Tag Archives: letter-mems-tech

EV Group (EVG), a supplier of wafer bonding and lithography equipment for the MEMS, nanotechnology and semiconductor markets, today introduced its SmartNIL large-area nanoimprint lithography (NIL) process. Available on all EV Group NIL platforms, including mask aligners as well as the industry benchmark EVG 720 and newly available EVG 7200 UV-NIL systems, SmartNIL provides a low-cost, large-area and high-volume-manufacturing solution for a variety of advanced devices, including:

  • Photonic-based devices such as light-emitting diodes (LEDs), lasers and photovoltaics
  • Micro arrays and nano-devices for medical devices and bioengineered applications
  • Advanced storage media, including newly emerging forms of non-volatile memory (NVM)

“SmartNIL is built on more than 15 years of NIL experience at EVG that includes the largest installed base of NIL systems worldwide, and is the only NIL technology currently used in high-volume manufacturing on substrates up to 200 mm today,” stated Paul Lindner, executive technology director at EV Group. “With our new EVG7200 UV-NIL system, which has industry-leading resolution down to 20 nm in volume production, EVG brings the advanced soft stamp and imprint capability of SmartNIL to larger substrates and smaller geometries. This enables our customers to achieve even greater cost-of-ownership (CoO) benefits and realize the full manufacturing potential of nanoimprint lithography.”

EVG153188

Seven companies selected from a pool of applicants will compete in MEMS Industry Group’s (MIG)’sElevator Pitch Session at MEMS Executive Congress. Making ‘Shark Tank’-style pitches to judges from the investment community, a mixture of startups, established companies, researchers and individuals will present products and technologies for potential funding — all in front of more than 250 attendees of MEMS Executive Congress.

This year’s finalists include:

  • CaddieON Inc.’s CaddieON®  uses RFID tags, a wrist-worn device, a smartphone app and a Web portal to empower golfers to make more informed decisions. By capturing stroke data — club used, lie, location and length — golfers get the performance data while on the course to choose the right club and plan optimal game strategy. The company is seeking a $1 million investment for marketing, sales and manufacturing.
  • Force Impact Technologies’ FitGuard™ is a Bluetooth-compatible accelerometer-enabled mouthguard that can measure the force of an impact and visually display the force from the impact via color-coded illuminated LEDs. The LEDs provide instant visual indication to coaches and officials when a player needs to come off the field to be properly evaluated. The company is seeking a $250,000 investment.
  • AnatoMotion’s Dental Imaging System will be an advanced and more affordable dental imaging system for diagnosing and treating a number of dental-related issues, including TMJ and bite dysfunctions. The company seeks a minimum investment of $150,000.
  • Indiana Integrated Circuits LLC’s Quilt Packaging (QP) technology is a new microchip interconnection technology that incorporates conductive “nodules” fabricated on the sides of chips. These nodule structures can serve as extremely wide-bandwidth, low-loss electrical I/O, enable sub-micron mechanical chip-to-chip alignment, and deliver a chip-to-chip gap as small as five microns. The company seeks funding and/or a commercialization partner to demonstrate feasibility of QP for specific MEMS products and to verify reliability of QP-enabled systems.
  • Sand 9’s MEMS resonators are the world’s smallest resonators. Because they eliminate the need for any external timing source, they are ideally suited for integration into a System-in-Package (SiP) or SoC environments. At the same time, they improve performance and reliability while reducing costs. By co-packaging Sand 9’s MEMS resonators with their SoC solutions, semiconductor manufacturers can now realize the next step in IoT/mobile product evolution.
  • Cambridge CMOS Sensors’ CCS801 is a miniaturized CMOS MEMS-based multi-gas sensor that can be used for detecting Ethanol (Alcohol), hazardous gases such as Carbon Monoxide (CO) and a wide range of Volatile Organic Compounds (VOCs) for Indoor Air Quality (IAQ) monitoring. Based on the company’s Micro-hotplate technology — a unique silicon platform that supports sensor miniaturization, significantly lower power consumption, and ultra-fast stabilization and response times — the CCS801 is suitable for smartphones, tablets and wearable devices.

