Reconfigurable Artificial Microswimmers with Internal Feedback

Abstract: Micron-size self-propelling particles are often proposed as synthetic models for biological microswimmers, yet they lack internally regulated adaptation, which is central to the autonomy of their biological counterparts. Conversely, adaptation and autonomy can be encoded in larger-scale soft-robotic devices, but transferring these capabilities to the colloidal scale remains elusive. Here, we create a new class of responsive microswimmers, powered by induced-charge electrophoresis, which can adapt their motility to external stimuli via an internal feedback. Using sequential capillary assembly, we fabricate deterministic colloidal clusters comprising soft thermoresponsive microparticles, which, upon spontaneous reconfiguration, induce motility changes, such as adaptation of the clusters' propulsion velocity and reversal of its direction. We rationalize the response in terms of a coupling between self-propulsion and variations of particle shape and dielectric properties. Harnessing those allows for strategies to achieve local dynamical control with simple illumination patterns, revealing exciting opportunities for the development of new tactic active materials.