Field-Induced Assembly and Propulsion of Colloids

Abstract

Electric and magnetic fields have enabled both technological applications and fundamental discoveries in the areas of bottom-up material synthesis, dynamic phase transitions, and biophysics of living matter. Electric and magnetic fields are versatile external sources of energy that power the assembly and self-propulsion of colloidal particles. In this Invited Feature Article, we classify the mechanisms by which external fields impact the structure and dynamics in colloidal dispersions and augment their nonequilibrium behavior. The paper is purposely intended to highlight the similarities between electrically and magnetically actuated phenomena, providing a brief treatment of the origin of the two fields to understand the intrinsic analogies and differences. We survey the progress made in the static and dynamic assembly of colloids and the self-propulsion of active particles. Recent reports of assembly-driven propulsion and propulsion-driven assembly have blurred the conceptual boundaries and suggest an evolution in the research of nonequilibrium colloidal materials. We highlight the emergence of colloids powered by external fields as model systems to understand living matter and provide a perspective on future challenges in the area of field-induced colloidal phenomena.

Long-range transport and directed assembly of charged colloids under aperiodic electrodiffusiophoresis

“…Upon application of an ac electric field, the charges inside and outside particles shift with time, leading to multipoles and induced flows. 1–3 Electric fields induce a variety of surface and body forces that have facilitated applications such as pumping, 4 separations, 5 and electrodeposition. 6 Recently, electric fields have been instrumental in advancing new paradigms in directed, 7–9 dynamic, 10,11 and reconfigurable assembly, 12 as well as in colloidal propulsion 13,14 and directed transport.…”

Nanoswimmers Based on Capped Janus Nanospheres

“…The packing depended on the motion of the swimmers and was different in the three studied movement conditions. This laid the groundwork for later studies in the propulsion-driven directed assembly in colloidal systems with mixed active and passive particles [57][58][59].…”

Tandem droplet locomotion in a uniform electric field

“…Electric fields are widely used to steer particles and droplets for applications in directed assembly (van Blaaderen et al. 2013; Harraq, Choudhury & Bharti 2022), microfluidics (Link et al. 2006; Hartmann, Schuer & Hardt 2022), ink-jet printing (Basaran, Gao & Bhat 2013), modulation of emulsion microstucture and rheology (Eow & Ghadiri 2002; Tao et al.…”