Chemical design of self-propelled Janus droplets

Caleb H. Meredith, Alexander C. Castonguay, Yu Jen Chiu, Allan M. Brooks, Pepijn G. Moerman, Peter Torab, Pak Kin Wong, Ayusman Sen, Darrell Velegol, Lauren D. Zarzar

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Solubilizing, self-propelling droplets have emerged as a rich chemical platform for the exploration of active matter, but isotropic droplets rely on spontaneous symmetry breaking to sustain motion. The introduction of permanent asymmetry, e.g., in the form of a biphasic Janus droplet, has not been explored as a comprehensive design strategy for active droplets, despite the widespread use of Janus structures in motile solid particles. Here, we uncover the chemomechanical framework underlying the self-propulsion of biphasic Janus oil droplets solubilizing in aqueous surfactant. We elucidate how droplet propulsion is influenced by the degree of oil mixing, droplet shape, and oil solubilization rates for a range of oil combinations. In addition, spatiotemporal control over droplet swimming speed and orientation is demonstrated through the application of thermal gradients applied via joule heating and laser illumination. We also explore the interactions between collections of Janus droplets, including the spontaneous formation of spinning multi-droplet clusters.

Original languageEnglish (US)
Pages (from-to)616-633
Number of pages18
Issue number2
StatePublished - Feb 2 2022

All Science Journal Classification (ASJC) codes

  • General Materials Science


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