New Way To Make Electricity from Magnetism

Credit: Kipp van Schooten and Dali Sun, University of Utah

By showing that a phenomenon dubbed the "inverse spin Hall effect" works in several organic semiconductors - including carbon-60 buckyballs - University of Utah physicists changed magnetic "spin current" into electric current. The efficiency of this new power conversion method isn't yet known, but it might find use in future electronic devices including batteries, solar cells and computers. "This paper is the first to demonstrate the inverse spin Hall effect in a range of organic semiconductors with unprecedented sensitivity," although a 2013 study by other researchers demonstrated it with less sensitivity in one such material, says Christoph Boehme, a senior author of the study published April 18 in the journal Nature Materials. The upper part of this illustration shows the device, built on a small glass slide, that was used in experiments showing that so-called spin current could be converted to electric current using several different organic polymer semiconductors and a phenomenon known as the inverse spin Hall effect. The bottom illustration shows the key, sandwich-like part of the device. An external magnetic field and pulses of microwaves create spin waves in the iron magnet. When those waves hit the polymer or organic semiconductor, they create spin current, which is converted to an electrical current at the copper electrodes. "The inverse spin Hall effect is a remarkable phenomenon that turns so-called spin current into an electric current. The effect is so odd that nobody really knows what this will be used for eventually, but many technical applications are conceivable, including very odd new power-conversion schemes," says Boehme, a physics professor. His fellow senior author, distinguished professor Z. Valy Vardeny, says that by using pulses of microwaves, the inverse spin Hall effect and organic semiconductors to convert spin current into electricity, this new electromotive force generates electrical current in a way different than existing sources. Coal, gas, hydroelectric, wind and nuclear plants all use dynamos to convert mechanical force into magnetic-field changes and then electricity. Chemical reactions power modern batteries and solar cells convert light to electrical current. Converting spin current into electrical current is another method. Scientists already are developing such devices, such as a thermoelectric generator, using traditional inorganic semiconductors. Vardeny says organic semiconductors are promising because they are cheap, easily processed and environmentally friendly. He notes that both organic solar cells and organic LED (light-emitting diode) TV displays were developed even though silicon solar cells and nonorganic LEDs were widely used. Vardeny and Boehme stressed that the efficiency at which organic semiconductors convert spin current to electric current remains unknown, so it is too early to predict the extent to which it might one day be used for new power conversion techniques in batteries, solar cells, computers, phones and other consumer electronics. "I want to invoke a degree of caution," Boehme says. "This is a power conversion effect that is new and mostly unstudied." Boehme notes that the experiments in the new study converted more spin current to electrical current than in the 2013 study, but Vardeny cautioned the effect still "would have to be scaled up many times to produce voltages equivalent to household batteries." From spin current to electric current Just as atomic nuclei and the electrons that orbit them carry electrical charges, they also have another inherent property: spin, which makes them behave like tiny bar magnets that can point north or south. Electronic devices store and transmit information using the flow of electricity in the form of electrons, which are negatively charged subatomic particles. The zeroes and ones of computer binary code are represented by the absence or presence of electrons within silicon or other nonorganic semiconductors. Spin electronics - spintronics - holds promise for faster, cheaper computers, better electronics and LEDs for displays, and smaller sensors to detect everything from radiation to magnetic fields. The inverse spin Hall effect first was demonstrated in metals in 2008, and then in nonorganic semiconductors, Vardeny says. In 2013, researchers elsewhere showed it occurred in an organic semiconductor named PEDOT:PSS when it was exposed to continuous microwaves that were relatively weak to avoid frying the semiconductor. University of Utah physicists Z. Valy Vardeny and Christoph Boehme published a new study in Nature Materials demonstrating that a range of organic semiconductors can be used to convert a so-called magnetic spin current into electric current. They don't yet know the efficiency of this power-conversion method, but say it has possible future uses in future solar cells, batteries and electronic devices like computers and cell phones. 

Credit: Lee J. Siegel, University of Utah

But Boehme and Vardeny say the electrical current generated in that study by the inverse spin Hall effect was small - nanovoltages - and was obscured by microwave heating of the sample and other undesired effects. "We thought, let's build different devices so these spurious effects were eliminated or very small compared with the effect we wanted to observe," Boehme says. In the new study, the researchers used short pulses of more powerful microwaves to utilize the inverse spin Hall effect and convert a spin current to electric current in seven organic semiconductors, mostly at room temperature. One organic semiconductor was PEDOT:PSS - the same material in the 2013 study. The others were three platinum-rich organic polymers, two so-called pi-conjugated polymers and the spherical carbon-60 molecule named buckminsterfullerene because it looks like a pair of geodesic domes popularized by the late architect Buckminster Fuller. The carbon-60 proved surprisingly to be the most efficient semiconductor at converting spin waves into electrical current, Vardeny says. How the experiments were performed The Utah physicists take multiple steps to convert spin current to electrical current. They begin with a small glass slide, about 2.1-inches long and one-sixth-inch wide. Two electrical contacts are attached to one end of the glass slide. Thin, flat copper wires run the length of the slide, connecting the contacts at one end with a "sandwich" at the other end that includes the glass at the bottom, the organic polymer semiconductor being tested in the middle and a nickel-iron ferromagnet on top. This device then is inserted lengthwise into a metal tube about 1-inch diameter and 3.5 inches long. A nonconducting material surrounds the device inside this tube, which then is inserted into a table-sized magnet that generates a magnetic field. "We apply a magnetic field and leave it more or less constant," Boehme says. "Then we hook up the two contacts to a voltage meter and start measuring the voltage coming out of the device as a function of time." A view of the University of Utah physics laboratory where researchers showed that a phenomenon named the inverse spin Hall effect works in several organic semiconductors when pulsed microwaves are applied to the materials. The effect converts so-called spin current to electric current and may find use in future generations of batteries, solar cells and electronic devices.

