Self-steering artificial microswimmers: Towards advanced navigation inside patterned environments.

Active colloids are promising candidates for many technological applications, e.g., in biomedicine and microsurgery. However, current realizations lack active response to confining surfaces: the ubiquitously studied pre-configured and mechanically rigid colloidal swimmers are predominantly captured at surfaces, which severely restricts their motion and hinders their applicability. To overcome this limitation, we examine the emergence of adaptive motility in self-assembled binary colloidal molecules that are both self-propelling and self-steering under an ac electric field due to physical interactions which promote dynamic shape reconfiguration. Combining experiments, simulations and analytical theory, we show that contrary to their pre-assembled counterparts, self-steering active assemblies exhibit a decoupling between translational and rotational motion, and a timescale for reorientation that is solely set by the molecule's internal reconfiguration and not by rotational diffusion. This novel property allows tailored interactions between dynamically reconfiguring active colloids and confining surfaces to enable new modes of environment navigation. Our results may aid the development of new design rules to implement functional artificial microswimmers in future applications.