Of all the energy-saving tips out there, probably the one we hear most often is to not leave lights on when we leave a room. It's good advice, yet cities around the world are not following it in one key way - their streetlights stay on all night long, even when no one is on the street. The Netherlands' Delft University of Technology is experimenting with a new streetlight system on its campus, however, in which motion sensor-equipped streetlights dim to 20 percent power when no people or moving vehicles are near them. The system is said to reduce energy consumption and CO2 emissions by up to 80 percent, plus it lowers maintenance costs and reduces light pollution.
Delft Management of Technology alumnus Chintan Shah designed the system, which can be added to any dimmable streetlight. The illumination comes from LED bulbs, which are triggered by motion sensors. As a person or car approaches, their movement is detected by the closest streetlight, and its output goes up to 100 percent. Because the lights are all wirelessly linked to one another, the surrounding lights also come on, and only go back down to 20 percent once the commuter has passed through. This essentially creates a "pool of light" that precedes and follows people wherever they go, so any thugs lurking in the area should be clearly visible well in advance.
The lights' wireless communications system also allows them to automatically notify a central control room when failures (such as burnt-out bulbs) occur. This should make maintenance much simpler, as crews will know exactly where to go, and when.
Some fine-tuning is still ongoing, in order to keep the lights from being activated by things like swaying branches or wandering cats. In the meantime, Shah has formed a spin-off company named Tvilight to market the Delft technology. He claims that municipalities utilizing the system should see it paying for itself within three to four years of use.
Storing the sun’s heat in chemical form — rather than converting it to electricity or storing the heat itself in a heavily insulated container — has significant advantages, since in principle the chemical material can be stored for long periods of time without losing any of its stored energy. The problem with that approach has been that until now the chemicals needed to perform this conversion and storage either degraded within a few cycles, or included the element ruthenium, which is rare and expensive.
Last year, MIT associate professor Jeffrey Grossman and four co-authors figured out exactly how fulvalene diruthenium — known to scientists as the best chemical for reversibly storing solar energy, since it did not degrade — was able to accomplish this feat. Grossman said at the time that better understanding this process could make it easier to search for other compounds, made of abundant and inexpensive materials, which could be used in the same way.
Now, he and postdoc Alexie Kolpak have succeeded in doing just that. A paper describing their new findings has just been published online in the journal Nano Letters, and will appear in print in a forthcoming issue.
The new material found by Grossman and Kolpak is made using carbon nanotubes, tiny tubular structures of pure carbon, in combination with a compound called azobenzene. The resulting molecules, produced using nanoscale templates to shape and constrain their physical structure, gain “new properties that aren’t available” in the separate materials, says Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering.
Not only is this new chemical system less expensive than the earlier ruthenium-containing compound, but it also is vastly more efficient at storing energy in a given amount of space — about 10,000 times higher in volumetric energy density, Kolpak says — making its energy density comparable to lithium-ion batteries. By using nanofabrication methods, “you can control [the molecules’] interactions, increasing the amount of energy they can store and the length of time for which they can store it — and most importantly, you can control both independently,” she says. Thermo-chemical storage of solar energy uses a molecule whose structure changes when exposed to sunlight, and can remain stable in that form indefinitely. Then, when nudged by a stimulus — a catalyst, a small temperature change, a flash of light — it can quickly snap back to its other form, releasing its stored energy in a burst of heat. Grossman describes it as creating a rechargeable heat battery with a long shelf life, like a conventional battery.
One of the great advantages of the new approach to harnessing solar energy, Grossman says, is that it simplifies the process by combining energy harvesting and storage into a single step. “You’ve got a material that both converts and stores energy,” he says. “It’s robust, it doesn’t degrade, and it’s cheap.” One limitation, however, is that while this process is useful for heating applications, to produce electricity would require another conversion step, using thermoelectric devices or producing steam to run a generator. While the new work shows the energy-storage capability of a specific type of molecule — azobenzene-functionalized carbon nanotubes — Grossman says the way the material was designed involves “a general concept that can be applied to many new materials.” Many of these have already been synthesized by other researchers for different applications, and would simply need to have their properties fine-tuned for solar thermal storage.
