Directed Interactions to Regulate the Steady State Assembly in Active-Passive Mixtures.*

Colloidal gels exhibit intriguing attributes due to their diverse building blocks and the cohesive forces governing the establishment of arrested networks during the gelation process. Recent studies have offered valuable insights into aspects such as configuration, interrupted aging, and enhanced dynamics that arise by integrating activity into gel networks. Motivated by active gels, we set to investigate experimentally the intricate interplay between interactions and activity on gel morphology and dynamics. In this talk, I will discuss our endeavors to study reversible active colloidal gel from a binary suspension of electric field driven active colloids and passive ones. Our experimental observations reveal that regulating the dipolar interactions between colloidal particles modulates the orientational ordering of the active colloids and thereby the network formation. We find that orientational ordering that is directly related to activity, in turn, plays a pivotal role in dictating the overall stability and dynamics of the network. We expect our study to be an experimental demonstration of a strategy to control the steady-state assembly in active-passive mixtures in-situ and reversibly.