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"Terradynamics" Could Help Designers Predict How Legged Robots Will Move on Granular Media

Thursday, March 21, 2013

Using a combination of theory and experiment, researchers have developed a new approach for understanding and predicting how small legged robots – and potentially also animals – move on and interact with complex granular materials such as sand.

The research could help create and advance the field of “terradynamics” – a name the researchers have given to the science of legged animals and vehicles moving on granular and other complex surfaces. Providing equations to describe and predict this type of movement – comparable to what has been done to predict the motion of animals and vehicles through the air or water – could allow designers to optimize legged robots operating in complex environments for search-and-rescue missions, space exploration or other tasks.

“We now have the tools to understand the movement of legged vehicles over loose sand in the same way that scientists and engineers have had tools to understand aerodynamics and hydrodynamics,” said Daniel Goldman, a professor in the School of Physics at the Georgia Institute of Technology. “We are at the beginning of tools that will allow us to do the design and simulation of legged robots to not only predict their performance, but also to optimize designs and allow us to create new concepts.”

The research behind “terradynamics” was described in the March 22 issue of the journal Science. The research was supported by the National Science Foundation Physics of Living Systems program, the Army Research Office, the Army Research Laboratory, the Burroughs Wellcome Fund and the Miller Institute for Basic Research in Science of the University of California, Berkeley.

Robots such as the Mars Rover have depended on wheels for moving in complex environments such as sand and rocky terrain. Robots envisioned for autonomous search-and-rescue missions also rely on wheels, but as the vehicles become smaller, designers may need to examine alternative means of locomotion, Goldman said.

Existing techniques for describing locomotion on surfaces are complex and can’t take into account the intrusion of legs into a granular surface. To improve and simplify the understanding, Goldman and collaborators Chen Li and Tingnan Zhang examined the motion of a small legged robot as it moved on granular media. Using a 3-D printer, they created legs in a variety of shapes and used them to study how different configurations affected the robot’s speed along a track bed. They then measured granular force laws from experiments to predict forces on legs, and created simulation to predict the robot’s motion.

The key insight, according to Goldman, was that the forces applied to independent elements of the robot legs could be simply summed together to provide a reasonably accurate measure of the net force on a robot moving through granular media. That technique, known as linear superposition, worked surprisingly well for legs moving in diverse kinds of granular media.

“We discovered that the force laws affecting this motion are generic in a diversity of granular media, including poppy seeds, glass beads and natural sand,” said Li, who is now a Miller postdoctoral fellow at the University of California at Berkeley. “Based on this generalization, we developed a practical procedure for non-specialists to easily apply terradynamics in their own studies using just a single force measurement made with simple equipment they can buy off the shelf, such as a penetrometer.”

For more complicated granular materials, although the terradynamics approach still worked well, an additional factor – perhaps the degree to which particles resemble a sphere – may be required to describe the forces with equivalent accuracy.

Beyond understanding the basic physics principles involved, the researchers also learned that convex legs made in the shape of the letter “C” worked better than other variations.

“As long as the legs are convex, the robot generates large lift and small body drag, and thus can run fast,” Goldman said. “When the limb shape was changed to flat or concave, the performance dropped. This information is important for optimizing the energy efficiency of legged robots.”

Aerodynamic designers have long used a series of equations known as Navier-Stokes to describe the movement of vehicles through the air. Similarly, these equations also allow hydrodynamics designers to know how submarines and other vehicles move through water.

“Terradynamics” could provide designers with an efficient technique for understanding motion through media that flows around legs of terrestrial animals and robots.

“Using terradynamics, our simulation is not only as accurate as the established discrete element method (DEM) simulation, but also much more computationally efficient,” said Zhang, who is a graduate student in Goldman’s laboratory. “For example, to simulate one second of robot locomotion on a granular bed of five million poppy seeds takes the DEM simulation a month using computers in our lab. Using terradynamics, the simulation takes only 10 seconds.”

The six-legged experimental robot was just 13 centimeters long and weighed about 150 grams. Robots of that size could be used in the future for search-and-rescue missions, or to scout out unknown environments such as the surface of Mars. They could also provide biologists with a better understanding of how animals such as sand lizards run and kangaroo rats hop on granular media.

“From a biological perspective, this opens up a new area,” said Goldman, who has studied a variety of animals to learn how their locomotion may assist robot designers. “These are the kinds of tools that can help understand why lizards have feet and bodies of certain shapes. The problems associated with movement in sandy environments are as important to many animals as they are to robots.”

