystals. These are typically biological, and are able to store energy and transmute it into spontaneous mechanical motion (a process used in intracellular transport, for example). An example is fluid extracted from cell cytoplasm and purified, or a dense suspension of bacteria. Their internal motion can be used to model the dynamics of herding sheep or shoals of fish.

It is hoped that in such fluids colloids will be able to self-assemble into more complex and dynamic structures. “The goal is to see if the interaction of the colloids in the liquid crystal, causing them to self-assemble, is enough to hold them together while the activity of the fluid moves them around, so that they can act as the components of a micro-robot might do,” said Dr Shendruk.

He added: “I’m trying to steam ahead with the theory and ask, what can you do with these active fluids.” While experimental scientists work to discover new examples of the fluids, “we want to see if we get these structures spontaneously forming, and do they propel themselves along?”

Applications could include acting as a carrier of drugs to places the drugs would not otherwise go, at a cellular level. Two different colloids could also carry two inert components of a drug which, like a two-part adhesive, would remain inert until brought together.

However Dr Shendruk is focused for the moment on the groundwork rather than applications. “In four or five years we’re hoping we’ve caught the excitement of enough experimentalists to want to build them,” he said.