Category Archives: Applications

Cambridge Nanotherm today announced that Ewald Braith has joined the board as a Non-Exec Director. Cambridge Nanotherm has already started to make significant inroads into the LED market with its innovative nano-ceramic thermal management solutions for LEDs and other electronics. Ewald has now been brought on board to lend his considerable expertise to aiding the company in its growth plans.

“We’re really excited to have Ewald on board,” commented Ralph Weir, CEO. “Ewald combines high-level strategic nous with a deep knowledge of electronic design. He’s a big-hitter in terms of his achievements in the power electronics and telco markets, and exposure to semiconductor technologies and vertical markets. Additionally, throughout his career, Ewald has led aggressive expansion into overseas markets. This is a world-class hire, and clearly indicates the level at which Cambridge Nanotherm is now operating.”

“Cambridge Nanotherm is a company with a passion for ‘growth’ and ‘innovation’,” added Braith. “I am joining the team at a very exciting point, both in terms of the company’s growth and the growth of the large scale industry and market opportunities. The markets for LED technologies are growing rapidly, and manufacturers are eager for effective ways to improve the competitiveness of their products. With its thermal management solutions Cambridge Nanotherm can and should be at the core of this opportunity. I look forward to working with the team to continue to build on the momentum already achieved, as well as helping to drive greater penetration of key high growth markets such as the US and Asia.”

Ewald has worked in a variety of high-profile companies over the last thirty years, with a focus on the telecoms and power semiconductor markets. These include Zytec, Artesyn Technologies and Emerson Network Power, as well as establishing his own consulting firm. Ewald has most recently been CEO at Detego, a RFID software solutions and services provider for the fashion industry, and he is also a member of the board at Salcomp PLC.

At next week’s SPIE Photonics West 2015, imec will present a new set of snapshot hyperspectral CMOS image sensors featuring spectral filter structures in a mosaic layout, processed per-pixel on 4×4 and 5×5 ‘Bayer-like’ arrays.

Imec’s hyperspectral filter structures are processed at wafer-level on commercially available CMOS image sensor wafers, enabling extremely compact, low cost and mass-producible hyperspectral imaging solutions. This paves the way to multiple applications ranging from machine vision, medical imaging, precision agriculture to higher volume industries such as security, automotive and consumer electronic devices.

“Imec’s latest achievements in hyperspectral imaging emphasize how our promising technology has become an industrially viable solution for a number of applications,” said Andy Lambrechts, program manager at imec. “The new mosaic architecture, and extended spectral range, brings unique advantages compared to our previously announced hyperspectral linescan sensors for applications in which scanning would not be practical. It enables spectral imaging in a truly compact, tiny form-factor, that can even be scaled to handheld devices. From the technology standpoint, we have now successfully demonstrated linescan and tiled sensors, in which spectral filters cover many pixels, to mosaic sensors, in which filters vary from pixel to pixel. At the same time, the spectral range is extended and now covers down to 470nm.”

The newly developed mosaic sensors feature one spectral filter per pixel, arranged in mosaics of 4×4 (16 spectral bands) or 5×5 (25 spectral bands) deposited onto a full array of 2 Million pixels 5.5µm size CMOSIS CMV2000 sensor. Two versions of the mosaic hyperspectral image sensors have been developed:

  • one 4×4 mosaic with 16 bands in the 470-630nm (visible range)
  • one 5×5 mosaic with 25 bands in the 600-1000nm range (Visible – NIR range)

“Imec’s hyperspectral imaging sensors (100bands linescan, 32bands tiled and 16/25bands mosaic designs) are off-the-shelf, commercially available engineering sample sensors that we developed to address the fragmented machine vision market and to trigger interest for this unique technology from potential end-users in other industries,” explained Jerome Baron, business development manager at imec. “We also offer customized spectral filtering solutions for companies that are already familiar with the technology and interested in developing proprietary solutions with a specific performance in terms of speed, compactness, spatial versus spectral resolution, bands selection, or cost.”

