New device measures viscosity of ketchup and cosmetics

ScienceDaily (Oct. 24, 2011) — A device that can measure and predict how liquids flow under different conditions will ensure consumer products -- from make-up to ketchup -- are of the right consistency.

The technology developed at the University of Sheffield enables engineers to monitor, in real time, how the viscous components (rheology) of liquids change during a production process, making it easier, quicker and cheaper to control the properties of the liquid.

The research is a joint project between the University's Department of Chemical and Biological Engineering and the School of Mathematics and Statistics. A paper describing the innovation is published Oct. 24, 2011 in the journal Measurement Science and Technology.

Dr Julia Rees from the University's Department of Applied Mathematics, who co-authored the study, said: "Companies that make liquid products need to know how the liquids will behave in different circumstances because these different behaviours can affect the texture, the taste or even the smell of a product."

The viscosity of most liquids changes under different conditions and designers often use complicated mathematical equations to determine what these changes might be.

The team from Sheffield has now developed a way of predicting these changes using a non-invasive sensor system that the liquid simply flows through. The sensor feeds information back through an electronic device that calculates a range of likely behaviours.

Dr Rees, from the Department of Applied Mathematics, explains: "Measuring the individual components of a liquid's viscosity is called rheometry. We can produce equations to measure a liquid's total viscosity, but the rheology of most liquids is very complicated. Instead, we look at properties in a liquid that we can measure easily, and then apply maths to calculate the viscosity. The sensor device we have developed will be able to make these calculations for companies using a straightforward testing process."

Companies developing new products will be able to incorporate the device into their development process, meaning there will no longer be a need for `grab samples' to be taken away for expensive laboratory testing, providing cost and efficiency savings.

The device can be made to any scale and can even be etched onto a microchip, with channels about the width of a human hair. This will be useful for testing where only small samples of fluid are available, for example in biological samples.

Dr Rees' team have developed a laboratory prototype of the system and are currently working to refine the technology and develop a design prototype.

Will Zimmerman, Professor of Biochemical Dynamical Systems in the Department of Chemical and Biological Engineering at the University of Sheffield, worked on the project alongside Dr Rees. He says: "Because the microrheometer works in real time, materials, time and energy will not be wasted when processing flaws are detected. Conservation is one of the best ways to 'green' industrial processing with greater efficiency. Ben Franklin's maxim, 'waste not, want not' is just as true today."

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The above story is reprinted from materials provided by University of Sheffield.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

H C Hemaka Bandulasena, William B Zimmerman, Julia M Rees. An inverse method for rheometry of power-law fluids. Measurement Science and Technology, 2011; 22 (12): 125402 DOI: 10.1088/0957-0233/22/12/125402

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'Microring' device could aid in future optical technologies

ScienceDaily (Oct. 20, 2011) — Researchers at Purdue University and the National Institute of Standards and Technology (NIST) have created a device small enough to fit on a computer chip that converts continuous laser light into numerous ultrashort pulses, a technology that might have applications in more advanced sensors, communications systems and laboratory instruments.

"These pulses repeat at very high rates, corresponding to hundreds of billions of pulses per second," said Andrew Weiner, the Scifres Family Distinguished Professor of Electrical and Computer Engineering.

The tiny "microring resonator" is about 80 micrometers, or the width of a human hair, and is fabricated from silicon nitride, which is compatible with silicon material widely used for electronics. Infrared light from a laser enters the chip through a single optical fiber and is directed by a structure called a waveguide into the microring.

The pulses have many segments corresponding to different frequencies, which are called "comb lines" because they resemble teeth on a comb when represented on a graph.

By precisely controlling the frequency combs, researchers hope to create advanced optical sensors that detect and measure hazardous materials or pollutants, ultrasensitive spectroscopy for laboratory research, and optics-based communications systems that transmit greater volumes of information with better quality while increasing bandwidth. The comb technology also has potential for a generation of high-bandwidth electrical signals with possible applications in wireless communications and radar.

The light originates from a continuous-wave laser, also called a single-frequency laser.

"This is a very common type of laser," Weiner said. "The intensity of this type of laser is constant, not pulsed. But in the microring the light is converted into a comb consisting of many frequencies with very nice equal spacing. The microring comb generator may serve as a competing technology to a special type of laser called a mode-locked laser, which generates many frequencies and short pulses. One advantage of the microrings is that they can be very small."

The laser light undergoes "nonlinear interaction" while inside the microring, generating acomb of new frequencies that is emitted out of the device through another optical fiber.

"The nonlinearity is critical to the generation of the comb," said doctoral student Fahmida Ferdous. "With the nonlinearity we obtain a comb of many frequencies, including the original one, and the rest are new ones generated in the microring."

Findings are detailed in a research paper appearing online this month in the journal Nature Photonics. The paper is scheduled for publication in the Dec. 11 issue.

Although other researchers previously have demonstrated the comb-generation technique, the team is the first to process the frequencies using "optical arbitrary waveform technology," pioneered by Purdue researchers led by Weiner. The researchers were able to control the amplitude and phase of each spectral line, learning that there are two types of combs -- "highly coherent" and "partially coherent" -- opening up new avenues to study the physics of the process.

