Printed protection: Low-cost paper-based wireless sensor could help detect explosive devices

ScienceDaily (Oct. 27, 2011) — Researchers at the Georgia Institute of Technology have developed a prototype wireless sensor capable of detecting trace amounts of a key ingredient found in many explosives.

The device, which employs carbon nanotubes and is printed on paper or paper-like material using standard inkjet technology, could be deployed in large numbers to alert authorities to the presence of explosives, such as improvised explosive devices (IEDs).

"This prototype represents a significant step toward producing an integrated wireless system for explosives detection," said Krishna Naishadham, a principal research scientist who is leading the work at the Georgia Tech Research Institute (GTRI). "It incorporates a sensor and a communications device in a small, low-cost package that could operate almost anywhere."

Other types of hazardous gas sensors are based on expensive semiconductor fabrication and gas chromatography, Naishadham said, and they consume more power, require human intervention, and typically do not operate at ambient temperatures. Furthermore, those sensors have not been integrated with communication devices such as antennas.

The wireless component for communicating the sensor information -- a resonant lightweight antenna -- was printed on photographic paper using inkjet techniques devised by Professor Manos Tentzeris of Georgia Tech's School of Electrical and Computer Engineering. Tentzeris is collaborating with Naishadham on development of the sensing device.

The sensing component, based on functionalized carbon nanotubes (CNTs), has been fabricated and tested for detection sensitivity by Xiaojuan (Judy) Song, a GTRI research scientist. The device relies on carbon-nanotube materials optimized by Song.

A presentation on this sensing technology was given in July at the IEEE Antennas and Propagation Symposium (IEEE APS) in Spokane, Wash., by Hoseon Lee, a Ph.D. student in ECE co-advised by Tentzeris and Naishadham. The paper received the Honorable Mention Award in the Best Student Paper competition at the symposium.

This is not the first inkjet-printed ammonia sensor that has been integrated with an antenna on paper, said Tentzeris. His group produced a similar integrated sensor last year in collaboration with the research group of C.P. Wong, who is Regents professor and Smithgall Institute Endowed Chair in the School of Materials Science and Engineering at Georgia Tech.

"The fundamental difference is that this newest CNT sensor possesses dramatically improved sensitivity to miniscule ammonia concentrations," Tentzeris said. "That should enable the first practical applications to detect trace amounts of hazardous gases in challenging operational environments using inkjet-printed devices."

Tentzeris explained that the key to printing components, circuits and antennas lies in novel "inks" that contain silver nanoparticles in an emulsion that can be deposited by the printer at low temperatures -- around 100 degrees Celsius. A process called sonication helps to achieve optimal ink viscosity and homogeneity, enabling uniform material deposition and permitting maximum operating effectiveness for paper-based components.

"Ink-jet printing is low-cost and convenient compared to other technologies such as wet etching," Tentzeris said. "Using the proper inks, a printer can be used almost anywhere to produce custom circuits and components, replacing traditional clean-room approaches."

Low-cost materials -- such as heavy photographic paper or plastics like polyethylene terephthalate -- can be made water resistant to ensure greater reliability, he added. Inkjet component printing can also use flexible organic materials, such as liquid crystal polymer (LCP), which are known for their robustness and weather resistance. The resulting components are similar in size to conventional components but can conform and adhere to almost any surface.

Naishadham explained that the same inkjet techniques used to produce RF components, circuits and antennas can also be used to deposit the functionalized carbon nanotubes used for sensing. These nanoscale cylindrical structures -- about one-billionth of a meter in diameter, or 1/50,000th the width of a human hair -- are functionalized by coating them with a conductive polymer that attracts ammonia, a major ingredient found in many IEDs.

Sonication of the functionalized carbon nanotubes produces a uniform water-based ink that can be printed side-by-side with RF components and antennas to produce a compact wireless sensor node.

"The optimized carbon nanotubes are applied as a sensing film, with specific functionalization designed for a particular gas or analyte," Song said. "The GTRI sensor detects trace amounts of ammonia usually found near explosive devices, and it can also be designed to detect similar gases in household, healthcare and industrial environments at very low concentration levels."

The sensor has been designed to detect ammonia in trace amounts -- as low as five parts per million, Naishadham said.

The resulting integrated sensing package can potentially detect the presence of trace explosive materials at a distance, without endangering human lives. This approach, called standoff detection, involves the use of RF technology to identify explosive materials at a relatively safe distance. The GTRI team has designed the device to send an alert to nearby personnel when it detects ammonia.

The wireless sensor nodes require relatively low power, which could come from a number of technologies including thin-film batteries, solar cells or power-scavenging and energy-harvesting techniques. In collaboration with Tentzeris's and Wong's groups, GTRI is investigating ways to make the sensor operate passively, without any power consumption.