Located at booth 4635 at SPIE Photonics West, imec will demonstrate the 3 different versions of these hyperspectral image sensors. First engineering samples have been manufactured and now available for evaluation to early partners.

Imec, Medtronic, Ghent University and their project partners today announced the launch of the CARDIS project. Together they will develop and validate an early-stage cardio vascular disease detection platform using integrated silicon photonics. The project is supported by the recently launched European Union’s Horizon 2020 Framework Programme for Industrial leadership in Information and Communication Technologies (H2020). The project’s overarching goal is the investigation and demonstration of a mobile, low-cost device based on a silicon photonics integrated laser Doppler vibrometer. The concept will be validated for the screening of arterial stiffness, detection of stenosis and heart failure in a clinical setting.

Early identification of individuals at risk for cardio vascular disease (CVD) allows early intervention for halting or reversing the pathological process. This drives the CARDIS project team to develop a mobile, low-cost, non-invasive, point-of-care screening device for CVD. Assessment of arterial stiffness by measurement of the aortic pulse wave velocity (aPWV) is included in the latest ESC/ESH guidelines for CVD risk prediction. Besides aPWV, early identification of arterial stenosis and cardiac contraction abnormalities can be used to improve CVD risk classification. To date, there are no tools available to screen a large population set at primary care level on these parameters, and individuals that are considered to be at low or moderate risk too often go undiagnosed.

The CARDIS research activities include:

  • The investigation, design and fabrication op the optical subsystems and components.
  • The integration of the subsystems and building of a multi-array laser interferometer system.
  • The development of a process flow scalable to high volumes for all subsystems and their integration steps.
  • The investigation and development of the biomechanical model for translating optical signals related to skin-level vibrations into underlying CVD physiological events.
  • The validation of the system in a clinical setting.

Over the next three and a half years, CARDIS will be managed by imec, through imec’s associated laboratory located at Ghent University (Photonics Research Group in the Department of Information Technology). Medtronic Bakken Research Center (Netherlands) will be responsible for the scientific and technical coordination of the project. Other industrial, academic and clinical partners will bring their expertise to the project: SIOS Messtechnik (Germany), University College Cork Tyndall (Ireland), INSERM (France), Queen Mary University of London (United Kingdom), Universiteit Maastricht (Netherlands), Ghent University and Fundico (Belgium).

Interested to learn more about the potential of silicon photonics? Imec is exhibiting at next week’s SPIE Photonics West in San Francisco (booth 4635) and organizing a workshop and demonstration session on Silicon Photoncis together with MOSIS (February 10-11).

Gov. Charlie Baker today announced a $4 million dollar grant from the Massachusetts Technology Collaborative (“MassTech”) to UMass Lowell to support development of a printed and flexible electronics industry cluster, an emerging field that has the potential to become a $76 billion global market in the next decade.

The new Printed Electronics Research Collaborative (PERC) at UMass Lowell intends to position Massachusetts employers, large and small, to capitalize on the burgeoning printed and flexible electronics field, whether through direct development of products or as a piece of the supply chain. The PERC will initially focus on supporting the state’s defense cluster in printed electronics, but long-term, these technologies are expected to also have a broad range of applications in fields including health care, telecommunications and renewable energy. Printable electronics is currently a $16 billion global market and is projected to quadruple in 10 years, according to a 2014 report by IDTechEx.

“It is a privilege to announce today’s grant as another positive step forward for UMass Lowell, students and businesses across the Commonwealth. We have already seen great success stem from this partnership to fund research, support education and make new strides in innovation,” said Gov. Baker. “By connecting the incredible resources in our universities with the business community, the Commonwealth will continue to stimulate economic growth and create more good-paying jobs.”

