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Li-Fi-like System Would Bring 100-Gbps Speeds Straight to Your Computer

The light that zips data across the Internet’s backbone used to stop a long way from the data’s final destination. Now it goes all the way to your home. Why not go the last step and take the light all the way to the computer or TV, projecting it through the air over the last few meters and only converting it to an electronic signal at the end? Oxford University is doing just that with a system that takes light from the fiber, amplifies it, and beams it across a room to deliver data at more than 100 gigabits per second.

Such indoor optical wireless probably wouldn’t replace Wi-Fi, says Ariel Gomez, a Ph.D. student in photonics at Oxford University who describes the system in IEEE Photonics Technology Letters. But with a potential for data rates of 3 terabits per second and up, it could certainly find its uses. Wi-Fi, by contrast, tops out at about 7 Gb/s. And with light, there’s no worry about sticking to a limited set of radio frequencies. “If you’re in the optical window, you have virtually unlimited bandwidth and unlicensed spectrum,” Gomez says.

To accomplish this, they’d install a base station on the ceiling of a room, which would project the light toward the computer and also receive data heading out from the computer to the Internet.

The trick, of course, is getting the light beam exactly where it needs to go. An optical fiber makes for a target that’s only 8 or 9 micrometers in diameter, after all. The team, which also included researchers from University College, London, accomplished this using so-called holographic beam steering at both the transmitter and receiver ends. These use an array of liquid crystals to create a programmable diffraction grating that reflects the light in the desired direction. The device is similar to that used in projectors, says Dominic O’Brien, a photonics engineer at Oxford who directed the work.

It’s important to use transceivers with a wide field of view to make the alignment task easier, particularly because the device relies on wavelength division multiplexing, which splits the signal into slightly different colors of light. Like a prism, the diffraction grating of the beam steerer bends each wavelength a different amount. With a 60° field of view, the team was able to transmit six different wavelengths, each at 37.4 Gb/s, for an aggregate bandwidth of 224 Gb/s. With a 36° field of view, they managed only three channels, for 112 Gb/s.

The system requires a direct line of sight, and for now the receiver must be in a fixed position. The next step, O’Brien says, is to develop a tracking and location system so that a user could place a laptop at a random spot on a table and have the system find it and create a link.

Brien is a member of the Ultra-Parallel Visible Light Communications project, with colleagues at the Universities of Edinburgh, Strathclyde, St. Andrews, and Cambridge. One of their goals is to develop LiFi, which uses the light that’s also illuminating a room as a way to send data signals. He says LiFi usually refers to schemes based on visible wavelengths of light, whereas this system relies on infrared light at 1550 nm, which is used in telecommunications.

All these technologies—Wi-Fi, LiFi, optical wireless—may wind up being part of how people link devices to the Internet. “The world of communications is a world where everybody always wants more bandwidth,” O’Brien says.

SpaceX Drone Platform Landing Scrubbed

Update, 12 February: The Falcon 9 rocket’s first stage pulled off a nice water splashdown despite the rough weather. “Rocket soft landed in the ocean within 10m of target & nicely vertical!” Musk tweeted. “High probability of good droneship landing in non-stormy weather.”

A huge storm forced private spaceflight firm SpaceX to cancel a pioneering demonstration of rocket science during today’s successful launch of a Falcon 9 rocket. The original plan to perform a test landing of SpaceX’s reusable rocket technology at sea was scrubbed as three-story high waves crashed over the decks of a drone ship struggling to hold its landing pad in position in the Atlantic Ocean.

Originally, the Falcon 9 rocket’s first stage would have tried for a pinpoint landing on the drone ship using rocket burns, guidance fins and four landing legs. But the extreme weather, coupled with just three of the drone ship’s four engines working, made that scenario impossible. The backup plan for the test of the Falcon 9 rocket’s return to Earth involved trying for a “soft landing” in rough seas, according to a SpaceX announcementan action with very little probability of survival for the rocket.

“Mega storm preventing droneship from remaining on station, so rocket will try to land on water,” Elon Musk tweeted. “Survival probability <1%.”

SpaceX has made reusable rockets a key part of its goal to dramatically reduce the cost of flying to space. The private spaceflight firm points out that most launch costs currently come from building rockets designed to fly just one time. Perfecting the ability to return rockets to Earth could make the Falcon 9 heavy rockets—each costing about as much as a commercial airliner—almost as reusable as aircraft.