Credit: Christoph Boehme, University of Utah

With just the magnetic field, no electrical current was detected. But then the Utah physicists bombarded the organic semiconductor device with pulses of microwaves - as powerful as those from a home microwave oven but in pulses ranging from only 100 to 5,000 nanoseconds (the latter equal to one 200,000th of a second). "All of a sudden we saw a voltage during that pulse," Boehme says. Vardeny says the microwave pulses generate spin waves in the device's magnet, then the waves are converted into spin current in the organic semiconductor, and then into an electric current detected as a voltage. Compared with the 2013 study, the use of microwave pulses in the Utah experiments meant "our power is much higher but the heating is much less and the inverse spin Hall effect is about 100 times stronger," Boehme says. In effect, the pulsed microwaves provide a way to enhance the inverse spin Hall effect so it can be used to convert power, Vardeny adds. The new study also showed that the conversion of spin current to electric current works in organic semiconductors via "spin-orbit coupling" - the same process found in inorganic conductors and semiconductors - even though the phenomenon in inorganic and organic materials works in fundamentally different ways, Boehme says. This coupling is much weaker in organic than in nonorganic semiconductors, but "the big achievement we made was to find an experimental method sensitive enough to reliably measure these very weak effects in organic semiconductors," Boehme says. The new study was funded by the National Science Foundation and the University of Utah-NSF Materials Research Science and Engineering Center. Study co-authors with Vardeny and Boehme were these University of Utah physicists: research assistant professors Dali Sun and Hans Malissa, postdoctoral researchers Kipp van Schooten and Chuang Zhang, and graduate students Marzieh Kavand and Matthew Groesbeck. 

• Contacts and sources: 
• Lee J. Siegel
• University of Utah
• Citation: "Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin–orbit coupling." Authors: Dali Sun, Kipp J. van Schooten, Marzieh Kavand, Hans Malissa, Chuang Zhang, Matthew Groesbeck, Christoph Boehme & Z. Valy Vardeny
• Nature Materials (2016) doi:10.1038/nmat4618 

http://dx.doi.org/10.1038/NMAT4618. Source: http://www.ineffableisland.com

Read More........→May 31, 2016

Google files patent for wearable medical device

Google has filed a patent application for a wearable medical device, able to use nanoparticles to detect and treat illnesses such as cancer.

For those wishing to protect their health and extend their lifespan, a futuristic medical device may become available in the next several years. Details of this wearable technology – known as a Nanoparticle Phoresis – have been published online by Google, via the World Intellectual Property Organisation. The patent application describes a strap, or band, mounted on the lower arm. Similar in appearance to a wristwatch, it would "automatically modify or destroy one or more targets in the blood that have an adverse health effect." This would be achieved by beaming energy into blood vessels to stimulate cells and molecules, increasing their effectiveness at fighting diseases. It could even be used on synthetic nanoparticles. Millions of these tiny objects would be introduced into the wearer's bloodstream, then activated by magnets in the wristband and directed to specific locations. In addition to its physical treatment abilities, the Nanoparticle Phoresis could generate vast amounts of data – not only helpful to the user, but also to researchers and doctors. It could accept inputs from the wearer regarding his or her health state, such as "feeling cold," "feeling tired," "pollen allergy symptoms today," "stressed," "feeling energetic," etc. According to the patent, these user inputs "may be used to complement any other physiological parameter data that the wearable device may collect and establish effective signal levels for and timing of modification of the target." Analysts forecast that wearable technology will see huge growth in the coming years, with unit sales potentially reaching into the

hundreds of millions. This new device from Google – if successfully developed – could become part of that rapidly evolving ecosystem. Initially aimed at patients who are seriously ill, this product (or its derivatives) could also be offered to mainstream consumers who aren't necessarily in bad health, but wish to monitor and improve their well-being. For those with a needle phobia, injections might be possible using high-pressure jets. Although the patent itself makes no mention of this, we can speculate that such a procedure would eventually be incorporated into a wristwatch form factor. Similar to the "hypospray" on Star Trek, these jets would ensure that the skin is not punctured. High-pressure jet injection was covered on our blog in May 2012. Looking further ahead, the prospects become even more exciting. Bill Maris – who helped form Google Calico – this month stated his belief that humans will live to be many centuries old in the future, while today's cancer treatments will seem "primitive" within just 20 years. His comments echo those of futurist and inventor Ray Kurzweil, also employed at Google and currently involved in AI research for the company. Kurzweil predicts that nanoparticles will be superseded by nanobots – small and compact enough to feature motors, sensors and other tools, allowing them to be controlled with extreme precision directly inside cells. If this idea sounds like science fiction, then consider this: a handheld smartphone today contains more processing power than a room-sized supercomputer of the 1980s. With ongoing advances in miniaturisation, together with new materials such as graphene, the future trend seems inevitable. As humans become ever more dependent on technology, our bodies will gradually begin to incorporate these and similar devices on a permanent basis. Later in the 21st century, the line between man and machine could become blurred. Source: Article

