The Kynix Blog

While investigating mass transit accidents, National Transportation Safety Board (NTSB) officials often rely on digital clues left behind in flash memories of any and all electronic devices—both personal and professional—at a crash site. With the physical forces and high-temperature fires associated with many crashes, memory units are often damaged and sometimes unreadable.Researchers at Binghamton University, State University of New York have figured out how much damage memory units can sustain before becoming unreadable and new repair techniques to retrieve clues off of damaged units, which might help prevent future tragedies."The biggest surprise was how much punishment these devices can take before ceasing to function," said Steve Cain, who is the project manager and a senior research support specialist in the Integrated Electronics Engineering Center (IEEC) at Binghamton University. "As part of their post-crash investigations, the NTSB collects anything and everything at the scene, including personal electronic devices. If the device was active during or just before the crash, it is possible that the data stored in the memory can provide clues as to the cause of the crash. Most of the time the device is ruined, but sometimes it is intact."The interdisciplinary Binghamton group of Cain, Preeth Sivakumar, Jack Lombardi, and Mark Poliks along with James Cash, Joseph Gregor, and Michael Budinski from the NTSB, presented "Fire Damage and Repair Techniques for Flash Memory Modules: Implication for Post-Crash Investigations" at the Fall 2016 International Symposium of Microelectronics.Scientists found plastic coverings started to break down after three hours of exposure to temperatures of 300 degrees Celsius, or about 572 degrees Fahrenheit or more, but memory chips were still readable.Researchers pointed out that even with the pressures and forces in play during past crashes, temperatures typically only reach those levels for short periods of time."Data integrity was maintained even in a plasma discharge," Cain said. "Basically, if the device doesn't burn up, there is a reasonable chance of the data being retained in the chip. The only problem is that the connections to the memory chips may be broken, so that the data cannot be read."For the second part of the study, researchers addressed the readability issue. The team purposely damaged memory units and then extracted memory chips using acid, lasers, plasma, or mechanical polishing.Lasers were the most effective extraction method and mechanical extractions was the simplest, but each method still damaged the wire bonds within memory chips and made many unreadable. A specialized metallic ink from a precision printer was used to restore functionality."These results expand the investigative scope for aviation accidents, where the data rather than the device is of paramount importance," the team concluded. "It is possible to repair the interconnections of flash memory modules, provided the chip is intact." Reference:MT16JTF51264AZ-1G6M1SDUS5EB-001GMD2202-D192 

Stream video on your smartphone, or use its GPS for an hour or two, and you'll probably see the battery drain significantly. As data rates climb and smartphones adopt more power-hungry features, battery life has become a concern. Now a technology developed by MIT spinout Eta Devices could help a phone's battery last perhaps twice as long, and help to conserve energy in cell towers.The primary culprit in smartphone battery drain is an inefficient power amplifier, a component that is designed to push the radio signal out through the phones' antennas. Similar larger modules are found in wireless base stations, where they might use 10 or even 100 times the power.Prepared to send sizeable chunks of data at any given time, the amplifiers stay at maximum voltage, eating away power—more than any other smartphone component, and about 75 percent of electricity consumption in base stations—and wasting more than half of that power as heat. This means smartphone batteries lose longevity, and base stations waste energy and lose money.But Eta Devices has developed a chip (for smartphones) and a shoebox-size module (for base stations)—based on nearly a decade of MIT research—to essentially "switch gears" to adjust voltage supply to power amplifiers as needed, cutting the waste."You can look at our technology as a high-speed gearbox that, every few nanoseconds, modulates the amount of power that the power amplifier draws from the battery," explains Joel Dawson, Eta Devices' chief technology officer and a former associate professor of electrical engineering and computer science who co-invented the technology. "That turns out to be the key to keeping the efficiency very high."When trialed in a base station last year, Eta Devices' module became the first transmitter for 4G LTE networks to achieve an average efficiency greater than 70 percent, Dawson says. "The highest number we've heard before that was 45 percent—and that's probably being generous," he says.Backed by millions in funding, Eta Devices—co-founded by David Perreault, an MIT professor of electrical engineering, and former MIT Sloan fellow Mattias Astrom—has partnered with a large base-station manufacturer. The goal is to deploy the technology in live base stations by the end of 2015. The savings could be substantial, Dawson says, noting that a large carrier could save $100 million in annual electricity costs.Eta Devices has also entered conversations with major manufacturers of LTE-enabled smartphones to incorporate their chips by the end of next year. Dawson says this could potentially double current smartphone battery life.Besides battery life, Dawson adds, there are many ways the telecommunications industry can take advantage of improved efficiency. Eta Devices' approach could lead to smaller handset batteries, for example, and even smaller handsets, since there would be less dissipating heat. The technology could also drive down operating costs for base stations in the developing world, where these stations rely on expensive diesel fuel for power.And ultimately, it could impact the environment: If all midsized carrier networks were to replace current radio amplifiers with Eta Devices' technology, he says, the reduction in greenhouse gases