Self-assembled active matter

At the early stages of life, reaction centres, e.g. in form of a nucleolus, had to form from a  dilute suspension. Part of this process involves the self-assembly of from simple building blocks into hierarchical structures.
In this project, we employed a binary suspension of colloids, light absorbing and non-absorbing. We observed that under light illumination colloids self-assembled into colloidal molecules. In their simplest configuration they formed a Janus dimer, which breaks the radial symmetry around the absorbing particle and thus acquires motility. Over time grow in size and change their shape which results into different behaviour. 
Moreover, for larger structures, droplets form around the molecules (see Figure below) thus providing boundary whose feedback couples back to their internal structure.

This simplified experimental system allows to test and understand the bottom-up formation process into complex biomimetic materials.
Under light illumination droplets with immersed colloidal molecules are forming, so called "active droploids", a portmanteau of the words droplet and colloids.


Kolloidphysik: Motorisierte Tröpfchen

Hartmut Löwen, Jens Grauer, Falko Schmidt, Benno Liebchen

Physik in unserer Zeit, vol. 53(1), 2022, pp. 9-10

Active droploids

Jens Grauer*, Falko Schmidt*, Jesùs Pineda, Benjamin Midtvedt, Hartmut Löwen, Giovanni Volpe, Benno Liebchen

Nature communications, vol. 12(1), 2021, pp. 1--8. *contributed equally

Measurement of anomalous diffusion using recurrent neural networks.

Stefano Bo, Falko Schmidt, Ralf Eichhorn, Giovanni Volpe

Physical Review E, vol. 100(1), 2019 Jun 17

Light-controlled assembly of active colloidal molecules.

Falko Schmidt, Benno Liebchen, Hartmut Löwen, Giovanni Volpe

Journal of Chemical Physics, vol. 150(9), 2019 Feb 7, pp. 94905-94905