Beyond optimizing the design of future small robots, the work could also lead to a better understanding of the complex environment through which they will have to move.

“We think that the kind of approach we are taking allows us to ask questions about the physics of granular materials that no one has asked before,” Goldman added. “This may reveal new features of granular materials to help us create more comprehensive models and theories of motion. We are now beginning to get the rules of how vehicles move through these materials.”

This research was supported by the Burroughs Wellcome Fund, the Army Research Laboratory Micro Autonomous Systems and Technology Collaborative Technology Alliance (CTA W911NF-08-2-004), the Army Research Office (W911NF-11-1-0514), the National Science Foundation (NSF) Physics of Living Systems program (PHY-1150760) and the Miller Institute for Basic Research in Science at the University of California, Berkeley. Any conclusions are those of the principal investigators, and do not necessarily represent the official position of the Army Research Laboratory, the Army Research Office or the NSF.

CITATION: Chen Li, Tingnan Zhang, Daniel I. Goldman. “A Terradynamics of Legged Locomotion on Granular Media,” Science (2013): http://dx.doi.org/10.1126/science.1229163.

Research News
Georgia Institute of Technology
177 North Avenue
Atlanta, Georgia  30332-0181

Media Relations Contact: John Toon (404-894-6986)(jtoon@gatech.edu).

Writer: John Toon

Media Contact: 

John Toon

Research News

jtoon@gatech.edu

(404) 894-6986

Summary: 

Using a combination of theory and experiment, researchers have developed a new approach for understanding and predicting how small legged robots – and potentially also animals – move on and interact with complex granular materials such as sand.

Intro: 

Using a combination of theory and experiment, researchers have developed a new approach for understanding and predicting how small legged robots – and potentially also animals – move on and interact with complex granular materials such as sand.

Alumni: 

Dynamics Days US 2014

Thursday, January 2, 2014

Dynamics Days 2014

International Conference on Chaos and Nonlinear Dynamics

Georgia Tech Campus

Clough Undergraduate Learning Commons - Room 152

Host: Roman Grigoriev


Summary: 

Dynamic Days 2014: January 2-5

Intro: 

Dynamic Days 2014: January 2-5

Alumni: 

Fabrication on Patterned Silicon Carbide Produces Bandgap for Graphene-Based Electronics

Sunday, November 18, 2012

By fabricating graphene structures atop nanometer-scale “steps” etched into silicon carbide, researchers have for the first time created a substantial electronic bandgap in the material suitable for room-temperature electronics. Use of nanoscale topography to control the properties of graphene could facilitate fabrication of transistors and other devices, potentially opening the door for developing all-carbon integrated circuits.

Researchers have measured a bandgap of approximately 0.5 electron-volts in 1.4-nanometer bent sections of graphene nanoribbons. The development could provide new direction to the field of graphene electronics, which has struggled with the challenge of creating bandgap necessary for operation of electronic devices.

“This is a new way of thinking about how to make high-speed graphene electronics,” said Edward Conrad, a professor in the School of Physics at the Georgia Institute of Technology. “We can now look seriously at making fast transistors from graphene. And because our process is scalable, if we can make one transistor, we can potentially make millions of them.”

The findings were reported November 18 in the journal Nature Physics. The research, done at the Georgia Institute of Technology in Atlanta and at SOLEIL, the French national synchrotron facility, has been supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Georgia Tech, the W.M. Keck Foundation and the Partner University Fund from the Embassy of France.

Researchers don’t yet understand why graphene nanoribbons become semiconducting as they bend to enter tiny steps – about 20 nanometers deep – that are cut into the silicon carbide wafers. But the researchers believe that strain induced as the carbon lattice bends, along with the confinement of electrons, may be factors creating the bandgap. The nanoribbons are composed of two layers of graphene.

Production of the semiconducting graphene structures begins with the use of e-beams to cut “trenches” into silicon carbide wafers, which are normally polished to create a flat surface for the growth of epitaxial graphene. Using a high-temperature furnace, tens of thousands of graphene ribbons are then grown across the steps, using photolithography.

During the growth, the sharp edges of trenches become smoother as the material attempts to regain its flat surface. The growth time must therefore be carefully controlled to prevent the narrow silicon carbide features from melting too much.