“If one can figure out how to effectively reuse rockets just like airplanes, the cost of access to space will be reduced by as much as a factor of a hundred,” says Elon Musk, founder and CEO of SpaceX. “A fully reusable vehicle has never been done before. That really is the fundamental breakthrough needed to revolutionize access to space.”

Getting a Falcon 9 rocket’s first stage back to Earth for a pinpoint landing aboard a drone ship at sea is no joke even in calm weather. The 14-story tall rocket stage uses hypersonic grid fins and three rocket burns to stabilize itself as it reenters the Earth’s atmosphere—a process that SpaceX has described as “trying to balance a rubber broomstick on your hand in the middle of a wind storm.” If all goes well, the rocket stage uses four landing legs to touch down upon the drone ship that serves as SpaceX’s oceangoing landing pad.

The latest Falcon 9 rocket launch was delayed from its initial scheduled launch on Sunday night because of a malfunction in the U.S. Air Force radar system being used to track the rocket during ascent, according to The Orlando SentinelA possible Monday launch was also pushed back because of bad weather.

SpaceX previously conducted two soft water landing tests with the Falcon 9 first stage in 2014. But the first 10 January landing attempt on the drone ship ended in a crash when the grid fins that guided the rocket’s descent ran out of hydraulic fuel just short of landing. The SpaceX team responded by upping the hydraulic fuel load by 50 percent for the latest attempt, according to Elon Musk’s Twitter account.

 The second attempt to land on the drone ship will actually be much more difficult than the first because, Musk tweeted, because the rocket reentered the atmosphere following a deep space mission. That means the Falcon 9 first stage endured almost double the force and four times the heat compared with the first hard landing attempt that followed a low-orbit space station resupply mission.

The latest Falcon 9 heavy rocket launch carried a Deep Space Climate Observatory (DSCOVR) satellite designed to help monitor space weather such as potentially dangerous solar storms. Previous Falcon 9 rockets have also ferried supplies to the International Space Station. In the future, the Dragon crew capsule aboard the rockets may also carry NASA astronauts to the orbital outpost.

Falcon 9 launches currently cost about $65 million to $70 million. If SpaceX can stick the rocket landing, it could lower costs to somewhere between $30 million to $40 million, said Marco Caceres, director of space studies at the Teal Group Corporation consultancy, in a Technology Review interview. 

But the SpaceX goal of eventually reducing costs by 100-fold could mean even cheaper space access. For instance, a $65 million Falcon 9 launch translates into roughly $2,240 per pound of payload for launches to low Earth orbit. A 100-fold drop in cost could mean Falcon 9 delivering payloads to low Earth orbit at a cost of just $22 per pound. (SpaceX’s even bigger Falcon Heavy rocket could theoretically drop the cost to just $10 per pound with a high enough flight rate, according to Popular Mechanics.)

Cheaper space launches could pave the way for much cheaper space missions supporting Earth-centric projects such as SpaceX’s plans to provide global Internet access through a network of satellites. They would also bring SpaceX one step closer to enabling founder Elon Musk’s dream of sending humans to colonize Mars.

A New Material For Wearable Spintronic Devices

Researchers in South Korea have taken a step towards wearable devices based on spintronics. They have made a stretchy thin film that retains its useful electric and magnetic properties even when highly curved.

While conventional electronic circuits exploit an electron’s charge-carrying property, spintronics harnesses the quantum mechanical property of electrons known as spin. The premise is that you can flip electrons’ spin by applying a small voltage in special multiferroic materials.

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U.S. Defense Department Chief Engineer: We Want Your Help With 2030's Tech

The U.S. Department of Defense has been responsible, in one way or another, for a huge number of technological innovations. Over the past half century or so, defense research (or funding) has resulted in ubiquitous technology like GPS, unmanned aircraft, and even the Internet itself. For decades, it’s been at the forefront of science and technology research, but the world is changing. Or at this point, it may be more accurate to say that the world has changed: innovation now happens at the speed of startups. In other words, far faster than the government is used to, comfortable with, or prepared for.

It's not like the DoD hasn't realized that it’s starting to get left behind, but understanding that and doing something about it are very different things for an organization with so much inertia. To try to shake things up a bit, DoD is trying something outside of its comfort zone—actively soliciting ideas from anyone who will talk to them about what kinds of technologies are going to be critical for the military in 2030. They want to hear from you, even if you send them your ideas on a cocktail napkin. Seriously.