"In future investigations, the ability to extract the phase of individual comb lines may furnish clues into the physics of the comb-generation process," Ferdous said. "Future work will include efforts to create devices that have the proper frequency for commercial applications."

The silicon-nitride device was fabricated by a team led by Houxun Miao, a researcher at NIST's Center for Nanoscale Science and Technology and the Maryland Nanocenter at the University of Maryland. Some of the work was performed at the Birck Nanotechnology Center in Purdue's Discovery Park, and experiments demonstrating short-pulse generation were performed in Purdue's School of Electrical and Computer Engineering.

The effort at Purdue is funded in part by the National Science Foundation and the Naval Postgraduate School.

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Story Source:

The above story is reprinted from materials provided by Purdue University. The original article was written by Emil Venere.

Note: ScienceDaily reserves the right to edit materials for content and length. For further information, please contact the source cited above.

Journal Reference:

Fahmida Ferdous, Houxun Miao, Daniel E. Leaird, Kartik Srinivasan, Jian Wang, Lei Chen, Leo Tom Varghese, Andrew M. Weiner. Spectral line-by-line pulse shaping of on-chip microresonator frequency combs. Nature Photonics, 2011; DOI: 10.1038/nphoton.2011.255

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

'Microring' device could aid in future optical technologies

ScienceDaily (Oct. 20, 2011) — Researchers at Purdue University and the National Institute of Standards and Technology (NIST) have created a device small enough to fit on a computer chip that converts continuous laser light into numerous ultrashort pulses, a technology that might have applications in more advanced sensors, communications systems and laboratory instruments.

"These pulses repeat at very high rates, corresponding to hundreds of billions of pulses per second," said Andrew Weiner, the Scifres Family Distinguished Professor of Electrical and Computer Engineering.

The tiny "microring resonator" is about 80 micrometers, or the width of a human hair, and is fabricated from silicon nitride, which is compatible with silicon material widely used for electronics. Infrared light from a laser enters the chip through a single optical fiber and is directed by a structure called a waveguide into the microring.

The pulses have many segments corresponding to different frequencies, which are called "comb lines" because they resemble teeth on a comb when represented on a graph.

By precisely controlling the frequency combs, researchers hope to create advanced optical sensors that detect and measure hazardous materials or pollutants, ultrasensitive spectroscopy for laboratory research, and optics-based communications systems that transmit greater volumes of information with better quality while increasing bandwidth. The comb technology also has potential for a generation of high-bandwidth electrical signals with possible applications in wireless communications and radar.

The light originates from a continuous-wave laser, also called a single-frequency laser.

"This is a very common type of laser," Weiner said. "The intensity of this type of laser is constant, not pulsed. But in the microring the light is converted into a comb consisting of many frequencies with very nice equal spacing. The microring comb generator may serve as a competing technology to a special type of laser called a mode-locked laser, which generates many frequencies and short pulses. One advantage of the microrings is that they can be very small."

The laser light undergoes "nonlinear interaction" while inside the microring, generating acomb of new frequencies that is emitted out of the device through another optical fiber.

"The nonlinearity is critical to the generation of the comb," said doctoral student Fahmida Ferdous. "With the nonlinearity we obtain a comb of many frequencies, including the original one, and the rest are new ones generated in the microring."

Findings are detailed in a research paper appearing online this month in the journal Nature Photonics. The paper is scheduled for publication in the Dec. 11 issue.

Although other researchers previously have demonstrated the comb-generation technique, the team is the first to process the frequencies using "optical arbitrary waveform technology," pioneered by Purdue researchers led by Weiner. The researchers were able to control the amplitude and phase of each spectral line, learning that there are two types of combs -- "highly coherent" and "partially coherent" -- opening up new avenues to study the physics of the process.

"In future investigations, the ability to extract the phase of individual comb lines may furnish clues into the physics of the comb-generation process," Ferdous said. "Future work will include efforts to create devices that have the proper frequency for commercial applications."

The silicon-nitride device was fabricated by a team led by Houxun Miao, a researcher at NIST's Center for Nanoscale Science and Technology and the Maryland Nanocenter at the University of Maryland. Some of the work was performed at the Birck Nanotechnology Center in Purdue's Discovery Park, and experiments demonstrating short-pulse generation were performed in Purdue's School of Electrical and Computer Engineering.

The effort at Purdue is funded in part by the National Science Foundation and the Naval Postgraduate School.

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Story Source:

The above story is reprinted from materials provided by Purdue University. The original article was written by Emil Venere.

Note: ScienceDaily reserves the right to edit materials for content and length. For further information, please contact the source cited above.

Journal Reference:

Fahmida Ferdous, Houxun Miao, Daniel E. Leaird, Kartik Srinivasan, Jian Wang, Lei Chen, Leo Tom Varghese, Andrew M. Weiner. Spectral line-by-line pulse shaping of on-chip microresonator frequency combs. Nature Photonics, 2011; DOI: 10.1038/nphoton.2011.255

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

Nanoscale nonlinear light source optical device can be controlled electronically

ScienceDaily (Sep. 22, 2011) — Not long after the development of the first laser in 1960 scientists discovered that shining a beam through certain crystals produced light of a different color; more specifically, it produced light of exactly twice the frequency of the original. The phenomenon was dubbed second harmonic generation.