would be equivalent to taking about 5 million cars off the road. "There are so many ways to leverage high efficiency if you have it," Dawson says.In August, the World Economic Forum named Eta Devices the 2015 Technology Pioneer, a designation awarded previously to Dropbox, Spotify, and Twitter, to name a few.In the mobile marketEta Devices' commercial success is, in part, a product of engineering ingenuity intersecting with business acumen at MIT.In 2008, Dawson and Perreault, who directs the Power Electronics Research Group, submitted an early concept of the Eta technology—then called asymmetrical multilevel outphasing (AMO)—to an Innovation Teams (i-Teams) class that brought together MIT students from across disciplines to develop commercial products.The AMO technology was a new transmitter architecture, where algorithms could choose from different voltages needed to transmit data in each power amplifier, and select the optimal choice for power conservation—and do so roughly 20 million times per second. This could be done on the transmitting and receiving end of data transfers.This caught the eye of Astrom, who had come to MIT after working in the mobile industry for 10 years, "looking for the next big thing." With help from Astrom, the professors started designing the technology for the mobile market—initially leaning toward base stations."At the time, I was suffering, as everyone else was, from my iPhone running out of battery at lunchtime," Astrom says. "The iPhone was only a year old, but you could see how much data traffic would explode."Fleshing out a business plan from an i-Teams draft, the two professors earned a Deshpande Center for Technological Innovation grant in 2009, allowing for the first demonstration of the hardware, showing a 77 percent gain in efficiency over standard systems. (A paper detailing the technology was presented at that year's IEEE Radio Frequency Integrated Circuits Symposium.)"That Deshpande Center grant was big in terms of the funding and connecting us with local venture capitalists, and really helping with being in that business mindset," Dawson says.Spinning out a company has been the best way to validate the technology—especially with novel power-electronics hardware, Dawson says. "People in our industry take ideas a lot more seriously when there's a company behind it," he says. "We had impressive performance at MIT, but now we have a team of professionals working on the technology full-time. The resulting performance numbers are jaw-dropping. Now people are going back and frantically studying the original MIT research papers."Luckily, Dawson says, several significant changes were made to those old research projects in order to develop today's ETAdvanced—so the secret ingredients of the technology are safe. "The joke I like to tell is: When I was a professor, I was going around the world trying to give the technology away," Dawson says, laughing. "If I had succeeded, then there'd be no business."Future-proofing technologyToday, Eta Devices' major advantage is that its technology is able to handle ever-increasing data bandwidths.A few major smartphone manufacturers are now using envelope tracking (ET), which adjusts voltage to power amplifiers on the fly. But by adjusting that voltage continuously, ET efficiency falls apart for 4G/LTE and 802.11ac (WiFi) wireless standards, even up to 20 MHz bandwidth. ETAdvanced, in contrast, already accommodates ultrahigh bandwidths used by newer communication standards, such as LTE Advanced (up to 80 megahertz), and the next-generation WiFi standard (up to 160 megahertz).Prepping for future communication standards is one thing that's helped the company thrive, Dawson says. "As a small company, you'll lose a fair fight with another technology—you have to have some overpowering advantage that they can't match you on," he says. "In introducing new hardware, you not only have to be better than the product of today, but also have to make compelling case for being future-proof."  

A team of researchers with members from the University of California and Rice University has found a way to get a flat transistor to defy theoretical limitations on Field Effect Transistors (FETs). In their paper, the team describes their work and why they believe it could lead to consumer devices that have both smaller electronics and longer battery life. Katsuhiro Tomioka with Erasmus MC University Medical Center in the Netherlands offers a News & Views article discussing the work done by the team in the same journal edition.As Tomioka notes, the materials and type of architecture currently used in creating small consumer electronic devices is rapidly reaching a threshold upon which a tradeoff will have to be made—smaller transistors or more power requirements—this is because of the unique nature of FETs, shortening the channel they use requires more power, on a logarithmic scale. Thus, to continue making FETs ever smaller and to get them to use less power means two things, the first is that a different channel material must be found, one that allow high switch-on currents at low voltages. The second is a way must be found to lower the voltage required for the FETs.Researchers have made inroads on the first requirement, building FETs with metal-oxide-semiconductor materials, for example. The second has proved to be more challenging. In this latest effort, the researchers looked to tunneling to reduce voltage demands, the results of which are called, quite naturally, tunneling FETs or TFETs—they require less voltage because they are covered (by a gate stack) and work by transporting a charge via quantum-tunneling. The device the team built is based on a 2D bilayer of molybdenum disulfide and bulk germanium—it demonstrated a negative differential resistance, a marker of tunneling, and a very steep subthreshold slope (the switching property associated with rapid turn-on) which fell below the classical theoretical limit.The work by the team represents substantial progress in solving the minituration problem for future electronics devices, but as the team notes, there is still much to do. They express optimism that further improvements will lead to not just better consumer devices, but tiny sensors that could be introduced into the body to help monitor health. 

