Category Archives: MEMS

This article originally appeared on SemiMD.com and was featured in the December 2016 issue of Solid State Technology.

By David Lammers, Contributing Editor

When analyst Linley Gwennap is asked about the chances that fully-depleted silicon-on-insulator (FD-SOI) technology will make it in the marketplace, he gives a short history lesson.

First, he makes clear that the discussion is not about “the older SOI,” – the partially depleted SOI that required designers to deal with the so-called “kink effect.” The FD-SOI being offered by STMicroelectronics and Samsung at 28nm design rules, and by GlobalFoundries at 22nm and 12nm, is a different animal: a fully depleted channel, new IP libraries, and no kink effect.

Bulk planar CMOS transistor scaling came to an end at 28nm, and leading-edge companies such as Intel, TSMC, Samsung, and GlobalFoundries moved into the finFET realm for performance-driven products, said Gwennap, founder of The Linley Group (Mountain View, Calif.) and publisher of The Microprocessor Report, said,

While FD-SOI at the 28nm node was offered by STMicrelectronics, with Samsung coming in as a second source, Gwennap said 28nm FD-SOI was not differentiated enough from 28nm bulk CMOS to justify the extra design and wafer costs. “When STMicro came out with 28 FD, it was more expensive than bulk CMOS, so the value proposition was not that great.”

NXP uses 28nm FD-SOI for its iMX 7 and iMX 8 processors, but relatively few other companies did 28nm FD-SOI designs. That may change as 22nm FD-SOI offers a boost in transistor density, and a roadmap to tighter design rules.

“For planar CMOS, Moore’s Law came to a dead end at 28nm. Some companies have looked at finFETs and decided that the cost barrier is just too high. They don’t have anywhere to go; for a few years now those companies have been at 28nm, they can’t justify the move on to finFETs, and they need to figure out how they can offer something new to their customers. For those companies, taking a risk on FD-SOI is starting to look like a good idea,” he said.

A cautious view 

Joanne Itow, foundry analyst at Semico Research (Phoenix), also has been observing the ups and downs of SOI technology over the last two decades. The end of the early heyday, marked by PD-SOI-based products from IBM, Advanced Micro Devices, Freescale Semiconductor, and several game system vendors, has led Itow to take a cautious, Show-Me attitude.

“The SOI proponents always said, ‘this is the breakout node,’ but then it didn’t happen. Now, they are saying the Fmax has better results than finFETs, and while we do see some promising results, I’m not sure everybody knows what to do with it. And there may be bottlenecks,” such as the design tools and IP cores.

Itow said she has talked to more companies that are looking at FD-SOI, and some of them have teams designing products. “So we are seeing more serious activity than before,” Itow said. “I don’t see it being the main Qualcomm process for high-volume products like the applications processors in smartphones. But I do see it being looked at for IoT applications that will come on line in a couple of years. And these things always seem to take longer than you think,” she said.

Sony Corp. has publicly discussed a GPS IC based on 28nm FD-SOI that is being deployed in a smartwatch sold by Huami, a Chinese brand, which is touting the long battery life of the watch when the GPS function is turned on.

GlobalFoundries claims it has more than 50 companies in various stages of development on its 22FDX process, which enters risk production early next year, and the company plans a 12nm FDX offering in several years.

IP libraries put together

The availability of design libraries – both foundation IP and complex cores – is an issue facing FD-SOI. Gwennap said GlobalFoundries has worked with EDA partners, and invested in an IP development company, Invecas, to develop an IP library for its FDX technology. “Even though GlobalFoundries is basically starting from scratch in terms of putting together an IP library, it doesn’t take that long to put together the basic IP, such as the interface cells, that their customers need.

“There is definitely going to be an unusual thing that probably will not be in the existing library, something that either GlobalFoundries or the customers will have to put together. Over time, I believe that the IP portfolio will get built out,” Gwennap said.

The salaries paid to design engineers in Asia tend to be less than half of what U.S.-based designers are paid, he noted. That may open up companies “with a lower cost engineering team” in India, China, Taiwan, and elsewhere to “go off in a different direction” and experiment with FD-SOI, Gwennap said.

Philippe Flatresses, a design architect at STMicro, said with the existing FDSOI ecosystem it is possible to design a complete SoC, including processor cores from ARM Ltd., high speed interfaces, USB, MIPI, memory controllers, and other IP from third-party providers including Synopsys and Cadence. Looking at the FD-SOI roadmap, several technology derivatives are under development to address the RF, ultra-low voltage, and other markets. Flatresses said there is a need to extend the IP ecosystem in those areas.

Wafer costs not a big factor

There was a time when the approximately $500 cost for an SOI wafer from Soitec (Grenoble, France) tipped the scales away from SOI technology for some cost-sensitive applications. Gwennap said when a fully processed 28nm planar CMOS wafer cost about $3,000 from a major foundry, that $500 SOI wafer cost presented a stumbling block to some companies considering FD-SOI.