The green laser pointers in use today to illustrate presentations are based on this science, but producing such a beautiful emerald beam is no easy feat. The green light begins as an infrared ray that must be first processed through a crystal, various lenses and other optical elements before it can illuminate that PowerPoint on the screen before you.

It was later discovered that applying an electrical field to some crystals produced a similar, though weaker, beam of light. This second discovery, known as EFISH -- for electric-field-induced second harmonic light generation -- has amounted mostly to an interesting bit of scientific knowledge and little more. EFISH devices are big, demanding high-powered lasers, large crystals and thousands of volts of electricity to produce the effect. As a result, they are impractical for all but a few applications.

In a paper published September 22 in Science, engineers from Stanford have demonstrated a new device that shrinks EFISH devices by orders of magnitude to the nanoscale. The result is an ultra-compact light source with both optical and electrical functions. Research implications for the device range from a better understanding of fundamental science to improved data communications.

Spring-loaded electrons

The device is based on the physical forces that bind electrons in orbit around a nucleus.

"It's like a spring," said Mark Brongersma, an associate professor of materials science and engineering at Stanford.

In most cases, when you shine a light on an atom, the added energy will pull the electron away from the positively charged nucleus very predictably, in a linear fashion, so that when the light is turned off and the electron springs back to its original orbit, the energy released is the same as the light that displaced it.

The key phrase here being: "in most cases." When the light source is a high-intensity laser shining on a solid, researchers discovered that the farther the electrons are pulled away from the nuclei the less linearly the light interacts with the atoms.

"In other words, the light-matter interaction becomes nonlinear," said Alok Vasudev, a graduate student and co-author of the paper. "The light you get out is different from the light you put in. Shine a strong near-infrared laser on the crystal and green light exactly twice the frequency emerges."

Engineering possibilities

"Now, Alok and I have taken this knowledge and reduced it to the nanoscale," said the paper's first author, Wenshan Cai, a post-doctoral researcher in Brongersma's lab. "For the first time we have a nonlinear optical device at the nanoscale that has both optical and electrical functionality. And this offers some interesting engineering possibilities."

For many photonic applications, including signal and information processing, it is desirable to electrically manipulate nonlinear light generation. The new device resembles a nanoscale bowtie with two halves of symmetrical gold leaf approaching, but not quite touching, in the center. This thin slit between the two halves is filled with a nonlinear material. The narrowness is critical. It is just 100 nanometers across.

"EFISH requires a huge electrical field. From basic physics we know that the strength of an electric field scales linearly with the applied voltage and inversely with the distance between the electrodes -- smaller distance, stronger field and vice versa," said Brongersma. "So, if you have two electrodes placed extremely close together, as we do in our experiment, it doesn't take many volts to produce a giant electrical field. In fact, it takes just a single volt."

"It is this fundamental science that allows us to shrink the device by orders of magnitude from the human scale to the nanoscale," said Cai.

Enter plasmonics

Brongersma's area of expertise, plasmonics, then enters the scene. Plasmonics is the study of a curious physical phenomenon that occurs when light and metal interact. As photons strike metal they produce waves of energy coursing outward over the surface of the metal, like the ripples when a pebble is dropped in a pond.

Engineers have learned to control the direction of the ripples by patterning the surface of the metal in such a way that almost all of the energy waves are funneled inward toward the slit between the two metallic electrodes.

The light pours into the crevice as if over the edge of a waterfall and there it intensifies, producing light some 80 times stronger than the already intense laser levels from which it came. The researchers next apply a modest voltage to the metal resulting in the tremendous electrical field necessary to produce an EFISH beam.

Practical applications

"This type of device may one day find application in the communications industry," says Brongersma. "Most of the masses of information and social media interaction we send through our data centers, and the future data we will someday create, are saved and transmitted as electrical energy -- ones and zeros."

"Those ones and zeroes are just a switch; one is on, zero is off," said Cai. "As more energy-efficient optical information transport is rapidly gaining in importance, it is not a great leap to see why devices that can convert electrical to optical signals and back are of great value."

For the time being, however, the researchers caution that practical applications remain down the road, but they have created something new.

"It's a great piece of basic science," said Brongersma. "It is work that combines several disciplines -- nonlinear optics, electronics, plasmonics, and nanoscale engineering -- into a really interesting device that could keep us busy for awhile."

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and Google +1:

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford School of Engineering. The original article was written by Andrew Myers.

Journal Reference:

W. Cai, A. P. Vasudev, M. L. Brongersma. Electrically Controlled Nonlinear Generation of Light with Plasmonics. Science, 2011; 333 (6050): 1720 DOI: 10.1126/science.1207858

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

Nanoscale nonlinear light source optical device can be controlled electronically

ScienceDaily (Sep. 22, 2011) — Not long after the development of the first laser in 1960 scientists discovered that shining a beam through certain crystals produced light of a different color; more specifically, it produced light of exactly twice the frequency of the original. The phenomenon was dubbed second harmonic generation.

