Magnetically Propelled Fish‐Like Nanoswimmers

TLDR

Fish locomotion relies on a deformable body interacting with surrounding fluid, yet scaling such propulsion to the micro‑ and nanoscale remains difficult. The authors aim to demonstrate a magnetically propelled, fish‑like nanoswimmer that mimics the body and caudal fin propulsion of real fish. They construct multisegment nanowire swimmers (gold head, nickel body, gold caudal fin, flexible silver hinges) and study their propulsion dynamics with the immersed boundary method. Under an oscillating magnetic field, the nanofish achieves speeds over 30 µm s⁻¹, exhibits high swimming efficiency, and shows promise as a biomimetic nanorobotic device for biomedical applications.

Abstract

The swimming locomotion of fish involves a complex interplay between a deformable body and induced flow in the surrounding fluid. While innovative robotic devices, inspired by physicomechanical designs evolved in fish, have been created for underwater propulsion of large swimmers, scaling such powerful locomotion into micro‐/nanoscale propulsion remains challenging. Here, a magnetically propelled fish‐like artificial nanoswimmer is demonstrated that emulates the body and caudal fin propulsion swimming mechanism displayed by fish. To mimic the deformable fish body for periodic shape changes, template‐electrosynthesized multisegment nanowire swimmers are used to construct the artificial nanofishes (diameter 200 nm; length 4.8 μm). The resulting nanofish consists a gold segment as the head, two nickel segments as the body, and one gold segment as the caudal fin, with three flexible porous silver hinges linking each segment. Under an oscillating magnetic field, the propulsive nickel elements bend the body and caudal fin periodically to generate travelling‐wave motions with speeds exceeding 30 μm s −1 . The propulsion dynamics is studied theoretically using the immersed boundary method. Such body‐deformable nanofishes exhibit a high swimming efficiency and can serve as promising biomimetic nanorobotic devices for nanoscale biomedical applications.