The smallest and fastest nanomotor: 1 micron, 18,000 RPM

Specialists from the University of Texas at Austin have collected the world's smallest and fastest artificial motor . According to the developers, the motor size of 1 micrometer rotated for 15 hours, accelerating to 18,000 RPM (300 revolutions per second). The total number of revolutions exceeded 240,000. This is a significant achievement, because previous models of such motors rotated no more than 5,000 RPM in just a few minutes.

Nanomotors are made of three basic components: a tiny wire Au / Ni / Au works like a rotor, located on an Au / M / Cr magnet with a quadrupole system of four microelectrodes connected in pairs. They play the role of a stator. In the composition of the magnet M is a magnetic material, for example, nickel and cobalt. The top layer of gold is used to adjust the distance between the magnet and the nanowire to change the magnetic attraction on the rotor.

A three-layer magnet is a key component of the system. Magnetic attraction is regulated so precisely that the magnet is able to attract the wire to the base, but not so much as to prevent its rotation.
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The engineers managed to solve two key problems: the automatic assembly of nanomotors and the control of their movement. The assembly was made with the help of a new technique of “electric tweezers”, which allows placing nanoparticles in a substrate along arbitrary paths with an accuracy of 150 nm, controlling their angle and speed in a pulsating current (see illustration c ).



The experiment showed that it is possible to remotely change the angle of inclination of nanomotors and control the speed of rotation of the rotors. Including simultaneously driving a group of motors. The rotational speed directly depends on the square of the electric field.

The development of efficient nanomotors is an important step towards the creation of nanoelectromechanical systems (NEMS), which in the future will perform medical operations. For example, make injections of medications inside the human body or even search for and remove diseased cells from the body, as shown in the illustration of the University of Texas at Austin.



Scientists emphasize that the maximum rotational speed was checked purely for the sake of experiment, in order to evaluate the reliability of the structure. In practice, so quickly rotating metal parts inside the body are unlikely to be beneficial.

Scientific work published in the April issue of the journal Nature Communications ( mirror ).