Researchers from BGU and the Weizmann Institute of Science have discovered the unique structure of the reflector underlying Shrimp’s retina. This reflector (a 'tapetum') is made of tightly packed nanoparticles that allows the eye to collect more light.
The secrets of the shrimp eye could inspire new, highly efficient paints and coatings which could be made ultra-thin, yet highly reflective. The Palmer group is now trying to understand the tricks the shrimps use to make such complex particles with the view to being able to re-create them in the lab.
Close-packed Assembly of Spherical Nanoparticles
The shrimp's reflector is composed of a close-packed assembly of spherical nanoparticles. Each of these nanoparticles is constructed from hundreds of crystal plates, which are arranged in concentric layers around a hollow core, closely resembling an onion.
The tiny platelets are arranged such that their highly reflective flat faces point away from the surface of the sphere in all directions – a bit like a disco ball shrunk down to the nanoscale.
This special configuration is known as a spherulite, and while physicists had theorized that dense assemblies of nanoscale spherulites could enhance reflectivity, they had not managed to create one artificially.
New Insights into Optics
The result of the unique nanoparticle configuration in the shrimp is a huge enhancement in the efficiency of its reflector. The finding has unveiled new insights into optics at the nanoscale.
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It's not often that new principles in optics are revealed by biological systems," adds Dr. Benjamin Palmer, lead author on the paper. Palmer has teamed up with Dr. Venkata Jayasurya Yallapragada, a postdoctoral fellow at Weizmann Institute, to map these crystals in the shrimp's eye and determine their properties.
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The more I thought about how light propagates through these particles, the more I was intrigued by them", says Yallapragada, who uses a variety of computational techniques to model the optics of spherulites.
Dr. Palmer has just been awarded a prestigious ERC Starting Grant.
Source: BGU