"We are focusing on providing standoff detection for those engaged in military or humanitarian missions and other hazardous situations," Naishadham said. "We believe that it will be possible, and cost-effective, to deploy large numbers of these detectors on vehicles or robots throughout a military engagement zone."

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The above story is reprinted from materials provided by Georgia Institute of Technology Research News. The original article was written by Rick Robinson.

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SideBySide projection system enables projected interaction between mobile devices

ScienceDaily (Oct. 20, 2011) — Researchers at Disney Research, Pittsburgh, and Carnegie Mellon University have devised a system called SideBySide that enables animated images from two separate handheld projectors to interact with each other on the same surface.

The system, suitable for games, education and a variety of other applications, is self-contained in special handheld devices. No external cameras or other sensors are required, which enables people to use the projectors to interact with each other anywhere and at anytime. SideBySide also can be used to exchange contact information, or even share data files. The technology can spur a more participatory and intimate style of interaction than is possible with computers or overhead projectors.

"Smartphones have made it possible for us to communicate, play games and retrieve information from the Web wherever we might be, but our interaction with the devices remains a largely solitary, single user experience," said Karl D.D. Willis, a Ph.D. candidate in computational design at Carnegie Mellon and a lab associate at Disney Research. "Now that handheld projectors have become a reality, we finally have a technology that allows us to create a new way for people to interact in the real world."

The handheld projectors are hybrid devices that emit both visible and infrared light and contain a camera for monitoring the projected images, a ranging sensor and an inertial measurement unit.

The infrared channel plays a key role in enabling interaction. It is used to project markers that help the system recognize when the images are moving or overlapping and to communicate information between the devices.

The researchers have developed a number of applications to demonstrate the capabilities of the technology. Games include Boxing, in which matches are performed without a ring; Cannon, in which players knock a stack of bricks off a platform by firing a cannon ball from one screen to another; and Gorilla, in which one player uses a plane and a net to catch the other player's gorilla. They also have developed a 3D viewer, which allows two users to control and explore a 3D model together, and applications for exchanging contact information and transferring files. A question & answer application can be used to teach basic vocabulary to young children.

A video demonstrating SideBySide can be viewed at http://www.disneyresearch.com/research/projects/hci_sidebyside_drp.htm

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Smartphone Accelerometers Could Be Used To Eavesdrop On Nearby Devices

Smartphone Accelerometers Could Be Used To Eavesdrop On Nearby Devices | Popular Science@import "/files/css/1857af3413d9ad8bd2f9d3926af8ec39.css";@import "/files/css/33f6b7ecb4513ed2fe6c670880a27187.css"; home Login/Register Newsletter Subscribe RSS GadgetsComputersCamerasSmartphonesVideo GamesCarsConceptsHybridsElectric CarsScienceFuture of the EnvironmentEnergyHealthPopSci Eco TourTechnologyMilitaryAviationSpaceRobotsEngineeringDIYProjectsHacksToolsAuto DIYMore From Our Partner: Toolmonger GalleriesVideosColumnsThe GrouseSex FilesGreen Dream Innovation ChallengesHow It WorksFeatures Tweet Digg Smartphone Accelerometers Could Be Used To Eavesdrop On Nearby Devices By Rebecca Boyle Posted 10.19.2011 at 11:07 am 3 Comments
SpyPhone Patrick Traynor shows off the "SpiPhone" app he created to tap keystrokes with phone accelerometers. Georgia Tech

As you logged in to write a comment this morning, think about where your smartphone was sitting. Was it next to your keyboard, where you could ensure you didn’t miss any notifications? If so, your phone could track everything you wrote. It could use the accelerometer to detect keyboard vibrations, deciphering every word of your insightful anonymous commentary. A hacker could conceivably use it to find out everything you write, with up to 80 percent accuracy, researchers say.

Here’s how it would work: An accelerometer samples a phone’s vibration about 100 times per second, so it would be able to detect pairs of keystrokes, according to a Georgia Tech news release about this research. It would model “keyboard events” and determine where the pairs of keys are located on the keyboard, and how far apart they are. Then it would compare the results against a dictionary the researchers developed for this demonstration. The dictionary defines words based on their locations on a typical QWERTY keyboard, like left/right or near/far. So in Georgia Tech’s example, the word “canoe” would translate to c-a, a-n, n-o, o-e possibilities. That works out to left-left-near, and so on. The location code is checked against the dictionary, and it turns up “canoe” as the most likely word.