Written by Rob MathesonAn exotic material called gallium nitride (GaN) is poised to become the next semiconductor for power electronics, enabling much higher efficiency than silicon.In 2013, the Department of Energy (DOE) dedicated approximately half of a $140 million research institute for power electronics to GaN research, citing its potential to reduce worldwide energy consumption. Now MIT spinout Cambridge Electronics Inc. (CEI) has announced a line of GaN transistors and power electronic circuits that promise to cut energy usage in data centers, electric cars, and consumer devices by 10 to 20 percent worldwide by 2025.Power electronics is a ubiquitous technology used to convert electricity to higher or lower voltages and different currents—such as in a laptop's power adapter, or in electric substations that convert voltages and distribute electricity to consumers. Many of these power-electronics systems rely on silicon transistors that switch on and off to regulate voltage but, due to speed and resistance constraints, waste energy as heat.CEI's GaN transistors have at least one-tenth the resistance of such silicon-based transistors, according to the company. This allows for much higher energy-efficiency, and orders-of-magnitude faster switching frequency—meaning power-electronics systems with these components can be made much smaller. CEI is using its transistors to enable power electronics that will make data centers less energy-intensive, electric cars cheaper and more powerful, and laptop power adapters one- third the size—or even small enough to fit inside the computer itself."This is a once-in-a-lifetime opportunity to change electronics and to really make an impact on how energy is used in the world," says CEI co-founder Tomás Palacios, an MIT associate professor of electrical engineering and computer science who co-invented the technology.Other co-founders and co-inventors are Anantha Chandrakasan, the Joseph F. and Nancy P. Keithley Professor in Electrical Engineering, now chair of CEI's technical advisory board; alumnus Bin Lu SM '07, PhD '13, CEI's vice president for device development; Ling Xia PhD'12, CEI's director of operations; Mohamed Azize, CEI's director of epitaxy; and Omair Saadat PhD '14, CEI's director of product reliability.Making GaN feasibleWhile GaN transistors have several benefits over silicon, safety drawbacks and expensive manufacturing methods have largely kept them off the market. But Palacios, Lu, Saadat, and other MIT researchers managed to overcome these issues through design innovations made in the late 2000s.Power transistors are designed to flow high currents when on, and to block high voltages when off. Should the circuit break or fail, the transistors must default to the "off" position to cut the current to avoid short circuits and other issues—an important feature of silicon power transistors.But GaN transistors are typically "normally on"—meaning, by default, they'll always allow a flow of current, which has historically been difficult to correct. Using resources in MIT's Microsystems Technology Laboratory, the researchers—supported by Department of Defense and DOE grants—developed GaN transistors that were "normally off" by modifying the structure of the material.To make traditional GaN transistors, scientists grow a thin layer of GaN on top of a substrate. The MIT researchers layered different materials with disparate compositions in their GaN transistors. Finding the precise mix allowed a new kind of GaN transistors that go to the off position by default."We always talk about GaN as gallium and nitrogen, but you can modify the basic GaN material, add impurities and other elements, to change its properties," Palacios says.But GaN and other nonsilicon semiconductors are also manufactured in special processes, which are expensive. To drop costs, the MIT researchers—at the Institute and, later, with the company—developed new fabrication technologies, or "process recipes," Lu says. This involved, among other things, switching out gold metals used in manufacturing GaN devices for metals that were compatible with silicon fabrication, and developing ways to deposit GaN on large wafers used by silicon foundries."Basically, we are fabricating our advanced GaN transistors and circuits in conventional silicon foundries, at the cost of silicon. The cost is the same, but the performance of the new devices is 100 times better," Lu says.Major applicationsCEI is currently using its advanced transistors to develop laptop power adaptors that are approximately 1.5 cubic inches in diameter—the smallest ever made.Among the other feasible applications for the transistors, Palacios says, is better power electronics for data centers run by Google, Amazon, Facebook, and other companies, to power the cloud.Currently, these data centers eat up about 2 percent of electricity in the United States. But GaN-based power electronics, Palacios says, could save a very significant fraction of that.Another major future application, Palacios adds, will be replacing the silicon-based power electronics in electric cars. These are in the chargers that charge the battery, and the inverters that convert the battery power to drive the electric motors. The silicon transistors used today have a constrained power capability that limits how much power the car can handle. This is one of the main reasons why there are few large electric vehicles.GaN-based power electronics, on the other hand, could boost power output for