Active droploids

Journal article

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

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Grauer*, J., Schmidt*, F., Pineda, J., Midtvedt, B., Löwen, H., Volpe, G., & Liebchen, B. (2021). Active droploids. Nature Communications, 12(1), 1–8. *contributed equally.

Grauer*, Jens, Falko Schmidt*, Jesùs Pineda, Benjamin Midtvedt, Hartmut Löwen, Giovanni Volpe, and Benno Liebchen. “Active Droploids.” Nature communications 12, no. 1 (2021): 1–8. *contributed equally.

Grauer*, Jens, et al. “Active Droploids.” Nature Communications, vol. 12, no. 1, 2021, pp. 1–8. *contributed equally.

Active matter comprises self-driven units, such as bacteria and synthetic microswimmers, that can spontaneously form complex patterns and assemble into functional microdevices. These processes are possible thanks to the out-of-equilibrium nature of active-matter systems, fueled by a one-way free-energy flow from the environment into the system. Here, we take the next step in the evolution of active matter by realizing a two-way coupling between active particles and their environment, where active particles act back on the environment giving rise to the formation of superstructures. In experiments and simulations we observe that, under light-illumination, colloidal particles and their near-critical environment create mutually-coupled co-evolving structures. These structures unify in the form of active superstructures featuring a droplet shape and a colloidal engine inducing self-propulsion. We call them active droploids—a portmanteau of droplet and colloids. Our results provide a pathway to create active superstructures through environmental feedback.

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When a large amount of absorbing colloids self-assembles under light illumination the temperature increases strongly such that droplets form inside a critical binary mixture .