Related ArticlesA DIY UAV That Hacks Wi-Fi Networks, Cracks Passwords, and Poses as a Cell Phone TowerYour iPhone Keeps a Secret Log of Everywhere You Go, Security Experts FindLast Shuttle Mission Will Carry iPhones to the Space StationTagsTechnology, Rebecca Boyle, accelerometer, iphone, keystrokes, malware, smartphones, spying, spyware, typingUsing a dictionary of about 58,000 words, the researchers were able to decipher typing with about 80 percent accuracy.

Researchers have studied smartphone as spy-phone before, using the phones’ microphones to sample vibrations and decipher keystrokes. But they are very sensitive and so a much more obvious security risk — many smartphones now will ask users to give a new app permission to access sensors like microphones. Not accelerometers, however. So how would an app with this capability get onto your smartphone? The authors of this study say it would probably be included as malware on an innocent-seeming app. Then when the phone is placed next to a keyboard, the malware turns on and starts listening, sending data to a hacker who wants to know what you have to say.

Granted, this all works only if your phone is pretty proximate to your keyboard, admits Patrick Traynor, an assistant professor in Georgia Tech’s School of Computer Science who was involved in the study. So just keep it elsewhere on your desk or in your bag. Plus it’s unlikely that anyone has to worry about this right now, he added.

“This was really hard to do. But could people do it if they really wanted to? We think yes.”

The work is being presented Thursday at the ACM Conference on Computer and Communications Security in Chicago.

Previous Article: Wearable Projector and Kinect-Like Camera Turns Any Object Into a TouchscreenNext Article: Germany's ROSAT Satellite Could Come Crashing Down Somewhere On Earth As Soon As Friday 3 Comments Link to this comment Midoman 10/19/11 at 11:39 am

SuperPhones take Phreaking to a whole new level.

Link to this comment Q 10/19/11 at 12:42 pm

The CIA, FBI, others and other countries have been doing this for years, but with big large electronics. I suppose what is novel today it's now an App.

Besides Governmental offices locking down what type of cell phones can be brought into their areas, this also applies to civilian companies.

This will open the door to gaining access to logins and passwords, everywhere.

Just listen and record the clicks several days in a row. Will an average 80% copy quality; it should only take a few days of listening to find the login and password.

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October 2011: The Search for Alien Life

This month, we examine all the ways we're looking for extraterrestrial life, within our solar system and beyond.

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Nanotechnology circuits for wireless devices: First wafer-scale graphene integrated circuit smaller than a pinhead

ScienceDaily (June 11, 2011) — IBM Research scientists have announced that they have achieved a milestone in creating a building block for the future of wireless devices. In a paper published in the journal Science, IBM researchers announced the first integrated circuit fabricated from wafer-size graphene, and demonstrated a broadband frequency mixer operating at frequencies up to 10 gigahertz (10 billion cycles/second).

Designed for wireless communications, this graphene-based analog integrated circuit could improve today's wireless devices and points to the potential for a new set of applications. At today's conventional frequencies, cell phone and transceiver signals could be improved, potentially allowing phones to work where they can't today while, at much higher frequencies, military and medical personnel could see concealed weapons or conduct medical imaging without the same radiation dangers of X-rays.

Graphene, the thinnest electronic material consisting of a single layer of carbon atoms packed in a honeycomb structure, possesses outstanding electrical, optical, mechanical and thermal properties that could make it less expensive and use less energy inside portable electronics like smart phones.

Despite significant scientific progress in the understanding of this novel material and the demonstration of high-performance graphene-based devices, the challenge of integrating graphene transistors with other components on a single chip had not been realized until now, mostly due to poor adhesion of graphene with metals and oxides and the lack of reliable fabrication schemes to yield reproducible devices and circuits.

This new integrated circuit, consisting of a graphene transistor and a pair of inductors compactly integrated on a silicon carbide (SiC) wafer, overcomes these design hurdles by developing wafer-scale fabrication procedures that maintain the quality of graphene and, at the same time, allow for its integration to other components in a complex circuitry.

How it Works

In this demonstration, graphene is synthesized by thermal annealing of SiC wafers to form uniform graphene layers on the surface of SiC. The fabrication of graphene circuits involves four layers of metal and two layers of oxide to form top-gated graphene transistor, on-chip inductors and interconnects.

The circuit operates as a broadband frequency mixer, which produces output signals with mixed frequencies (sum and difference) of the input signals. Mixers are fundamental components of many electronic communication systems. Frequency mixing up to 10 GHz and excellent thermal stability up to 125°C has been demonstrated with the graphene integrated circuit.

The fabrication scheme developed can also be applied to other types of graphene materials, including chemical vapor deposited (CVD) graphene films synthesized on metal films, and are also compatible with optical lithography for reduced cost and throughput.