The graphene fabrication also must be controlled along a specific direction so that the carbon atom lattice grows into the steps along the material’s “armchair” direction. “It’s like trying to bend a length of chain-link fence,” Conrad explained. “It only wants to bend one way.”

The new technique permits not only the creation of a bandgap in the material, but potentially also the fabrication of entire integrated circuits from graphene without the need for interfaces that introduce resistance. On either side of the semiconducting section of the graphene, the nanoribbons retain their metallic properties.

“We can make thousands of these trenches, and we can make them anywhere we want on the wafer,” said Conrad. “This is more than just semiconducting graphene. The material at the bends is semiconducting, and it’s attached to graphene continuously on both sides. It’s basically a Shottky barrier junction.”

By growing the graphene down one edge of the trench and then up the other side, the researchers could in theory produce two connected Shottky barriers – a fundamental component of semiconductor devices. Conrad and his colleagues are now working to fabricate transistors based on their discovery.

Confirmation of the bandgap came from angle-resolved photoemission spectroscopy measurements made at the Synchrotron CNRS in France. There, the researchers fired powerful photon beams into arrays of the graphene nanoribbons and measured the electrons emitted.

“You can measure the energy of the electrons that come out, and you can measure the direction from which they come out,” said Conrad. “From that information, you can work backward to get information about the electronic structure of the nanoribbons.”

Theorists had predicted that bending graphene would create a bandgap in the material. But the bandgap measured by the research team was larger than what had been predicted.

Beyond building transistors and other devices, in future work the researchers will attempt to learn more about what creates the bandgap – and how to control it. The property may be controlled by the angle of the bend in the graphene nanoribbon, which can be controlled by altering the depth of the step.

“If you try to lay a carpet over a small imperfection in the floor, the carpet will go over it and you may not even know the imperfection is there,” Conrad explained. “But if you go over a step, you can tell. There are probably a range of heights in which we can affect the bend.”

He predicts that the discovery will create new activity as other graphene researchers attempt to utilize the results.

“If you can demonstrate a fast device, a lot of people will be interested in this,” Conrad said. “If this works on a large scale, it could launch a niche market for high-speed, high-powered electronic devices.”

In addition to Conrad, the research team included J. Hicks, M.S. Nevius, F. Wang, K. Shepperd, J. Palmer, J. Kunc, W.A. De Heer and C. Berger, all from Georgia Tech; A. Tejeda from the Institut Jean Lamour, CNES – Univ. de Nancy and the Synchrotron SOLEIL; A. Taleb-Ibrahimi from the CNRS/Synchrotron SOLEIL, and F. Bertran and P. Le Fevre from Synchrotron SOLEIL.

This research was supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Georgia Tech under Grants DMR-0820382 and DMR-1005880, the W.M. Keck Foundation, and the Partner University Fund from the Embassy of France. The content of the article is the responsibility of the authors and does not necessarily represent the views of the National Science Foundation.

CITATION: Hicks, J., A wide-bandgap metal-semiconductor-metal nanostructure made entirely from graphene, Nature Physics (2012). http://dx.doi.org/10.1038/NPHYS2487.

Research News & Publications Office
Georgia Institute of Technology
177 North Avenue
Atlanta, Georgia  30332-0181

Media Relations Contact: John Toon (404-894-6986)(jtoon@gatech.edu)
Writer: John Toon

Media Contact: 

John Toon

Research News & Publications Office

(404) 894-6986

jtoon@gatech.edu

Summary: 

By fabricating graphene structures atop nanometer-scale “steps” etched into silicon carbide, researchers have for the first time created a substantial electronic bandgap in the material suitable for room-temperature electronics. Use of nanoscale topography to control the properties of graphene could facilitate fabrication of transistors and other devices, potentially opening the door for developing all-carbon integrated circuits.

Intro: 

By fabricating graphene structures atop nanometer-scale “steps” etched into silicon carbide, researchers have for the first time created a substantial electronic bandgap in the material suitable for room-temperature electronics. Use of nanoscale topography to control the properties of graphene could facilitate fabrication of transistors and other devices, potentially opening the door for developing all-carbon integrated circuits.

Alumni: 

Study Shows How a Hopping Robot Could Conserve its Energy

Friday, October 26, 2012

A new study shows that jumping can be much more complicated than it might seem. In research that could extend the range of future rescue and exploration robots, scientists have found that hopping robots could dramatically reduce their power demands by adopting a unique two-part “stutter jump.”

