Have you ever wondered how fish manage to see underwater? After all, conditions aren’t always the best. Water can be murky and sunlight does not penetrate murky water. Yet, fish are able to find food and hide from predators. What is their secret?
As it turns out, it’s no secret, it’s the fish’s eyes, specifically the retina. The retina of the Elephant Nose Fish was studied as a guide for a contact lens for presbyopia.
Researchers at the University of Wisconsin, Madison, lead by Hongrui Jiang, Ph.D designed a contact lens that has algorithm-driven sensors and miniature electronic circuits that adjust the shape of the lens according to the viewers needs.
“This would be a nice way to restore youthful eyesight for the elderly,” said Jiang, who published the study in Proceedings of the National Academy of Sciences.
Jiang and his team used the retina of the elephant nose fish as a starting point for the project. The retina of this fish has deep cup-like structures with reflective sidewalls. It is this structure that helps to gather light needed for the fish to see. Jiang’s contact lens has thousands of finger-like microscopic glass light collectors. The light collectors are coated with reflective aluminum. The light hits the collectors and is focused by the reflective sidewalls.
The researchers designed and tested different materials for the lens. One was a liquid lens formed from silcone oil and water. The droplet rests in a chamber on a flexible platform, while electrodes produce charges which alter the surface tension of each liquid. This squeezes the droplet into different focal lengths. This type of lens can focus on something as thin as a human hair. Fascinating!
Of course, fish aren’t the only ones with cool eyes. Insect eyes are interesting, as well. Insect eyes are compound eyes. They feature a collection of many microlenses that allow them to process information faster then other organisms. That’s why it is so hard to swat a fly. While the flyswatter or rolled newspaper looks like a fast blur to us, it is moving in slow motion to the fly, so it sees the object coming and gets out of the way.
Jiang’s lab also developed a lens based on insect eyes. Like an insect eye, it contains microlenses that are made from a “forest” of silicon nanowires. These lenses provide greater resolution than the liquid lens and the flexibility makes it good, not just for contacts but also for other uses, such as laparoscopic surgical scopes that provide 360 degree views. Yet, there’s the question of the power supply for such a lens. One possible solution is a solar cell that gathers electrons from sunlight, converts them to electricity, and stores energy in a network of nanostructures.
A prototype is expected to be developed in five to 10 years, and it may not cost more than conventional lenses. This is brand new technology, and we have fish and bugs to thank for it!