A new 3-D printed electric thruster could one day help make advanced miniature satellites significantly easier and more affordable to build, a new study finds.
Conventional rockets use chemical reactions to generate propulsion. In contrast, electric thrusters produce thrust by using electric fields to accelerate electrically charged propellants away from a spacecraft.
The main weakness of electric propulsion is that it generates much less thrust than chemical rockets, making it too weak to launch a spacecraft from Earth’s surface. On the other hand, electric thrusters are extremely efficient at generating thrust, given the small amount of propellant they carry. This makes them very useful where every bit of weight matters, as in the case of a satellite that’s already in orbit.
According to Google, North Korean-backed hackers are pretending to be security researchers, complete with a fake research blog and bogus Twitter profiles. These actions are supposedly part of spying efforts against actual security experts.
In an online report posted on 25 January, Google’s Threat Analysis Group, which focuses on government-backed attacks, provided an update on this ongoing campaign, which Google identified over the past several months. The North Korean hackers are apparently focusing on computer scientists at different companies and organizations working on research and development into computer security vulnerabilities.
“Sophisticated security researchers and professionals often have important information of value to attackers, and they often have special access privileges to sensitive systems. It is no wonder they are targets,” says Salvatore Stolfo, a computer scientist specializing in computer security at Columbia University, who did not take part in this research. “Successfully penetrating the security these people employ would provide access to very valuable secrets.”
A low-power and non-volatile technology called the memristor shows initial promise as a basis for machine learning. According to new research, memristors efficiently tackle AI medical diagnosis problems, an encouraging development that suggests additional applications in other fields, especially low-power or network “edge” applications. This may be, the researchers say, because memristors artificially mimic some of the neuron’s essential properties.
Memristors, or memory resistors, are a kind of building block for electronic circuits that scientists predicted roughly 50 years ago but only created for the first time a little more than a decade ago. These components, also known as resistive random access memory (RRAM) devices, are essentially electric switches that can remember whether they were toggled on or off after their power is turned off. As such, they resemble synapses—the links between neurons in the human brain—whose electrical conductivity strengthens or weakens depending on how much electrical charge has passed through them in the past.
It may be theoretically impossible for humans to control a superintelligent AI, a new study finds. Worse still, the research also quashes any hope for detecting such an unstoppable AI when it’s on the verge of being created.
Slightly less grim is the timetable. By at least one estimate, many decades lie ahead before any such existential computational reckoning could be in the cards for humanity.
By shining light beams in liquid resin, a new 3-D printing technique dubbed “xolography” can generate complex hollow structures, including simple machines with moving parts, a new study finds.
“I like to imagine that it’s like the replicator from Star Trek,” says study co-author Martin Regehly, an experimental physicist at the Brandenburg University of Applied Science in Germany. “As you see the light sheet moving, you can see something created from nothing.”
A thin holographic display could one day enable 4K 3-D videos on mobile devices as well as household and office electronics, Samsung researchers and their colleagues say.
Conventional holograms are photographs that, when illuminated, essentially act like 2D windows looking onto 3D scenes. The pixels of each hologram scatter light waves falling onto them, making the light waves interact with each other in ways that generate an image with the illusion of depth.
Holography creates static holograms by using laser beams to encode an image onto a recording medium such as a film or plate. By sending the coherent light from lasers through a device known as a spatial light modulator—which can actively manipulate features of light waves such as their amplitude or phase—scientists can instead produce holographic videos.
Ever have a song you can’t remember the name of, nor any of its words? Now Google has a new feature where you can simply hum the melody and it can hopefully name that tune.
The idea of identifying songs through singing, humming or whistling instead of lyrics is not a new idea—the music app SoundHound has possessed hum-to-search for at least a decade. Google’s new feature should help the search engine with the many requests it receives to identify music. Aparna Chennapragada, a Google vice president who introduced the new feature during a streamed event Oct. 15, said people ask Google “what song is playing” nearly 100 million times each month.
Terahertz rays could have a dizzying array of applications, from high-speed wireless networks to detecting cancers and bombs. Now researchers say they may finally have created a portable, high-powered terahertz laser.
