Nanoscale machines convert light into work

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Nanoscale machines convert light into work
Researchers created an optical matter machine that operates much like a mechanical machine in which if one gear is turned, a smaller interlocking gear will spin in the opposite direction (a). The optical matter machine (b) uses circularly polarized light to create a nanoparticle array that acts like the larger gear by spinning in the optical field. This makes a probe particle – analogous to the second smaller gear – orbit the nanoparticle array in the opposite direction. Credit: Norbert F. Scherer, University of Chicago

Researchers have developed a tiny new machine that converts laser light into work. These optically powered machines self-assemble and could be used for nanoscale manipulation of tiny cargo for applications such as nanofluidics and particle sorting.

“Our work addresses a long-standing goal in the nanoscience community to create self-assembling nanoscale machines that can perform work in conventional environments such as room temperature liquids,” said research team leader Norbert F. Scherer from the University of Chicago.

Scherer and colleagues describe the new nanomachines in Optica. The machines are based on a type of matter known as optical matter in which metal nanoparticles are held together by light rather than the chemical bonds that hold together the atoms that make up typical matter.

“Both the energy for assembling the machine and the power to make it work come from light,” said Scherer. “Once the laser light is introduced to a solution containing nanoparticles, the entire process occurs on its own. Although the user does not need to actively control or direct the outcome, this could readily be done to tailor the machines for various applications.”

Creating optical matter

In optical matter, a laser light field creates interactions between metal nanoparticles that are much smaller than the wavelength of light. These interactions cause the particles to self-assemble