electric cars, while making them more energy-efficient and lighter—and, therefore, cheaper and capable of driving longer distances. "Electric vehicles are popular, but still a niche product. GaN power electronics will be key to make them mainstream," Palacios says.Innovative ideasIn launching CEI, the MIT founders turned to the Institute's entrepreneurial programs, which contributed to the startup's progress. "MIT's innovation and entrepreneurial ecosystem has been key to get things moving and to the point where we are now," Palacios says.Palacios first earned a grant from the Deshpande Center for Technological Innovation to launch CEI. Afterward, he took his idea for GaN-based power electronics to Innovation Teams (i-Teams), which brings together MIT students from across disciplines to evaluate the commercial feasibility of new technologies. That program, he says, showed him the huge market pull for GaN power electronics, and helped CEI settle on its first products."Many times, it's the other way around: You come out with an amazing technology looking for an application. In this case, thanks to i-Teams, we found there were many applications looking for this technology," Palacios says.For Lu, a key element for growing CEI was auditing Start6, a workshop hosted by the Department of Electrical Engineering and Computer Science, where entrepreneurial engineering students are guided through the startup process with group discussions and talks from seasoned entrepreneurs. Among other things, Lu gained perspective on dividing equity, funding, building a team, and other early startup challenges."It's a great class for a student who has an idea, but doesn't know exactly what's going on in business," Lu says. "It's kind of an overview of what the process is going to be like, so when you start your own company you are ready."   

Clinical breast examinations can save women's lives, but, as doctors-in-training, new residents sometimes aren't thorough or experienced enough to detect potentially cancerous abnormalities.Now, future physicians could learn to give high-quality breast exams with help from high-tech sensors developed by University of Wisconsin-Madison engineers."This whole project is about facilitating the training of residents," says Hongrui Jiang, Lynn H. Matthias Professor in Engineering and Vilas Distinguished Achievement Professor in electrical and computer engineering.The project is working toward creating small fingertip sensors that can measure the pressure and hand motions used by physicians when probing for lumps. New residents will be able to compare their own exams against standards established from experienced doctors, and obtain feedback on whether or not they are being sufficiently thorough.Experienced clinicians long have been looking for an effective tool to establish standards for high-quality breast exams. Dr. Carla Pugh, the Susan Behrens, MD Professor of Surgical Education and a professor of industrial and systems engineering at UW-Madison, has attempted for years to create such a device, but the available sensing technology simply couldn't capture all of the subtle motions necessary for performing a comprehensive breast examination."They were using commercial products—but the sensors were not very good," says Jiang. "Commercial sensors have serious limitations."While some of the existing devices could quantify direct pressure reasonably well, nothing existed that could also measure the side-to-side and circular motion that real-world clinical procedures entail. So Pugh approached Jiang for help."It was very hard; we couldn't figure out a nice way to handle the problem until a year ago, when we had an 'aha' moment," says Jiang.Jiang and his student, Jayer Fernandez, realized that one traditional capacitive sensor alone couldn't possibly measure all of the necessary parameters. Instead, they fashioned a device that integrates information from four overlapping components to quantify pressure and shear from all three dimensions.That novel approach earned Fernandez top honors at the Institute of Electrical and Electronics Engineers' prestigious Sensors Conference in fall 2016. Fernandez gave a brief, informal presentation to a panel of experts, who were impressed by the capabilities of the device."I've never done an elevator pitch before, but it went well. People asked me a lot of interesting questions. I described why our sensor is more sensitive to the force range that we're looking at and gives us a nice way to do the readout in different directions," says Fernandez.Currently the researchers are working to further miniaturize the sensor, and to combine data from multiple devices at once. They will continue to collaborate with Pugh and other clinicians to develop the most useful device for working doctors."There's a real need to improve physician training," says Jiang. "We didn't realize there was such a clinical need. It's a very challenging problem, but very interesting and very significant." Reference:OVM7695-RAEAOV09726-A40A-1DOV05633 

