Optically Driven Microgear Transmission System via Optical, Hydrodynamic, and Frictional Coupling

Optical tweezers, with noncontact and high-precision manipulation, offer unique advantages in micro-nano mechanics and microfluidics. Here, we demonstrate an all-optical microgear transmission strategy based on dynamically assembled microrotors driven by vortex beams. The microrotors driven by the optical torque of vortex beams can generate localized flow fields, combined with optical forces and interparticle friction, forming a coupled transmission mechanism for angular momentum transfer. We further investigate dual-rotor systems with tunable distance, rotation direction, and topological charge, achieving two coupling modes. Corotating rotors generate conveyor-belt-like flow fields for continuous particle transport, while synchronous counter-rotating rotors form gear-meshing-like flow fields for directed particle accumulation. Quantitative experimental analysis confirms the feasibility of the coupled transmission coupling mechanism. This strategy achieves reconfigurable and scalable manipulation of microparticles via real-time light-driven assembled microrotors without prefabricated nanostructures, offering a new approach for constructing micro/nano optical contactless transmission systems for optical sorting, microfluidic, and programmable optomechanical systems.