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Wonder Material Brings New Light to Night-Vision Gear

June 2012
By Max Cacas, SIGNAL Magazine
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The U.S. Army is partnering with graphene researchers to enable low-cost thermal imaging for all warfighters.

Night-vision capability embedded in a smartphone could be in the future equipment pack of every military service member if the Army Research Laboratory and Northeastern University successfully tap into the promise of graphene—carbon atoms so tightly packed that they resemble a honeycomb. The laboratory has embarked on a three-year collaboration with the Boston-based school to develop a new generation of low-cost infrared imaging devices using the material.

“The goal of this project,” explains Dr. Madan Dubey, a research physical scientist with the Army Research Laboratory (ARL), “is to make a new kind of night-vision device which can work with optical and infrared images without additional cooling, and which are very cost-effective, robust and reliable.”

The ARL hopes to leverage scientific advances in the manipulation of graphene to create improved night-vision goggles, as well as other useful optical equipment for warfighters.

Graphene is widely considered by scientists around the world to be a wonder material with a long list of unusual and highly desirable characteristics. Its primary structure is just one atom thick, and it is composed of carbon atoms densely packed in a sheet-like honeycomb lattice. Layers or clusters of graphene form the basis for more familiar materials such as graphite, charcoal and carbon nanotubes.

But it is the long list of physical, electronic and optical properties of graphene that have had scientists excited for at least a decade. For example, graphene is 200 times stronger than structural steel, and it conducts electricity as well as copper. It is very lightweight and can be made from recyclable materials. Two physicists from Britain’s University of Manchester won the 2010 Nobel Prize for Physics for their work with graphene.

The project is a collaborative research agreement among the ARL’s Sensors and Electron Devices Directorate in Adelphi, Maryland; the Electronic Materials Research Institute (EMRI) at Northeastern’s College of Science; and the Microsystems Technology Office (MTO) at the Defense Advanced Research Projects Agency (DARPA). The agreement was signed last December.

The three-year program, which is funded in part by a $300,000 DARPA research grant, is designed to yield devices based on EMRI’s recent breakthroughs in graphene research, which can one day be manufactured in quantity and used by the military.

The special optical and heat-sensing properties of graphene attracted the ARL to the agreement with Northeastern scientists to develop those capabilities into a low-cost infrared imaging system.

Dubey says that researchers hope to overcome one significant limitation of current night-vision technology, which is that current devices only deal with images and thermal information from a narrow portion of the spectrum, known as part-color imaging. “If a particular wavelength is not in the camera detector, then the device will not see that image,” he explains.

A graphene-based night-vision device, he continues, will be able to process information from both a wider range of infrared information and from normal optical images in the same camera. The result, Dubey says, is that a soldier is less likely to be blindsided in the field by objects that might be missed using current technology night-vision equipment. “Day or night,” he says, “you’ll be able to use the same camera, which will be small and light and will have virtually no power requirement.”

Another unique characteristic of graphene is that combined with special chemicals, the material is capable of consistently generating small but storable amounts of electrical energy that can help reduce the outside power requirements currently supplied by batteries.

The collaborative agreement to develop new graphene-based night-vision devices for the military will build upon the work of Professor Srinivas Sridhar, director of Northeastern’s EMRI, and his colleague, Assistant Professor of Physics Swastik Kar, who have been researching graphene together for the last four years.

Sridhar explains that their work for the ARL will focus on developing improved graphene-based bolometers, the primary component in night-vision gear that measures heat generated by objects or people.

He explains that he and Kar have developed the ability to combine graphene with other chemical compounds to increase the sensitivity of the material to a wider range of thermal wavelengths, especially in what he calls the long-wave infrared band. Sridhar says that yet another benefit of graphene, which lends itself to developing low-cost night-vision devices, is the relative ease of producing the material.

“You can make sheets of this,” he says, as opposed to other electro-optical material now in use in night-vision devices, which require more costly and, in some cases, more toxic base materials. Because the basic material for graphene is a simple carbon atom, graphene also is a more environmentally friendly, renewable, recyclable and sustainable material for electronic devices. Dubey estimates that based on EMRI’s current research, the use of graphene-based sensors for night-vision equipment could reduce by a factor of 10 the cost of such devices within three to five years. Present-day night-vision equipment can range in price from $3,000 to $4,000.

The ARL-Northeastern EMRI graphene program is part of a DARPA program called Low Cost Thermal Imager–Manufacturing, which exploits cutting-edge materials research, according to Dr. Nibir Dhar, program manager with DARPA’s MTO. He says that, “The goal is to make these thermal cameras small, and very low-cost, so every warfighter can have one.”

Dhar explains that his office also is exploring carbon nanotubes (CNT). These nanotubes are molecule-width tubes constructed of clustered carbon atoms, joined in hexagonal arrangements, which have similar material and electronic characteristics as graphene. Just as with the ARL-Northeastern project, DARPA also is providing support for a parallel effort to embed CNT-based night vision inexpensively in handheld devices such as smartphones to improve the performance. DARPA is backing similar research partnership arrangements with other university institutions and defense contractors, with military research facilities such as the ARL serving as the supervising contract agents.

Based on current research, Dhar foresees numerous military and civilian applications beyond night-vision devices for graphene and CNT. Doctors one day will be able to create special graphene filters that will be able to block specific atoms of harmful bacteria from entering a patient’s bloodstream. The enhanced night-vision capabilities now being developed for the military could be used for improved safety devices in civilian automobiles. Research is underway into advanced manufacturing techniques, which could yield lightweight, flexible, roll-up computer and equipment displays built with graphene sheets.

Dubey reports that other researchers are exploring the high electrical conductivity characteristics of graphene that could one day make it possible for higher-bandwidth digital communications to transmit large data files more quickly. Because of its unique strengths, graphene also is seen as a possible material for a new generation of nanomechanical devices, such as microscopic pumps that can be used for the timed delivery of medication.

The ARL, DARPA and EMRI expect to have working proof-of-concept prototypes of graphene-based thermal-imaging/night-vision devices available for testing within the next three to four years.

WEB RESOURCES
Army Research Laboratory (ARL)-Northeastern graphene agreement: www.arl.army.mil/www/default.cfm?page=847
DARPA-Northeastern University-ARL graphene agreement: www.northeastern.edu/news/stories/2011/12/armyresearchlaboratory.html
ARL: www.arl.army.mil
Northeastern University Electronic Materials Research Institute: www.emri.neu.edu
DARPA Microsystems Technology Office: www.darpa.mil/Our_Work/MTO