Now, however, a fully-processed finFET wafer costs $7,000 or more from the major foundries, Gwennap said, and the cost of the SOI wafer is a much smaller fraction of the total cost equation. When companies compare planar FD-SOI to finFETs, that $500 wafer cost, Gwennap said, “just isn’t as important as it used to be. And some of the other advantages in terms of cost savings or power savings are pretty attractive in markets where cost is important, such as consumer and IoT products. They present a good chance to get some key design wins.”

Soitec claims it can ramp up to 1.5 million FD-SOI wafers a year with its existing facility in 18 months, and has the ability to expand to 3 million wafers if market demand expands.

Jamie Schaeffer, the FDX program manager at GlobalFoundries, acknowledges that the SOI wafers are three to four times more expensive than bulk silicon wafers. Schaeffer said a more important cost factor is in the mask set. A 22FDX chip with eight metal layers can be constructed with “just 39 mask layers, compared with 60 for a finFET design at comparable performance levels.” And no double patterning is required for the 22FDX transistors.

Technology advantages claimed

Soitec senior fellow Bich-Yen Nguyen, who spent much of her career at Freescale Semiconductor in technology development, claims several technical advantages for FD-SOI.

FD-SOI has a high transconductance-to-drain current ratio, is superior in terms of the short channel effect, and has a lower fringing and effective capacitance and lower gate resistance, due partly to a gate-first process approach to the high-k/metal gate steps, Nguyen said.

Back and forward biasing is another unique feature of FD-SOI. “When you apply body-bias, the fT and fmax curves shift to a lower Vt.  This is an additional benefit allowing the RF designer to achieve higher fT and fmax at much lower gate voltage (Vg) over a wider Vg range.  That is a huge benefit for the RF designer,” she said. Figure 1 illustrates the unique benefit of back-bias.

“To get the full benefit of body bias for power savings or performance improvement, the design teams must consider this feature from the very beginning of product development,” she said. While biasing does not require specific EDA tools, and can be achieve with an extended library characterization, design architects must define the best corners for body bias in order to gain in performance and power. And design teams must implement “the right set of IPs to manage body biasing,” such as a BB generator, BB monitors, and during testing, a trimming methodology.

Nguyen acknowledged that finFETs have drive-current advantages. But compared with bulk CMOS, FD-SOI has superior electrostatics, which enables scaling of analog/RF devices while maintaining a high transistor gain. And drive current increases as gate length is scaled, she said.

For 14/16 nm finFETs, Nguyen said the gate length is in the 25-30 nm range. The 22FDX transistors have a gate length in the 20nm range. “The very short gate length results in a small gate capacitance, and total lower gate resistance,” she said.

For fringing capacitance, the most conservative number is that 22nm FD-SOI is 30 percent lower than leading finFETs, though she said “finFETs have made a lot of progress in this area.”

Analog advantages

It is in the analog and RF areas that FD-SOI offers the most significant advantages, Nguyen said. The fT and fMAX of 350 and 300 GHz, respectively, have been demonstrated by GlobalFoundries for its 22nm FD-SOI technology. For analog devices, she claimed that FD-SOI offers better transistor mismatch, high intrinsic device gain (Gm/Gds ratio), low noise, and flexibility in Vt tuning. Figure 2 shows how 22FDX outperforms finFETs for fT/fMax.

“FDSOI is the only device architecture that meets all those requirements. Bulk planar CMOS suffers from large transistor mismatch due to random dopant fluctuation and low device gain due to poor electrostatics. FinFET technology improves on electrostatics but it lacks the back bias capability.”

The undoped channel takes away the random doping effect of a partially depleted (doped) channel, reducing variation by 50-60 percent.

Analog designers using FD-SOI, she said, have “the ability to tune the Vt by back-bias to compensate for process mismatch or drift, and to offer virtually any Vt desired. Near-zero Vt can also be achieved in FD-SOI, which enables low voltage analog design for low power consumption applications.”

“If you believe the future is about mobility, about more communications and low power consumption and cost sensitive IoT chips where analog and RF is about 50 percent of the chip, then FD-SOI has a good future.

“No single solution can fit all. The key is to build up the ecosystem, and with time, we are pushing that,” she said.

Valencell, an innovator in performance biometric data sensor technology, and STMicroelectronics (NYSE: STM) announced today the launch of a new, highly accurate and scalable development kit for biometric wearables that includes ST’s compact SensorTile turnkey multi-sensor module integrated with Valencell’s Benchmark(TM) biometric sensor system. Together, SensorTile and Benchmark deliver the most useful portfolio of sensors to support the most advanced wearable use cases.

The SensorTile is a tiny IoT (Internet of Things) module (13.5mm x 13.5mm) that packs on board a powerful STM32L4 microcontroller, a Bluetooth® Low Energy chipset, a wide spectrum of high-accuracy motion and environmental MEMS sensors (accelerometer, gyroscope, magnetometer, pressure, temperature sensor), and a digital MEMS microphone.