Elevator Pitch Coaches and Judges

This year’s finalists will each receive pre-event coaching, before they make their pitch to a panel of judges.

2014 Elevator Pitch coaches include:

2014 Elevator Pitch judges include:

The Elevator Pitch Session winner will receive an iGrant from Rogue Valley Microdevices and Sustainable Valley Technology Group that is valued at $160K plus one free year of MIG membership.

As in Alice’s journey through the looking-glass to Wonderland, mirrors in the real world can sometimes behave in surprising and unexpected ways, including a new class of mirror that works like no other.

As reported this week in The Optical Society’s (OSA) new high-impact journal Optica, scientists have demonstrated, for the first time, a new type of mirror that forgoes a familiar shiny metallic surface and instead reflects infrared light by using an unusual magnetic property of a non-metallic metamaterial.

By placing nanoscale antennas at or very near the surface of these so-called “magnetic mirrors,” scientists are able to capture and harness electromagnetic radiation in ways that have tantalizing potential in new classes of chemical sensors, solar cells, lasers, and other optoelectronic devices.

“We have achieved a new milestone in magnetic mirror technology by experimentally demonstrating this remarkable behavior of light at infrared wavelengths. Our breakthrough comes from using a specially engineered, non-metallic surface studded with nanoscale resonators,” said Michael Sinclair, co-author on the Optica paper and a scientist at Sandia National Laboratories in Albuquerque, New Mexico, USA who co-led a research team with fellow author and Sandia scientist Igal Brener.

These nanoscale cube-shaped resonators, based on the element tellurium, are each considerably smaller than the width of a human hair and even tinier than the wavelengths of infrared light, which is essential to achieve magnetic-mirror behavior at these incredibly short wavelengths.

“The size and shape of the resonators are critical,” explained Sinclair “as are their magnetic and electrical properties, all of which allow them to interact uniquely with light, scattering it across a specific range of wavelengths to produce a magnetic mirror effect.”

Early magnetic mirror designs

Conventional mirrors reflect light by interacting with the electrical component of electromagnetic radiation. Because of this, however, they do more than reverse the image; they also reverse light’s electrical field. Though this has no impact on the human eye, it does have major implications in physics, especially at the point of reflection where the opposite incoming and outgoing electrical fields produce a canceling effect. This temporary squelching of light’s electrical properties prevents components like nanoscale antennas and quantum dots from interacting with light at the mirror’s surface.

A magnetic mirror, in contrast, reflects light by interacting with its magnetic field, preserving its original electrical properties. “A magnetic mirror, therefore, produces a very strong electric field at the mirror surface, enabling maximum absorption of the electromagnetic wave energy and paving the way for exciting new applications,” said Brener.

Unlike silver and other metals, however, there is no natural material that reflects light magnetically. Magnetic fields can reflect and even bottle-up charged particles like electrons and protons. But photons, which have no charge, pass through freely.

“Nature simply doesn’t provide a way to magnetically reflect light,” explained Brener. Scientists, therefore, are developing metamaterials (materials not found in nature, engineered with specific properties) that are able to produce the magnetic-mirror effect.

Initially, this could only be achieved at long microwave frequencies, which would enable only a few applications, such as microwave antennas.

More recently, other researchers have achieved limited success at shorter wavelengths using “fish-scale” shaped metallic components. These designs, however, experienced considerable loss of signal, as well as an uneven response due to their particular shapes.

Mirrors without metals

To overcome these limitations, the team developed a specially engineered two-dimensional array of non-metallic dielectric resonators—nanoscale structures that strongly interact with the magnetic component of incoming light. These resonators have a number of important advantages over the earlier designs.

First, the dielectric material they use, tellurium, has much lower signal loss than do metals, making the new design much more reflective at infrared wavelengths and creating a much stronger electrical field at the mirror’s surface. Second, the nanoscale resonators can be manufactured using standard deposition-lithography and etching processes, which are already widely used in industry.