Terahertz waves (also called submillimeter radiation or far-infrared light) lie between optical waves and microwaves on the electromagnetic spectrum. Ranging in frequency from 0.1 to 10 terahertz, terahertz rays could find many applications in imaging, such as detecting many explosives and illegal drugs, scanning for cancers, identifying protein structures, non-destructive testing and quality control. They could also be key to future high-speed wireless networks, which will transmit data at terabits (trillions of bits) per second.
However, terahertz rays are largely restricted to laboratory settings due to a lack of powerful and compact terahertz sources. Conventional semiconductor devices can generate terahertz waves ranging either below 1 terahertz or above 10 terahertz in frequency. The range of frequencies in the middle, known as the terahertz gap, might prove especially valuable for imaging, bomb detection, cancer detection and chemical analysis applications, says Qing Hu, an electrical engineer at MIT.
A new OLED display from Samsung and Stanford can achieve more than 10,000 pixels per inch, which might lead to advanced virtual reality and augmented reality displays, researchers say.
An organic light-emitting diode (OLED) display possesses a film of organic compounds that emits light in response to an electric current. A commercial large-scale OLED television might have a pixel density of about 100 to 200 pixels per inch (PPI), whereas a mobile phone’s OLED display might achieve 400 to 500 PPI.
Two different kinds of OLED displays have reached commercial success in mobile devices and large-scale TVs. Mobile devices mostly used red, green and blue OLEDs, which companies manufacture by depositing dots of organic film through metal sheets with many tiny holes punched in them. However, the thickness of these metal sheets limits how small these fabricated dots can be and sagging of these metal sheets limits how large these displays can get.
In contrast, large-scale TVs use white OLEDs with color filters placed over them. However, these filters absorb more than 70% of light from the OLEDs. As such, these displays are power-hungry and can suffer “burn-in” of images that linger too long. The filters also limit how much the pixels can scale down in size.
The new display uses OLED films to emit white light between two reflective layers, one of which is made of a silver film, whereas the other is a “metasurface,” or forest of microscopic pillars each spaced less than a wavelength of light apart. Square clusters of these 80-nanometer-high, 100-nanometer-wide silver pillars served as pixels each roughly 2.4 microns wide, or slightly less than 1/10,000th of an inch.
Each pixel in the new display’s metasurface is divided into four subpixels of equal size. In principle, the OLED films can specify which subpixels they illuminate. The nano-pillars in each subpixel manipulate white light falling onto them, such that each subpixel can reflect a specific color of light, depending on the amount of spacing between its nano-pillars. In each pixel, the subpixel with the most densely packed nano-pillars yields red light; the one with moderately densely packed nano-pillars yields green light; and the two with the least densely packed nano-pillars yield blue light.
Emitted light reflects back and forth between the display’s reflective layers until it finally escapes through the silver film out the display’s surface. The way in which light can build up within the display gives it twice the luminescence efficiency of standard color-filtered white OLED displays, as well as higher color purity, the researchers say.
“If you think of a musical instrument, you often see an acoustic cavity that sounds come out of that helps make a nice and beautiful pure tone,” says study senior author Mark Brongersma, an optical engineer at Stanford University. “The same happens here with light — the different colors of light can resonate in these pixels.”
In the near term, one potential application for this new display is with virtual reality (VR). Since VR headsets place their displays close to a user’s eyes, high-resolutions are key to help create the illusion of reality, Brongersma says.
As impressive as 10,000 pixels per inch might sound, “according to our simulation results, the theoretical scaling limit of pixel density is estimated to be 20,000 pixels per inch,” says study lead author Won-Jae Joo, a nanophotonic engineer at the Samsung Advanced Institute of Technology in Suwon, Korea. “The challenge is the trade-off in brightness when the pixel dimensions go below one micrometer.”
Other research groups have developed displays they say range from 10,000 to 30,000 pixels per inch, typically using micro-LED technology, such as Jade Bird Display in China and VueReal in Canada. In terms of how the new OLED display compares with those others, “our color purity is very high,” Brongersma says.
In the future, metasurfaces might also find use trapping light in applications such as solar cells and light sensors, Brongersma says.
The scientists detailed their findings online Oct. 22 in the journal Science.
New circuits can get printed directly on human skin to help monitor vital signs, a new study finds.
Wearable electronics are growing increasingly more comfortable and more powerful. A next step for such devices might include electronics printed directly onto the skin to better monitor and interface with the human body.
