Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Thermal vision: Graphene light detector first to span infrared spectrum

17.03.2014

The first room-temperature light detector that can sense the full infrared spectrum has the potential to put heat vision technology into a contact lens.

Unlike comparable mid- and far-infrared detectors currently on the market, the detector developed by University of Michigan engineering researchers doesn't need bulky cooling equipment to work.

"We can make the entire design super-thin," said Zhaohui Zhong, assistant professor of electrical engineering and computer science. "It can be stacked on a contact lens or integrated with a cell phone."

Infrared light starts at wavelengths just longer than those of visible red light and stretches to wavelengths up to a millimeter long. Infrared vision may be best known for spotting people and animals in the dark and heat leaks in houses, but it can also help doctors monitor blood flow, identify chemicals in the environment and allow art historians to see Paul Gauguin's sketches under layers of paint.

Unlike the visible spectrum, which conventional cameras capture with a single chip, infrared imaging requires a combination of technologies to see near-, mid- and far-infrared radiation all at once. Still more challenging, the mid-infrared and far-infrared sensors typically need to be at very cold temperatures.

Graphene, a single layer of carbon atoms, could sense the whole infrared spectrum—plus visible and ultraviolet light. But until now, it hasn't been viable for infrared detection because it can't capture enough light to generate a detectable electrical signal. With one-atom thickness, it only absorbs about 2.3 percent of the light that hits it. If the light can't produce an electrical signal, graphene can't be used as a sensor.

"The challenge for the current generation of graphene-based detectors is that their sensitivity is typically very poor," Zhong said. "It's a hundred to a thousand times lower than what a commercial device would require."

To overcome that hurdle, Zhong and Ted Norris, the Gerard A. Mourou Professor of Electrical Engineering and Computer Science, worked with graduate students to design a new way of generating the electrical signal. Rather than trying to directly measure the electrons that are freed when light hits the graphene, they amplified the signal by looking instead at how the light-induced electrical charges in the graphene affect a nearby current.

"Our work pioneered a new way to detect light," Zhong said. "We envision that people will be able to adopt this same mechanism in other material and device platforms."

To make the device, they put an insulating barrier layer between two graphene sheets. The bottom layer had a current running through it. When light hit the top layer, it freed electrons, creating positively charged holes. Then, the electrons used a quantum mechanical trick to slip through the barrier and into the bottom layer of graphene.

The positively charged holes, left behind in the top layer, produced an electric field that affected the flow of electricity through the bottom layer. By measuring the change in current, the team could deduce the brightness of the light hitting the graphene. The new approach allowed the sensitivity of a room-temperature graphene device to compete with that of cooled mid-infrared detectors for the first time.

The device is already smaller than a pinky nail and is easily scaled down. Zhong suggests arrays of them as infrared cameras.

"If we integrate it with a contact lens or other wearable electronics, it expands your vision," Zhong said. "It provides you another way of interacting with your environment."

While full-spectrum infrared detection is likely to find application in military and scientific technologies, the question for the general tech market may soon be, "Do we want to see in infrared?"

The device is described in a paper titled "Graphene photodetectors with ultra-broadband and high responsivity at room temperature," which appears online in Nature Nanotechnology.

###

This work was supported by the National Science Foundation in part through Michigan Engineering's Center for Photonic and Multiscale Nanomaterials, and was carried out with help from electrical engineering and computer science doctoral students Chang-Hua Liu and You-Chia Chang.

Zhaohui Zhong: http://www.eecs.umich.edu/zhonglab

Center for Photonic and Multiscale Nanomaterials: http://cphom.engin.umich.edu

Kate McAlpine | EurekAlert!

Further reports about: Photonic Thermal cameras detector electrons graphene lens sensitivity spectrum technologies wavelengths

More articles from Physics and Astronomy:

nachricht Active pits on Rosetta’s comet
03.07.2015 | Max Planck Institute for Solar System Research, Göttingen

nachricht Researchers find the macroscopic Brownian motion phenomena of self-powered liquid metal motors
02.07.2015 | Science China Press

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Viaducts with wind turbines, the new renewable energy source

Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.

The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...

Im Focus: X-rays and electrons join forces to map catalytic reactions in real-time

New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions

A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...

Im Focus: Iron: A biological element?

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...

Im Focus: Thousands of Droplets for Diagnostics

Researchers develop new method enabling DNA molecules to be counted in just 30 minutes

A team of scientists including PhD student Friedrich Schuler from the Laboratory of MEMS Applications at the Department of Microsystems Engineering (IMTEK) of...

Im Focus: Bionic eye clinical trial results show long-term safety, efficacy vision-restoring implant

Patients using Argus II experienced significant improvement in visual function and quality of life

The three-year clinical trial results of the retinal implant popularly known as the "bionic eye," have proven the long-term efficacy, safety and reliability of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

World Conference on Regenerative Medicine: Abstract Submission has been extended to 24 June

16.06.2015 | Event News

MUSE hosting Europe’s largest science communication conference

11.06.2015 | Event News

 
Latest News

Siemens receives order for offshore wind power plant in Great Britain

03.07.2015 | Press release

'Déjà vu all over again:' Research shows 'mulch fungus' causes turfgrass disease

03.07.2015 | Agricultural and Forestry Science

Discovery points to a new path toward a universal flu vaccine

03.07.2015 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>