By: Giorgio Volpe
From: Department of Chemistry, University College London
At: C1, 1.4.14
At all scales, active particles are entities capable of taking up energy from their environment and converting it into directed motion. Because of this constant flow of energy, their behavior can only be explained and understood within the framework of non-equilibrium physics. In particular, many living systems, such as schools of fish, flocking birds and bacterial colonies, exhibit collective and dynamic behaviors that are not attainable by their counterparts at thermal equilibrium. In this seminar, with a focus on the basic physical features of the interactions of active particles with their complex environment, I will present recent experimental results where we show that the emergence of these behaviors is very sensitive to changes in environmental conditions – environment that is often highly heterogeneous and disordered for realistic natural systems. In particular, I will show how a collection of colloidal active particles switches between gathering and dispersal of individuals in response to the amount of disorder in the environment introduced with random optical potentials. Interestingly, the statistical properties of the disordered potentials allow one to dynamically control the long-term collective behavior of the active colloidal system. Finally, I will also discuss implications of these results to the design of optimal artificial micro- and nano-agents for applications in drug delivery and random searches.