A Strain-Engineered Helical Structure As A Self-Adaptive Magnetic Microswimmer

Inspired by flagellar bacteria, helical microswimmers are proposed in many biomedical applications due to their efficient propulsion at low Reynolds numbers. And the ability to swim through a confined environment such as a blood capillary is an urgent issue to further expand their functions both in vivo and in vitro. Herein, we report an inorganic but soft helical microswimmer that can accurately navigate and achieve self-adaptive locomotion driven by a weak magnetic field. The microswimmer is made via nanomembrane self-rolling method. The motion of helical microswimmer is influenced by its structures such as size and pitch, which can be precisely manipulated by strain engineering during fabrication. Self-adaptive motion is demonstrated in a confined capillary filled with viscous fluid. This helical microswimmer is expected as a magnetic microtool applied to thrombosis treatment as a combination of rigid inorganic materials and soft helical structure.