The reflective properties of the resonators emerge because they behave, in some respects, like artificial atoms, absorbing and then reemitting photons. Atoms naturally do this by absorbing photons with their outer electrons and then reemitting the photons in random directions. This is how molecules in the atmosphere scatter specific wavelengths of light, causing the sky to appear blue during the day and red at sunrise and sunset.

The metamaterials in the resonators achieve a similar effect, but absorb and reemit photons without reversing their electric fields.

Proof of the process

Confirming that the team’s design was actually behaving like a magnetic mirror required exquisite measurements of how the light waves overlap as they pass each other coming in and reflecting off of the mirror surface. Since normal mirrors reverse the phase of light upon reflection, evidence that the phase signature of the wave was not reversed would be the “smoking gun” that the sample was behaving as a true magnetic mirror.

To make this detection, the Sandia team used a technique called time-domain spectroscopy, which has been widely used to measure phase at longer terahertz wavelengths. According to the researchers, only a few groups in the world have demonstrated this technique at shorter wavelengths (less than 10 microns). The power of this technique is that it can map both the amplitude and phase information of light’s electric field.

“Our results clearly indicated that there was no phase reversal of the light,” remarked Sheng Liu, Sandia postdoctoral associate and lead author on the Optica paper. “This was the ultimate demonstration that this patterned surface behaves like an optical magnetic mirror.”

Next steps

Looking to the future, the researchers will investigate other materials to demonstrate magnetic mirror behavior at even shorter, optical wavelengths, where extremely broad applications can be found. “If efficient magnetic mirrors could be scaled to even shorter wavelengths, then they could enable smaller photodetectors, solar cells, and possibly lasers,” Liu concluded.

Paper:  S. Liu, M. B. Sinclair, T. S. Mahony, Y. C. Jun, S. Campione, J. Ginn, D. Bender, J. R. Wendt, J.F. Ihlefeld, P. G. Clem, J. B. Wright, I. Brener, “Optical Magnetic Mirrors without Metals,” Optica 4, 247-253 (2014).

Specifications of reed relays, which are used for current switching in ATE and other applications are explained, including carry current, lifetime, minimum switch capacity, hot switching, operating speed and thermoelectric switching.

BY KEVIN MALLETT, Pickering Electronics, Clacton-on-Sea, Essex, U.K.

Reed relays, which use an electromagnet to control one or more reed switches without requiring an armature, are used for instrumentation and automatic test equipment (ATE), high voltage switching, low thermal EMF, direct drive from CMOS, RF switching and other specialized applications.

Reed relays are deceptively simple devices in principle. They contain a reed switch, a coil for creating a magnetic field, an optional diode for handling back EMF from the coil, a package and a method of connecting to the reed switch and the coil to outside of the package. The reed switch is itself a simple device in principle and relatively low cost to manufacture thanks to modern manufacturing technology.

The reed switch has two shaped metal blades made of a ferromagnetic material (roughly 50:50 nickel iron) and glass envelope that serves to both hold the metal blades in place and to provide a hermetic seal that prevents any contaminants entering the critical contact areas inside the glass envelope. Most (but not all) reed switches have open contacts in their normal state.

If a magnetic field is applied along the axis of the reed blades the field is intensified in the reed blades because of their ferromagnetic nature, the open contacts of the reed blades are attracted to each other and the blades deflect to close the gap. With enough applied field the blades make contact and electrical contact is made.

The only movable part in the reed switch is the deflection of the blades, there are no pivot points or materials trying to slide past each other. The reed switch is considered to have no moving parts, and that means there are no parts that mechanically wear. The contact area is enclosed in a hermetically sealed envelope with inert gasses, or in the case of high voltage switches a vacuum, so the switch area is sealed against external contamination. This gives the reed switch an exceptionally long mechanical life

Inevitably in practice the issues are a little more complicated. The ferromagnetic material is not a good conductor and in particular the material does not make a good switch contact. So the reed blades have to have a precious metal cover in the contact area, the precious metal may not stick to the blade material very well so an underlying metal barrier may be required to ensure good adherence. Some types of reed relay use mercury wetted contacts, consequently reed relays that use plated contacts are often referred to as “dry” reed relays. The metals can be added by selective plating or by sputtering processes. Where the reed blade passes through the glass envelope any plating (in many cases there may be none) requires controlling to avoid adversely affecting the glass to metal hermetic seal. Outside the glass seal the reed blades have to be suitably finished to allow them to be soldered or welded into the reed relay package, usually requiring a different plating finish to that used inside the glass envelope.

