Flagella-like Propulsion for Microrobots Using a Nanocoil and a Rotating Electromagnetic Field

A propulsion system similar in size and motion to the helical bacterial flagella motor is presented. The system consists of a magnetic nanocoil as a propeller (27 nm thick ribbon, 3 μm in diameter, 30-40 μm long) driven by an arrangement of macro coils. The macro coils generate a rotating field that induces rotational motion in the nanocoil. Viscous forces during rotation result in a net axial propulsion force on the nanocoil. Modeling of fluid mechanics and magnetics was used to estimate the requirements for such a system. The fabrication of the magnetic nanocoils and the system setup are explained. Experimental results from electromagnetic actuation of nanocoils as well as from their propulsion in both paraffin oil and water are presented. This is the first time a propulsion system of this size and motion-type has been fabricated and experimentally verified.