Taking a short hop before a big jump could allow spring-based “pogo-stick” robots to reduce their power demands as much as ten-fold. The formula for the two-part jump was discovered by analyzing nearly 20,000 jumps made by a simple laboratory robot under a wide range of conditions.

“If we time things right, the robot can jump with a tenth of the power required to jump to the same height under other conditions,” said Daniel Goldman, an assistant professor in the School of Physics at the Georgia Institute of Technology. “In the stutter jumps, we can move the mass at a lower frequency to get off the ground. We achieve the same takeoff velocity as a conventional jump, but it is developed over a longer period of time with much less power.”

The research was reported October 26 in the journal Physical Review Letters. The work was supported by the Army Research Laboratory’s MAST program, the Army Research Office, the National Science Foundation, the Burroughs Wellcome Fund and the GEM Fellowship.

Jumping is an important means of locomotion for animals, and could be important to future generations of robots. Jumping has been extensively studied in biological organisms, which use stretched tendons to store energy.

The Georgia Tech research into robot jumping began with a goal of learning how hopping robots would interact with complicated surfaces – such as sand, granular materials or debris from a disaster. Goldman quickly realized he’d need to know more about the physics of jumping to separate the surface issues from the factors controlled by the dynamics of jumping.

Inspired by student-directed experiments on the dynamics of hopping in his nonlinear dynamics and chaos class, Goldman asked Jeffrey Aguilar, a graduate student in the George W. Woodruff School of Mechanical Engineering, to construct the simplest jumping robot.

Aguilar built a one-kilogram robot that is composed of a spring beneath a mass capable of moving up and down on a thrust rod. Aguilar used computer controls to vary the starting position of the mass on the rod, the amplitude of the motion, the pattern of movement and the frequency of movement applied by an actuator built into the robot’s mass. A high-speed camera and a contact sensor measured and recorded the height of each jump.

Aguilar and Goldman then collaborated with theorists Professor Kurt Wiesenfeld and Alex Lesov, from the Georgia Tech School of Physics, to explain the results of the experiments.

The researchers expected to find that the optimal jumping frequency would be related to the resonant frequency of the spring and mass system, but that turned out not to be true. Detailed evaluation of the jumps showed that frequencies above and below the resonance provided optimal jumping – and additional analysis revealed what the researchers called the “stutter jump.”

“The preparatory hop allows the robot to time things such that it can use a lower power to get to the same jump height,” Goldman explained. “You really don’t have to move the mass rapidly to get a good jump.”

The amount of energy that can be stored in batteries can limit the range and duration of robotic missions, so the stutter jump could be helpful for small robots that have limited power. Optimizing the efficiency of jumping could therefore allow the robots to complete longer and more complex missions.

But because it requires longer to perform than a simple jump, the two-step jump may not be suitable for all conditions.

“If you’re a small robot and you want to jump over an obstacle, you could use low power by using the stutter jump even though that would take longer,” said Goldman. “But if a hazard is threatening, you may need to generate the additional power to make a quick jump to get out of the way.”

For the future, Goldman and his research team plan to study how complicated surfaces affect jumping. They are currently studying the effects of sand, and will turn to other substrates to develop a better understanding of how exploration or rescue robots can hop through them.

Goldman’s past work has focused on the lessons learned from the locomotion of biological systems, so the team is also interested in what the robot can teach them about how animals jump. “What we have learned here can function as a hypothesis for biological systems, but it may not explain everything,” he said.

The simple jumping robot turned out to be a useful system to study, not only because of the interesting behaviors that turned up, but also because the results were counter to what the researchers had expected.

“In physics, we often study the steady-state solution,” Goldman noted. “If we wait enough time for the transient phenomena to die off, then we can study what’s left. It turns out that in this system, we really care about the transients.”

This research is supported by the Army Research Laboratory under cooperative agreement number W911NF-08-2-004, by the Army Research Office under cooperative agreement W911NF-11-1-0514, and by the National Science Foundation under contract PoLS PHY-1150760. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Army Research Laboratory, the Army Research Office or the National Science Foundation.

CITATION: Aguilar, Jeffrey et al., “Lift-off dynamics in a simple jumping robot,” Physical Review Letters (2012): http://prl.aps.org/abstract/PRL/v109/i17/e174301

Research News & Publications Office
Georgia Institute of Technology
75 Fifth Street, N.W., Suite 309
Atlanta, Georgia  30308  USA

Media Relations Contact: John Toon (404-894-6986)(jtoon@gatech.edu)
Writer: John Toon

Media Contact: 

John Toon

Research News  & Publications Office

(404) 894-6986

jtoon@gatech.edu

Summary: 

A new study shows that jumping can be much more complicated than it might seem. In research that could extend the range of future rescue and exploration robots, scientists have found that hopping robots could dramatically reduce their power demands by adopting a unique two-part “stutter jump.”