The materials used for the precious metal contact areas inside the glass envelope have a significant impact on the reed switch (and therefore the relay) characteristics. Some materials have excellent contact resistance stability; others resist the mechanical erosion that occurs during hot switch events. Commonly used materials are ruthenium, rhodium and iridium– all of which are in the relatively rare platinum precious metal group. Tungsten is often used for high power or high voltage reed switches due to its high melting point. The material for the contact is chosen to best suit the target performance – bearing in mind the material chosen can also have a significant impact on manufacturing cost. Sealed in a long, narrow glass tube, the contacts are protected from corrosion, and are usually plated with silver, which has very low resistivity but is prone to corrosion when exposed, rather than corrosion-resistant but more resistive gold as used in the exposed contacts of high quality relays. The glass envelope may contain multiple reed switches or multiple reed switches can be inserted into a single bobbin and actuate simultaneously. As the moving parts are small and lightweight, reed relays can switch much faster than relays with armatures. They are mechanically simple, making for reliability and long life.

This article reviews and explains common specifications used for reed relays (FIGURE 1).

FIGURE 1. Reed relays are used for current switching in ATE and other applications.

FIGURE 1. Reed relays are used for current switching in ATE and other applications.

Carry current

Carry current is the current that the reed relay can support through its contact without long term damage. The life of the relay should be indefinite under this condition though some reed relays may also have a pulse current rating which can be applied to the relay without damage.

The carry current is determined primarily by the contact resistance of the relay and the heat sinking to the environment. As the current increases the temperature of the reed blades increases until it reaches a temperature where the material is no longer ferromagnetic (Curie Temperature). Once that temperature is reached the relay contacts may open since the blades no longer respond to the magnetic field. The blade temper- ature is clearly dependent upon the current and relay path resistance – the normal assumption is that this is a square law (with current) relationship. In reality, the temperature rise is significantly more than a square law since the metallic resistance also increases with temperature, the magnetic field drops with temperature because of coil resistance rise and the mechanical properties of the blade can change. Consequently like all relays, exceeding the rating can result in a type of thermal runaway.

The packaging of the reed switch has a significant impact on the temperature rise, a lead frame tends to conduct heat to the outside world while the plastic encapsulation materials insulate it. The packaged reed relay will always have a lower current rating than that of the reed switch because manufacturers quote the rating with the reed switch directly exposed (no coil, no plastic packaging). The coil power will also add to the heating effect. Consequently Pickering Electronics always de-rates the reed relay ratings to ensure that the relay switch remains within its design limits.

There is also another subtle effect that occurs as the carry current increases – the signal creates its own magnetic field that twists the blades and therefore can modulate the contact resistance. The blade twisting may start to see a contact resistance rise as the blade contact area reduces or changes.

Care must be taken not to exceed the relays ratings and pulse ratings should take account of the square law relationship between current and temperature.

It becomes difficult to manufacture reed relays with a carry current of greater than 2A because the contact area has to be increased and that tends to make the bladed stiffer and require a higher magnetic field strength to operate them.

Lifetime

The lifetime of reed relays is critically dependent on the load conditions the reed switch encounters. For reed relays which are instrument grade the mechanical lifetime is much greater than 1 billion operations – they are mechanically simple devices that rely purely on the deflection of a blade to operate and there are conse- quently fewer wear out mechanisms.