The key to controlling solar thermal storage is an energy barrier separating the two stable states the molecule can adopt; the detailed understanding of that barrier was central to Grossman’s earlier research on fulvalene dirunthenium, accounting for its long-term stability. Too low a barrier, and the molecule would return too easily to its “uncharged” state, failing to store energy for long periods; if the barrier were too high, it would not be able to easily release its energy when needed. “The barrier has to be optimized,” Grossman says.
Already, the team is “very actively looking at a range of new materials,” he says. While they have already identified the one very promising material described in this paper, he says, “I see this as the tip of the iceberg. We’re pretty jazzed up about it.”
Yosuke Kanai, assistant professor of chemistry at the University of North Carolina at Chapel Hill, says “the idea of reversibly storing solar energy in chemical bonds is gaining a lot of attention these days. The novelty of this work is how these authors have shown that the energy density can be significantly increased by using carbon nanotubes as nanoscale templates. This innovative idea also opens up an interesting avenue for tailoring already-known photoactive molecules for solar thermal fuels and storage in general.”
Berlusconi, who failed to secure a majority in a crucial vote on Tuesday, stepped down as prime minister after parliament passed a package of measures demanded by European partners to restore market confidence in Italy's strained public finances.
Former European Commissioner Mario Monti is expected to be given the task of trying to form a new administration to face a widening financial crisis which has sent Italy's borrowing costs to unmanageable levels.
More than a thousand demonstrators waving banners mocking Berlusconi flocked to the president's residence at the Quirinale Palace as the motorcade carrying the billionaire media entrepreneur, who has been Italy's longest serving prime minister, entered.
The crowd grew so unruly that Berlusconi was forced to leave secretly via a side entrance and return to his private residence.
Cheers broke out when they heard that Berlusconi had resigned and the square broke out into a party atmosphere. People sang, danced and some broke open bottles of champagne.
An orchestra near the palace played the Hallelujah chorus from Handel's Messiah. "We are here to rejoice," one said.
Demonstrators chanting "resign, resign, resign" also gathered outside the prime minister's office and parliament, heckling ministers as they walked between the two buildings.
A small group of pro-Berlusconi demonstrators gathered outside his residence but were hugely outnumbered by opponents.
After the resignation, hundreds shouting "Jail, Jail, Jail,"
moved from the presidential palace to Berlusconi's residence to continue the noisy celebrations below his windows.
"This is something that deeply saddens me," the Italian news agency Ansa quoted Berlusconi as telling aides.
President Giorgio Napolitano will begin consultations with political leaders at 5:00 a.m. EST on Sunday morning. He was expected to ask Monti for form a government on Sunday night.
Italy, the euro zone's third largest economy, came close to disaster this week when yields on 10-year bonds soared over 7.6 percent, the kind of level which forced Ireland, Portugal and Greece to seek international bailouts.
Berlusconi, who failed to secure a majority in a vote on Tuesday, promised to resign once parliament passed the package of economic reforms demanded by European partners to restore confidence in Italy's battered public finances.
Monti, named by Napolitano as a Senator for Life on Wednesday, is expected to appoint a relatively small cabinet of technocrat specialists to steer Italy through the crisis.
With the next election not due until 2013, a technocrat government could have about 18 months to pass painful economic reforms but will need to secure the backing of a majority in parliament and could fall before then.
With a public debt of more than 120 percent of gross domestic product and more than a decade of anemic economic growth behind it, Italy is at the heart of the euro zone debt crisis and would be too big for the bloc to bail out.
Financial markets have backed a Monti government and as prospects of Berlusconi going became firmer last week, yields dropped below the critical 7 percent level, although they remain close.
"We don't yet have a new government in Italy and we have to wait, but I'm sure if Mario Monti will be appointed he will do whatever is necessary in order to restore the confidence of the financial markets in Italy," Alessandro Profumo, former head of Unicredit, Italy's largest bank, told Reuters.
SIGNS OF OPPOSITION MOUNT
Berlusconi, fighting an array of scandals and facing trials on charges ranging from tax fraud to paying for sex with an under-aged prostitute, had been under pressure to resign for weeks as the market crisis threatened to spin out of control.
