A study describes the collective motion of rotating particles applicable to biological systems

Particle rotation allows the system to go from a state in which all particles build up a flock, a pattern in which smaller groups –called microflocks- are created.
Particle rotation allows the system to go from a state in which all particles build up a flock, a pattern in which smaller groups –called microflocks- are created.
Research
(27/09/2017)

A team of researchers of the University of Barcelona and the University of Edinburgh has described the collective motion chiral active matter, i.e. matter constituted by self-propelled particles that move in circles. This behaviour is seen in living matter systems such as sperm or flagellated bacteria like Escherichia Coli.

Particle rotation allows the system to go from a state in which all particles build up a flock, a pattern in which smaller groups –called microflocks- are created.
Particle rotation allows the system to go from a state in which all particles build up a flock, a pattern in which smaller groups –called microflocks- are created.
Research
27/09/2017

A team of researchers of the University of Barcelona and the University of Edinburgh has described the collective motion chiral active matter, i.e. matter constituted by self-propelled particles that move in circles. This behaviour is seen in living matter systems such as sperm or flagellated bacteria like Escherichia Coli.

In a study published in the journal Physical Review Letters, the researchers proved that “this is not a simple extension of what was already known from studies on linear active matter, this kind of movement gives rise to new behaviours that were unknown”, says Demian Levis, one of the authors of the study and Marie Curie researcher from the UB Institute of Complex Systems (UBICS). According to Levis, “the results of this study can be applied to diverse contexts such as material science or the control of crowds, which are of great interest to design, for instance, evacuation planning guides for stadiums”.

So far, models described the behaviour of systems made of particles in linear motion, aiming to control and use the locomotion of these groups in detail. As observed in this study, unlike these lineal systems, the fact that these particles move in circles allows researchers to control and predict with detail the size of the patterns or the flocks to be created. Moreover, the rotation widens the systemʼs likelihood to create a consistent state of movement where all the units move in the same direction. Also, rotations allow the system to go from a state in which all particles form a big flock to a pattern in which smaller groups, called microflocks, are created. This change of pattern is similar to the one seen in experiments with sperm.

“Apart from living matter systems, there are other synthetic systems of active matter with which lots of research groups are working to understand the properties of ʻbiomimeticʼ materials, those that mimic nature but are created in the laboratory aiming to design new materials” he concludes.

Article reference:
B. Liebchen, D. Levis. 'Collective behaviour of chiral active matter: Pattern formation and enhanced flocking'. Physical Review Letters, August 2017. DOI:10.1103/PhysRevLett.119.058002