The four-year grant award will be matched by $12 million in industry support and is being made as part of the Collaborative Research and Development Matching Grant Program, a $50 million dollar capital fund formed to support large-scale, long-term research projects that have high potential to spur innovation, cluster development and job growth in the Commonwealth. The fund was created as part of the 2012 Jobs Bill and is managed by the Innovation Institute at MassTech. Proposals are reviewed by an Investment Advisory Committee composed of executives from academia, industry, and the venture capital communities.

UMass Lowell Chancellor Marty Meehan and MassTech CEO Pamela Goldberg joined Gov. Baker at UMass Lowell’s Mark and Elisia Saab Emerging Technologies and Innovation Center, an 84,000-square-foot, state-of-the-art research facility where PERC will connect businesses with the expertise of UMass Lowell researchers. The MassTech grant will outfit laboratories and other research space at the Saab Center, also home to the Raytheon-UMass Lowell Research Institute, which will be among the participants in PERC. Other companies that have signed on include MicroChem of Westborough, Rogers Corp. of Burlington, SI2 Technologies of Billerica and Triton Systems of Chelmsford and more are expected, according to UMass Lowell Vice Provost for Research Julie Chen.

“Our mission is to convene industry, academia and government to catalyze economic opportunity in regions and clusters around the Commonwealth,” said Pamela Goldberg, CEO of the Massachusetts Technology Collaborative. “This project hits the mark on several fronts, including the potential to drive the development of innovative products and business growth. We are excited to partner with UMass Lowell and regional industry partners like Raytheon to expand R&D capacity and help advance this exciting new industry cluster.”

“UMass Lowell has decades of experience in partnering with businesses, large and small, to advance technologies and economic development. Not only does bringing our researchers together with innovators in industry stimulate economic growth, it offers our students unparalleled opportunities for experiential education,” Meehan told attendees, including representatives of the business and technology communities, UMass Lowell and the Lowell legislative delegation. “We are grateful to the Commonwealth for its investment in what we believe will be a model for academic and industry collaboration.”

Highlighting the importance of both public and private investment in the University of Massachusetts, today’s event also included the announcement by UMass Lowell that two of its most successful and generous alumni are making another multimillion-dollar gift to the campus and students, bringing their total commitment to the campus to nearly $10 million.

Robert and Donna Manning, Methuen natives who earned degrees at UMass Lowell, will commit an additional $4 million to the university to be used specifically for strategic initiatives in UMass Lowell’s Robert J. Manning School of Business and the School of Nursing.

The gift, combined with the MassTech grant, will strengthen the university’s North Campus Innovation District, located on University Avenue in Lowell. Made up of the Saab Center, the Manning School, the Lydon Library and nearby academic and laboratory complex, the district brings together the expertise of UMass Lowell’s engineering, science and business programs to provide ease of access for students, entrepreneurs and industry partners.

The business school was named for Rob Manning in May 2011 in recognition of the couple’s earlier multimillion-dollar commitment to the university. Since the Mannings graduated from UMass Lowell in the 1980s, they have supported capital and other initiatives at the university, including establishing the Robert and Donna Manning Endowment Fund, which supports scholarships for students majoring in nursing and business. Rob Manning began his career at MFS Investment Management shortly after receiving his UMass Lowell degree in business administration. He worked his way up from research analyst to chairman, a role he has held since 2010, overseeing billions of dollars in assets and employees in 80 countries around the world.  Donna Manning – whose career as an oncology nurse at a Boston hospital spans three decades – earned degrees in nursing and business administration at UMass Lowell.

“Donna and I received a world-class education at UMass Lowell that allowed us to become successful in our careers and our passion is to give back to future generations so they can fulfill their hopes and dreams,” said Rob Manning.

The latest commitment to UMass Lowell by the Mannings will support strategic priorities in the university’s School of Nursing and the Manning School of Business. Those include providing resources for the new dean of the business school as its new home, the Pulichino Tong Business Building, is constructed and outfitted, as well as equipping the new nursing simulation laboratory in the Health and Social Sciences Building.