International leaders including U.S. President Barack Obama, French President Nicolas Sarkozy and the head of the International Monetary Fund Christine Lagarde have expressed hopes a new government can be in place quickly.
Talks with Italian political parties are expected to begin on Sunday with hopes that a new government can be in place in time for the opening of financial markets on Monday.
However, even as preparations for a transition begin, signs of opposition have appeared, with Berlusconi's PDL party split between factions ready to accept a Monti government and others deeply opposed.
Berlusconi had a working lunch with Monti before the vote, suggesting the outgoing government will not try to block a quick handover, but the attitude of the center-right as a whole remains unclear.
The PDL's main coalition ally, the regional pro-devolution Northern League, has declared it will go into opposition, underlining the risk that the new government will lack the broad parliamentary support it will need to pass deep reforms.
"The convulsions in the center-right at the prospect of a government led by Mario Monti signal a danger: that a divided coalition may be tempted to unload its divisions on the country," the daily Corriere della Sera said.
The center-left Democratic party and smaller centrist parties have pledged support to Monti. Italy's main business and banking associations and some of the moderate trade unions have also called for a government of national unity.
Source: Reuters - (Additional reporting by James Mackenzie and Paolo Biondi; Writing by Philip Pullella and James Mackenzie; Editing by Janet Lawrence and Andrew Heavens)
The technology amplifies any anthrax DNA present in the sample and can reveal the presence of just 40 microscopic cells of the deadly bacteria Bacillus anthracis.
B. anthracis, commonly known as anthrax, is a potentially lethal microbe that might be used intentionally to infect victims through contamination of food and water supplies, aerosolized particles, or even dried powders, such as those used in bioterrorist attacks in the USA. Detection is crucial to preventing widespread fatalities in the event of an anthrax attack. However, the complexity of the microbe's biology have so far made it difficult to build a portable system that can be employed quickly in the field. That said, there are several systems available that use PCR to amplify a particular component of the genetic material present in anthrax and then to flag this amplified signal. These systems are fast and sensitive but do not integrate sample preparation and so are not as convenient as a single detector unit would be.
A photomicrograph of Bacillus anthracis bacteria using Gram-stain technique. Anthrax is diagnosed by isolating B. anthracis from the blood, skin lesions, or respiratory secretions, or by measuring specific antibodies in the blood of persons with suspected cases. Photo: CDC
Writing in the International Journal of Biomedical Nanoscience and Nanotechnology this month, Nathaniel Cady of the College of Nanoscale Science and Engineering (CNSE) of the University at Albany and colleagues there and at Cornell University, New York, explain how they have constructed nanofabricated fluidic cartridges that can be used to carry out detection of anthrax. The device is a so-called "lab-on-a-chips" device, or more properly a 3D microfluidic network that contains nanofabricated pillar structures.
The device has fluidic inputs for adding sample and reagents, removing waste, for carrying out DNA purification, and critically an integrated chamber for amplifying only the target DNA in the sample using the polymerase chain reaction (PCR) system. The chip also contains a wave guide for the fluorescence-based identification of the amplified DNA and thus the target microbe. Importantly, the system works without manual intervention other than loading a droplet of sample into the detector.
"The average time required for DNA purification during these experiments was approximately 15 min, and when combined with real-time PCR analysis, this resulted in an average time to detection of 60 min," the team says. The system can detect as few as 40 B. anthracis cells. "Due to its small size and low power requirements, this system can be further developed as a truly portable, hand-held device," the researchers conclude.
You could never prosecute WikiLeaks without criminalizing all journalism in the United States.- Glenn Greenwald
This is a "WikiLeaks News Update", a news update of stories relating directly to WikiLeaks and also freedom of information, transparency, cybersecurity, and freedom of expression.