Scientists wanted a way to sinter—that is, use heat to fuse—metal nanoparticles to fabricate circuits directly on skin, fabric or paper. However, sintering usually requires heat levels far too high for human skin. Other techniques for fusing metal nanoparticles into circuits, such as lasers, microwaves, chemicals or high pressure, are similarly dangerous for skin.
In the new study, researchers developed a way to sinter nanoparticles of silver at room temperature. The key behind this advance is a so-called a sintering aid layer, consisting of a biodegradable polymer paste and additives such as titanium dioxide or calcium carbonate.
Positive electrical charges in the sintering aid layer neutralized the negative electrical charges the silver nanoparticles could accumulate from other compounds in their ink. This meant it took less energy for the silver nanoparticles printed on top of the sintering aid layer to come together, says study senior author Huanyu Cheng, a mechanical engineer at Pennsylvania State University.
The sintering aid layer also created a smooth base for circuits printed on top of it. This in turn improved the performance of these circuits in the face of bending, folding, twisting and wrinkling.
In experiments, the scientists placed the silver nanoparticle circuit designs and the sintering aid layer onto a wooden stamp, which they pressed onto the back of a human hand. They next used a hair dryer set to cool to evaporate the solvent in the ink. A hot shower could easily remove these circuits without damaging the underlying skin.
After the circuits sintered, they could help the researchers measure body temperature, skin moisture, blood oxygen, heart rate, respiration rate, blood pressure and bodily electrical signals such as electrocardiogram (ECG or EKG) readings. The data from these sensors were comparable to or better than those measured using conventional commercial sensors that were simply stuck onto the skin, Cheng says.
The scientists also used this new technique to fabricate flexible circuitry on a paper card, to which they added a commercial off-the-shelf chip to enable wireless connectivity. They attached this flexible paper-based circuit board to the inside of a shirt sleeve and showed it could gather and transmit data from sensors printed on the skin.
“With the use of a novel sintering aid layer, our method allows metal nanoparticles to be sintered at low or even room temperatures, as compared to several hundreds of degrees Celsius in alternative approaches,” Cheng says. “With enhanced signal quality and improved performance over their commercial counterparts, these skin-printed sensors with other expanded modules provide a repertoire of wearable electronics for health monitoring.”
The scientists are now interested in applying these sensors for diagnostic and treatment applications “for cardiopulmonary diseases, including COVID-19, pneumonia, and fibrotic lung diseases,” Cheng says. “This sensing technology can also be used to track and monitor marine mammals.”
The number one cause of mortality worldwide is cardiovascular disease. Now scientists reveal electronic blood vessels might one day use electricity to stimulate healing and deliver gene therapies to help treat such maladies, a new study finds.
One-third of all U.S. deaths are linked to cardiovascular disease, according to the American Heart Association. When replacement blood vessels are needed to treat advanced cases of cardiovascular disease, doctors prefer ones taken from the patient’s own body, but sometimes the patient’s age or condition prevents such a strategy.
Artificial blood vessels that can prove helpful in cases where replacements more than 6 millimeters wide are needed are now commercially available. However, when it comes to smaller artificial blood vessels, so far none have succeeded in clinical settings. That’s because a complex interplay between such vessels and blood flow often triggers inflammatory responses, causing the walls of natural blood vessels to thicken and cut off blood flow, says Xingyu Jiang, a biomedical engineer at the Southern University of Science and Technology in Shenzhen, China. Jiang and his team report having developed a promising new artificial blood vessel that doesn’t cause inflammatory response. The scientists detailed their findings online on 1 October in the journal Matter.
Details on the design and clinical tests of an open-source bionic leg are now freely available online, so that researchers can hopefully create and test safe and useful new prosthetics.
Bionic knees, ankles and legs under development worldwide to help patients walk are equipped with electric motors. Getting the most from such powered prosthetics requires safe and reliable control systems that can account for many different types of motion: for example, shifting from striding on level ground to walking up or down ramps or stairs.
However, developing such control systems has proven difficult. “The challenge stems from the fact that these limbs support a person’s body weight,” says Elliott Rouse, a biomedical engineer and director of the neurobionics lab at the University of Michigan, Ann Arbor. “If it makes a mistake, a person can fall and get seriously injured. That’s a really high burden on a control system, in addition to trying to have it help people with activities in their daily life.”
