Laser Light Controls Linear Nanomotors

Researchers created novel linear nanomotors that move in controlled directions using laser light. This research paves the way for new microfluidics applications, such as lab-on-a-chip systems with optically actuated pumps and valves.

The researchers developed a system of linear motors made of gold nanorods that move in a controlled direction when exposed to laser light. These nanomotors, like a sailboat that can move in any direction by adjusting the rigging, are not limited to following the direction of the light. They move based on their orientation, even when exposed to a laser beam from a different angle.

The lateral optical force generated by the particles’ sideways laser light scattering propels the motion. As a result, the previously difficult task of focusing or shaping the laser beam with lenses is no longer required. Furthermore, unlike previous devices, motor sizes are not limited by light wavelength.

Instead of being limited to moving in the direction of laser light or the field gradient, the nanoparticles’ orientation determines the direction. The key to this technology is the localized surface plasmon resonance—collective oscillations of free electrons—within periodic arrays of nanorods. These can cause scattered light in a specific direction.

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