Regensburg 2025 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 13: Active Matter III (joint session DY/BP/CPP)
BP 13.5: Vortrag
Dienstag, 18. März 2025, 10:30–10:45, H47
Active Particles in Tunable Colloidal Environments — •Abhimanyu Nowbagh1, Venkata M.S.G. Tanuku2, Thomas Palberg2, and Ivo Buttinoni1 — 1Institute of Experimental Colloidal Physics, Heinrich-Heine University, 40225 Düsseldorf — 2Institute of Physics, Johannes-Gutenberg University, 55128 Mainz
Active colloids are microscopic particles which propel through aqueous media by converting the externally available energy into directed motion. Using non equilibrium thermodynamics to understand biological systems: interactions of active colloids with crowded systems, and emergent phenomena of ensembles of active particles, remain an important and open question.
In this work, we investigate the dynamics of active particles in crowded environments subjected to alternating-current (AC) electric fields. The AC electric field is used to control: i) the velocity of active particles and ii) the inter-particle interaction between passive colloids. As we increase electric field strength, the velocity of active particles increases and the inter-particle interaction between passive colloids becomes stronger. We study the behaviour of active particles as a function of: i) the frequency of the applied AC electric field, ii) the area fraction of the passive crowd, iii) the active to passive particle number ratio, and iv) the velocity of the active particles.
Our experimental findings show that the active particles reorient faster with an increasing electric field strength. With an increase in the active to passive particle ratio, we show that cluster formation is non-monotonically sensitive to the passive crowd density.
Keywords: Colloids; Induced Charge Electro Osmosis (Phoresis); Non-Equilibrium Statistical Mechanics; Active-Passive Interaction; Cluster Formation