Untethered Magnetic Microswimmers for Targeted Particle Transport and Flow Manipulation

Abstract Untethered microrobotic technologies based on magnetic materials are increasingly explored for programmable flow manipulation and precise control within confined microenvironments. In conventional microfluidics, the reconfiguration of the flow relies on tethered microvalves and micropumps, which typically suffer from structural rigidity and limited adaptability. To overcome these constraints, this work introduces magnetically actuated microswimmers to dynamically reconfigure fluid flow within a single microfluidic device. Multiple homogeneous microswimmers are independently controlled by an external magnetic field to perform translational and rotational motions, thereby inducing real‐time flow manipulation. For demonstration purposes, two flow‐driven experiments, such as i) targeted particle transport and ii) fluid mixing and routing, are conducted. In the first experiment, particles of different sizes (0.2 mm and 0.4 mm) are transported along uniaxial and biaxial trajectories into designated downstream branches within 3 s. During the mixing experiment, a dye mixing efficiency of 80.2 % is achieved through localized shear generated by the microswimmers' motions. Simultaneously, the fluid flow is observed to be reconfigured, resulting in the mixture being routed into the desired outlet among multiple downstream channels. This work represents a step forward in the field of reconfigurable microfluidics using microrobotic technology, broadening potential applications in biomedical and lab‑on‑chip technologies.