Integrating ST’s SensorTile development kit with Valencell’s Benchmark sensor technology simplifies the prototyping, evaluation, and development of innovative wearable and IoT solutions by delivering a complete Valencell PerformTek technology package, ready for immediate integration and delivery into wearable devices. The collaboration with ST expands on previous work that incorporated the company’s STM32 MCUs and sensors into Valencell’s Benchmark sensor system.

“Valencell’s Benchmark solution leverages the high accuracy of ST’s MEMS sensor technology along with SensorTile’s miniature form factor, flexibility, and STM32 Open Development Environment-based ecosystem,” said Tony Keirouz, Vice President Marketing and Applications, Microcontrollers, Security, and Internet of Things, STMicroelectronics. “Combined, SensorTile and Benchmark enable wearable makers to quickly and easily develop the perfect product for any application that integrates highly accurate biometrics.”

“Working with ST has allowed us to bring together the best of all sensors required to support the most advanced wearable use cases through our groundbreaking Benchmark sensor system,” said Dr. Steven LeBoeuf, president and co-founder of Valencell. “What attracted us to the SensorTile was the flexibility of the platform and the ultra-low power consumption, which will enable our customers to create highly-accurate and powerful wearables and hearables in any form factor.”

At just over 180mm2, STMicroelectronics’ SensorTile is currently the smallest turnkey sensor board of its type, and it is jam-packed with a MEMS accelerometer, gyroscope, magnetometer, pressure sensor, and a MEMS microphone. With the on-board low-power STM32L4 microcontroller, it can be used as a sensing and connectivity hub for developing firmware and shipping in products such as wearables, gaming accessories, and smart-home or IoT devices.

Adding to its features, SensorTile has a complete Bluetooth® Low Energy transceiver including a miniature single-chip balun on-board, as well as a broad set of system interfaces. It can be simply plugged to a host board, and when powered it immediately starts streaming inertial, audio, and environmental data to ST’s BlueMS smartphone app that can be downloaded free of charge from popular app stores.

The market leader, Valencell’s PerformTek sensor systems provide accurate, robust and flexible technology, powering more biometric hearables and wearables. The technology gives wearable and hearable devices the ability to continuously and accurately measure blood flow signals, even during extreme physical activity or when the optical signals are weak. These signals can be translated into biometric data, including continuous heart rate, VO2 and VO2 max, resting heart rate, heart rate response, heart rate recovery, continuous energy expenditure (calorie burn), cardiac efficiency and heart rate variability assessments.

STMicroelectronics and Valencell will showcase the new integrated development kit at CES in the Valencell Booth # 44330 and in a private STMicroelectronics suite.

By Christian G. Dieseldorff, Industry Research & Statistics Group at SEMI 

Data from SEMI’s recently updated World Fab Forecast report reveal that 62 new Front End facilities will begin operation between 2017 and 2020.  This includes facilities and lines ranging from R&D to high volume fabs, which begin operation before high volume ramp commences.  Most of these newly operating facilities will be volume fabs; only 7 are R&Ds or Pilot facilities.

Between 2017 and 2020, China will see 26 facilities and lines beginning operation, about 42 percent of the worldwide total currently tracked by SEMI.  The majority of the facilities starting operation in 2018 are Chinese-owned companies. The peak for China in 2018 comes mainly from foundry facilities (54 percent). The Americas region follows with 10 facilities, and Taiwan with 9 facilities. See Figure 1.

Figure 1 depicts the regions in which new facilities will begin operation.

Figure 1 depicts the regions in which new facilities will begin operation.

By product type, the forecast for new facilities and lines include: 20 (32 percent) are forecast to be foundries, followed by 13 Memory (21 percent), seven LED (11 percent), six Power (10 percent) and five MEMS (8 percent). See Figure 2

Figure 2: New facilities & lines starting operation by product type from 2017 to 2020

Figure 2: New facilities & lines starting operation by product type from 2017 to 2020

Because the forecast extends several years, it includes facilities and lines of all probabilities, including rumored projects and projects which have been announced, but have a low probability of actually happening.  See Table 1.

FabForecast-table1

 

Probabilities of less than 50 percent are considered unconfirmed, while a probability of 80 to 85 percent means that the facility is currently in construction mode.  Projects with 90 percent probability are currently equipping. As the forecast gets farther out, more of the projects have lower probabilities.

The projects under construction, or soon to be under construction, will be key drivers in equipment spending for this industry over the next several years — with China expected to be the key spending market.

SEMI’s World Fab Forecast provides detailed information about each of these fab projects, such as milestone dates, spending, technology node, products, and capacity information. Since the last publication in August 2016, the research team has made 249 changes on 222 facilities/lines.

The World Fab Forecast Report, in Excel format, tracks spending and capacities for over 1,100 facilities including future facilities across industry segments from Analog, Power, Logic, MPU, Memory, and Foundry to MEMS and LEDs facilities.  Using a bottoms-up approach methodology, the SEMI Fab Forecast provides high-level summaries and graphs, and in-depth analyses of capital expenditures, capacities, technology and products by fab.

