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Propulsion and Assembly of Microparticles in External Fields

Speaker
Bhuvnesh Bharti from Louisiana State University
Date
Location
Zoom

Colloidal particles are emerging as models for understanding the governing principles of assembly and non-equilibrium response of advanced materials. Our work focuses on understanding the universal principles governing the structure and dynamics of matter using colloids as model building blocks.  In this talk, I will present our work on the use of external fields to direct the assembly and spatial migration of colloids. First, I will introduce the principles of controlling and directing motion of metal-dielectric patchy colloids using external electric field. The electric field drives a local force imbalance around the metal patched particle, resulting into its direction motion. I will demonstrate how coupling of translation and rotational component of the energy enables programming helical motion in spherical colloids and provides an alternative mode of navigating through complex cross-linked matrices. Secondly, I will introduce our recent work which uncovers the dual nature of ferrofluids, particulate and continuous, to design a colloidal platform that couples competitive interactions with non-equilibrium dynamics. Using a binary suspension of microspheres in ferrofluid, we describe cyclical order-disorder-order transitions, and we access dynamic cluster states. I will show that crystal and fluid states represent two extremes in the competition between attraction and repulsion, while arrangement into clusters is a pseudo-equilibrium only observed from the true balance of interaction forces. Our findings establish a platform for experimental modeling of living matter with tunable competition between equilibrium and non-equilibrium forces.