Engineering micromachines open interesting perspectives to probe and manipulate matters at small scale but it also encounters the challenge of assembly and reconfigurability at this size. We previously demonstrated a new approach, templated assembly, which exploits optical forces and the activity of the colloids to create autonomous, mobile, stable and reprogrammable architectures.
We show the assembly and control of a family of self-spinning cogwheels with varying teeth numbers, formed by colloidal microswimmers that power the structure. Leveraging the angular momentum of optical vortices, we control the direction of rotation of these centrosymmetric structures. We study pairs of interlocking cogwheels that roll over each other in a random walk and curvature-dependent mobility. We take advantage of this feature to achieve self-positioning of cogwheels on structures with variable curvature and program micro-robots. We finally highlight their practical relevance for operation at small scale with the ability to pick up, transport and release a load.
This work highlights untapped opportunities of manufacturing at microscale using self-positioning components and constitutes a step towards autonomous machinery with external control and programmable micro-robots.