Quantum computers based on photons may possess key advantages over those based on electrons. To benefit from those advantages, quantum computing startup Xanadu has, for the first time, made a photonic quantum computer publicly available over the cloud.
Whereas classical computers switch transistors either on or off to symbolize data as ones and zeroes, quantum computers use quantum bits or “qubits” that, because of the surreal nature of quantum physics, can be in a state known as superposition where they can act as both 1 and 0. This essentially lets each qubit perform two calculations at once.
If two qubits are quantum-mechanically linked, or entangled, they can help perform 2^2 or four calculations simultaneously; three qubits, 2^3 or eight calculations; and so on. In principle, a quantum computer with 300 qubits could perform more calculations in an instant than there are atoms in the visible universe.
Electronic waste could get recycled into strong, protective coatings for steel, a new study finds.
Recycling typically converts large quantities of items made of a single material, such as aluminum cans or glass bottles, into more of the same. However, this approach is not feasible for complex garbage such as electronic waste, or e-waste, because it contains many different materials that cannot be easily separated.
Still, there are many reasons to recycle e-waste. For example, there is a growing amount of it—the United Nations found that people generated 44.7 million metric tons of e-waste globally in 2016, and expected that to grow to 52.2 million metric tons by 2021. In addition, precious metals are often scattered within e-waste, although this fact can at times lead to appalling scenarios involving child workers scavenging amidst toxic waste.
“We’ve developed a throwaway mentality, where we use something until it’s worn out or we don’t need it or want it any more, and we get rid of it,” says study senior author Veena Sahajwalla, a materials scientist and founding director of the Center for Sustainable Materials Research and Technology at the University of New South Wales in Sydney, Australia. “That would be fine if we had unlimited resources and unlimited space for disposal, but we don’t.”
Previous research showed the careful use of heat could selectively break and reform chemical bonds in e-waste to form new environmentally friendly materials. For instance, mixes of glass and plastic could find use in valuable silicon-loaded ceramics.
“It is very exciting that these waste materials have lot of valuable elements that could be reformed into brand-new products,” Sahajwalla says. “To take just one example, some types of e-waste like printed circuit boards contain between 10% and 20% copper, while copper ore only contains up to 3%.”
In the new study, researchers investigated the properties of copper and silica compounds often found in old printed circuit boards and computer monitors. They suspected that after these substances were extracted from e-waste, they could get combined to create a durable new hybrid material potentially useful for protecting metal surfaces against corrosion and wear.
First the researchers heated glass and plastic powder from old computer monitor screens and shells to 1,500 degrees C, generating silicon carbide wires 10 to 50 nanometers (billionths of a meter) in diameter. They next combined these ceramic nanowires with copper recovered from ground-up circuit boards, placed the mix on a steel surface, and then heated it up to 1,000 degrees C. This melted the copper to form a thin film 1 micron thick atop the steel. (The scientists noted this width could get adjusted to range from a few nanometers to a few hundred microns.)
This structural bonding of different elements creates new properties that are superior to the parent materials. “Say, for example, the metal structure has a good toughness but a poor hardness. In contrast, a ceramic has a high hardness but it’s very brittle,” Sahajwalla says. “Combining these two structures together successfully by the judicious choice of temperature after understanding the the raw material can create a completely new hybrid material that has a ceramic-like hardness and metal-like toughness. And surprisingly, all this could be done from waste sources, which can prevent these resources going to a landfill.”
The scientists found the micron-thick hybrid layer increased the surface hardness of the steel by about 125%. In addition, microscope images revealed that when this hybrid layer was struck with a nano-sized indenter, it remained firmly bonded to the steel without cracking or chipping.
“For a long time, we have relied on mining to provide the raw materials we need, and we’ve thrown much of our waste into landfill,” Sahajwalla says. “In the future, we may be mining those same landfill sites for our resources.”
Sahajwalla and her colleague Rumana Hossain detailed their findings online July 13 in the journal ACS Omega.
In novel materials known as topological insulators, electricity or light can flow around corners and defects with virtually no losses. All topological insulators produced so far are comprised of an insulating bulk and perfectly conductive edges. Now scientists have found—at least in theory—that fractal topological insulators could possibly be made up only of edges, with no bulk at all.