WikiLeaks News: Collateral Murder changes US interrogator's views, WL/Bradley #Manning Support
On Veteran's day,The AtlanticinterviewsMichael Patterson, a former U.S. army interrogator whose decision to leave the army and current participation in the Occupy Movement (Michael is staying at Occupy DC) were motivated by the videoCollateral Murder, released by WikiLeaks on the 5th April 2010:
"... I ask him what was the switch for him and when. He explained that it was WikiLeaks.It was the footage of the Apache helicopter gunning down Iraqis released by WikiLeaks in April of 2010. Up to that point he had been interrogating Iraqis and using what he describes as psychological torture.He was 10 years old when the World Trade Center was hit. He wanted to fight terrorism in Iraq. He bought into the whole thing, he tells me. He had been looking forward to signing up ever since the 5th grade and then, suddenly, last November, he found himself watching a video of his fellow soldiers gunning down Iraqis on the street and it all changed for him.
The Apache video, to a civilian, makes war look like a video game, but to Patterson,it was the first time he saw Iraqis as real people. Random people, with children and families who care about them.He tried to get out of the military as a conscientious objector after that. He was told it wouldn't work because he's an atheist."So I just smoked a bunch of pot and got kicked out," he says. He was officially discharged on June 7th of this year. He went back home to Alaska, where he read about Occupy Wall Street on Reddit.
He then went to D.C. to sleep in a tent a block away from the White House."
EFF and ACLU respond to Court rulingWikiLeaks' associates private twitter records are to be disclosed to the US government, as part of a Grand Jury investigation on WikiLeaks. Astatementreleased by EFF (Electronic Frontier Foundations), titled 'Privacy Loses in Twitter/Wikileaks Records Battle' reads:
'... Jonsdottir and others only found out about the government requests for information because Twitter took steps to notify them of the court order. EFF is urging other companies to follow Twitter's lead, stand with their customers, and promise to inform users when their data is sought by the government, as part of ourWho Has Your Back?campaign.'
Both organizations represent Icelandic MP and former WikiLeaks volunteer Birgitta Jonsdottir in the case. Read ACLU's press release on this subjecthere. In an interview to The Guardian, Birgittadeclaredthe intention to take the case to the Council of Europe.
Vigil for Bradley Manning on his 24th Birthday
Saturday, December 17 · 12:00am - 11:30pm On the 17th of December - his 24th birthday - Bradley Manning will have been incarcerated for 571 days.
On this day stand in solidarity with Bradley Manning whose only crime was revealing the truth - congregate at the White House, your city hall or town square, or your nearest US Embassy or Consulate - peacefully and solemnly. [For more details, see Vigil for Bradley Manning on his 24th Birthday'sfacebookpage.] Other upcoming campaigns in support of Bradley Manning:
*Bradley's 24th birthday will be onDecember 17th. This is the second birthday the alleged whistleblower will have spent detained in a military prison, without trial. Everyone is encouraged togather supportfor Bradley Manning on this day and tosendsmall gifts and birthday cards to the following address
Bradley Manning 89289 830 Sabalu Road Fort Leavenworth, KS 6602
Julian Assange/WikiLeaks Support Campaigns
* November 17: Headed by Christine Assange, Julian Assange's mother, a protest against Julian's extradition and US government actions against WikiLeaks will occur in front of the Parliament House in Canberra on the occasion of US President Obama's visit to Australia. Please join. Knowmoreabout this protest.
*Online Human Rightspetitiondemanding Julian Assange be protected by the Australian Parliament from extradition to the United States.
Julian Assange has been under house arrest for 339 days without having been charged of a crime. (VisitSweden vs. Assangefor all information on this case.) Bradley Manning has spent 535 days detained without trial. A Fair Trials Internationalcampaignwas launched to end pre-trial detention within the EU. Fair Trials International also advocate thereformof the European Arrest Warrant:
TheEAW has removed many of the traditional safeguards in the extradition process. If a court in one country demands a person’s arrest and extradition, courts and police in other countries must act on it. In 2009, this fast track extradition system was used to extradite over 4,000 people across the EU (700 people from the UK alone).
Although it was intended to deliver justice, the current system is actually resulting in cases of serious injustice. Our own casework repeatedly demonstrates the human cost of EU extradition. Fair Trials International will continue to press for an EU extradition system which is both fair and effective. Through our Justice in Europe campaign, we are succeeding in making the case for reform.
