Controllable Microfluidic Fabrication of Magnetic Hybrid Microswimmers with Hollow Helical Structures

Controllable magnetic hybrid microswimmers with hollow helical structures are fabricated, by a facile strategy based on microfluidic template synthesis and biosilicification, to achieve enhanced rotation-based locomotion for cargo transport. The magnetic hybrid microswimmers are fabricated by first synthesizing Fe3O4 nanoparticles-containing helical Caalginate microfibers from microfluidics, followed with biosilicification and controllable dicing to engineer their rigid hollow helical structures. The microswimmers show hollow helical structures consisting of a rigid, biocompatible alginate/protamine/silica shell embedded with Fe3O4 nanoparticles. Their helical structures can be engineered into open tubular structures or closed compartmental structures by using microfibers or diced microfibers as templates for biosilicification. Powered by a simple rotating magnet, the microswimmers can achieve enhanced rotation-based locomotion and provide good mechanical strength for supporting cargo for transportation. This work provides a simple and efficient strategy for fabricating controllable magnetic hybrid microswimmers with hollow helical structures to achieve enhanced rotation-based locomotion for cargo transport, encapsulation, and delivery.