Active matter is the marvel of nature. The challenge lies in commanding its chaotic behavior. By dispersing swimming bacteria in a liquid crystalline (LC) environment with spatially varying orientation defined by the liquid crystalline polymer networks, we demonstrate control over the distribution of bacterial concentration, as well as the geometry and polarity of their trajectories. Bacteria recognize subtle differences in the topological structures in the LC, engaging in bipolar swimming in regions of pure splay and bend but switching to unipolar swimming in mixed splay-bend regions. Next, I will talk about how to use the morphology changes of the light-driven disclination networks to transport the colloids. The colloidal assemblies can be collectively transported and assembled in a programmable fashion. Besides, after the colloids are combined with the disclination lines, the lines can be extended around the colloids to form topological entanglement structures with different chirality. The response of nematic colloidal entanglement in the non-equilibrium morphology changes of disclination lines is a nontrivial fundamental question. This work demonstrates the chirality conversion of colloidal entanglement as a response to the changes of topological profiles in non-equilibrium translation of disclination lines. Besides, during the morphology changes of disclination networks with changing geometrical profiles, the colloidal entanglement can assemble, split, rotate and form double helix structures. Our programmable active matter will open opportunities in future developments of multi-functional devices for soft-robotics, flexible electronics, and biomedicine.

Please contact phweb@ust.hk should you have questions about the talk.