And, the study found, pet owners were just as close to key people in their lives as to their animals, indicating no evidence that relationships with pets came at the expense of relationships with other people, or that people relied more on pets when their human social support was poorer.
Psychologists at Miami University and Saint Louis University conducted three experiments to examine the potential benefits of pet ownership among what they called everyday people. The results of the current study were reported in the Journal of Personality and Social Psychology, published online by APA.
“We observed evidence that pet owners fared better, both in terms of well-being outcomes and individual differences, than non-owners on several dimensions,” said lead researcher Allen R. McConnell, PhD, of Miami University in Ohio. “Specifically, pet owners had greater self-esteem, were more physically fit, tended to be less lonely, were more conscientious, were more extraverted, tended to be less fearful and tended to be less preoccupied than non-owners.”
Until now, most research into the benefits of pets has been correlational, meaning it looked at the relationship between two variables but didn’t show that one caused the other. For example, prior research showed that elderly Medicare patients with pets had fewer doctor visits than similar patients without pets, or that HIV-positive men with pets were less depressed than those without.
In this study, 217 people (79 percent women, mean age 31, mean annual family income $77,000) answered surveys aimed at determining whether pet owners in the group differed from people who didn’t have pets in the areas of well-being, personality type and attachment style. Several differences between the groups emerged, and in all cases, pet owners were happier, healthier and better adjusted than were non-owners.
A second experiment, involving 56 dog owners (91 percent of whom were women, with a mean age of 42 and average annual family income of $65,000), examined whether pet owners benefit more when their pet is perceived to fulfill their social needs better. This study found greater well-being among owners whose dogs increased their feelings of belonging, self-esteem and meaningful existence.
The last study, comprising 97 undergraduates with an average age of 19, found that pets can make people feel better after experiencing rejection. Subjects were asked to write about a time when they felt excluded. Then they were asked to write about their favorite pet, or to write about their favorite friend, or to draw a map of their campus. The researchers found that writing about pets was just as effective as writing about a friend when it came to staving off feelings of rejection.
“[T]he present work presents considerable evidence that pets benefit the lives of their owners, both psychologically and physically, by serving as an important source of social support,” the researchers wrote. “Whereas past work has focused primarily on pet owners facing significant health challenges … the present study establishes that there are many positive consequences for everyday people who own pets.”
The company uses nanostructures for battery materials that, like other recent nanostructures, let the materials deliver the large bursts of power needed for acceleration while maintaining energy storage capacity. But the Wuhe advance also makes the materials easier to work with than similar electrode materials, and as a result, it could cut battery-cell manufacturing costs by 10 percent.
Power structure: A micrograph shows nanoparticles embedded in larger particle of porous carbon. Yu-Guo Guo
Battery packs are the most expensive item on electric cars such as the Tesla Roadster and the Nissan Leaf. The cost either makes electric cars too expensive for most people, or it prompts automakers to use small battery packs, which limits the range of the cars.
To reduce battery costs and improve their performance, Wuhe founder Yu-Guo Guo, a professor of chemistry at the Chinese Academy of Sciences in Beijing, has developed new, low-cost ways to improve the properties of lithium-iron phosphate, one of the leading lithium-ion battery electrode materials, and other promising electrode materials.
Ordinarily, the conductivity of lithium-iron phosphate is too low to be useful. The conductivity can be increased by milling it into extremely fine nanoscale powders—as companies such as A123 Systems do. Because the particles are small, electrons or lithium ions—both of which are necessary to create current—can move in and out of them quickly. But this powder is difficult to work with, which raises manufacturing costs.
Guo's solution has been to incorporate iron-phosphate nanoparticles, which are easier to pack closely, and are less likely become airborne, but retain high conductivity. He isn't giving precise details, but he says the technology is based on some of his earlier published work. In one example of that work, he embedded the nanoparticles in larger particles made of porous carbon. The carbon conducts electricity well, and the pores host electrolyte materials that conduct lithium ions well.
Guo says the materials are only 10 to 20 percent more expensive to make than bulk lithium-iron phosphate. But they can deliver about twice as much power as the bulk material, and make twice as much of the energy in lithium-iron phosphate available, roughly doubling the energy storage capacity. Per watt-hour, the materials cost the same as other lithium-iron-phosphate electrode materials, he says. But since the material is easier to work with, it will cut the cost of incorporating the materials into battery cells.
