New Graphene-Based Light Detector Could Peer Below the Surface of Bodies

First Posted: Sep 08, 2014 10:32 AM EDT
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Scientists have created a new detector that may eventually lead to a generation of devices that can peer below the surface of bodies, walls and other objects. Using graphene, scientists have constructed a prototype detector that can see a broad band of wavelengths.

The light that illuminates everyday objects actually consists of a very narrow band of wavelengths and frequencies. The ones used in the new device, though, include terahertz waves, which are invisible to the naked eye. Terahertz light waves' long wavelengths and low frequencies fall between microwaves and infrared waves. The light in these wavelengths can pass through materials that we normally think of as opaque, such as skin, plastics, clothing and cardboard. It can also be used to identify chemical signatures that are emitted only in the terahertz range.

In order to detect terahertz waves, the scientists turned to graphene, a single layer of interconnected carbon atoms. By utilizing the special properties of graphene, the researchers were able to increase the speed of the detector and maintain its sensitivity at room temperature; other detectors could only maintain their sensitivity at extremely cold temperatures around -452 degrees Fahrenheit.

"Light is absorbed by the electrons in graphene, which heat up but don't lose their energy easily," said Dennis Drew, one of the researchers, in a news release. "So they remain hot while the carbon atomic lattice remains cold."

The electrical signal detects the presence of terahertz waves beneath the surface of materials that appear opaque to the human eye. This could be extremely useful when it comes to imaging in the future. While X-rays go straight through the skin to the bone, this new detector represents an intermediate stage that allows researchers to see just beneath the layers of skin, for example. This opens the door to future discoveries when it comes to this in-between zone.

The findings are published in the journal Nature Nanotechnology.

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