“Once again, UMass Lowell is grateful to Rob and Donna Manning for their generosity and their support for the future of business and nursing education on our campus. They understand firsthand how a UMass Lowell education positions students for success after graduation and thanks to their gift, our students will be even more prepared they enter the job market,” said Meehan.

The automotive semiconductor market did exceptionally well in 2014, according to new analysis from IHS. Robust vehicle production growth, together with increased semiconductor content in cars charted a path of 10 percent growth year over year to reach $29B in 2014. IHS reports the fastest growing segments for automotive semiconductors are hybrid electric vehicles, telematics and connectivity and advanced driver assistance systems (ADAS).

The semiconductor revenue in these applications is forecast to achieve a compound annual growth rate (CAGR 2013–2018) of 20 percent, 19 percent and 18 percent respectively. The outlook for 2015 is also promising and the automotive semiconductor market is forecast to reach $31B, a strong 7.5 percent improvement over 2014.

Main growth drivers

Emissions legislations are leading semiconductor take rates in powertrain applications in regions around the world.

“The new concepts in emissions mitigation in the engine and in exhaust aftertreatment systems require advance sensors for their operation, said Ahad Buksh, analyst, automotive semiconductors, at IHS. “For example, a hybrid electric vehicle demands ten times more semiconductor content in powertrain,” he said.

Some of the key semiconductor applications for these vehicles include: a motor inverter is needed to convert the direct current to alternating current and vice versa, DC/DC converter is needed for bidirectional voltage control, battery management system is needed to monitor the state of the battery and plug-in charger required for charging the battery. All these applications require high-power management which will be achieved mainly with analog integrated circuits (ICs) and discrete components. After 24 percent growth in 2014, this segment is forecast to increase 22 percent in 2015, the highest of any automotive application.

Safety mandates and guidelines are driving the adoption of ADAS technology. Because of the encouragement of regional authorities and regulators for better safety standards, OEMs are increasingly adopting ADAS applications such as Lane Departure Warning (LDW), Forward Collision Warning (FCW) and Automatic Emergency Braking (AEB), among other technologies. These applications are being implemented with a front view camera module besides radar and lidar modules, providing high potential for semiconductor growth. A higher processing power (DMIPS) in micro-component ICs, increased non-volatile memory for image storage and increased volatile memory for execution of image processing functions would be required for these applications. The semiconductor market for ADAS technology is expected to reach $1.8B in 2015, a 21 percent increase over 2014.

The infotainment domain also provides strong growth opportunities for the future.  An important trend in head-units is the high-definition video function. It primarily comes from the adoption of consumer and mobile devices. This is also reflected in the incredible growth of the consumer electronic suppliers in the automotive industry, including Nvidia, which is estimated to have grown more than 80 percent in 2014.

The next five years are extremely important for telematics and broadband technology as well. 4G LTE technology will continue to grow in 2015, marking an inflection point toward sunset on 2G and 2.5G solutions in years to come. In the instrument cluster, the trend is moving from conventional analog to hybrid and fully digital instrument clusters. At the moment, the premium OEMs are going for a digital approach for their high-end vehicles, but in the long run, having digital instrument clusters in all the vehicles could be an option as well.

2014 Winners

2014 has seen a major change in the automotive supply chain, according to the Competitive Landscaping Tool CLT – Automotive – Q4 2014, now available from IHS Technology.  It has been a great year for Infineon, which enjoyed double digit revenue growth. Infineon has a strong presence in Powertrain, Chassis and Safety and Body and Convenience domains. Increased electrification in vehicles has helped its power management solutions, including the micro-component ICs.  Infineon, which was lagging more than $500 million behind Renesas in 2013, has now taken the lead over Renesas, who had been leading the market for many years.

IHS research indicates this change is largely due to fluctuation rates between the U.S. Dollar and the Japanese Yen, but it does not take into account the acquisition of International Rectifier, which was still in process in 2014. Now that the acquisition is complete, Infineon will further increase its lead over Renesas. International Rectifier’s strong presence in low-power insulated-gate bipolar transistor (IGBT), power modules and power metal-oxide-semiconductor field-effect transistor (MOSFET) arenas will particularly reinforce Infineon’s position in the key growing applications.

