Motion Enhancement of Spherical Surface Walkers with Microstructures

Abstract

Surface walkers are widely studied as carriers for biomedical applications, such as targeted drug delivery and cell manipulation. For in vivo/in vitro therapeutic applications, high movement velocity is necessary for efficient operation on targets with high throughput. Herein, a fast underwater microstructured spherical surface walker (i.e., microsphere) driven by a rotating magnetic field is reported, and the effect of the surface microstructures on the mobility of microspheres is explored. Compared with the motion of smooth sphere walking nearby a smooth plane, a twofold and a fourfold increases in the velocity are found for the microstructured sphere (MS) walking nearby a smooth plane and a patterned plane, respectively. A hydrodynamic model of MS moving nearby a plane is used to reveal the underlying mechanism of the enhanced motion, which demonstrates that the slippage of fluid on the microstructured surface and the interaction between fluid and microstructures are crucial to the motion enhancement. The result of motion enhancement induced by microstructures can be used for the design of fast biomimetic microrobots, anti‐adhesion, cell manipulation, and targeted drug delivery in complex aqueous environments.