The SEMI Worldwide Semiconductor Equipment Market Subscription (WWSEMS) data tracks only new equipment for fabs and test and assembly and packaging houses.  The SEMI World Fab Forecast and its related Fab Database reports track any equipment needed to ramp fabs, upgrade technology nodes, and expand or change wafer size, including new equipment, used equipment, or in-house equipment. Also check out the Opto/LED Fab Forecast.

Learn more about the SEMI fab databases at: www.semi.org/en/MarketInfo/FabDatabase and www.youtube.com/user/SEMImktstats.

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences have made the world’s smallest radio receiver – built out of an assembly of atomic-scale defects in pink diamonds.

This tiny radio — whose building blocks are the size of two atoms — can withstand extremely harsh environments and is biocompatible, meaning it could work anywhere from a probe on Venus to a pacemaker in a human heart.

The research was led by Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering at SEAS, and his graduate student Linbo Shao and published in Physical Review Applied.

The radio uses tiny imperfections in diamonds called nitrogen-vacancy (NV) centers. To make NV centers, researchers replace one carbon atom in a diamond crystal with a nitrogen atom and remove a neighboring atom — creating a system that is essentially a nitrogen atom with a hole next to it. NV centers can be used to emit single photons or detect very weak magnetic fields. They have photoluminescent properties, meaning they can convert information into light, making them powerful and promising systems for quantum computing, phontonics and sensing.

Radios have five basic components — a power source, a receiver, a transducer to convert the high-frequency electromagnetic signal in the air to a low-frequency current, speaker or headphones to convert the current to sound and a tuner.

In the Harvard device, electrons in diamond NV centers are powered, or pumped, by green light emitted from a laser. These electrons are sensitive to electromagnetic fields, including the waves used in FM radio, for example. When NV center receives radio waves it converts them and emits the audio signal as red light. A common photodiode converts that light into a current, which is then converted to sound through a simple speaker or headphone.

An electromagnet creates a strong magnetic field around the diamond, which can be used to change the radio station, tuning the receiving frequency of the NV centers.

Shao and Loncar used billions of NV centers in order to boost the signal, but the radio works with a single NV center, emitting one photon at a time, rather than a stream of light.

The radio is extremely resilient, thanks to the inherent strength of diamond. The team successfully played music at 350 degrees Celsius — about 660 Fahrenheit.

“Diamonds have these unique properties,” said Loncar. “This radio would be able to operate in space, in harsh environments and even the human body, as diamonds are biocompatible.”

Scientists at the National Institute of Standards and Technology (NIST) have developed a new device that measures the motion of super-tiny particles traversing distances almost unimaginably small–shorter than the diameter of a hydrogen atom, or less than one-millionth the width of a human hair. Not only can the handheld device sense the atomic-scale motion of its tiny parts with unprecedented precision, but the researchers have devised a method to mass produce the highly sensitive measuring tool.

Schematic shows laser light interacting with a plasmonic gap resonator, a miniature device designed at NIST to measure with unprecedented precision the nanoscale motions of nanoparticles. An incident laser beam (pink beam at left) strikes the resonator, which consists of two layers of gold separated by an air gap. The top gold layer is embedded in an array of tiny cantilevers (violet)--vibrating devices resembling a miniature diving board. When a cantilever moves, it changes the width of the air gap, which, in turn, changes the intensity of the laser light reflected from the resonator. The modulation of the light reveals the displacement of the tiny cantilever. Credit: Brian Roxworthy/NIST

Schematic shows laser light interacting with a plasmonic gap resonator, a miniature device designed at NIST to measure with unprecedented precision the nanoscale motions of nanoparticles. An incident laser beam (pink beam at left) strikes the resonator, which consists of two layers of gold separated by an air gap. The top gold layer is embedded in an array of tiny cantilevers (violet)–vibrating devices resembling a miniature diving board. When a cantilever moves, it changes the width of the air gap, which, in turn, changes the intensity of the laser light reflected from the resonator. The modulation of the light reveals the displacement of the tiny cantilever. Credit: Brian Roxworthy/NIST

It’s relatively easy to measure small movements of large objects but much more difficult when the moving parts are on the scale of nanometers, or billionths of a meter. The ability to accurately measure tiny displacements of microscopic bodies has applications in sensing trace amounts of hazardous biological or chemical agents, perfecting the movement of miniature robots, accurately deploying airbags and detecting extremely weak sound waves traveling through thin films.

NIST physicists Brian Roxworthy and Vladimir Aksyuk describe their work (link is external) in the Dec. 6, 2016, Nature Communications.

The researchers measured subatomic-scale motion in a gold nanoparticle. They did this by engineering a small air gap, about 15 nanometers in width, between the gold nanoparticle and a gold sheet. This gap is so small that laser light cannot penetrate it.

However, the light energized surface plasmons–the collective, wave-like motion of groups of electrons confined to travel along the boundary between the gold surface and the air.