Based on the IHS analysis, other suppliers and their ranks are as follows:

Top Winners among Automotive Semiconductors Suppliers in 2014

Supplier

Rank, 2014

Rank, 2013

Market Share, 2014

Market Share, 2013

Key Drivers

Infineon

1

2

9.8%

9.2%
  • Strong growth in Chassis and Safety, Powertrain and Body and Convenience
  • Infineon’s power management solution benefit from HEV/EVs market

Freescale

4

4

7.4%

7.0%
  • Distinctive presence in fast growing segments such as Infotainment, ADAS and HEV/EVs

Texas Instruments

5

7

6.4%

5.3%
  • Strong year for TI’s embedded processors especially in ADAS and Infotainment

On Semiconductors

8

8

3.6%

2.9%
  • Increased position in ADAS with acquisition of Aptina’s CMOS imaging sensors

Micron

9

13

2.5%

1.8%
  • Increased its share in memory ICs for infotainment with its DRAM and eMMC solutions

Source: IHS

New pathway to valleytronics


January 27, 2015

A potential avenue to quantum computing currently generating quite the buzz in the high-tech industry is “valleytronics,” in which information is coded based on the wavelike motion of electrons moving through certain two-dimensional (2D) semiconductors. Now, a promising new pathway to valleytronic technology has been uncovered by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab).

Feng Wang, a condensed matter physicist with Berkeley Lab’s Materials Sciences Division, led a study in which it was demonstrated that a well-established phenomenon known as the “optical Stark effect” can be used to selectively control photoexcited electrons/hole pairs – referred to as excitons -in different energy valleys. In valleytronics, electrons move through the lattice of a 2D semiconductor as a wave with two energy valleys, each valley being characterized by a distinct momentum and quantum valley number. This quantum valley number can be used to encode information when the electrons are in a minimum energy valley. The technique is analogous to spintronics, in which information is encoded in a quantum spin number.

“This is the first demonstration of the important role the optical Stark effect can play in valleytronics,” Feng says. “Our technique, which is based on the use of circularly polarized femtosecond light pulses to selectively control the valley degree of freedom, opens up the possibility of ultrafast manipulation of valley excitons for quantum information applications.”

Wang, who also holds an appointment with the University of California (UC) Berkeley Physics Department, has been working with the 2D semiconductors known as MX2 materials, monolayers consisting of a single layer of transition metal atoms, such as molybdenum (Mo) or tungsten (W), sandwiched between two layers of chalcogen atoms, such as sulfur (S). This family of atomically thin 2D semiconductors features the same hexagonal “honeycombed” lattice as graphene. Unlike graphene, however, MX2 materials have natural energy band-gaps that facilitate their use in transistors and other electronic devices.

This past year, Wang and his group reported the first experimental observation of ultrafast charge transfer in photo-excited MX2 materials. The recorded charge transfer time of less than 50 femtoseconds established MX2 materials as competitors with graphene for future electronic devices. In this new study, Wang and his group generated ultrafast and ultrahigh pseudo-magnetic fields for controlling valley excitons in triangular monolayers of WSe2 using the optical Stark effect.

“The optical Stark effect describes the energy shift in a two-level system induced by a non-resonant laser field,” Wang says.

“Using ultrafast pump-probe spectroscopy, we were able to observe a pure and valley-selective optical Stark effect in WSe2 monolayers from the non-resonant pump that resulted in an energy splitting of more than 10 milli-electron volts between the K and K? valley exciton transitions. As controlling valley excitons with a real magnetic field is difficult to achieve even with superconducting magnets, a light-induced pseudo-magnetic field is highly desirable.”

Like spintronics, valleytronics offer a tremendous advantage in data processing speeds over the electrical charge used in classical electronics. Quantum spin, however, is strongly linked to magnetic fields, which can introduce stability issues. This is not an issue for quantum waves.

