Bacteria Flagella-Mimicking Polymer Multilayer Magnetic Microrobots.

Mass production of biomedical microrobots demands expensive and complex preparation techniques and versatile biocompatible materials. Learning from natural bacteria flagella, the study demonstrates a magnetic polymer multilayer cylindrical microrobot that bestows the controllable propulsion upon an external rotating magnetic field with uniform intensity. The magnetic microrobots are constructed by template-assisted layer-by-layer technique and subsequent functionalization of magnetic particles onto the large opening of the microrobots. Geometric variables of the polymer microrobots, such as the diameter and wall thickness, can be controlled by selection of porous template and layers of assembly. The microrobots perform controllable propulsion through the manipulation of magnetic field. The comparative analysis of the movement behavior reveals that the deformation of microrobots may be attributed to the propulsion upon rotating magnetic field, which is similar to that of natural bacteria. The influence of actuation and frequency on the velocity of the microrobots is studied. Such polymer multilayer magnetic microrobots may provide a novel concept to develop rapidly delivering drug therapeutic agents for diverse practical biomedical uses.