The researchers exploited the light’s wavelength, the distance between successive peaks of the light wave. With the right choice of wavelength, or equivalently, its frequency, the laser light causes plasmons of a particular frequency to oscillate back and forth, or resonate, along the gap, like the reverberations of a plucked guitar string.

Meanwhile, as the nanoparticle moves, it changes the width of the gap and, like tuning a guitar string, changes the frequency at which the plasmons resonate.

The interaction between the laser light and the plasmons is critical for sensing tiny displacements from nanoscale particles, notes Aksyuk. Light can’t easily detect the location or motion of an object smaller than the wavelength of the laser, but converting the light to plasmons overcomes this limitation. Because the plasmons are confined to the tiny gap, they are more sensitive than light is for sensing the motion of small objects like the gold nanoparticle.

The amount of laser light reflected back from the plasmon device reveals the width of the gap and the motion of the nanoparticle. Suppose, for example, that the gap changes–due to the motion of the nanoparticle–in such a way that the natural frequency, or resonance, of the plasmons more closely matches the frequency of the laser light. In that case, the plasmons are able to absorb more energy from the laser light, and less light is reflected.

To use this motion-sensing technique in a practical device, Aksyuk and Roxworthy embedded the gold nanoparticle in a microscopic-scale mechanical structure–a vibrating cantilever, sort of a miniature diving board–that was a few micrometers long, made of silicon nitride. Even when they’re not set in motion, such devices never sit perfectly still, but vibrate at high frequency, jostled by the random motion of their molecules at room temperature. Even though the amplitude of the vibration was tiny–moving subatomic distances–it was easy to detect with the new plasmonic technique. Similar, though typically larger, mechanical structures are commonly used for both scientific measurements and practical sensors; for example, detecting motion and orientation in cars and smartphones. The NIST scientists hope their new way of measuring motion at the nanoscale will help to further miniaturize and improve performance of many such micromechanical systems.

“This architecture paves the way for advances in nanomechanical sensing,” the researchers write. “We can detect tiny motion more locally and precisely with these plasmonic resonators than any other way of doing it,” said Aksyuk.

The team’s fabrication approach allows production of some 25,000 of the devices on a computer chip, with each device tailored to detect motion according to the needs of the manufacturer.

At last week’s IEEE International Electron Devices Meeting (IEDM) in San Francisco (USA), imec, the world-leading research and innovation hub in nano-electronics and digital technology and Holst Centre debuted a miniaturized sensor that simultaneously determines pH and chloride (Cl–)levels in fluid. This innovation is a must have for accurate long-term measurement of ion concentrations in applications such as environmental monitoring, precision agriculture and diagnostics for personalized healthcare. The sensor is an industry first and thanks to the SoC (system on chip) integration it enables massive and cost-effective deployments in Internet-of-Things (IoT) settings. Its innovative electrode design results in a similar or better performance compared to today’s standard equipment for measuring single ion concentrations and allows for additional ion tests.

Sensors based on ion-selective membranes are considered the gold standard to measure ion concentrations in many applications, such as water quality, agriculture, and analytical chemistry. They consist of two electrodes, the ion-sensitive electrode with the membrane (ISE) and a reference electrode (RE). When these electrodes are immersed in a fluid, a potential is generated that scales with the logarithm of the ion activity in the fluid, forming a measure for the concentration. However, the precision of the sensor depends on the long-term stability of the miniaturized RE, a challenge that has now been overcome.

“The common issue with such designs is the leaching of ions from the internal electrolyte, causing the sensor to drift over time,” stated Marcel Zevenbergen, senior researcher at imec/Holst Centre. “To suppress such leaching, we designed and fabricated an RE with a microfluidic channel as junction and combined it with solid-state iridium oxide (IrOx) and silver chloride (AgCl) electrodes fabricated on a silicon substrate, respectively as indicating electrodes for pH and Cl–. Our tests demonstrated this to be a long-term stable solution with the sensor showing a sensitivity, accuracy and response time that are equal or better than existing solutions, while at the same time being much smaller and potentially less expensive.”

“We are providing groundbreaking sensing and analytics solutions for the IoT,” stated John Baekelmans, Managing Director of imec in The Netherlands. “This new multi-ion sensor is one in a series that Holst Centre is currently developing with its partners to form the senses of the IoT. For each sensor, the aim is to leapfrog the current performance of the state-of-the-art sensors in a mass-producible, wireless, energy optimized and miniaturized package.”

imec iot sensor

Outfitting the future


December 12, 2016

Wearable technology is about more than smartwatches or counting steps. Across North Carolina State University, researchers are using it to solve problems — monitoring heart rate and environmental dangers, powering electronic devices, delivering medications, building better prosthetics and improving safety.

wearable-tech-top-1500x650

They’re developing technologies that are functional, efficient, innovative and practical, and that could have an impact on countless lives.

Here are a few of the NC State projects at the forefront of this evolving field.

