Microparticles found in the secretions of cicadas can become the secret ingredient for the production of the invisibility cloak. These particles change the wavelength of light, which can be used to achieve the invisibility effect.
The particles produced by cicadas not only repel water from their wings, but also alter the wavelengths of light, which could be useful to researchers in their long-term attempts to create an invisibility cloak.
The key to making objects invisible is to find a way to absorb light that obscures objects. It turns out that this is exactly what the cicada does, hiding from predators.
Scientists at the University of Pennsylvania have created a synthetic material that mimics the microparticles used by cicadas. This is achieved by using nanometer-sized wells capable of absorbing light in a wide range of waves coming from different directions.
This material provides a better understanding of why cicada microparticles (brochosomes) are so effective at camouflaging an insect, and can be used to camouflage anything.
“We knew that our synthetic particles could be interesting optically because of their structure,” said one of the researchers Tak-Sing Wong. - Subsequently, the head of the study, Shikuan Yang, indicated that the cicada produces a coating whose structure is very close to our synthetic material. This gave us a reason to think about how the cicadas use this material."
Brochosomes are like tiny soccer balls. Scientists have long tried to recreate them in an artificial way.
Using a complex process involving five steps, scientists were able to create similar microparticles capable of capturing up to 99 percent of light in the ultraviolet, visible and infrared ranges. The lack of reflected light means that the observer simply has nothing to see.
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The study of these artificial brochosomes helped to understand the mechanism of the "disappearance" of cicadas, since predatory insects and birds preying on them see in the ultraviolet and visible ranges.
When the synthetic material was applied to the leaves, in the emulation of the ladybug's vision (with the limitation of the visible spectrum), the colors of the leaves and microparticles practically coincided.
The creation of the invisibility cloak is still beyond our capabilities - and some physicists are sure that this is simply impossible - but the researchers believe that the results obtained from cicadas can be expanded and used in real materials.
“Different materials have different uses,” says Wong. “For example, manganese oxide is widely used in supercapacitors and batteries. Due to their large surface area, our particles can be good for battery electrodes, accelerating the chemical reaction."
As an antireflection coating, the new material could help sensors and cameras improve signal-to-noise ratio, enhance telescopes' capabilities, and even improve the efficiency of solar cells. In all these cases, the level of absorption of light energy is very important.
It looks like we will have to do without the invisibility cloak for a while; nevertheless, this study opens up new perspectives, and scientists hope to make the material work at longer wavelengths.
“By making this structure larger, it could possibly be able to absorb longer electromagnetic waves, such as mid-infrared, and this will expand the range of applications as a sensor and energy storage,” says Wong.
Vadim Tarabarko