Intro: 

A new study shows that jumping can be much more complicated than it might seem. In research that could extend the range of future rescue and exploration robots, scientists have found that hopping robots could dramatically reduce their power demands by adopting a unique two-part “stutter jump.”

Alumni: 

Georgia Tech Joins the NSF Physics of Living Systems Student Research Network

Friday, September 21, 2012

The Georgia Institute of Technology has become the newest node in the National Science Foundation’s (NSF) Physics of Living Systems Student Research Network.

Principal investigators on the project include Physics Assistant Professors Daniel Goldman, Jennifer Curtis and Harold Kim; School of Biology Associate Professor Joshua Weitz, who also holds an adjunct appointment in the School of Physics; and Assistant Professor David Hu, who holds a joint appointment in the George W. Woodruff School of Mechanical Engineering and the School of Biology. School of Physics Professor Kurt Wiesenfeld will serve as a senior adviser for the network.

For the full article, please visit http://www.gatech.edu/newsroom/release.html?nid=156081

Summary: 

The Georgia Institute of Technology has become the newest node in the National Science Foundation’s (NSF) Physics of Living Systems Student Research Network.

Intro: 

The Georgia Institute of Technology has become the newest node in the National Science Foundation’s (NSF) Physics of Living Systems Student Research Network.

Alumni: 

Regents Professor Walter de Heer has been awarded the 2012 Jesse W. Beams Research Award

Friday, September 21, 2012

 

Regents Professor Walter de Heer has been awarded the 2012 Jesse W. Beams Research Award by the Southeastern Section of the American Physical Society.

The Beams Award honors those whose research led to the discovery of new phenomena or states of matter, provided fundamental insights in physics, or involved the development of experimental or theoretical techniques that enabled others to make key advances in physics with critical acclaim of peers nationally and internationally.

Summary: 

Regents Professor Walter de Heer has been awarded the 2012 Jesse W. Beams Research Award by the Southeastern Section of the American Physical Society.

Intro: 

Regents Professor Walter de Heer has been awarded the 2012 Jesse W. Beams Research Award by the Southeastern Section of the American Physical Society.

Alumni: 

Xtreme Astrophysics: A Center for Relativistic Astrophysics Mini-Symposium

Wednesday, August 22, 2012

In celebration of its 4th anniversary, the Center for Relativistic Astrophysics is hosting the mini-symposium Xtreme Astrophysics.

The mini-symposium is an opportunity for participants to share their insights and experience on research focusing on extreme astrophysical phenomena such as black holes, gamma ray bursts, cosmology and sources of the high energy gamma rays and neutrinos.

The mini-symposium will be held Monday and Tuesday, August 27 & 28 at Room 1-90 (CRA Visualization room) in the Boggs Building at Georgia Tech, 770 State St, Atlanta GA, 30332.

 

There is no registration. For more information contact Pablo Laguna at plaguna [at] gatech.edu.

Summary: 

In celebration of its 4th anniversary, the Center for Relativistic Astrophysics is hosting the mini-symposium Xtreme Astrophysics.

Intro: 

In celebration of its 4th anniversary, the Center for Relativistic Astrophysics is hosting the mini-symposium Xtreme Astrophysics.

Alumni: 

Cesar Flores awarded 2012 PhD fellowship from CONACyT

Thursday, August 9, 2012

Cesar Flores, PhD Candidate in Physics, was awarded a prestigious 2012 PhD fellowship from CONACyT for his doctoral work on "Structural analysis of infection networks between viruses and bacteria."  

CONACyT is the National Council for Science and Technology in Mexico.  CONACyT fellowships are awarded on a competitive basis to support the doctoral research of Mexican nationals both in Mexico and abroad.

Mr. Flores will continue his research in the group of Joshua Weitz at Georgia Tech: http://ecotheory.biology.gatech.edu

Summary: 

Cesar Flores, PhD Candidate in Physics, was awarded a prestigious 2012 PhD fellowship from CONACyT.

Intro: 

Cesar Flores, PhD Candidate in Physics, was awarded a prestigious 2012 PhD fellowship from CONACyT.