Previously, the team has demonstrated standalone graphene transistors with a cut-off frequency as high as 100 GHz and 155 GHz for epitaxial and CVD graphene, for a gate length of 240 and 40 nm, respectively.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by IBM Research.

Journal Reference:

Y.-M. Lin, A. Valdes-Garcia, S.-J. Han, D. B. Farmer, I. Meric, Y. Sun, Y. Wu, C. Dimitrakopoulos, A. Grill, P. Avouris, K. A. Jenkins. Wafer-Scale Graphene Integrated Circuit. Science, 2011; 332 (6035): 1294 DOI: 10.1126/science.1204428

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Nanotechnology circuits for wireless devices: First wafer-scale graphene integrated circuit smaller than a pinhead

ScienceDaily (June 11, 2011) — IBM Research scientists have announced that they have achieved a milestone in creating a building block for the future of wireless devices. In a paper published in the journal Science, IBM researchers announced the first integrated circuit fabricated from wafer-size graphene, and demonstrated a broadband frequency mixer operating at frequencies up to 10 gigahertz (10 billion cycles/second).

Designed for wireless communications, this graphene-based analog integrated circuit could improve today's wireless devices and points to the potential for a new set of applications. At today's conventional frequencies, cell phone and transceiver signals could be improved, potentially allowing phones to work where they can't today while, at much higher frequencies, military and medical personnel could see concealed weapons or conduct medical imaging without the same radiation dangers of X-rays.

Graphene, the thinnest electronic material consisting of a single layer of carbon atoms packed in a honeycomb structure, possesses outstanding electrical, optical, mechanical and thermal properties that could make it less expensive and use less energy inside portable electronics like smart phones.

Despite significant scientific progress in the understanding of this novel material and the demonstration of high-performance graphene-based devices, the challenge of integrating graphene transistors with other components on a single chip had not been realized until now, mostly due to poor adhesion of graphene with metals and oxides and the lack of reliable fabrication schemes to yield reproducible devices and circuits.

This new integrated circuit, consisting of a graphene transistor and a pair of inductors compactly integrated on a silicon carbide (SiC) wafer, overcomes these design hurdles by developing wafer-scale fabrication procedures that maintain the quality of graphene and, at the same time, allow for its integration to other components in a complex circuitry.

How it Works

In this demonstration, graphene is synthesized by thermal annealing of SiC wafers to form uniform graphene layers on the surface of SiC. The fabrication of graphene circuits involves four layers of metal and two layers of oxide to form top-gated graphene transistor, on-chip inductors and interconnects.

The circuit operates as a broadband frequency mixer, which produces output signals with mixed frequencies (sum and difference) of the input signals. Mixers are fundamental components of many electronic communication systems. Frequency mixing up to 10 GHz and excellent thermal stability up to 125°C has been demonstrated with the graphene integrated circuit.

The fabrication scheme developed can also be applied to other types of graphene materials, including chemical vapor deposited (CVD) graphene films synthesized on metal films, and are also compatible with optical lithography for reduced cost and throughput.

Previously, the team has demonstrated standalone graphene transistors with a cut-off frequency as high as 100 GHz and 155 GHz for epitaxial and CVD graphene, for a gate length of 240 and 40 nm, respectively.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by IBM Research.

Journal Reference:

Y.-M. Lin, A. Valdes-Garcia, S.-J. Han, D. B. Farmer, I. Meric, Y. Sun, Y. Wu, C. Dimitrakopoulos, A. Grill, P. Avouris, K. A. Jenkins. Wafer-Scale Graphene Integrated Circuit. Science, 2011; 332 (6035): 1294 DOI: 10.1126/science.1204428

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Engineers envision 2-dimensional graphene metamaterials and 1-atom-thick optical devices

ScienceDaily (June 9, 2011) — Two University of Pennsylvania engineers have proposed the possibility of two-dimensional metamaterials. These one-atom- thick metamaterials could be achieved by controlling the conductivity of sheets of graphene, which is a single layer of carbon atoms.

Professor Nader Engheta and graduate student Ashkan Vakil, both of the Department of Electrical and Systems Engineering in Penn's School of Engineering and Applied Science, published their theoretical research in the journal Science.

The study of metamaterials is an interdisciplinary field of science and engineering that has grown considerably in recent years. It is premised on the idea that materials can be designed so that their overall wave qualities rely not only upon the material they are made of but also on the pattern, shape and size of irregularities, known as "inclusions," or "meta-molecules" that are embedded within host media.

"By designing the properties of the inclusions, as well as their shapes and density, you achieve in the bulk property something that may be unusual and not readily available in nature," Engheta said.

These unusual properties generally have to do with manipulating electromagnetic (EM) or acoustic waves; in this case, it is EM waves in the infrared spectrum

Changing the shape, speed and direction of these kinds of waves is a subfield of metamaterials known as "transformation optics" and may find applications in everything from telecommunications to imaging to signal processing.