“The valley-dependent optical Stark effect offers a convenient and ultrafast way of enabling the coherent rotation of resonantly excited valley polarizations with high fidelity,” Wang says. “Such coherent manipulation of valley polarization should open up fascinating opportunities for valleytronics.”

Sound waves passing through the air, objects that break a body of water and cause ripples, or shockwaves from earthquakes all are considered “elastic” waves. These waves travel at the surface or through a material without causing any permanent changes to the substance’s makeup. Now, engineering researchers at the University of Missouri have developed a material that has the ability to control these waves, creating possible medical, military and commercial applications with the potential to greatly benefit society.

“Methods of controlling and manipulating subwavelength acoustic and elastic waves have proven elusive and difficult; however, the potential applications–once the methods are refined–are tremendous,” said Guoliang Huang, associate professor of mechanical and aerospace engineering in the College of Engineering at MU. “Our team has developed a material that, if used in the manufacture of new devices, could have the ability to sense sound and elastic waves. By manipulating these waves to our advantage, we would have the ability to create materials that could greatly benefit society–from imaging to military enhancements such as elastic cloaking–the possibilities truly are endless.”

In the past, scientists have used a combination of materials such as metal and rubber to effectively ‘bend’ and control waves. Huang and his team designed a material using a single component: steel. The engineered structural material possesses the ability to control the increase of acoustical or elastic waves. Improvements to broadband signals and super-imaging devices also are possibilities.

The material was made in a single steel sheet using lasers to engrave “chiral,” or geometric microstructure patterns, which are asymmetrical to their mirror images. It’s the first such material to be made out of a single medium. Huang and his team intend to introduce elements they can control that will prove its usefulness in many fields and applications.

“In its current state, the metal is a passive material, meaning we need to introduce other elements that will help us control the elastic waves we send to it,” Huang said. “We’re going to make this material much more active by integrating smart materials like microchips that are controllable. This will give us the ability to effectively ‘tune in’ to any elastic sound or elastic wave frequency and generate the responses we’d like; this manipulation gives us the means to control how it reacts to what’s surrounding it.”

Going forward, Huang said there are numerous possibilities for the material to control elastic waves including super-resolution sensors, acoustic and medical hearing devices, as well as a “superlens” that could significantly advance super-imaging, all thanks to the ability to more directly focus the elastic waves.

Propelled by the arrival of the Apple Watch, the global market for wireless power and charging in wearable applications is set to attain a gargantuan 3,000 percent expansion this year compared to 2014, according to IHS Technology.

Global revenue this year from shipments of wireless power receivers and transmitters in wearable applications will surge to more than $480 million, up from just $15 million last year, as shown in the attached figure. By 2019, wireless charging in wearables will generate revenue exceeding $1 billion.

“Growth this year will be remarkable for wireless charging in wearable electronic devices, even if in reality the overall penetration of wireless charging into wearables is relatively low given the billions of wearables  that are shipped into the consumer market every year,” said Vicky Yussuff, analyst for wireless charging at IHS Technology. “Still, interest in the use of wireless charging remains high on the part of wearable technology providers and device original equipment manufacturers. As a result, penetration is expected to escalate rapidly over the next five years.”

Apple Watch to spark growth 

In particular, 2015 is anticipated to be an important year for wearable electronics with many of the leading consumer electronics suppliers introducing wireless charging in their products, including smartwatches.

The highest-profile example is the Apple Watch. The smartwatch will ship with Apple’s proprietary MagSafe inductive charging solution, and is expected for release by the end of the second quarter this year. While Apple’s announcement at the end of 2014 did not really promote the benefits that wireless charging technology has to offer, the product is still expected to drive some awareness of wireless charging. Of the total number of wireless-charging-enabled receiver devices forecast to be shipped in wearable electronics in 2015, Apple Watch is projected to take a dominant share, accounting for more than 70 percent of total revenue in wireless-charging-enabled wearable devices.