The green laser pointers in use today to illustrate presentations are based on this science, but producing such a beautiful emerald beam is no easy feat. The green light begins as an infrared ray that must be first processed through a crystal, various lenses and other optical elements before it can illuminate that PowerPoint on the screen before you.

It was later discovered that applying an electrical field to some crystals produced a similar, though weaker, beam of light. This second discovery, known as EFISH -- for electric-field-induced second harmonic light generation -- has amounted mostly to an interesting bit of scientific knowledge and little more. EFISH devices are big, demanding high-powered lasers, large crystals and thousands of volts of electricity to produce the effect. As a result, they are impractical for all but a few applications.

In a paper published September 22 in Science, engineers from Stanford have demonstrated a new device that shrinks EFISH devices by orders of magnitude to the nanoscale. The result is an ultra-compact light source with both optical and electrical functions. Research implications for the device range from a better understanding of fundamental science to improved data communications.

Spring-loaded electrons

The device is based on the physical forces that bind electrons in orbit around a nucleus.

"It's like a spring," said Mark Brongersma, an associate professor of materials science and engineering at Stanford.

In most cases, when you shine a light on an atom, the added energy will pull the electron away from the positively charged nucleus very predictably, in a linear fashion, so that when the light is turned off and the electron springs back to its original orbit, the energy released is the same as the light that displaced it.

The key phrase here being: "in most cases." When the light source is a high-intensity laser shining on a solid, researchers discovered that the farther the electrons are pulled away from the nuclei the less linearly the light interacts with the atoms.

"In other words, the light-matter interaction becomes nonlinear," said Alok Vasudev, a graduate student and co-author of the paper. "The light you get out is different from the light you put in. Shine a strong near-infrared laser on the crystal and green light exactly twice the frequency emerges."

Engineering possibilities

"Now, Alok and I have taken this knowledge and reduced it to the nanoscale," said the paper's first author, Wenshan Cai, a post-doctoral researcher in Brongersma's lab. "For the first time we have a nonlinear optical device at the nanoscale that has both optical and electrical functionality. And this offers some interesting engineering possibilities."

For many photonic applications, including signal and information processing, it is desirable to electrically manipulate nonlinear light generation. The new device resembles a nanoscale bowtie with two halves of symmetrical gold leaf approaching, but not quite touching, in the center. This thin slit between the two halves is filled with a nonlinear material. The narrowness is critical. It is just 100 nanometers across.

"EFISH requires a huge electrical field. From basic physics we know that the strength of an electric field scales linearly with the applied voltage and inversely with the distance between the electrodes -- smaller distance, stronger field and vice versa," said Brongersma. "So, if you have two electrodes placed extremely close together, as we do in our experiment, it doesn't take many volts to produce a giant electrical field. In fact, it takes just a single volt."

"It is this fundamental science that allows us to shrink the device by orders of magnitude from the human scale to the nanoscale," said Cai.

Enter plasmonics

Brongersma's area of expertise, plasmonics, then enters the scene. Plasmonics is the study of a curious physical phenomenon that occurs when light and metal interact. As photons strike metal they produce waves of energy coursing outward over the surface of the metal, like the ripples when a pebble is dropped in a pond.

Engineers have learned to control the direction of the ripples by patterning the surface of the metal in such a way that almost all of the energy waves are funneled inward toward the slit between the two metallic electrodes.

The light pours into the crevice as if over the edge of a waterfall and there it intensifies, producing light some 80 times stronger than the already intense laser levels from which it came. The researchers next apply a modest voltage to the metal resulting in the tremendous electrical field necessary to produce an EFISH beam.

Practical applications

"This type of device may one day find application in the communications industry," says Brongersma. "Most of the masses of information and social media interaction we send through our data centers, and the future data we will someday create, are saved and transmitted as electrical energy -- ones and zeros."

"Those ones and zeroes are just a switch; one is on, zero is off," said Cai. "As more energy-efficient optical information transport is rapidly gaining in importance, it is not a great leap to see why devices that can convert electrical to optical signals and back are of great value."

For the time being, however, the researchers caution that practical applications remain down the road, but they have created something new.

"It's a great piece of basic science," said Brongersma. "It is work that combines several disciplines -- nonlinear optics, electronics, plasmonics, and nanoscale engineering -- into a really interesting device that could keep us busy for awhile."

Recommend this story on Facebook, Twitter,
and Google +1:

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford School of Engineering. The original article was written by Andrew Myers.

Journal Reference:

W. Cai, A. P. Vasudev, M. L. Brongersma. Electrically Controlled Nonlinear Generation of Light with Plasmonics. Science, 2011; 333 (6050): 1720 DOI: 10.1126/science.1207858

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

Single GFP-expressing cell is basis of living laser device

ScienceDaily (June 13, 2011) — It sounds like something out of a comic book or a science fiction movie -- a living laser -- but that is exactly what two investigators at the Wellman Center for Photomedicine at Massachusetts General Hospital have developed. In a report that will appear in the journal Nature Photonics and is receiving advance online release, Wellman researchers Malte Gather, PhD, and Seok Hyun Yun, PhD, describe how a single cell genetically engineered to express green fluorescent protein (GFP) can be used to amplify the light particles called photons into nanosecond-long pulses of laser light.