The blade contact area though stills wears as they are opened and closed. If the signal load when the blade closes or opens is low then the wear out is very slow, as the load increases and hot switching (interruption or closure of a signal live carrying significant current or voltage) occurs higher temperatures are generated at the contact interface and this makes the materials more prone to wear. DC signals can also result in the migration of metal from one contact to another and without regular polarity reversal eventually the underlying contact materials are exposed with their poorer conduction characteristics. Hot switching can also create a temporary plasma in the contact area with high local temperatures, rapid operation of a relay under load can start to raise the contacts temperature to an extent where premature wear out can occur. The life an instrument grade reed relay can vary by three orders of magnitude according to the load conditions, perhaps 5 billion operations under no or light load to 5 million operations at a heavy load.

Minimum switch capacity

Some types of relay have a minimum switch capacity, if the relay is closed on a very low level signal (current or voltage) oxide or debris on the relay contacts can remain at the interface and cause a higher than expected resistance, or even an open circuit. This tends not to be the case with reed relays because the precious metal contacts are sealed in a hermetic glass envelope containing inert gas. Minimum switch capacity tends to be a characteristic of higher power mechanical (EMR) relays.

Hot switching

Hot switching occurs whenever a relay contact is opened or closed with a signal (current and voltage) is present. As the contacts move apart or close an arc can be created which transfers material from one contact to another, or simply redistributing the material. As the contact plating is damaged the resistance will eventually start to rise until the relay is no longer fit for the intended application.

For reed relays hot switching tests are always conducted into resistive loads. The hot switch capacity of a reed relay is typically quoted at a current/voltage that results in the number of operations that the relay will support around 10million operations. The data sheet specifies a hot switch current (the limiting factor at low voltages), a hot switch voltage (limiting factor at low current) and a power (from the product of the open contact voltage and the closed contact current).

Operating speed

The operate time is the time from when the relay coil is energized or de-energized to when the contact reaches a stable position.

For a normally open contact when the coil is energized the current, and therefore the magnetic
field, in the coil rises until the blades start to move closer together until they make contact. The contacts may impact each other sufficiently rapidly that there is bounce where for a short duration the contact is inter- mittently closed then opened. The operate time should be the time from when the relay coil was energized until the contacts are stably closed.

If the coil is driven from a higher than specified coil voltage the closing speed of the relay will be faster, however once the contacts make there may be more contact bounce as they meet with greater force. Overdriving the coil can also increase the release time since the magnetic field takes longer to collapse to the point where the contacts start to open.

For a normally open Form A (SPST) contact the release time is the time from when the coil is de-energised to when the contact is open. This operate time can be dependent on how the reed relay is driven, the presence of a protection diode on the coil will increase the release time. Typically, the release time is around one half the operate time.

Soft and hard weld failures

Operation of reed relays (or EMRs) under high load conditions causes one of the most common failure mechanisms for relays – a failure where the contacts are welded together. By convention these welds are classified as being either soft or hard failures. In the event of hard failure the contacts tend to be welded together and nothing will separate them. This is an easy fault to identify. Soft failures occur where the contacts sick but eventually come apart without any additional assistance. The failure is caused by small areas on the contact welding together, but the weld area is sufficiently small that the reed blades will separate because of their sprung nature. They could spring apart very quickly, or it may take several seconds to spring apart depending on how hard the weld is.

In either case the impact on the user is that the switching function of the relay is impaired and this is likely to have an adverse impact on the user application. So in either case the relay will require replacing since the defect is unlikely to improve with time. The cause of the weld will also need to be investigated and corrected.

Thermoelectric EMF

The cause of thermoelectric voltages is often misunderstood by users, and often misrepresented in articles and on the internet. The effect of thermoelectric EMF’s is to generate a small voltage (measured in microvolts) across the relay terminals when the relay is closed (FIGURE 2).

FIGURE 2. Thermoelectric EMF’s are used to generate a small voltage (measured in microvolts) across the relay terminals when the relay is closed.

FIGURE 2. Thermoelectric EMF’s are used to generate a small voltage (measured in microvolts) across the relay terminals when the relay is closed.