What’s NEXT in wearables

What if the clothes you already wear not only covered your body but also kept track of how it’s functioning — and all you had to do was put them on?

Finding innovative, useful and economical ways to integrate electronics into clothing is the mission of the College of Textiles’ Nano-Extended Textiles (NEXT) Research Group.

Headed by Jesse Jur, assistant professor in the Department of Textile Engineering, Chemistry and Science, the NEXT group seeks to create cost-effective, energy-efficient wearable technology that’s powered by the user’s own body.

Jur’s team has gained attention for projects like customizable, iron-on sensors that monitor the heart’s performance and transmit the readings to a smartphone, or that monitor environmental levels of potentially dangerous gases like carbon monoxide and ozone.

The NEXT group has also explored bioluminescence in fashion through a collaboration with recent College of Textiles graduate Jazsalyn McNeil, who joined the group as a “fusion designer” to meld her design sensibility with the group’s research. McNeil’s Pulse Dress incorporates screen-printed sensors that make LED lights blink with the wearer’s heartbeat. NEXT and McNeil hope that the eye-catching dress will both influence fashion and draw attention to the possibilities of wearable electronics.

Heating up wearable tech

In recent years, smartwatches have turned up on the arms of millions of people who want convenient ways to keep track of their fitness, but these still depend on conventional batteries. At NC State’s Center for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) — a National Science Foundation Nanosystems Engineering Research Center — researchers are developing innovative health-monitoring devices that are battery-free and body-powered.

“The goal of ASSIST is to make wearable technologies that can be used for long-term health monitoring, such as devices that track heart health or monitor physical and environmental variables to predict and prevent asthma attacks,” said Daryoosh Vashaee, an associate professor of electrical and computer engineering in the NC State College of Engineering.

Vashaee and a team of undergraduates and faculty members have developed a new approach for harvesting body heat and converting it into electricity to power wearable electronics. The prototype armbands and embedded sensors in T-shirts are lightweight, conform to the shape of the body and can generate far more electricity than previous lightweight heat-harvesting technologies.

“We want to make devices that don’t rely on batteries,” Vashaee said. “And we think this design and prototype moves us much closer to making that a reality.”

Taking the sting out of diabetes

For some people with serious health issues, wearable technology has the potential to offer more than bells and whistles — it could make their treatments easier and even save lives.

Zhen Gu, an associate professor in the UNC/NC State Joint Department of Biomedical Engineering, has developed a glucose-responsive insulin patch for people living with Type 1 Diabetes. At around the size of a penny, the thin, square patch contains more than a hundred tiny, painless needles that supply the wearer with insulin as needed. This potential treatment could help to ensure consistent blood-sugar levels — and spare patients regular injections.

Gu, who has been honored as one of MIT Technology Review’s “Innovators Under 35” for his work with innovative drug-delivery systems, received $4.6 million in funding from JDRF (formerly the Juvenile Diabetes Research Foundation) and multinational pharmaceutical company Sanofi for the project. The patch is currently in animal trials. Gu is also working on patches to deliver melanoma drugs directly to tumor sites and to deliver blood thinners as needed to prevent blood clots.

Walking wearables

Amputees have always been among the earliest adopters of wearable technology, as even minor advances in prosthetics can markedly improve their mobility. Helen Huang, associate professor of biomedical engineering and director of the Rehabilitation Engineering Core in the UNC/NC State Joint Department of Biomedical Engineering, has made it her mission to develop the next generation of powered prosthetic limbs.

Huang’s projects include software that allows powered prosthetics to tune themselves automatically, making the devices more responsive and lowering the costs associated with powered prosthetic use.

“People are dynamic — a patient’s physical condition may change as he or she becomes accustomed to a prosthetic leg, for example, or they may gain weight,” said Huang. “These changes mean the prosthetic needs to be re-tuned, and working with a prosthetist takes time and money.”

Huang’s team has also worked on technology that translates electrical signals in human muscles into signals that control powered prosthetic limbs — enabling sensors in the prosthetics to follow simple cues from the user’s brain such as “open hand” or “close hand.”

A bright idea for safety

For College of Textiles alumnus Jeremy Wall, a near miss with a car while he was riding his bike one night became an unexpected source of inspiration: He now heads a company, Lumenus, that’s developing clothing and accessories with embedded smart LED lighting.

Wall, a 2014 graduate in fashion and textile management, began working on his tech with the help of an undergraduate research scholarship while he was still a student. His goal was to help cyclists, motorcyclists and runners be more visible to motorists at night while staying stylish and functional during the day.

The company will soon hit the market with apparel and accessories including jackets, vests, leggings, backpacks and armbands. It’s also licensing its technology to companies such as backpack manufacturer Timbuk2 and working with the Department of Defense to develop sensors for military gear.

Lumenus has also created an app that adds extra features to the apparel. For example, the wearer can enter a destination on the app, and the LED lights on the garment will flash strategically at intersections or other potentially hazardous points along the route.