"Since they were first developed some 50 years ago, lasers have used synthetic materials such as crystals, dyes and purified gases as optical gain media, within which photon pulses are amplified as they bounces back and forth between two mirrors," says Yun, corresponding author of the report. "Ours is the first report of a successful biological laser based on a single, living cell."

Adds Gather, a research fellow and the paper's lead author, "Part of the motivation of this project was basic scientific curiosity. In addition to realizing that biological substances had not played a major role in lasers, we wondered whether there was a fundamental reason why laser light, as far as we know, does not occur in nature or if we could find a way to achieve lasing in biological substances or living organisms."

The investigators chose GFP for their exploration of those questions because the protein -- originally found in a species of jellyfish -- can be induced to emit light without the application of additional enzymes. Its properties are well understood, and there are established techniques to genetically program many organisms to express GFP. To determine the protein's potential for generating laser light, the researcher first assembled a device consisting of an inch-long cylinder, with mirrors at each end, filled with a solution of GFP in water. After first confirming that the GFP solution could amplify input energy into brief pulses of laser light, the researchers estimated the concentration of GFP required to produce the laser effect.

Using that information, their next step was to develop a line of mammalian cells expressing GFP at the required levels. The cellular laser was assembled by placing a single GFP-expressing cell -- with a diameter of from 15 to 20 millionths of a meter -- in a microcavity consisting of two highly reflective mirrors spaced 20 millionths of a meter apart. Not only did the cell-based device produce pulses of laser light as in the GFP solution experiment, the researchers also found that the spherical shape of the cell itself acted as a lens, refocusing the light and inducing emission of laser light at lower energy levels than required for the solution-based device. The cells used in the device survived the lasing process and were able to continue producing hundreds of pulses of laser light.

"While the individual laser pulses last for only a few nanoseconds, they are bright enough to be readily detected and appear to carry very useful information that may give us new ways to analyze the properties of large numbers of cells almost instantaneously," says Yun, who is an associate professor of Dermatology at Harvard Medical School. "And the ability to generate laser light from a biocompatible source placed inside a patient could be useful for photodynamic therapies, in which drugs are activated by the application of light, or novel forms of imaging."

Gather adds, "One of our long-term goals will be finding ways to bring optical communications and computing, currently done with inanimate electronic devices, into the realm of biotechnology. That could be particularly useful in projects requiring the interfacing of electronics with biological organisms. We also hope to be able to implant a structure equivalent to the mirrored chamber right into a cell, which would the next milestone in this research." The study was supported by grants from the National Science Foundation and the Korea National Research Foundation.

Story Source:

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

Journal Reference:

Malte C. Gather, Seok Hyun Yun. Single-cell biological lasers. Nature Photonics, 2011; DOI: 10.1038/nphoton.2011.99

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

First self-powered device with wireless data transmission

ScienceDaily (June 16, 2011) — Scientists are reporting development of the first self-powered nano-device that can transmit data wirelessly over long distances. In a study in ACS's journal Nano Letters, they say it proves the feasibility of a futuristic genre of tiny implantable medical sensors, airborne and stationary surveillance cameras and sensors, wearable personal electronics, and other devices that operate independently without batteries on energy collected from the environment.

Zhong Lin Wang and colleagues explain that advances in electronics have opened the door to developing tiny devices that operate battery-free on minute amounts of electricity that can be harvested from the pulse of a blood vessel, a gentle breeze, or the motions of a person walking. "It is entirely possible to drive the devices by scavenging energy from sources in the environment such as gentle airflow, vibration, sonic wave, solar, chemical, and/or thermal energy," the scientists explain.

The device consists of a nanogenerator that produces electricity from mechanical vibration/triggering, a capacitor to store the energy, and electronics that include a sensor and a radio transmitter similar to those in Bluetooth mobile phone headsets. Their device transmitted wireless signals that could be detected by an ordinary commercial radio at distances of more than 30 feet.

The authors acknowledge funding from DARPA and the U.S. Department of Energy, Basic Energy Sciences.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Chemical Society.

Journal Reference:

Youfan Hu, Yan Zhang, Chen Xu, Long Lin, Robert L. Snyder, Zhong Lin Wang. Self-Powered System with Wireless Data Transmission. Nano Letters, 2011; : 110523140742088 DOI: 10.1021/nl201505c

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

First self-powered device with wireless data transmission

ScienceDaily (June 16, 2011) — Scientists are reporting development of the first self-powered nano-device that can transmit data wirelessly over long distances. In a study in ACS's journal Nano Letters, they say it proves the feasibility of a futuristic genre of tiny implantable medical sensors, airborne and stationary surveillance cameras and sensors, wearable personal electronics, and other devices that operate independently without batteries on energy collected from the environment.

Zhong Lin Wang and colleagues explain that advances in electronics have opened the door to developing tiny devices that operate battery-free on minute amounts of electricity that can be harvested from the pulse of a blood vessel, a gentle breeze, or the motions of a person walking. "It is entirely possible to drive the devices by scavenging energy from sources in the environment such as gentle airflow, vibration, sonic wave, solar, chemical, and/or thermal energy," the scientists explain.

