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, we present a versatile fabrication strategy that combines nanofabrication and lithography techniques to create colloidal actuators with a range of isotropic and anisotropic geometries. Our method enables independent encoding of both shape and internal structure using responsive soft materials, such as liquid crystal elastomers. We demonstrate a broad range of actuation modes driven by the interplay between geometry and internal composition. We explore the self-assembly behavior of these actuators, going beyond conventional studies of self-assembly in particles with discrete characteristics. Finally, we demonstrate the potential of these colloidal actuators to form programmable fluids with tunable macroscopic properties, including viscosity, optical behavior, and thermal conductivity. We envision these colloidal actuators evolving into microrobots equipped with sensing and communication capabilities, paving the way for applications in environmental monitoring such as atmospheric sensing and disease detection.