Engheta and Vakil's research shows how transformation optics might now be achieved using graphene, a lattice of carbon a single atom thick.

Researchers, including many at Penn, have devoted considerable effort into developing new ways to manufacture and manipulate graphene, as its unprecedented conductivity would have many applications in the field of electronics. Engheta and Vakil's interest in graphene, however, is due to its capability to transport and guide EM waves in addition to electrical charges and the fact that its conductivity can be easily altered.

Applying direct voltage to a sheet of graphene, by way of ground plate running parallel to the sheet, changes how conductive the graphene is to EM waves. Varying the voltage or the distance between the ground plate and the graphene alters the conductivity, "just like tuning a knob," Engheta said.

"This allows you to change the conductivity of different segments of a single sheet of graphene differently from each other," he said. And if you can do that, you can navigate and manipulate a wave with those segments. In other words, you can do transformation optics using graphene."

In this marriage between graphene and metamaterials, the different regions of conductivity on the effectively two-dimensional, one-atom-thick sheet function as the physical inclusions present in three-dimensional versions.

The examples Engheta and Vakil have demonstrated with computer models include a sheet of graphene with two areas that have different conductivities, one that can support a wave, and one that cannot. The boundary between the two areas acts as a wall, capable of reflecting a guided EM wave on the graphene much like one would in a three dimensional space.

Another example involves three regions, one that can support a wave surrounded by two that cannot. This produces a "waveguide," which functions like a one-atom-thick fiber optic cable. A third example builds on the waveguide, adding another non-supporting region to split the waveguide into two.

"We can 'tame' the wave so that it moves and bends however we like," Engheta said. "Rather than playing around with the boundary between two media, we're thinking about changes of conductivity across a single sheet of graphene."

Other applications include lensing and the ability to do "flatland" Fourier transforms, a fundamental aspect of signal processing that is found in nearly every piece of technology with audio or visual components.

"This will pave the way to the thinnest optical devices imaginable," Engheta said. "You can't have anything thinner than one atom!"

Support for this research came from U.S. Air Force Office of Scientific Research.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Pennsylvania.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Engineers envision 2-dimensional graphene metamaterials and 1-atom-thick optical devices

ScienceDaily (June 9, 2011) — Two University of Pennsylvania engineers have proposed the possibility of two-dimensional metamaterials. These one-atom- thick metamaterials could be achieved by controlling the conductivity of sheets of graphene, which is a single layer of carbon atoms.

Professor Nader Engheta and graduate student Ashkan Vakil, both of the Department of Electrical and Systems Engineering in Penn's School of Engineering and Applied Science, published their theoretical research in the journal Science.

The study of metamaterials is an interdisciplinary field of science and engineering that has grown considerably in recent years. It is premised on the idea that materials can be designed so that their overall wave qualities rely not only upon the material they are made of but also on the pattern, shape and size of irregularities, known as "inclusions," or "meta-molecules" that are embedded within host media.

"By designing the properties of the inclusions, as well as their shapes and density, you achieve in the bulk property something that may be unusual and not readily available in nature," Engheta said.

These unusual properties generally have to do with manipulating electromagnetic (EM) or acoustic waves; in this case, it is EM waves in the infrared spectrum

Changing the shape, speed and direction of these kinds of waves is a subfield of metamaterials known as "transformation optics" and may find applications in everything from telecommunications to imaging to signal processing.

Engheta and Vakil's research shows how transformation optics might now be achieved using graphene, a lattice of carbon a single atom thick.

Researchers, including many at Penn, have devoted considerable effort into developing new ways to manufacture and manipulate graphene, as its unprecedented conductivity would have many applications in the field of electronics. Engheta and Vakil's interest in graphene, however, is due to its capability to transport and guide EM waves in addition to electrical charges and the fact that its conductivity can be easily altered.

Applying direct voltage to a sheet of graphene, by way of ground plate running parallel to the sheet, changes how conductive the graphene is to EM waves. Varying the voltage or the distance between the ground plate and the graphene alters the conductivity, "just like tuning a knob," Engheta said.

"This allows you to change the conductivity of different segments of a single sheet of graphene differently from each other," he said. And if you can do that, you can navigate and manipulate a wave with those segments. In other words, you can do transformation optics using graphene."

In this marriage between graphene and metamaterials, the different regions of conductivity on the effectively two-dimensional, one-atom-thick sheet function as the physical inclusions present in three-dimensional versions.

The examples Engheta and Vakil have demonstrated with computer models include a sheet of graphene with two areas that have different conductivities, one that can support a wave, and one that cannot. The boundary between the two areas acts as a wall, capable of reflecting a guided EM wave on the graphene much like one would in a three dimensional space.