The device consists of a nanogenerator that produces electricity from mechanical vibration/triggering, a capacitor to store the energy, and electronics that include a sensor and a radio transmitter similar to those in Bluetooth mobile phone headsets. Their device transmitted wireless signals that could be detected by an ordinary commercial radio at distances of more than 30 feet.

The authors acknowledge funding from DARPA and the U.S. Department of Energy, Basic Energy Sciences.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Chemical Society.

Journal Reference:

Youfan Hu, Yan Zhang, Chen Xu, Long Lin, Robert L. Snyder, Zhong Lin Wang. Self-Powered System with Wireless Data Transmission. Nano Letters, 2011; : 110523140742088 DOI: 10.1021/nl201505c

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

Single GFP-expressing cell is basis of living laser device

ScienceDaily (June 13, 2011) — It sounds like something out of a comic book or a science fiction movie -- a living laser -- but that is exactly what two investigators at the Wellman Center for Photomedicine at Massachusetts General Hospital have developed. In a report that will appear in the journal Nature Photonics and is receiving advance online release, Wellman researchers Malte Gather, PhD, and Seok Hyun Yun, PhD, describe how a single cell genetically engineered to express green fluorescent protein (GFP) can be used to amplify the light particles called photons into nanosecond-long pulses of laser light.

"Since they were first developed some 50 years ago, lasers have used synthetic materials such as crystals, dyes and purified gases as optical gain media, within which photon pulses are amplified as they bounces back and forth between two mirrors," says Yun, corresponding author of the report. "Ours is the first report of a successful biological laser based on a single, living cell."

Adds Gather, a research fellow and the paper's lead author, "Part of the motivation of this project was basic scientific curiosity. In addition to realizing that biological substances had not played a major role in lasers, we wondered whether there was a fundamental reason why laser light, as far as we know, does not occur in nature or if we could find a way to achieve lasing in biological substances or living organisms."

The investigators chose GFP for their exploration of those questions because the protein -- originally found in a species of jellyfish -- can be induced to emit light without the application of additional enzymes. Its properties are well understood, and there are established techniques to genetically program many organisms to express GFP. To determine the protein's potential for generating laser light, the researcher first assembled a device consisting of an inch-long cylinder, with mirrors at each end, filled with a solution of GFP in water. After first confirming that the GFP solution could amplify input energy into brief pulses of laser light, the researchers estimated the concentration of GFP required to produce the laser effect.

Using that information, their next step was to develop a line of mammalian cells expressing GFP at the required levels. The cellular laser was assembled by placing a single GFP-expressing cell -- with a diameter of from 15 to 20 millionths of a meter -- in a microcavity consisting of two highly reflective mirrors spaced 20 millionths of a meter apart. Not only did the cell-based device produce pulses of laser light as in the GFP solution experiment, the researchers also found that the spherical shape of the cell itself acted as a lens, refocusing the light and inducing emission of laser light at lower energy levels than required for the solution-based device. The cells used in the device survived the lasing process and were able to continue producing hundreds of pulses of laser light.

"While the individual laser pulses last for only a few nanoseconds, they are bright enough to be readily detected and appear to carry very useful information that may give us new ways to analyze the properties of large numbers of cells almost instantaneously," says Yun, who is an associate professor of Dermatology at Harvard Medical School. "And the ability to generate laser light from a biocompatible source placed inside a patient could be useful for photodynamic therapies, in which drugs are activated by the application of light, or novel forms of imaging."

Gather adds, "One of our long-term goals will be finding ways to bring optical communications and computing, currently done with inanimate electronic devices, into the realm of biotechnology. That could be particularly useful in projects requiring the interfacing of electronics with biological organisms. We also hope to be able to implant a structure equivalent to the mirrored chamber right into a cell, which would the next milestone in this research." The study was supported by grants from the National Science Foundation and the Korea National Research Foundation.

Story Source:

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

Journal Reference:

Malte C. Gather, Seok Hyun Yun. Single-cell biological lasers. Nature Photonics, 2011; DOI: 10.1038/nphoton.2011.99

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

New device could reduce surgical scarring

ScienceDaily (May 24, 2011) — Researchers at Stanford University have developed a special wound dressing that they report was able to significantly reduce scar tissue caused by incisions.

Results of animal tests and of an early clinical trial of the dressing were "stunning," said Michael Longaker, MD, MBA, the Deane P. and Louise Mitchell Professor at the School of Medicine and senior author of a study that details the findings. "It was a surprisingly effective treatment."

The study will be published online May 23 in the Annals of Surgery.

After sutures are removed, the edges of a healing incision are pulled in different directions by the taut, surrounding skin, causing scar tissue to thicken and spread. The novel dressing, which the authors refer to as a "stress-shielding device," eliminates this tension and hence a considerable amount of scarring.

"This work actually started 20 years ago when I was an intern at Massachusetts General Hospital," said lead author Geoffrey Gurtner, MD, professor and associate chair of surgery. "I realized early on that we were not going to solve the problem of scarring with current surgical tools and techniques."