Wuhe, which Guo founded at the end of last year, already has the capacity to produce 300 metric tons of electrode material a year, enough for about 30 million standard lithium-ion battery cells. It also makes battery cells, with the first application being electric bicycles. It can currently make enough cells for roughly 500 electric cars a year.
Jeff Dahn, professor of physics and chemistry at Dalhousie University, says that, based on the company's performance figures, the iron-phosphate batteries will be "very useful" and could perform better than the batteries used now in the electric Chevrolet Volt. And he predicts Wuhe will find a market.
The laser stimulation of optic nerves is the focus of this research to develop a vision prosthesis - perhaps a tiny laser device fitted in a pair of spectacles - much like the cochlear implant for restoring hearing. Swinburne's Applied Optics and Biomedical Engineering Groups are seeking government and philanthropic funding to progress this research using gold nanoparticles to amplify laser light.
These microscopic nanoparticles, fixed to optical nerves and assembled to respond to different laser light wavelength, could become the key to restoring vision to people who have lost their sight through degenerative eye disease.
The researchers are looking for a non-contact method of stimulating nerves and are exploring the use of laser light, rather than the direct electrical stimulation techniques that have become the conventional approach.
Using a very low intensity laser source they are trying to generate the right amount of heat required to elicit a response from nerve cells without damaging them. According to researcher PhD student Chiara Paviolo, the new concept explores the potential for light to deliver far more precise nerve cell stimulation than electrodes. "Electrodes need an electrical current and so they consequently stimulate a group of nerves," Paviolo said. "Light, however, allows us to target individual nerves and this should mean more accurate communication of optical signals - an essential outcome if the information delivered to the brain via a prosthesis is to mean anything useful in terms of shapes, colours, dimensions. You don't just want optical ‘noise'."
The initial goal is to successfully bond the nanoparticles to the nerve and then achieve a response to light heat. Gold nanoparticles are being used because gold is inert, biocompatible and has plasmonic or light-responsive properties. The gold nanoparticles can also be fabricated to respond to different wavelengths, making the interface controllable.
"One of the challenges is to develop nanoparticles that are thermally stable," said Professor of Biointerface Engineering Sally McArthur . "While on one hand heat is necessary, it also has to be limited to avoid damaging cells. Laser heat has long been used in medicine to deliberately kill tissue, but in this instance the opposite result is sought."
To measure and control the heat, the Swinburne team is building a molecular thermal sensor to measure how much heat is produced, so they can then work out how to control it. The team's ultimate ambition for its technology is a prosthesis that in the first instance will restore vision to people who have lost their sight through retinitis pigmentosis or macular degeneration.
"With these diseases the nerve is still alive, making it a strong candidate for a prosthesis," Paviolo said. Paviolo said international interest is already building in the Swinburne project because the concept of using light stimulation combined with nanotechnology is novel.
By scavenging this ambient energy from the air around us, the technique could provide a new way to power networks of wireless sensors, microprocessors and communications chips.
"There is a large amount of electromagnetic energy all around us, but nobody has been able to tap into it," said Manos Tentzeris, a professor in the Georgia Tech School of Electrical and Computer Engineering who is leading the research. "We are using an ultra-wideband antenna that lets us exploit a variety of signals in different frequency ranges, giving us greatly increased power-gathering capability."
Tentzeris and his team are using inkjet printers to combine sensors, antennas and energy scavenging capabilities on paper or flexible polymers. The resulting self powered wireless sensors could be used for chemical, biological, heat and stress sensing for defense and industry; radio frequency identification (RFID) tagging for manufacturing and shipping, and monitoring tasks in many fields including communications and power usage.
Caption: Georgia Tech School of Electrical and Computer Engineering professor Manos Tentzeris holds a sensor (left) and an ultra-broadband spiral antenna for wearable energy-scavenging applications. Both were printed on paper using inkjet technology. - Credit: Georgia Tech Photo: Gary Meek
A presentation on this energy scavenging technology was given July 6 at the IEEE Antennas and Propagation Symposium in Spokane, Wash. The discovery is based on research supported by multiple sponsors, including the National Science Foundation, the Federal Highway Administration and Japan's New Energy and Industrial Technology Development Organization (NEDO).