As we push the limits of agriculture to feed more people in a warmer world, we do not understand how plants sense temperature.In a surprising turn of events scientists have just learned that plant light sensors also respond to temperature.Plants contain specialized light-sensitive proteins that change shape when they absorb light, much as do the photopigments in the human eye. All plants have three main red-light photoreceptors, called phytochrome A, B and C.As part of an effort to create plants that can tolerate different growth conditions, Richard Vierstra the George and Charmaine Mallinckrodt Professor in Arts & Sciences at Washington University in St. Louis has been developing a library of phytochrome B mutants, including ones that are much more or less sensitive to light than the wild type plant.To better understand their mutant plants, the Vierstra lab shared them with Jorge J. Casal lab in Argentina where doctoral student Martina Legris grew them under a wide variety of carefully controlled conditions."We got 'weird' results that couldn't be explained unless the phytochrome we were working with was sensitive to temperature as well as light," Vierstra said.As the temperature rose, some plants exposed to constant sunlight generate less of the biologically active form of phytochrome B—not more, as you'd expect.At summer temperatures, these plants behave as though they're in dim light even though they're in bright sun.The findings will be published in the Oct. 27 issue of Science, together with a companion paper also on plant temperature sensors by a lab at the University of Cambridge in England.A switch with the jittersVierstra explains that phytochrome proteins work by switching between two forms, called Pr and Pfr.The Pr form is best at absorbing red light, which is plentiful in full sun. When it absorbs red light, phytochrome converts to the Pfr state, which is better at absorbing far-red light that dominates in shade. When the Pfr absorbs far-red light, it switches back to the Pr form.This clever little system is able to detect many different qualities of light, including the light intensity (encoded in the speed at which the molecule bounces from one form to another), and the color of the light (encoded by the ratio of the Pfr form to the Pr form). Intensity tells a seed when to emerge from the soil and color tells the seeding when to grow tall to avoid shade."The beauty of this is you can purify the phytochromes, put them in a test tube and watch them switch forms simply by shining red or far-red light on the solutions," Vierstra said. "So they're not figments of our imagination."An hour glass that runs too fastBut this description leaves out one conversion. Pfr can convert to Pr by absorbing far-red light but also by a process called thermal reversion, which occurs without light.People thought thermal reversion worked like an hour glass, Vierstra said. As soon as the sun set, the hour glass started running, and Pfr started trickling back to the Pr form. The amount of Pfr at the end of the night then told the plant how long the night was.This is important because the length of night varies with the season, especially away from the Equator. So changes in day (and night) length helps plants to tell where they are in the seasonal cycle, which in turn helps them to flower in the right season.Nobody had been able to test the idea that thermal reversion was an hourglass, or timer, however. But as they were tinkering with phytochrome B, the Vierstra lab made phytochrome mutants that were fast reverters and ones that were slow reverters. And these mutants were among those that traveled to Argentina.When they grew the plants, the Casals lab got strange results they could understand only if thermal reversion is much faster than anyone realized; and only if the rate of reversion is very sensitive to temperature. In other words, the only possible interpretationwas that phytochrome B in the wild type (unmodified) plant is a temperature as well as light sensor."The plant is looking for Pfr, which tells it the light is on," said Vierstra. "In sunlight a plant slowly makes more and more Pfr until the reaction that converts Pr to Pfr saturates. But as the temperature rises, the thermal reversion starts running so fast, the plants accumulate relatively little Pfr."You would expect that at higher temperatures the Pr -> Pfr reaction would go faster," Vierstra said, "and it probably does, but thermal reversion goes even faster. It erases the light signal because the reversion reaction is more sensitive to temperature than the one creating the light signal."You can predict what this will do as temperature rises," Vierstra said. "Plants that make lots of Pfr are short, intensely green and happy. But thermal reversion will draw down the Pfr at higher temperatures, so that plants will respond as if they are in the dark (even though they are in the light) and grow tall and leggy.""We don't yet know right now whether it's just phytochrome B that's a temperature sensor," Vierstra said. So right now members of his team, including Research Scientist Sethe Burgie, are trying to get accurate measurement on the other phytochromes. "Once we have this figured out, we could make mutants that are less or more sensitive to temperature by modifying thermal reversion."Coming in from the cold"Phytochromes are the worst to work on," Vierstra said. "You have to spend four days in the dark to purify them. They are incredibly unstable, they are present at very low levels, and they have got all kinds of variants. And unlike most other proteins, their amino-acid sequences also don't tell us how phytochromes work."So when people purify phytochromes, they want to keep the proteins as happy as possible and that means keeping them as cold as possible. All the experiments are done on ice!"And that's why we didn't realize until now that phytochromes could act as temperature sensors!"Reference:LM50BIM3/NOPBLM61CIM3XTMP03FT9Z