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Molybdenum Disulfide Shows Promise For High-Temperature Electronics

Electronics and sensors that relay information from inside jet engines and deep oil and gas wells could improve efficiency and save millions of dollars. Researchers have been looking for cost-effective electronic circuits that would work in those extreme-temperature environments.

Now a team from the University of Calfornia at Riverside and Rensselaer Polytechnic Institute has found that the two-dimensional electronic material molybdenum disulfide (MoS2) is a promising candidate for high-temperature transistors. They have made MoS2 thin-film transistors that work at temperatures exceeding 220 °C and remain stable over two months of operation. The results are published in the Journal of Applied Physics.

Conventional silicon logic chips typically break down past 350 °C. Though researchers are pursuing silicon carbide and gallium nitride circuits as an alternative for extreme environments, these materials “hold promise for extended high-temperature operation, [but] are still not cost-effective for high volume applications," said Alexander Balandin, a professor of electrical and computer engineering at UCR, in a press release.

Molybdenum disulfide, which is found as the mineral molybdenite, is an abundant, naturally occurring material. It can be synthesized by chemical vapor deposition and could also be made into solutions that serve as inks for printable electronics. Researchers have been pursuing its development, along with graphene, as the material of choice for post-silicon electronics.

The reason MoS2 transistors work well at high temperatures is because of the material’s wide bandgap of 1.9 electron volts (silicon’s is 1.1 eV). That wide bandgap keeps high temperatures from driving electrons into the conduction band, causing an undesired flow of current.

Transistors made of silicon carbide—which has an even wider bandgap, in excess 3 eV—can work at over 500 °C, but those devices have yet to be tested for longevity. A University of Utah team recently made plasma transistors for nuclear reactor electronics that function at temperatures as high as 790 °C, but those would be impractical and expensive for other applications.

To be competitive with silicon and silicon carbide, Balandin and his team will have to show that MoS2 transistors work at even higher temperatures. One challenge with making transistors that are resistant to extreme heat is designing other components (chip packaging, interconnect metals, and contacts, for example) that can survive the harsh environment.

How to Build a Better Entangled-photon Detector Array

Entangled single photons will play an important role, as information carriers, in quantum computing and quantum encryption, as well as in quantum cryptography. A very sensitive way to detect these single photons is by depositing arrays of superconducting nanowire single-photon detectors (SNSPDs) onto photonic integrated circuits (PICs).But creating such PICs has been problematic because the majority of the deposited SNSPDs fail to work.

Now a team of researchers from several U.S. research labs, led by physicist Dirk Englund at MIT, describe in the 9 January issue of Nature Communications how they succeeded in detecting single entangled photons using SNSPDs that were integrated with a PIC using a new approach.

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Something’s Fishy: New Device Sniffs Out Seafood Fraud

Appreciate a well-cooked tuna steak or salmon wrapped in a sushi roll? There’s a good chance the fish sitting on your plate or in your grocery store’s seafood case is not what its label says it is, according to the ocean conservancy group Oceana. So you could be paying a premium for red snapper that’s really just plain old tilapia.

University of South Florida scientists have now made a handheld device that could help fight such seafood fraud. The instrument genetically verifies whether fish being called grouper is really grouper or less expensive, potentially harmful substitutes like catfish or mackerel. A quarter of grouper in the United States is mislabeled, according to Oceana, making it the fourth most commonly mislabeled fish in the country. (Snapper was the most comonly mislabeled.)

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$34 Diagnostic Tool for STDs Plugs into Smartphone, Rivals $18,000 Lab Equipment

Public health workers in Africa place HIV and syphilis at the top of their lists of diseases they see among pregnant women, and a new tool recently tested in Rwanda may help ease their diagnostic burden. The portable device, which plugs into a smartphone’s audio jack, performs three tests (one for HIV, two for syphilis) using just a fingerprick of blood, and displays results in 15 minutes.

In their report, the inventors estimate the tool’s cost at $34 plus the cost of a smartphone. They say it provides comparable results to gold-standard lab tests, whose cost they estimate at $18,450 plus the cost of a computer. 

“Lots of newborns are dying every year from congenital syphilis,” says Samuel Sia, one of the device’s inventors and an associate professor of biomedical engineering at Columbia University. “Should we be looking at new drugs for syphilis? No, it’s a diagnostic issue,” Sia says, noting that treatment for syphilis typically requires only one dose of penicillin. 

As for HIV, global health agencies have recently rallied around the goal of ensuring that at least 90 percent of people living with HIV know their HIV status. Right now that figure stands at less than 50 percent. Knowing one’s status is the obvious first step to getting access to anti-retroviral drug treatments. 