Wall recently returned to NC State for help getting his company off the ground, enlisting three College of Textiles undergraduates to work with Lumenus as part of their senior design project.

The next time you place your coffee order, imagine slapping onto your to-go cup a sticker that acts as an electronic decal, letting you know the precise temperature of your triple-venti no-foam latte. Someday, the high-tech stamping that produces such a sticker might also bring us food packaging that displays a digital countdown to warn of spoiling produce, or even a window pane that shows the day’s forecast, based on measurements of the weather conditions outside.

Engineers at MIT have invented a fast, precise printing process that may make such electronic surfaces an inexpensive reality. In a paper published today in Science Advances, the researchers report that they have fabricated a stamp made from forests of carbon nanotubes that is able to print electronic inks onto rigid and flexible surfaces.

A. John Hart, the Mitsui Career Development Associate Professor in Contemporary Technology and Mechanical Engineering at MIT, says the team’s stamping process should be able to print transistors small enough to control individual pixels in high-resolution displays and touchscreens. The new printing technique may also offer a relatively cheap, fast way to manufacture electronic surfaces for as-yet-unknown applications.

“There is a huge need for printing of electronic devices that are extremely inexpensive but provide simple computations and interactive functions,” Hart says. “Our new printing process is an enabling technology for high-performance, fully printed electronics, including transistors, optically functional surfaces, and ubiquitous sensors.”

Sanha Kim, a postdoc in MIT’s departments of Mechanical Engineering and Chemical Engineering, is the lead author, and Hart is the senior author. Their co-authors are mechanical engineering graduate students Hossein Sojoudi, Hangbo Zhao, and Dhanushkodi Mariappan; Gareth McKinley, the School of Engineering Professor of Teaching Innovation; and Karen Gleason, professor of chemical engineering and MIT’s associate provost.

A stamp from tiny pen quills

There have been other attempts in recent years to print electronic surfaces using inkjet printing and rubber stamping techniques, but with fuzzy results. Because such techniques are difficult to control at very small scales, they tend to produce “coffee ring” patterns where ink spills over the borders, or uneven prints that can lead to incomplete circuits.

“There are critical limitations to existing printing processes in the control they have over the feature size and thickness of the layer that’s printed,” Hart says. “For something like a transistor or thin film with particular electrical or optical properties, those characteristics are very important.”

Hart and his team sought to print electronics much more precisely, by designing “nanoporous” stamps. (Imagine a stamp that’s more spongy than rubber and shrunk to the size of a pinky fingernail, with patterned features that are much smaller than the width of a human hair.) They reasoned that the stamp should be porous, to allow a solution of nanoparticles, or “ink,” to flow uniformly through the stamp and onto whatever surface is to be printed. Designed in this way, the stamp should achieve much higher resolution than conventional rubber stamp printing, referred to as flexography.

Kim and Hart hit upon the perfect material to create their highly detailed stamp: carbon nanotubes — strong, microscopic sheets of carbon atoms, arranged in cylinders. Hart’s group has specialized in growing forests of vertically aligned nanotubes in carefully controlled patterns that can be engineered into highly detailed stamps.

“It’s somewhat serendipitous that the solution to high-resolution printing of electronics leverages our background in making carbon nanotubes for many years,” Hart says. “The forests of carbon nanotubes can transfer ink onto a surface like massive numbers of tiny pen quills.”

Printing circuits, roll by roll

To make their stamps, the researchers used the group’s previously developed techniques to grow the carbon nanotubes on a surface of silicon in various patterns, including honeycomb-like hexagons and flower-shaped designs. They coated the nanotubes with a thin polymer layer (developed by Gleason’s group) to ensure the ink would penetrate throughout the nanotube forest and the nanotubes would not shrink after the ink was stamped. Then they infused the stamp with a small volume of electronic ink containing nanoparticles such as silver, zinc oxide, or semiconductor quantum dots.

The key to printing tiny, precise, high-resolution patterns is in the amount of pressure applied to stamp the ink. The team developed a model to predict the amount of force necessary to stamp an even layer of ink onto a substrate, given the roughness of both the stamp and the substrate, and the concentration of nanoparticles in the ink.

To scale up the process, Mariappan built a printing machine, including a motorized roller, and attached to it various flexible substrates. The researchers fixed each stamp onto a platform attached to a spring, which they used to control the force used to press the stamp against the substrate.

“This would be a continuous industrial process, where you would have a stamp, and a roller on which you’d have a substrate you want to print on, like a spool of plastic film or specialized paper for electronics,” Hart says. “We found, limited by the motor we used in the printing system, we could print at 200 millimeters per second, continuously, which is already competitive with the rates of industrial printing technologies. This, combined with a tenfold improvement in the printing resolution that we demonstrated, is encouraging.”

After stamping ink patterns of various designs, the team tested the printed patterns’ electrical conductivity. After annealing, or heating, the designs after stamping — a common step in activating electronic features — the printed patterns were indeed highly conductive, and could serve, for example, as high-performance transparent electrodes.