Topology is the branch of mathematics that explores what aspects of shapes can survive deformation. For example, an object shaped like a doughnut can get deformed into the shape of a mug, with the doughnut’s hole forming the hole in the cup’s handle, but it could not get pushed or pulled into a shape that lacked a hole without ripping the item apart.
Employing insights from topology, researchers developed the first electronic topological insulators in 2007. Electrons zipping along the edges or surfaces of these materials strongly resist any disturbances that might hamper their flow, much as a doughnut might resist any change that would remove its hole.
Imagine the big game is on, and you’re watching your favorite team trounce its rival on a 122-inch screen that displays every detail. But the curved display is actually only a 32-inch model that, when you place your face near it, generates the illusion of a much more massive display. A new light-field display now seeks to create such an immersive panoramic virtual screen without goggles.
Immersive displays generally either involve giant screens à la IMAX, virtual reality (VR), or augmented reality (AR) headsets that place tiny screens and lenses close to a person’s eyes to simulate large screens that encompass most of a user’s field of view. Engaging as immersive displays are, electrical engineer Barmak Heshmat and his colleagues at an AR startup, “realized the bitter reality that people don’t want to wear headgear; it’s just too much friction to have something on your face. I think people can talk volumes about that, considering that now everyone has to wear masks.
“Just imagine wearing a 200-gram object on your face for 6.5 hours,” Heshmat says. “It is really exhausting, but 6.5 hours is the average time we spend in front of computers, easily, every day.”
In the wake of new Black Lives Matter protests, one company hopes to use virtual reality to help people better understand others by putting them in their colleagues’ shoes. The aim is to create better workplaces by helping employees develop and practice more respectful ways of interacting with each other.
By immersing people in realistic digital environments, virtual reality (VR) can lead to mind-bending experiences, such as making users feel as if they have swapped bodies with someone else. The effects of VR can persist long after these experiences; psychologists hope this can help in therapies for ailments such as phobias and post-traumatic stress disorder.
Right now, almost 70,000 people in the United States alone are on active waiting lists for organ donations. The dream of bio-printing is that one day, instead of waiting for a donor, a patient could receive, say, a kidney assembled on demand from living cells using 3-D printing techniques. But one problem with this dream is that bio-printing an organ outside the body necessarily requires surgery to implant it. This may mean large incisions, which in turn adds the risk of infection and increased recovery time for patients. Doctors would also have to postpone surgery until the necessary implant was bio-printed, vital time patients might not have.
A way around this problem could be provided by new bio-ink, composed of living cells suspended in a gel, that is safe for use inside people and could help enable 3-D printing in the body. Doctors could produce living parts inside patients through small incisions using minimally invasive surgical techniques. Such an option might prove safer and faster than major surgery.
A weakness of lasers integrated onto microchips is how they can each generate only one color of light at a time. Now researchers have come up with a simple integrated way to help these lasers fire multiple colors, a new study finds.
When it comes to data and telecommunications applications, integrated lasers would ideally generate multiple frequencies of light to boost how much information they could transmit. One way to achieve this end is an “optical frequency comb,” which converts a pulse of light from a single laser into a series of pulses equally spaced in time and made up of different, equally spaced frequencies of light.
Generating combs long required equipment that was expensive, bulky, complex, and delicate. However, in the past decade or so, researchers began developing miniature and integrated comb systems. These microcombs passed light from a laser through a waveguide to a microresonator—a ring in which circulating light could become a soliton, a kind of wave that preserves its shape as it travels. When solitons left these microresonators, they each did so as very stable, regular streams of pulses—in other words, as frequency combs.
A space-based, virtually unhackable quantum Internet may be one step closer to reality due to satellite experiments that linked ground stations more than 1,000 kilometers apart, a new study finds.
Quantum physics makes a strange effect known as entanglement possible. Essentially, two or more particles such as photons that get linked or “entangled” can influence each other simultaneously no matter how far apart they are.
Entanglement is an essential factor in the operations of quantum computers, the networks that would connect them, and the most sophisticated kinds of quantum cryptography, a theoretically unhackable means of securing information exchange.
The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.