The new dongle draws all its power from a smartphone via its audio jack. It performed 41 tests when attached to an older Apple device; Sia says a new smartphone could perform many more before depleting the phone’s battery. His team ensured that the dongle would be low-power by doing away with the pump that often drives blood samples through microfluidic testing devices. Instead, the health care worker depresses a button to activate a vacuum chamber that sucks the sample through microfluidic channels, where reagents react to the presence of HIV or syphilis biomarkers. The dongle draws power only when it performs the optical assessment of the reactions, and when it transmits data back to the phone for read-out.   

Spectrum recently reported on dedicated diagnostic devices that are portable, cheap, and rugged enough to bring lab testing to remote African villages. Sia says his team initially built its own hardware and software, “but then we realized it was a losing proposition.” They decided to work off existing smartphone technology instead. 

That may be a good bet. Africa has been called “the mobile continent” in recognition of the many ways cheap mobile phones are transforming society. According to an Ericsson research report, Sub-Saharan Africa will have about 930 million mobile phones by 2019, three-quarters of which will be smartphones. 

However, the dongle will have to prove more useful than even cheaper paper-based diagnostic tests (based on the same principle as a home pregancy test), which are already widely available for HIV testing. Sia argues that his device is more accurate and reliable, and can also be used to conduct many lab tests at once from a single fingerprick of blood. He also sees value in the digital record of the tests that the phone can transmit to the cloud for integration into an electronic medical record. “It’s all part of leveraging the smartphone platform,” he says.  

Vie for the Tech-Prediction Prize

When we first wrote about the prediction-market collaboration between IEEE Spectrum and SciCast, one reader pointed out:

Competition works great when the outcome includes a desirable prize for the winners. What is the prize for winning on SciCast? Bragging rights on [a] little known website?

He has a point—cash and bling do concentrate one’s self-interest wonderfully (to misquote Samuel Johnson)—and SciCast is quite aware of the power of prizes.

As SciCast principal investigator, co-founder, and George Mason University professor Charles R. Twardy commented, SciCast runs periodic tournaments that offer cash prizes for the most accurate forecasts. “Right now,” he says, “we're in the middle of a 4-month accuracy contest. The Top 15 [forecasters] will receive $2250 in Amazon gift cards. The next 135 will receive $225.”

The competition is still going on, and runs through February. SciCast is eager to enroll Spectrum readers (and Spectrum would like to see its readers shine). At this point, the 15 top prizes are probably out of a newcomer’s reach…but $30,375 worth of $225 prizes is still achievable—especially when one considers that IEEE participants have already shown themselves to be among the most active and enthusiastic futures traders on the site.

Competition questions at are marked with a gold “Au” icon. You can find all 80-odd listed at the contest URL. There are six pages of rules and disclaimers that competitors should look at. (And how often will one see contest rules that include Bayesian double summations?)

The contest questions roam all over the fields of science and technology, including topics in:

  • Linguistics: How many languages will the Ethnologue language catalog’s 18th edition report as spoken by no one as a first language? (Today’s consensus: 200 to 224)
  • Epidemiology: How many cases of flu will be reported during the U.S. 2014-2015 flu season? (Current forecast: 440,000)
  • Physics: Will a lab experiment demonstrate Breit-Wheeler conversion of light into matter by the end of the year. (The forecasters say there’s just a 6 percent chance.)

But the biggest tranche of questions fall squarely in the EE’s wheelhouse:

  • Who will win the DARPA Robotics Challenge this coming June? (MIT leads, but there’s no clear favorite.)
  • How many teams will be awarded a full prize in the final round of the Qualcomm Tricorder X-Prize competition? (The majority opinion is 3.)
  • Will LG unveil a smartphone with a 4K display in March? (Today’s line gives it a 22 percent chance.)
  • Will an unmanned aerial vehicle (UAV) break the 14-day world endurance record before the end of 2015? (SciCast handicappers say there’s a 42 percent probability that it will happen.)

There’s a lot more. So, for fun and possible profit, take a look at the SciCast competition questions, sign up, and make your predictions.

Eye-Tracking Tech Could Spot Concussions Quickly

Though the sight of Cliff Avril leaving last night’s Super Bowl might make it seem like there is a gold-standard for diagnosing concussion, experts say there really isn’t. But there may be soon if researchers in New York  and Texas are right. They’ve come up with a way to diagnose concussions and other brain injuries using eye-tracking technology.

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