The voltage arises whenever a metal wire has a temperature gradient across it (the Seebeck Effect), if one end of the wire is at a different temperature to the other then a voltage will appear which is dependent on the temperature difference and the materials that make up the wire. Reed relays use a mix of metals, and these can have different temperature drops across them which results in a voltage appearing at the relay connection terminals. The voltage is not created at a connection junction. Nickel iron has quite a strong thermoelectric EMF, so designing reed relays with low thermal EMF’s can be a challenge.

The number and type of materials varies according to FIGURE 2. Thermoelectric EMF’s are used to generate a small voltage (measured in microvolts) across the relay terminals when the relay is closed. to the way the reed switch is designed and how it is packaged. If the relay was perfectly symmetric in construction (so the materials used from each contact to the reed switch were the same and the reed itself was perfectly symmetric in all materials and dimensions) and all heat sources in the relay body (primarily due to the coil) then this would be the case. However in reality the symmetry is not perfect so a residual voltage will arise.

Users can also degrade the performance by how they use the relay. When mounted on a PCB if the PCB has a temperature profile across it then that will generate an additional thermal EMF. Relay manufacturers usually assume that the thermal EMF is zero when the relay is first closed since up to that point no heat source exists inside the relay body. However, a temperature profile across the PCB (caused by the presence of other heat sources or forced air cooling) will create a thermal EMF.

Reed relays that have excellent Thermal EMF performance are typically designed to be as symmetric in design as possible and to use highly efficient coils to avoid heating the reed switch. Typically though, this results in a physically larger relay.

Two pole designs often quote the Differential Thermal EMF, this is the voltage generated between the two switches (usually) in a single package.

Assuming the relay design is reasonably symmetrical to a first order the voltage in one switch is the same as the other, so the differential voltage can be much smaller for the relay. Differential and single ended Thermo Electric EMF numbers should not be directly compared or confused with each other.

Scientists from the University of Leeds have taken a crucial step forward in bio-nanotechnology, a field that uses biology to develop new tools for science, technology and medicine.

The new study, published in print today in the journal Nano Letters, demonstrates how stable “lipid membranes” – the thin “skin” that surrounds all biological cells – can be applied to synthetic surfaces.

Importantly, the new technique can use these lipid membranes to “draw” – akin to using them like a biological ink – with a resolution of 6 nanometres (6 billionths of a meter), which is much smaller than scientists had previously thought was possible.

“This is smaller than the active elements of the most advanced silicon chips and promises the ability to position functional biological molecules – such as those involved in taste, smell, and other sensory roles – with high precision, to create novel hybrid bio-electronic devices,” said Professor Steve Evans, from the School of Physics and Astronomy at the University of Leeds and a co-author of the paper.

In the study, the researchers used something called Atomic Force Microscopy (AFM), which is an imaging process that has a resolution down to only a fraction of a nanometer and works by scanning an object with a miniscule mechanical probe. AFM, however, is more than just an imaging tool and can be used to manipulate materials in order to create nanostructures and to “draw” substances onto nano-sized regions. The latter is called “nano-lithography” and was the technique used by Professor Evans and his team in this research.

The ability to controllably “write” and “position” lipid membrane fragments with such high precision was achieved by Mr George Heath, a PhD student from the School of Physics and Astronomy at the University of Leeds and the lead author of the research paper.

Mr Heath said: “The method is much like the inking of a pen. However, instead of writing with fluid ink, we allow the lipid molecules – the ink – to dry on the tip first. This allows us to then write underwater, which is the natural environment for lipid membranes. Previously, other research teams have focused on writing with lipids in air and they have only been able to achieve a resolution of microns, which is a thousand times larger than what we have demonstrated.”

The research is of fundamental importance in helping scientists understand the structure of proteins that are found in lipid membranes, which are called “membrane proteins.” These proteins act to control what can be let into our cells, to remove unwanted materials, and a variety of other important functions.

For example, we smell things because of membrane proteins called “olfactory receptors,” which convert the detection of small molecules into electrical signals to stimulate our sense of smell. And many drugs work by targeting specific membrane proteins.