At present, wireless charging solutions typically consist of a pad or mat on which consumers can place an enabled device for charging, without having to connect the device and the pad or mat physically. The enabled device, such as a smartwatch, can be picked up for use and replaced for charging—often termed “drop and charge.” However, advancements are also taking place in wireless charging technology, and even more versatile solutions are emerging offering greater spatial freedom, including wireless charging through surfaces like a desk, support for wireless charging of multiple devices from the same wireless charger and even wireless charging over distances.

Apple’s solution for the Apple Watch, which uses inductive charging, is not a “drop and charge” mechanism, nor does it offer any range of freedom of movement to the user. In essence, the smartwatch is physically tethered to the charger at all times while charging and being held in place by a magnet. But IHS projects that by the end of 2017, shipments of wearable-technology wireless charging receivers that allow charging over distances will overtake inductive or tightly coupled solutions.

These findings are contained in the report, “Wireless Charging in Wearable Technology Report – 2015,” from the Wireless Power Intelligence Service at IHS.  The IHS report, now available for service subscribers, includes an analysis of opportunities for wireless charging in wearable electronics across key applications and products with forecasts through 2018.

2015-01-13_Wireless_Charging

University of Wisconsin-Madison materials engineers have made a significant leap toward creating higher-performance electronics with improved battery life — and the ability to flex and stretch.

Led by materials science Associate Professor Michael Arnold and Professor Padma Gopalan, the team has reported the highest-performing carbon nanotube transistors ever demonstrated. In addition to paving the way for improved consumer electronics, this technology could also have specific uses in industrial and military applications.

In a paper published recently in the journal ACS Nano, Arnold, Gopalan and their students reported transistors with an on-off ratio that’s 1,000 times better and a conductance that’s 100 times better than previous state-of-the-art carbon nanotube transistors.

“Carbon nanotubes are very strong and very flexible, so they could also be used to make flexible displays and electronics that can stretch and bend, allowing you to integrate electronics into new places like clothing,” says Arnold. “The advance enables new types of electronics that aren’t possible with the more brittle materials manufacturers are currently using.”

Carbon nanotubes are single atomic sheets of carbon rolled up into a tube. As some of the best electrical conductors ever discovered, carbon nanotubes have long been recognized as a promising material for next-generation transistors, which are semiconductor devices that can act like an on-off switch for current or amplify current. This forms the foundation of an electronic device.

However, researchers have struggled to isolate purely semiconducting carbon nanotubes, which are crucial, because metallic nanotube impurities act like copper wires and “short” the device. Researchers have also struggled to control the placement and alignment of nanotubes. Until now, these two challenges have limited the development of high-performance carbon nanotube transistors.

Building on more than two decades of carbon nanotube research in the field, the UW-Madison team drew on cutting-edge technologies that use polymers to selectively sort out the semiconducting nanotubes, achieving a solution of ultra-high-purity semiconducting carbon nanotubes.

Previous techniques to align the nanotubes resulted in less-than-desirable packing density, or how close the nanotubes are to one another when they are assembled in a film. However, the UW-Madison researchers pioneered a new technique, called floating evaporative self-assembly, or FESA, which they described earlier in 2014 in the ACS journal Langmuir. In that technique, researchers exploited a self-assembly phenomenon triggered by rapidly evaporating a carbon nanotube solution.

The team’s most recent advance also brings the field closer to realizing carbon nanotube transistors as a feasible replacement for silicon transistors in computer chips and in high-frequency communication devices, which are rapidly approaching their physical scaling and performance limits.

“This is not an incremental improvement in performance,” Arnold says. “With these results, we’ve really made a leap in carbon nanotube transistors. Our carbon nanotube transistors are an order of magnitude better in conductance than the best thin film transistor technologies currently being used commercially while still switching on and off like a transistor is supposed to function.”

The researchers have patented their technology through the Wisconsin Alumni Research Foundation and have begun working with companies to accelerate the technology transfer to industry.