Another example involves three regions, one that can support a wave surrounded by two that cannot. This produces a "waveguide," which functions like a one-atom-thick fiber optic cable. A third example builds on the waveguide, adding another non-supporting region to split the waveguide into two.

"We can 'tame' the wave so that it moves and bends however we like," Engheta said. "Rather than playing around with the boundary between two media, we're thinking about changes of conductivity across a single sheet of graphene."

Other applications include lensing and the ability to do "flatland" Fourier transforms, a fundamental aspect of signal processing that is found in nearly every piece of technology with audio or visual components.

"This will pave the way to the thinnest optical devices imaginable," Engheta said. "You can't have anything thinner than one atom!"

Support for this research came from U.S. Air Force Office of Scientific Research.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Pennsylvania.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Exotic behavior when mechanical devices reach the nanoscale

ScienceDaily (May 15, 2011) — Mechanical resonators are extensively used in high-tech industry, to mark time in electronic components, and to stabilize radio transmissions. Most mechanical resonators damp (slow down) in a well-understood linear manner, but ground-breaking work by Prof. Adrian Bachtold and his research group at the Catalan Institute of Nanotechnology has shown that resonators formed from nanoscale graphene and carbon nanotubes exhibit nonlinear damping, opening up exciting possibilities for super-sensitive detectors of force or mass.

In an article recently published in Nature Nanotechnology Prof. Bachtold and his co-researchers describe how they formed nano-scale resonators by suspending tiny graphene sheets or carbon nanotubes and clamping them at each end. These devices, similar to guitar strings, can be set to vibrate at very specific frequencies.

In all mechanical resonators studied to date, from large objects several metres in size down to tiny components just a few tens of nanometers in length, damping has always been observed to occur in a highly predictable, linear manner. However Prof. Bachtold´s research demonstrates that this linear damping paradigm breaks down for resonators with critical dimensions on the atomic scale. Of particular importance they have shown that the damping is strongly nonlinear for resonators based on nanotubes and graphene, a characteristic that facilitates amplification of signals and dramatic improvements in sensitivity.

The finding has profound consequences. Damping is central to the physics of nanoelectromechanical resonators, lying at the core of quantum and sensing experiments. Therefore many predictions that have been made for nanoscale electro-mechanical devices now need to be revisited when considering nanotube and graphene resonators.

This new insight into the dynamics of nano-scale resonators will also enable dramatic improvements in the performance of numerous devices. Already the Prof. Bachtold´s group has achieved a new record in quality factor for graphene resonators and ultra-weak force sensing with a nanotube resonator.

The work is particularly timely because an increasing number of research groups around the world with diverse backgrounds are choosing to study nanotube/graphene resonators, which have a number of uniquely useful properties.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Institut Català de Nanotecnologia, via EurekAlert!, a service of AAAS.

Journal Reference:

A. Eichler, J. Moser, J. Chaste, M. Zdrojek, I. Wilson-Rae, A. Bachtold. Nonlinear damping in mechanical resonators made from carbon nanotubes and graphene. Nature Nanotechnology, 2011; DOI: 10.1038/NNANO.2011.71

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Exotic behavior when mechanical devices reach the nanoscale

ScienceDaily (May 15, 2011) — Mechanical resonators are extensively used in high-tech industry, to mark time in electronic components, and to stabilize radio transmissions. Most mechanical resonators damp (slow down) in a well-understood linear manner, but ground-breaking work by Prof. Adrian Bachtold and his research group at the Catalan Institute of Nanotechnology has shown that resonators formed from nanoscale graphene and carbon nanotubes exhibit nonlinear damping, opening up exciting possibilities for super-sensitive detectors of force or mass.

In an article recently published in Nature Nanotechnology Prof. Bachtold and his co-researchers describe how they formed nano-scale resonators by suspending tiny graphene sheets or carbon nanotubes and clamping them at each end. These devices, similar to guitar strings, can be set to vibrate at very specific frequencies.

In all mechanical resonators studied to date, from large objects several metres in size down to tiny components just a few tens of nanometers in length, damping has always been observed to occur in a highly predictable, linear manner. However Prof. Bachtold´s research demonstrates that this linear damping paradigm breaks down for resonators with critical dimensions on the atomic scale. Of particular importance they have shown that the damping is strongly nonlinear for resonators based on nanotubes and graphene, a characteristic that facilitates amplification of signals and dramatic improvements in sensitivity.

The finding has profound consequences. Damping is central to the physics of nanoelectromechanical resonators, lying at the core of quantum and sensing experiments. Therefore many predictions that have been made for nanoscale electro-mechanical devices now need to be revisited when considering nanotube and graphene resonators.

