Scientists have developed an innovative new sensor that would allow for creation of contact lenses that act like night vision goggles. The new lenses, created by researchers in the United States, allow the person wearing them to see infrared radiation.
Researchers from the University of Michigan have built a super-thin light detector out of graphene, an atom-thin material made from carbon. The prototype sensor is thin, and smaller than a fingernail.
University of Michigan Assistant Professor of electrical and computer engineering Zhaohui Zhong led the team that created this novel new lens technology.
The sensor, if it were integrated into a contact lenses would allow the wearer to see ultraviolet radiation as well as infrared and visible light. While those contact lenses are still a dream, this new, graphene-based sensor does make such an invention just a little more realistic.
Existing night-vision technology used by the military, law enforcement, and some hunters requires cooling equipment, so the sensors don’t get fooled by their own waste heat. Graphene models can cool themselves by using a few layers of the material, which is only one atom thick.
One advantage of using grapheme is the material’s extreme thinness. The lens like the one made by Zhong’s team could be layered on top of a conventional contact lens or integrated into a cell phone.
Graphene reacts strongly when struck by light. Zhong’s team used this property to build a three-layer light detector thin enough to place on a contact lens. The sensor uses two graphene layers with a funneling layer in between.
One layer of graphene is a million times thinner than a sheet of paper. Graphene is also the world’s strongest material.
Night vision scopes and goggles work by capturing light from the infrared portion of the electromagnetic spectrum. Infrared radiation is heat energy emitted by objects, rather than reflected light. This new sensor could one day lead to contact lenses that act like bulky old night vision goggles.
Zhong characterized the device as an “ultra-broadband photo-detector” built using layers of graphene. Their test device detected light from near-infrared through visible light.
The thin sensors could easily be used to create contact lenses with IR-vision, as a replacement for the bulky and expensive night vision goggles that represent the current state-of-the-art.
The technology has other potential uses. Doctors could use the ultra-thin IR sensors to monitor a patient’s blood. Art historians might use the technology to scan a painting, to get a look at the paint below the surface.
The low efficiency of graphene did pose a problem. A single layer of graphene absorbs roughly 2.3 percent of the light that hits it. Researchers managed to increase the light-gathering ability of graphene to amplify that low efficiency to a point where the light energy could generate an electrical signal.
The study that produced this new light sensor appeared in Nature Nanotechnology.
According to Zhong, current graphene-based sensors are a “hundred to a thousand times less” sensitive than necessary for a commercially-viable device. While there is still no such thing as night vision contact lenses, Zhong’s research could lead produce new sensors that act like night vision goggles.
Commentary By Chester Davis