“Currently, scientists only know the structure of a small handful of membrane proteins. Our research paves the way to understand the structure of the thousands of different types of membrane proteins to allow the development of many new drugs and to aid our understanding of a range of diseases,” explained Professor Evans.

Aside from biological applications, this area of research could revolutionise renewable energy production.

Working in collaboration with researchers at the University of Sheffield, Professor Evans and his team have all of the membrane proteins required to construct a fully working mimic of the way plants capture sunlight. Eventually, the researchers will be able to arbitrarily swap out the biological units and replace them with synthetic components to create a new generation of solar cells.

Professor Evans concludes: “This is part of the emerging field of synthetic biology, whereby engineering principles are being applied to biological parts – whether it is for energy capture, or to create artificial noses for the early detection of disease or simply to advise you that the milk in your fridge has gone off.

“The possibilities are endless.”

When someone crumples a sheet of paper, that usually means it’s about to be thrown away. But researchers have now found that crumpling a piece of graphene “paper” — a material formed by bonding together layers of the two-dimensional form of carbon — can actually yield new properties that could be useful for creating extremely stretchable supercapacitors to store energy for flexible electronic devices.

The finding is reported in the journal Scientific Reports by MIT’s Xuanhe Zhao, an assistant professor of mechanical engineering and civil and environmental engineering, and four other authors. The new, flexible superconductors should be easy and inexpensive to fabricate, the team says.

“Many people are exploring graphene paper: It’s a good candidate for making supercapacitors, because of its large surface area per mass,” Zhao says. Now, he says, the development of flexible electronic devices, such as wearable or implantable biomedical sensors or monitoring devices, will require flexible power-storage systems.

Like batteries, supercapacitors can store electrical energy, but they primarily do so electrostatically, rather than chemically — meaning they can deliver their energy faster than batteries can. Now Zhao and his team have demonstrated that by crumpling a sheet of graphene paper into a chaotic mass of folds, they can make a supercapacitor that can easily be bent, folded, or stretched to as much as 800 percent of its original size. The team has made a simple supercapacitor using this method as a proof of principle.

The material can be crumpled and flattened up to 1,000 times, the team has demonstrated, without a significant loss of performance. “The graphene paper is pretty robust,” Zhao says, “and we can achieve very large deformations over multiple cycles.” Graphene, a structure of pure carbon just one atom thick with its carbon atoms arranged in a hexagonal array, is one of the strongest materials known.

To make the crumpled graphene paper, a sheet of the material was placed in a mechanical device that first compressed it in one direction, creating a series of parallel folds or pleats, and then in the other direction, leading to a chaotic, rumpled surface. When stretched, the material’s folds simply smooth themselves out.

Forming a capacitor requires two conductive layers — in this case, two sheets of crumpled graphene paper — with an insulating layer in between, which in this demonstration was made from a hydrogel material. Like the crumpled graphene, the hydrogel is highly deformable and stretchable, so the three layers remain in contact even while being flexed and pulled.

Though this initial demonstration was specifically to make a supercapacitor, the same crumpling technique could be applied to other uses, Zhao says. For example, the crumpled graphene material might be used as one electrode in a flexible battery, or could be used to make a stretchable sensor for specific chemical or biological molecules.

The National Science Foundation (NSF) and Semiconductor Research Corporation (SRC) today announced nine research awards to 10 universities totaling nearly $4 million under a joint program focused on Secure, Trustworthy, Assured and Resilient Semiconductors and Systems (STARSS).

The awards support research at the circuit, architecture and system levels on new strategies, methods and tools to decrease the likelihood of unintended behavior or access; increase resistance and resilience to tampering; and improve the ability to provide authentication throughout the supply chain and in the field.

“The processes and tools used to design and manufacture semiconductors ensure that the resulting product does what it is supposed to do. However, a key question that must also be addressed is whether the product does anything else, such as behaving in ways that are unintended or malicious,” said Keith Marzullo, division director of NSF’s Computer and Network Systems Division, which leads the NSF/SRC partnership on STARSS. “Through this partnership with SRC, we are pleased to focus on hardware and systems security research addressing this challenge and to provide a unique opportunity to facilitate the transition of this research into practical use.”