This new insight into the dynamics of nano-scale resonators will also enable dramatic improvements in the performance of numerous devices. Already the Prof. Bachtold´s group has achieved a new record in quality factor for graphene resonators and ultra-weak force sensing with a nanotube resonator.

The work is particularly timely because an increasing number of research groups around the world with diverse backgrounds are choosing to study nanotube/graphene resonators, which have a number of uniquely useful properties.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Institut Català de Nanotecnologia, via EurekAlert!, a service of AAAS.

Journal Reference:

A. Eichler, J. Moser, J. Chaste, M. Zdrojek, I. Wilson-Rae, A. Bachtold. Nonlinear damping in mechanical resonators made from carbon nanotubes and graphene. Nature Nanotechnology, 2011; DOI: 10.1038/NNANO.2011.71

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Forecast calls for nanoflowers to help return eyesight: Physicist leads effort to design fractal devices to put in eyes

ScienceDaily (May 6, 2011) — University of Oregon researcher Richard Taylor is on a quest to grow flowers that will help people who've lost their sight, such as those suffering from macular degeneration, to see again.

These flowers are not roses, tulips or columbines. They will be nanoflowers seeded from nano-sized particles of metals that grow, or self assemble, in a natural process -- diffusion limited aggregation. They will be fractals that mimic and communicate efficiently with neurons.

Fractals are "a trademark building block of nature," Taylor says. Fractals are objects with irregular curves or shapes, of which any one component seen under magnification is also the same shape. In math, that property is self-similarity. Trees, clouds, rivers, galaxies, lungs and neurons are fractals, Taylor says. Today's commercial electronic chips are not fractals, he adds.

Eye surgeons would implant these fractal devices within the eyes of blind patients, providing interface circuitry that would collect light captured by the retina and guide it with almost 100 percent efficiency to neurons for relay to the optic nerve to process vision.

In an article titled "Vision of beauty" for Physics World, Taylor, a physicist and director of the UO Materials Science Institute, describes his envisioned approach and how it might overcome the problems occurring with current efforts to insert photodiodes behind the eyes. Current chip technology is limited, because it doesn't allow sufficient connections with neurons.

"The wiring -- the neurons -- in the retina is fractal, but the chips are not fractal," Taylor says. "They are just little squares of electrodes that provide too little overlap with the neurons."

Beginning this summer, Taylor's doctoral student Rick Montgomery will begin a yearlong collaboration with Simon Brown at the University of Canterbury in New Zealand to experiment with various metals to grow the fractal flowers on implantable chips.

The idea for the project emerged as Taylor was working under a Cottrell Scholar Award he received in 2003 from the Research Corporation for Science Advancement. His vision is now beginning to blossom under grants from the Office of Naval Research (ONR), the U.S. Air Force and the National Science Foundation.

Taylor's theoretical concept for fractal-based photodiodes also is the focus of a U.S. patent application filed by the UO's Office of Technology Transfer under Taylor's and Brown's names, the UO and University of Canterbury.

The project, he writes in the Physics World article, is based on "the striking similarities between the eye and the digital camera." (Physics World article is available at: http://physicsworld.com/cws/article/indepth/45840)

"The front end of both systems," he writes, "consists of an adjustable aperture within a compound lens, and advances bring these similarities closer each year." Digital cameras, he adds, are approaching the capacity to capture the 127 megapixels of the human eye, but current chip-based implants, because of their interface, are only providing about 50 pixels of resolution.

Among the challenges, Taylor says, is determining which metals can best go into body without toxicity problems. "We're right at the start of this amazing voyage," Taylor says. "The ultimate thrill for me will be to go to a blind person and say, we're developing a chip that one day will help you see again. For me, that is very different from my previous research, where I've been looking at electronics to go into computers, to actually help somebody … if I can pull that off that will be a tremendous thrill for me."

Taylor also is working under a Research Corp. grant to pursue fractal-based solar cells.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Oregon.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Forecast calls for nanoflowers to help return eyesight: Physicist leads effort to design fractal devices to put in eyes

ScienceDaily (May 6, 2011) — University of Oregon researcher Richard Taylor is on a quest to grow flowers that will help people who've lost their sight, such as those suffering from macular degeneration, to see again.

These flowers are not roses, tulips or columbines. They will be nanoflowers seeded from nano-sized particles of metals that grow, or self assemble, in a natural process -- diffusion limited aggregation. They will be fractals that mimic and communicate efficiently with neurons.

Fractals are "a trademark building block of nature," Taylor says. Fractals are objects with irregular curves or shapes, of which any one component seen under magnification is also the same shape. In math, that property is self-similarity. Trees, clouds, rivers, galaxies, lungs and neurons are fractals, Taylor says. Today's commercial electronic chips are not fractals, he adds.