Read More........→February 15, 2016

Could Pirates Spoof A Super Yacht At Sea And Lead It Off Course? In A Word Yes, Say Texas Researchers

Is it possible to coerce a 213-foot yacht off its course — without touching the boat’s steering wheel — using a custom-made GPS device? That’s what Todd Humphreys wanted to find out. Humphreys, a researcher in the Department of Aerospace Engineering and Engineering Mechanics at the Cockrell School of Engineering, and his team successfully “spoofed” an $80 million private yacht using the world’s first openly acknowledged GPS spoofing device. Spoofing is a technique that creates false civil GPS signals to gain control of a vessel’s GPS receivers. The purpose of the experiment was to measure the difficulty of carrying out a spoofing attack at sea and to determine how easily sensors in the ship’s command room could identify the threat. The animation in the video explains how the research team

performed the GPS spoofing experiment on the yacht. The researchers hope their demonstration will shed light on the perils of navigation attacks, serving asevidence that spoofing is a serious threat to marine vessels and other forms of transportation. Last year, Humphreys and a group of students led thefirst public capture of a GPS-guided unmanned aerial vehicle (UAV), or drone, using a GPS device created by Humphreys and his students.“With 90 percent of the world’s freight moving across the seas and a great deal of the world’s human transportation going across the skies, we have to gain a better understanding of the broader implications of GPS spoofing,” Humphreys said. “I didn’t know, until we performed this experiment, just how possible it is to spoof a marine vessel and how difficult it is to detect this attack.” In June, the team was invited aboard the yacht, called the White Rose of Drachs, while it traveled from Monaco to Rhodes, Greece, on the Mediterranean Sea. The experiment took place about 30 miles off the

GPS Spoofing of Superyacht

coast of Italy as the yacht sailed in international waters. This summer, assistant professor Todd Humphreys, in the Department of Aerospace Engineering andEngineering Mechanics, and his research team, graduate students Jahshan Bhatti and Ken Pesyna, spent time aboard the White Rose of Drachs, successfully performing GPS spoofing attacks on the 213-foot superyacht while it traveled on the Mediterranean Sea. From the White Rose’s upper deck, graduate students Jahshan Bhatti and Ken Pesyna broadcasted a faint ensemble of civil GPS signals from their spoofing device — a blue box about the size of a briefcase — toward the ship’s two GPS antennas. The team’s counterfeit signals slowly

overpowered the authentic GPS signals until they ultimately obtained control of the ship’s navigation system. Unlike GPS signal blocking or jamming, spoofing triggers no alarms on the ship’s navigation equipment. To the ship’s GPS devices, the team’s false signals were indistinguishable from authentic signals, allowing the spoofing attack to happen covertly. Once control of the ship’s navigation system was gained, the team’s strategy was to coerce the ship onto a new course using subtle maneuvers that positioned the yacht a few degrees off its original course. Once a location discrepancy was reported by the ship’s navigation system, the crew initiated a course correction. In reality, each course correction was setting the ship slightly off its course line. Inside the yacht’s command room, an electronic chart showed its progress along a fixed line, but in its wake there was a pronounced curve showing that the ship had

turned. “The ship actually turned and we could all feel it, but the chart display and the crew saw only a straight line,” Humphreys said. After several such maneuvers, the yacht had been tricked onto a parallel track hundreds of meters from its intended one — the team had successfully spoofed the ship. The experiment helps illustrate the wide gap between the capabilities of spoofing devices and what the transportation industry’s technology can detect, Humphreys said. Chandra Bhat, director of the Center for Transportation Research at UT Austin, believes that the experiment highlights the vulnerability of the transportation sector to such attacks. “The surprising ease with which Todd and his team were able to

control a (multimillion) dollar yacht is evidence that we must invest much more in securing our transportation systems against potential spoofing,” Bhat said. It’s important for the public and policymakers to understand that spoofing poses a threat that has far-reaching implications for transportation, Humphreys said. “This experiment is applicable to other semi-autonomous vehicles, such as aircraft, which are now operated, in part, by autopilot systems,” Humphreys said. “We’ve got to put on our thinking caps and see what we can do to solve this threat quickly.” As part of an ongoing research project, funding and travel expenses for this experiment were supported by UT Austin’s Wireless Networking and Communications Group through the WNCG’s Industrial Affiliates program. Contacts and sources: By Sandra Zaragoza, Cockrell School of Engineering, Animation by Erik Zumalt, Cockrell School of Engineering. University of Texas at Austin. Source: Article

Read More........→January 02, 2014