Co-author Reinhold Dauskardt, PhD, professor of materials science and engineering in the School of Engineering, recalled a meeting he had with Gurtner that launched the effort to create a stress-shielding device. "We were talking about our respective research," Dauskardt said. "Geoff had a lot of experience in wound healing and was thinking about factors that led to scarring. He said, 'If only we could keep in check the mechanical forces acting on the wound.' I had multiple programs on skin biomechanics and transdermal-drug delivery. I said, 'I think I can do that.'"

Dauskardt and his colleagues created the dressing in his lab. It is made of a thin and elastic silicone plastic that is stretched over the incision after sutures have been removed. The dressing sticks to the skin with the help of an adhesive. As it contracts, it provides uniform compression across the wound.

Scar tissue, which is less flexible than regular skin, can cause functional problems, such as limiting motion. Hair does not grow in a scar, and it doesn't have sweat glands. In addition, scars do not look like regular skin: They are often raised and have a pinkish hue. Many people consider them unattractive. Yet they are an unavoidable side effect of surgery. Every year in the United States, more than 50 million incisions are created during operations. Meanwhile, hundreds of millions of people already have scars that they would prefer to eliminate. Current scar-removal techniques, including surgical excision, steroid injections and laser therapy, are generally expensive, painful or simply not very effective, the authors say.

The researchers predicted the dressing will be used not only to reduce scarring from incisions, but also to make the surgical revision of existing scars a more appealing option; the second scar would be much less visible, if visible at all.

In pigs, which have skin similar to that of humans, the area of scars caused by roughly 1-inch incisions was reduced six-fold by the stress-shielding device, compared to pigs in a control group with the same-sized incisions, the study said. The stress-shielded wounds "demonstrated nearly scarless closure" eight weeks after sutures had been removed.

The researchers also tested the device on roughly 1-by-1.5-inch excisions -- a wound mimicking the kind caused by scar removal -- and found that "stress shielding dramatically decreased scar area" compared to unshielded wounds of the same size. "The device seemed to promote regenerative-like repair rather than scar formation," the authors wrote.

Next, the researchers tested the device on nine female patients who had undergone abdominoplasties (tummy tucks). Given the quantity of tissue removed during this elective surgery, a tremendous amount of tension occurred across the wound after closure. (Scars from these procedures are typically wide and thick.) Longaker said he and his colleagues deliberately chose to test the dressing on incisions closed with high tension: If the dressing could reduce scarring in such cases, it would surely work on any other kind of incision.

One side of the abdomen-wide incision on each patient was treated with the stress-shielding dressing; the other half was not. A panel of three plastic surgeons unaffiliated with the research, as well as a panel of three people not in the medical profession, acted as judges. On a 100-point scale, the lay panel scored the appearance of stress-shielded wounds an average of 13.2 points higher than the control wounds. The expert panel scored the scar appearance of the treated incisions 39.2 points higher. In both of these analyses, the difference between the treated side and the control side were highly significant, the researchers said.

But they noted that some of the wounds demonstrated more dramatic improvement than others. They speculate this may have been due to differences in the amount of tension present in the dressings when they were applied to the wounds. In any case, the researchers cautioned that this was a preliminary clinical study designed only to show "proof of principle in humans."

"Larger clinical trials are being planned to include greater ethnic diversity within the patient population and to determine the optimal range of stress-shielding forces for anatomic region- and dimension-specific wounds," the authors wrote.

Other co-authors of the paper, all at Stanford, were: Victor Wong, MD, and Kirit Bhatt, MD, postdoctoral research fellows in the Department of Surgery; Kenneth Wu, PhD, a recent postdoctoral scholar in the Department of Materials Science and Engineering; Ivan Vial, a medical student; Karine Padois, PhD, a postdoctoral scholar in the Department of Materials Science and Engineering; and Joshua Korman, MD, an adjunct clinical assistant professor of plastic and reconstructive surgery.

The research was supported by a Wallace H. Coulter Translational Partners Grant; the Armed Forces Institute of Regenerative Medicine; the Hagey Family Endowed Fund in Stem Cell Research and Regenerative Medicine; and the Oak Foundation.

Neodyne Biosciences Inc. provided the special surgical dressings for the study. Gurtner, Dauskardt and Longaker are founders and hold equity in the company.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford University Medical Center.

Journal Reference:

Geoffrey C. Gurtner, Reinhold H. Dauskardt, Victor W. Wong, Kirit A. Bhatt, Kenneth Wu, Ivan N. Vial, Karine Padois, Joshua M. Korman, Michael T. Longaker. Improving Cutaneous Scar by Controlling the Mechanical Environment. Annals of Surgery, 2011; DOI: 10.1097/SLA.0b013e318220b159

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

New device could reduce surgical scarring

ScienceDaily (May 24, 2011) — Researchers at Stanford University have developed a special wound dressing that they report was able to significantly reduce scar tissue caused by incisions.

Results of animal tests and of an early clinical trial of the dressing were "stunning," said Michael Longaker, MD, MBA, the Deane P. and Louise Mitchell Professor at the School of Medicine and senior author of a study that details the findings. "It was a surprisingly effective treatment."

The study will be published online May 23 in the Annals of Surgery.

