Small carts controlled by the power of light |

Light has an inherent power that can move microscopic objects. This discovery underpins the Nobel Prize-winning optical tweezers, as the researchers were able to show how a focused laser beam can pick up and carry particles with great precision.

Now a research group at Chalmers University of Technology and the University of Gothenburg has shown that the power of unfocused light, the so-called plane wave, can be used to control tiny particles in a controlled orbit. The research was recently presented in a scientific article in the journal Nature’s nanotechnology.

One thousandth of a millimeter

The tiny vessels the researchers created are ten micrometers wide and one micrometer thick, just one-thousandth of a millimeter. The minimum number of particles was coated with an artificial substance – the so-called superstructure.

METATOR It consists of carefully designed, interacting nanoparticles engineered to control light in unusual and innovative ways. In the future, it is hoped that metasurfaces will be able to be used in, among other things, cameras, microscopes, electronic monitors and other technological tools that require advanced optical components. Superficial surfaces are usually seen as stationary objects that can control and influence light. But in this case, the research team chose to flip it around and use instead how the energy from the light affects the meta surface itself.

Watch the movie about metaphors

Like two billiard balls collide with each other

The researchers placed the microscopic particles – metaphorically – at the bottom of a bowl filled with water and illuminated them with laser light. Through a purely mechanical process, which occurs independently of the heat generated by the light, the scientists were able to control the movement and speed of metaphors with great precision and even direct them in different directions and in different configurations by changing the polarization of the laser light.

According to Newton’s third law, there is an equal and opposite reaction to every event. In this case, it means that when the light reaches the superficial surface, it is deflected in a new direction, and the interaction force causes the microscopic vessel to move in the opposite direction. It’s like playing pool and two balls hitting each other and going in different directions. You can compare the superficial and the light, photons, of two billiard balls colliding with each other, says Michael Kall, a professor in the Department of Physics at Chalmers University of Technology and responsible for the research project.

You can put other particles in front of it

The super ships are stable, and we can navigate between them in a predictable and controllable way. With advanced automatic feedback systems and more complex control of the intensity and polarization of a light source, even more complex navigation could be possible, says Daniel Andrin, a former doctoral student in the Department of Physics and first author of the article.

The researchers were also able to use metaphors as vectors by having them place small particles in front of them in a tank of water. It can easily move, among other things, microplastic particles and yeast cells. The metaphorical ship even managed to move a grain of dust 15 times larger than itself.

– In the exploration of the forces of light, there are many interesting effects that are not yet fully understood. It is not apps that drive this kind of research, but to explore different possibilities. In a number of different stages ahead, you’ll never know what’s going to happen. But the fact that we’re showing that you can use the particles to move other things suggests that they can be used as carriers for other things, for example in cell solutions, says Michael Kall.

Scientific material:

Microscopic metamorphic molecules are supported and directed by embedded optical surfaces(Daniel Andrin, Dennis J. Baranoff, Stephen Jones, Giovanni Volpi, Ruggero Ferri and Mikael Cal), Nature’s nanotechnology.

Call:

Daniel Andren, former PhD student in the Department of Physics at Chalmers University of Technology, [email protected]
Michael Kall, Professor in the Department of Physics at Chalmers University of Technology, [email protected]

margin:

The project is funded by Nano Excellence Initiative at Chalmers University of Technology, the Swedish Research Council and the Knut and Alice Wallenberg Foundation. Microscopic metaphors are manufactured at Myfab Chalmers.