14 DAY TRIAL // Physicists in the United Kingdom, at the University of Southampton, propose the existence of a new force that is capable of making metamaterials attach themselves to other surfaces. The work is heavily influenced by a theory proposed by scientist James Clerk Maxwell, back in 1871.
At the time, the expert predicted that light produces a small force whenever it hits a surface. By the 1900s, this had been experimentally proven. Radiation pressure has since become the controlling principle behind such applications as laser cooling and solar sails.
Now, USouthampton investigators led by John Zhang propose that light may act with another force as well, but this time inside metamaterials. These are structures that are engineered from scratch, for the sole purpose of manipulating light in whatever way scientists see fit, Technology Review reports.
These special optical properties allows this class of materials to develop a powerful optical force between itself and a metal or dielectric plate. This can only happen if tiny oscillations of electrons called plasmons develop on the surface of metamaterials.
The field of plasmonics is one of the newest in science, but also one that carries great potential for the future. In metamaterials, specifically, plasmonic oscillations are very small, just a few nanometers across. They are engineered in such a way as to coincide with the wavelengths of visible light.
If the plasmons are activated any time such a material is brought closer to either a metal or a dielectric surface, then the oscillations should interact with the electrons in the nearby materials, giving birth to an interesting resonant effect that should theoretically pull the two surfaces together.
The effect would only occur when plasmons at particular resonant frequencies are activated with photons at the appropriate frequency. If this is done properly, then the effect should be very strong.
University of Southampton investigators say that the frequency and intensity of incident light is what controls the strength of the overall resonant effect, at least in theory. They've named this the “near field force,” and hypothesized that it must be stronger than other short-range effects, such as Casimir forces.
Interestingly, the effect could also be stronger than gravity. The new research may have just provided us with a new force, this time one that can be controlled – turned on and off – at the touch of a button.
“This near-field force can exceed radiation pressure and Casimir forces to provide an optically controlled adhesion mechanism mimicking the gecko toe: at illumination intensities of just a few tens of nW/µm^2 it is sufficient to overcome the Earth's gravitational pull,” the team explains.