After sutures are removed, the edges of a healing incision are pulled in different directions by the taut, surrounding skin, causing scar tissue to thicken and spread. The novel dressing, which the authors refer to as a "stress-shielding device," eliminates this tension and hence a considerable amount of scarring.

"This work actually started 20 years ago when I was an intern at Massachusetts General Hospital," said lead author Geoffrey Gurtner, MD, professor and associate chair of surgery. "I realized early on that we were not going to solve the problem of scarring with current surgical tools and techniques."

Co-author Reinhold Dauskardt, PhD, professor of materials science and engineering in the School of Engineering, recalled a meeting he had with Gurtner that launched the effort to create a stress-shielding device. "We were talking about our respective research," Dauskardt said. "Geoff had a lot of experience in wound healing and was thinking about factors that led to scarring. He said, 'If only we could keep in check the mechanical forces acting on the wound.' I had multiple programs on skin biomechanics and transdermal-drug delivery. I said, 'I think I can do that.'"

Dauskardt and his colleagues created the dressing in his lab. It is made of a thin and elastic silicone plastic that is stretched over the incision after sutures have been removed. The dressing sticks to the skin with the help of an adhesive. As it contracts, it provides uniform compression across the wound.

Scar tissue, which is less flexible than regular skin, can cause functional problems, such as limiting motion. Hair does not grow in a scar, and it doesn't have sweat glands. In addition, scars do not look like regular skin: They are often raised and have a pinkish hue. Many people consider them unattractive. Yet they are an unavoidable side effect of surgery. Every year in the United States, more than 50 million incisions are created during operations. Meanwhile, hundreds of millions of people already have scars that they would prefer to eliminate. Current scar-removal techniques, including surgical excision, steroid injections and laser therapy, are generally expensive, painful or simply not very effective, the authors say.

The researchers predicted the dressing will be used not only to reduce scarring from incisions, but also to make the surgical revision of existing scars a more appealing option; the second scar would be much less visible, if visible at all.

In pigs, which have skin similar to that of humans, the area of scars caused by roughly 1-inch incisions was reduced six-fold by the stress-shielding device, compared to pigs in a control group with the same-sized incisions, the study said. The stress-shielded wounds "demonstrated nearly scarless closure" eight weeks after sutures had been removed.

The researchers also tested the device on roughly 1-by-1.5-inch excisions -- a wound mimicking the kind caused by scar removal -- and found that "stress shielding dramatically decreased scar area" compared to unshielded wounds of the same size. "The device seemed to promote regenerative-like repair rather than scar formation," the authors wrote.

Next, the researchers tested the device on nine female patients who had undergone abdominoplasties (tummy tucks). Given the quantity of tissue removed during this elective surgery, a tremendous amount of tension occurred across the wound after closure. (Scars from these procedures are typically wide and thick.) Longaker said he and his colleagues deliberately chose to test the dressing on incisions closed with high tension: If the dressing could reduce scarring in such cases, it would surely work on any other kind of incision.

One side of the abdomen-wide incision on each patient was treated with the stress-shielding dressing; the other half was not. A panel of three plastic surgeons unaffiliated with the research, as well as a panel of three people not in the medical profession, acted as judges. On a 100-point scale, the lay panel scored the appearance of stress-shielded wounds an average of 13.2 points higher than the control wounds. The expert panel scored the scar appearance of the treated incisions 39.2 points higher. In both of these analyses, the difference between the treated side and the control side were highly significant, the researchers said.

But they noted that some of the wounds demonstrated more dramatic improvement than others. They speculate this may have been due to differences in the amount of tension present in the dressings when they were applied to the wounds. In any case, the researchers cautioned that this was a preliminary clinical study designed only to show "proof of principle in humans."

"Larger clinical trials are being planned to include greater ethnic diversity within the patient population and to determine the optimal range of stress-shielding forces for anatomic region- and dimension-specific wounds," the authors wrote.

Other co-authors of the paper, all at Stanford, were: Victor Wong, MD, and Kirit Bhatt, MD, postdoctoral research fellows in the Department of Surgery; Kenneth Wu, PhD, a recent postdoctoral scholar in the Department of Materials Science and Engineering; Ivan Vial, a medical student; Karine Padois, PhD, a postdoctoral scholar in the Department of Materials Science and Engineering; and Joshua Korman, MD, an adjunct clinical assistant professor of plastic and reconstructive surgery.

The research was supported by a Wallace H. Coulter Translational Partners Grant; the Armed Forces Institute of Regenerative Medicine; the Hagey Family Endowed Fund in Stem Cell Research and Regenerative Medicine; and the Oak Foundation.

Neodyne Biosciences Inc. provided the special surgical dressings for the study. Gurtner, Dauskardt and Longaker are founders and hold equity in the company.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford University Medical Center.

Journal Reference:

Geoffrey C. Gurtner, Reinhold H. Dauskardt, Victor W. Wong, Kirit A. Bhatt, Kenneth Wu, Ivan N. Vial, Karine Padois, Joshua M. Korman, Michael T. Longaker. Improving Cutaneous Scar by Controlling the Mechanical Environment. Annals of Surgery, 2011; DOI: 10.1097/SLA.0b013e318220b159

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