NOV 03, 2018 10:30 PM PDT

Tiny Light Detectors Inspired by Directional Hearing in Geckos

WRITTEN BY: Nouran Amin

Many animals, like geckos, have difficulty triangulating the location of noises due to the small size of their heads.


Gecko ears contain a mechanism similar to Stanford researchers’ system for detecting the angle of incoming light.

Image credit: Vitaliy Halenov via Stanford University

To facilitate noise detection, many of these animals will have a tiny tunnel placed through their heads that will measure the way incoming sound waves are bouncing around in order to figure out which direction these noises are coming from. This particular process of noise detection, in animals like the geckos, has influenced a research study at Stanford University that examined a similar system for detecting the angle of incoming light.

The system will allow tiny cameras to detect where light is coming from without the use of bulky large lens which can provide advances in lens-less cameras and important applications in augmented reality, robotic vision, and autonomous cars.

Results of the study were published in Nature Nanotechnology.

"Making a little pixel on your photo camera that says light is coming from this or that direction is hard because, ideally, the pixels are very small -- these days about 1/100th of a hair," says Mark Brongersma, senior author of the study professor of materials science and engineering. "So it's like having two eyes very close together and trying to cross them to see where the light is coming from."

The researchers worked on tiny detectors that can record many characteristics of light, such as color, polarity and, the angle of an incoming light wave. The system described in the study is the first to provide evidence of the possibility of angle light determination using such a small setup.

"The typical way to determine the direction of light is by using a lens. But those are big and there are no comparable mechanisms when you shrink a device so it's smaller than most bacteria," said Shanhui Fan, professor of electrical engineering and a co-author of the study.

Anatomy of a light wave. Image Credit: Khan Academy

Using the gecko as the inspiration, researchers mimicked the structure in their photodetector by using two silicon nanowires -- lined up next to each other and positioned very close. Such positioning will allow the light wave to cast a shadow as it comes in at an angle.

"On the theory side, it's actually very interesting to see many of the basic interference concepts that go all the way to quantum mechanics show up in a device that can be practically used," said Fan.

Source: Nature Nanotechnology, Stanford University

About the Author
Doctorate (PhD)
Nouran is a scientist, educator, and life-long learner with a passion for making science more communicable. When not busy in the lab isolating blood macrophages, she enjoys writing on various STEM topics.
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