Alumni: 

NuSTAR Provides New Look at Black Holes

Monday, June 11, 2012

When NASA launches a new telescope this Wednesday that will look at black holes in ways never seen before, Georgia Tech astrophysicist David Ballantyne will be more than a curious bystander. He helped plan the mission.

Ballantyne, one of the Institute’s black hole experts, is on the science team of NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which is scheduled for launch Wednesday morning. He’s one of a handful of people who decided where the high-energy X-ray telescope will point while in orbit. NuSTAR’s technology will allow it to image areas of the universe in never-before-seen ways. Ballantyne will be among the first scientists to see the images and examine the data when it becomes available this later this summer.  

“NuSTAR will provide a window to the murky world of black holes,” said Ballantyne, an assistant professor in the School of Physics. “The high-energy X-ray technology will allow us to see black holes that are buried deep inside their galaxies, hidden behind thick clouds of dust and gas. The goal is to unmask these black holes, study their host galaxies, and figure out how the black holes affect galaxy formation and evolution.”

Ballantyne has worked on the project, which is overseen by Fiona Harrison, a professor at the California Institute of Technology, since 2007. He and his peers have plotted three areas in the sky to survey, the largest of which spans approximately five full moons. Together, the surveys will uncover about 500 black holes, some of which have never been detected by any other telescope.

Seeing more means learning more, according to Ballantyne. He compares the study of black holes with learning about mankind.

“If you knew nothing about humans and looked at one person, you would quickly discover that we have two eyes, a nose and a mouth,” said Ballantyne. “But the deeper knowledge – traits such as aging, cultures – is only discovered by looking at a wide range of people. The more black holes we discover and study, the more we will understand about their roles in the cosmos.”

NuSTAR is the first telescope capable of focusing high-energy X-rays. It will also map supernova explosions and microflares on the surface of the sun. It is the first American high-energy telescope launched since 2008 and the last one for the foreseeable future. There are no other planned projects. 

NuSTAR will lift off aboard an airplane in the South Pacific. The plane will then launch a Pegasus rocket, which will carry the telescope into orbit. Images and data should be available for Ballantyne and his colleagues about a month after liftoff. Selected images and science stories will be made available for the public throughout the mission.

NuSTAR is a Small Explorer mission led by the California Institute of Technology and managed by NASA's Jet Propulsion Laboratory, both in Pasadena, Calif., for NASA's Science Mission Directorate. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center in Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Calif.; and ATK Aerospace Systems, Goleta, Calif. NuSTAR will be operated by UC Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

Summary: 

Georgia Tech researcher on science team of new NASA telescope

Intro: 

Georgia Tech researcher on science team of new NASA telescope

Alumni: 

Metastable Material: Study Shows Availability of Hydrogen Controls Chemical Structure of Graphene Oxide

Thursday, May 24, 2012

A new study shows that the availability of hydrogen plays a significant role in determining the chemical and structural makeup of graphene oxide, a material that has potential uses in nano-electronics, nano-electromechanical systems, sensing, composites, optics, catalysis and energy storage.

The study also found that after the material is produced, its structural and chemical properties continue to evolve for more than a month as a result of continuing chemical reactions with hydrogen.

Understanding the properties of graphene oxide – and how to control them – is important to realizing potential applications for the material. To make it useful for nano-electronics, for instance, researchers must induce both an electronic band gap and structural order in the material. Controlling the amount of hydrogen in graphene oxide may be the key to manipulating the material properties.

“Graphene oxide is a very interesting material because its mechanical, optical and electronic properties can be controlled using thermal or chemical treatments to alter its structure,” said Elisa Riedo, an associate professor in the School of Physics at the Georgia Institute of Technology. “But before we can get the properties we want, we need to understand the factors that control the material’s structure. This study provides information about the role of hydrogen in the reduction of graphene oxide at room temperature.”

The research, which studied graphene oxide produced from epitaxial graphene, was reported on May 6 in the journal Nature Materials. The research was sponsored by the National Science Foundation, the Materials Research Science and Engineering Center (MRSEC) at Georgia Tech, and by the U.S. Department of Energy.

(For the full article, please visit this page)

Summary: 

Metastable Material: Study Shows Availability of Hydrogen Controls Chemical Structure of Graphene Oxide

Intro: 

Metastable Material: Study Shows Availability of Hydrogen Controls Chemical Structure of Graphene Oxide

Alumni: 

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