Going forward, Hart and his team plan to pursue the possibility of fully printed electronics.

“Another exciting next step is the integration of our printing technologies with 2-D materials, such as graphene, which together could enable new, ultrathin electronic and energy conversion devices,” Hart says.

Researchers in AMBER, the Science Foundation Ireland-funded materials science research centre, hosted in Trinity College Dublin, have used the wonder material graphene to make the novelty children’s material silly putty (polysilicone) conduct electricity, creating extremely sensitive sensors. This world first research, led by Professor Jonathan Coleman from TCD and in collaboration with Prof Robert Young of the University of Manchester, potentially offers exciting possibilities for applications in new, inexpensive devices and diagnostics in medicine and other sectors. The AMBER team’s findings have been published this week in the leading journal Science*.

Prof Coleman, Investigator in AMBER and Trinity’s School of Physics along with postdoctoral researcher Conor Boland, discovered that the electrical resistance of putty infused with graphene (“G-putty”) was extremely sensitive to the slightest deformation or impact. They mounted the G-putty onto the chest and neck of human subjects and used it to measure breathing, pulse and even blood pressure. It showed unprecedented sensitivity as a sensor for strain and pressure, hundreds of times more sensitive than normal sensors. The G-putty also works as a very sensitive impact sensor, able to detect the footsteps of small spiders. It is believed that this material will find applications in a range of medical devices.

Prof Coleman said, “What we are excited about is the unexpected behaviour we found when we added graphene to the polymer, a cross-linked polysilicone. This material as well known as the children’s toy silly putty. It is different from familiar materials in that it flows like a viscous liquid when deformed slowly but bounces like an elastic solid when thrown against a surface. When we added the graphene to the silly putty, it caused it to conduct electricity, but in a very unusual way. The electrical resistance of the G-putty was very sensitive to deformation with the resistance increasing sharply on even the slightest strain or impact. Unusually, the resistance slowly returned close to its original value as the putty self-healed over time.”

He continued, “While a common application has been to add graphene to plastics in order to improve the electrical, mechanical, thermal or barrier properties, the resultant composites have generally performed as expected without any great surprises. The behaviour we found with G-putty has not been found in any other composite material. This unique discovery will open up major possibilities in sensor manufacturing worldwide.”

Professor Mick Morris, Director of AMBER, said: “This exciting discovery shows that Irish research is at the leading edge of materials science worldwide. Jonathan Coleman and his team in AMBER continue to carry out world class research and this scientific breakthrough could potentially revolutionise certain aspects of healthcare.”

The Semiconductor Industry Association (SIA), representing U.S. leadership in semiconductor manufacturing, design, and research, today announced worldwide sales of semiconductors reached $30.5 billion for the month of October 2016, an increase of 3.4 percent from last month’s total of $29.5 billion and 5.1 percent higher than the October 2015 total of $29.0 billion. All monthly sales numbers are compiled by the World Semiconductor Trade Statistics (WSTS) organization and represent a three-month moving average. Additionally, a new WSTS industry forecast projects roughly flat annual semiconductor sales in 2016, followed by slight market growth in 2017 and 2018.

“The global semiconductor market has rebounded in recent months, with October marking the largest year-to-year sales increase since March 2015,” said John Neuffer, president and CEO, Semiconductor Industry Association. “Sales increased compared to last month across all regional markets and nearly every major semiconductor product category. Meanwhile, the latest industry forecast has been revised upward and now calls for flat annual sales in 2016 and small increases in 2017 and 2018. All told, the industry is well-positioned for a strong close to 2016.

Regionally, year-to-year sales increased in China (14.0 percent), Japan (7.2 percent), Asia Pacific/All Other (1.9 percent), and the Americas (0.1 percent), but decreased in Europe (-3.0 percent). Compared with last month, sales were up across all regional markets: the Americas (6.5 percent), China (3.2 percent), Japan (3.0 percent), Europe (2.2 percent), and Asia Pacific/All Other (2.0 percent).

Additionally, SIA today endorsed the WSTS Autumn 2016 global semiconductor sales forecast, which projects the industry’s worldwide sales will be $335.0 billion in 2016, a 0.1 percent decrease from the 2015 sales total. WSTS projects a year-to-year increase in Japan (3.2 percent) and Asia Pacific (2.5 percent), with decreases expected in Europe (-4.9 percent) and the Americas (-6.5 percent). Among major semiconductor product categories, WSTS forecasts growth in 2016 for sensors (22.6 percent), discretes (4.2 percent), analog (4.8 percent) and MOS micro ICs (2.3 percent), which include microprocessors and microcontrollers.

Beyond 2016, the semiconductor market is expected to grow at a modest pace across all regions. WSTS forecasts 3.3 percent growth globally for 2017 ($346.1 billion in total sales) and 2.3 percent growth for 2018 ($354.0 billion). WSTS tabulates its semi-annual industry forecast by convening an extensive group of global semiconductor companies that provide accurate and timely indicators of semiconductor trends.