LISE 303 12pm – 1pm April 25, 2025
Dr. Hamed Almohammadi
Prof. Aizenberg Group, Harvard

Abstract: Colloidal-scale robots—a few micrometers in size and capable of sensing, moving, and responding to their environment—hold significant potential for applications such as monitoring in remote areas like oil conduits, marine environments, and the atmosphere. These microrobots also show promise as building blocks for hierarchical materials and programmable fluids, with unparalleled levels of adaptability. However, realizing such systems with precise control over particle geometry, internal architecture, and actuation modes at the microscale remains challenging, hindering progress in the field. Here, I present a versatile fabrication strategy that combines nanofabrication and lithography techniques to create colloidal actuators with a range of isotropic and anisotropic geometries. This approach enables independent encoding of both shape and internal structure using responsive soft materials, such as liquid crystal elastomers. I demonstrate a broad range of actuation modes driven by the interplay between geometry and internal composition. Finally, I discuss the self-assembly behavior of these actuators, going beyond conventional studies of self-assembly in particles with discrete characteristics.

About the speaker: Hamed Almohammadi is currently a Swiss National Science Foundation (SNSF) Postdoctoral Fellow in Joanna Aizenberg’s group at Harvard University, where he focuses on developing colloidal actuators as building blocks for designing materials and fluids with programmable properties. Before moving to the United States, Hamed completed his Ph.D. at ETH Zurich, Switzerland, with Raffaele Mezzenga, focusing on the self-assembly of anisotropic colloidal particles. Hamed has a background in Mechanical Engineering, having completed his MSc in Canada, where he studied droplet and surface interactions, and his BSc in Iran, where he investigated heat transfer in colloidal systems.