Communications devices transmit energy in many different frequency ranges, or bands. The team's scavenging devices can capture this energy, convert it from AC to DC, and then store it in capacitors and batteries. The scavenging technology can take advantage presently of frequencies from FM radio to radar, a range spanning 100 megahertz (MHz) to 15 gigahertz (GHz) or higher.
Scavenging experiments utilizing TV bands have already yielded power amounting to hundreds of microwatts, and multi-band systems are expected to generate one milliwatt or more. That amount of power is enough to operate many small electronic devices, including a variety of sensors and microprocessors.
And by combining energy scavenging technology with supercapacitors and cycled operation, the Georgia Tech team expects to power devices requiring above 50 milliwatts. In this approach, energy builds up in a battery-like supercapacitor and is utilized when the required power level is reached.
The researchers have already successfully operated a temperature sensor using electromagnetic energy captured from a television station that was half a kilometer distant. They are preparing another demonstration in which a microprocessor-based microcontroller would be activated simply by holding it in the air.
Exploiting a range of electromagnetic bands increases the dependability of energy scavenging devices, explained Tentzeris, who is also a faculty researcher in the Georgia Electronic Design Center at Georgia Tech. If one frequency range fades temporarily due to usage variations, the system can still exploit other frequencies.
The scavenging device could be used by itself or in tandem with other generating technologies. For example, scavenged energy could assist a solar element to charge a battery during the day. At night, when solar cells don't provide power, scavenged energy would continue to increase the battery charge or would prevent discharging.
Utilizing ambient electromagnetic energy could also provide a form of system backup. If a battery or a solar-collector/battery package failed completely, scavenged energy could allow the system to transmit a wireless distress signal while also potentially maintaining critical functionalities.
The researchers are utilizing inkjet technology to print these energy scavenging devices on paper or flexible paper-like polymers – a technique they already using to produce sensors and antennas. The result would be paper-based wireless sensors that are self powered, low cost and able to function independently almost anywhere.
To print electrical components and circuits, the Georgia Tech researchers use a standard materials inkjet printer. However, they add what Tentzeris calls "a unique in house recipe" containing silver nanoparticles and/or other nanoparticles in an emulsion. This approach enables the team to print not only RF components and circuits, but also novel sensing devices based on such nanomaterials as carbon nanotubes.
When Tentzeris and his research group began inkjet printing of antennas in 2006, the paper-based circuits only functioned at frequencies of 100 or 200 MHz, recalled Rushi Vyas, a graduate student who is working with Tentzeris and graduate student Vasileios Lakafosis on several projects.
"We can now print circuits that are capable of functioning at up to 15 GHz -- 60 GHz if we print on a polymer," Vyas said. "So we have seen a frequency operation improvement of two orders of magnitude."
The researchers believe that self-powered, wireless paper-based sensors will soon be widely available at very low cost. The resulting proliferation of autonomous, inexpensive sensors could be used for applications that include:
Airport security: Airports have both multiple security concerns and vast amounts of available ambient energy from radar and communications sources. These dual factors make them a natural environment for large numbers of wireless sensors capable of detecting potential threats such as explosives or smuggled nuclear material.
Energy savings: Self-powered wireless sensing devices placed throughout a home could provide continuous monitoring of temperature and humidity conditions, leading to highly significant savings on heating and air conditioning costs. And unlike many of today's sensing devices, environmentally friendly paper-based sensors would degrade quickly in landfills.
Structural integrity: Paper or polymer-based sensors could be placed throughout various types of structures to monitor stress. Self powered sensors on buildings, bridges or aircraft could quietly watch for problems, perhaps for many years, and then transmit a signal when they detected an unusual condition.
Food and perishable material storage and quality monitoring: Inexpensive sensors on foods could scan for chemicals that indicate spoilage and send out an early warning if they encountered problems.
Wearable bio-monitoring devices: This emerging wireless technology could become widely used for autonomous observation of patient medical issues.