Nanoengineers at the University of California, San Diego have tested a temporary tattoo that both extracts and measures the level of glucose in the fluid in between skin cells. This first-ever example of the flexible, easy-to-wear device could be a promising step forward in noninvasive glucose testing for patients with diabetes.

The sensor was developed and tested by graduate student Amay Bandodkar and colleagues in Professor Joseph Wang’s laboratory at the NanoEngineering Department and the Center for Wearable Sensors at the Jacobs School of Engineering at UC San Diego. Bandodkar said this “proof-of-concept” tattoo could pave the way for the Center to explore other uses of the device, such as detecting other important metabolites in the body or delivering medicines through the skin.

Nanoengineers at the University of California, San Diego have tested a temporary tattoo that both extracts and measures the level of glucose in the fluid in between skin cells. CREDIT Jacobs School of Engineering/UC San Diego

Nanoengineers at the University of California, San Diego have tested a temporary tattoo that both extracts and measures the level of glucose in the fluid in between skin cells. CREDIT: Jacobs School of Engineering/UC San Diego

At the moment, the tattoo doesn’t provide the kind of numerical readout that a patient would need to monitor his or her own glucose. But this type of readout is being developed by electrical and computer engineering researchers in the Center for Wearable Sensors. “The readout instrument will also eventually have Bluetooth capabilities to send this information directly to the patient’s doctor in real-time or store data in the cloud,” said Bandodkar.

The research team is also working on ways to make the tattoo last longer while keeping its overall cost down, he noted. “Presently the tattoo sensor can easily survive for a day. These are extremely inexpensive–a few cents–and hence can be replaced without much financial burden on the patient.”

The Center “envisions using these glucose tattoo sensors to continuously monitor glucose levels of large populations as a function of their dietary habits,” Bandodkar said. Data from this wider population could help researchers learn more about the causes and potential prevention of diabetes, which affects hundreds of millions of people and is one of the leading causes of death and disability worldwide.

People with diabetes often must test their glucose levels multiple times per day, using devices that use a tiny needle to extract a small blood sample from a fingertip. Patients who avoid this testing because they find it unpleasant or difficult to perform are at a higher risk for poor health, so researchers have been searching for less invasive ways to monitor glucose.

In their report in the journal Analytical Chemistry, Wang and his co-workers describe their flexible device, which consists of carefully patterned electrodes printed on temporary tattoo paper. A very mild electrical current applied to the skin for 10 minutes forces sodium ions in the fluid between skin cells to migrate toward the tattoo’s electrodes. These ions carry glucose molecules that are also found in the fluid. A sensor built into the tattoo then measures the strength of the electrical charge produced by the glucose to determine a person’s overall glucose levels.

“The concentration of glucose extracted by the non-invasive tattoo device is almost hundred times lower than the corresponding level in the human blood,” Bandodkar explained. “Thus we had to develop a highly sensitive glucose sensor that could detect such low levels of glucose with high selectivity.”

A similar device called GlucoWatch from Cygnus Inc. was marketed in 2002, but the device was discontinued because it caused skin irritation, the UC San Diego researchers note. Their proof-of-concept tattoo sensor avoids this irritation by using a lower electrical current to extract the glucose.

Wang and colleagues applied the tattoo to seven men and women between the ages of 20 and 40 with no history of diabetes. None of the volunteers reported feeling discomfort during the tattoo test, and only a few people reported feeling a mild tingling in the first 10 seconds of the test.

To test how well the tattoo picked up the spike in glucose levels after a meal, the volunteers ate a carb-rich meal of a sandwich and soda in the lab. The device performed just as well at detecting this glucose spike as a traditional finger-stick monitor.

The researchers say the device could be used to measure other important chemicals such as lactate, a metabolite analyzed in athletes to monitor their fitness. The tattoo might also someday be used to test how well a medication is working by monitoring certain protein products in the intercellular fluid, or to detect alcohol or illegal drug consumption.