Eye surgeons would implant these fractal devices within the eyes of blind patients, providing interface circuitry that would collect light captured by the retina and guide it with almost 100 percent efficiency to neurons for relay to the optic nerve to process vision.

In an article titled "Vision of beauty" for Physics World, Taylor, a physicist and director of the UO Materials Science Institute, describes his envisioned approach and how it might overcome the problems occurring with current efforts to insert photodiodes behind the eyes. Current chip technology is limited, because it doesn't allow sufficient connections with neurons.

"The wiring -- the neurons -- in the retina is fractal, but the chips are not fractal," Taylor says. "They are just little squares of electrodes that provide too little overlap with the neurons."

Beginning this summer, Taylor's doctoral student Rick Montgomery will begin a yearlong collaboration with Simon Brown at the University of Canterbury in New Zealand to experiment with various metals to grow the fractal flowers on implantable chips.

The idea for the project emerged as Taylor was working under a Cottrell Scholar Award he received in 2003 from the Research Corporation for Science Advancement. His vision is now beginning to blossom under grants from the Office of Naval Research (ONR), the U.S. Air Force and the National Science Foundation.

Taylor's theoretical concept for fractal-based photodiodes also is the focus of a U.S. patent application filed by the UO's Office of Technology Transfer under Taylor's and Brown's names, the UO and University of Canterbury.

The project, he writes in the Physics World article, is based on "the striking similarities between the eye and the digital camera." (Physics World article is available at: http://physicsworld.com/cws/article/indepth/45840)

"The front end of both systems," he writes, "consists of an adjustable aperture within a compound lens, and advances bring these similarities closer each year." Digital cameras, he adds, are approaching the capacity to capture the 127 megapixels of the human eye, but current chip-based implants, because of their interface, are only providing about 50 pixels of resolution.

Among the challenges, Taylor says, is determining which metals can best go into body without toxicity problems. "We're right at the start of this amazing voyage," Taylor says. "The ultimate thrill for me will be to go to a blind person and say, we're developing a chip that one day will help you see again. For me, that is very different from my previous research, where I've been looking at electronics to go into computers, to actually help somebody … if I can pull that off that will be a tremendous thrill for me."

Taylor also is working under a Research Corp. grant to pursue fractal-based solar cells.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Oregon.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Functioning synapse created using carbon nanotubes: Devices might be used in brain prostheses or synthetic brains

ScienceDaily (Apr. 22, 2011) — Engineering researchers the University of Southern California have made a significant breakthrough in the use of nanotechnologies for the construction of a synthetic brain. They have built a carbon nanotube synapse circuit whose behavior in tests reproduces the function of a neuron, the building block of the brain.

The team, which was led by Professor Alice Parker and Professor Chongwu Zhou in the USC Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering, used an interdisciplinary approach combining circuit design with nanotechnology to address the complex problem of capturing brain function.

In a paper published in the proceedings of the IEEE/NIH 2011 Life Science Systems and Applications Workshop in April 2011, the Viterbi team detailed how they were able to use carbon nanotubes to create a synapse.

Carbon nanotubes are molecular carbon structures that are extremely small, with a diameter a million times smaller than a pencil point. These nanotubes can be used in electronic circuits, acting as metallic conductors or semiconductors.

"This is a necessary first step in the process," said Parker, who began the looking at the possibility of developing a synthetic brain in 2006. "We wanted to answer the question: Can you build a circuit that would act like a neuron? The next step is even more complex. How can we build structures out of these circuits that mimic the function of the brain, which has 100 billion neurons and 10,000 synapses per neuron?"

Parker emphasized that the actual development of a synthetic brain, or even a functional brain area is decades away, and she said the next hurdle for the research centers on reproducing brain plasticity in the circuits.

The human brain continually produces new neurons, makes new connections and adapts throughout life, and creating this process through analog circuits will be a monumental task, according to Parker.

She believes the ongoing research of understanding the process of human intelligence could have long-term implications for everything from developing prosthetic nanotechnology that would heal traumatic brain injuries to developing intelligent, safe cars that would protect drivers in bold new ways.

For Jonathan Joshi, a USC Viterbi Ph.D. student who is a co-author of the paper, the interdisciplinary approach to the problem was key to the initial progress. Joshi said that working with Zhou and his group of nanotechnology researchers provided the ideal dynamic of circuit technology and nanotechnology.

"The interdisciplinary approach is the only approach that will lead to a solution. We need more than one type of engineer working on this solution," said Joshi. "We should constantly be in search of new technologies to solve this problem."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Southern California, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here