Nanomotors controlled by laser light

Researchers at the Institute of Industrial Technology, University of Tokyo (Utokyo-IIS) have developed novel linear nanomotors that can be moved in a controlled direction using light. This work paves the way for new microfluidics, including lap-on non-a-chip systems with optically activated pumps and valves.

The world of nanoscale machines looks much more than the shrinkage for which we are accustomed. For example, powering and precisely controlling a motor smaller than a bacterium can be more difficult than driving a car.

Now, a team of scientists led by Utokyo-IIS has introduced a system of linear motors made of gold nanorods that can move in a controlled direction when exposed to laser light. Unlike sailboats that can move in any desired direction by adjusting the raging, these nanomotors are not restricted to following the direction of light. Lata, even when they are in contact with a laser beam traveling from another angle, they move forward depending on their approach.

The motion is driven by the lateral optical force, which is caused by the scattering of light from the particles. As a result, the need to focus or shape the lens beam, which was once a difficult task, has disappeared. In addition, the size of the motor is not controlled by the wavelength of light like previous devices.

Says first author Yoshito Tanaka, “Rather than being limited to the direction of the laser light or the gradient of the field, the direction is determined by the approach of the nanoparticles. The key to this technique is the mass os selection of local surface plazion resonance ance free electrons within the periodic array of nanorods. This can produce light scattered in a particular direction. “The formation of different parts between nanorods leads to constructive interference in one direction and destructive interference in the other. This allows us to produce directional scattering to move the nanomotor forward,” says senior author Susutomu Shimura.

Researchers envisioned using this technology to create a new platform for nano-sized machinery in which moving parts follow predefined paths when pushed with it by unstable light. This will greatly reduce the cost and complexity of the devices while also improving the accuracy and reliability.

The work is published Science progress “Platermonic linear nanomotor, which activates lateral optical forces.”