NSF’s involvement in STARSS is part of its Secure and Trustworthy Cyberspace (SaTC) portfolio, which in August announced nearly $75 million in cybersecurity awards.

The STARRS program expands SRC’s Trustworthy and Secure Semiconductors and Systems (T3S) program, engaging 10 universities across the U.S. Initial T3S industry participants are Freescale, Intel Corporation and Mentor Graphics. NSF is the first federal partner.

“The goal of SRC’s T3S initiative is to develop cost-effective strategies and tools for the design and manufacture of chips and systems that are reliable, trustworthy and secure,” said Celia Merzbacher, SRC Vice President for Innovative Partnerships. “This includes designing for security and assurance at the outset so as to build in resistance and resilience to attack or tampering. The research enabled by the STARSS program with NSF is a cornerstone of this overall effort.”

SRC is a university-research consortium for semiconductors and related technologies.

A number of trends are motivating industry and government to support research in hardware and system security. The design and manufacture of semiconductor circuits and systems requires many steps and involves the work of hundreds of engineers — typically distributed across multiple locations and organizations worldwide. Moreover, a typical microprocessor is likely to include dozens of design modules from various sources. Designers at each level need assurance that the components being incorporated can be trusted in order for the final system to be trustworthy.

Today, the design and manufacture of semiconductor circuits and systems includes extensive verification and testing to ensure the final product does what it is intended to do. Similar approaches are needed to provide assurance that the product is authentic and does not allow unwanted functionality, access or control. This includes strategies, tools and methods at all stages, from architecture through manufacture  and throughout the lifecycle of the product.

The first round of awards made through the STARSS program will support nine research projects with diverse areas of focus. They are:

·      “Combating integrated circuit counterfeiting using secure chip odometers” – Carnegie Mellon University researchers will design and implement secure chip odometers to provide integrated circuits (ICs) with both a secure gauge of use/age and an authentication of provenance to detect counterfeit ICs;

·      “Intellectual Property (IP) Trust-A comprehensive framework for IP integrity validation”- Case Western Reserve University and University of Florida researchers will develop a comprehensive and scalable framework for IP trust analysis and verification by evaluating IPs of diverse types and forms and develop threat models, taxonomy and instances of IP trust/integrity issues.

·      “Design of low-cost, memory-based security primitives and techniques for high-volume products” – University of Connecticut researchers will develop metrics and algorithms to make static RAM physical “unclonable” functions that are substantially more reliable at extreme operating conditions and aging, and extend this to dynamic RAM and Flash;

·      “Trojan detection and diagnosis in mixed-signal systems using on-the-fly learned, pre-computed and side channel tests” – Georgia Institute of Technology researchers will leverage knowledge of state of the art mixed-signal/analog/radio frequency for detection of Trojans in generic mixed-signal systems;

·      “Metric and CAD for differential power analysis (DPA) resistance” – Iowa State University researchers will investigate statistical metrics and design techniques to measure and defend against DPA attacks;

·      “Design of secure and anti-counterfeit integrated circuits” – University of Minnesota researchers will develop hierarchical approaches for authentication and obfuscation of chips;

·      “Hardware authentication through high-capacity, physical unclonable functions (PUF)-based secret key generation and lattice coding” – University of Texas at Austin researchers will develop strong machine-learning resistant PUFs, capable of producing high-entropy outputs, and a new lattice-based stability algorithm for high-capacity secret key generation; and

·      “Fault-attack awareness using microprocessor enhancements” – Virginia Institute of Technology and State University researchers will develop a collection of hardware techniques for microprocessor architectures to detect fault injection attacks, and to mitigate fault analysis through an appropriate response in software.

·      “Invariant carrying machine for hardware assurance” – Northwestern University researchers will develop techniques for improving the reliability and trustworthiness of hardware systems via an Invariant-Carrying Machine approach.

An international team of physicists, led by a research group at the University of Arkansas, has discovered that heating can be used to control the curvature of ripples in freestanding graphene.

The finding provides fundamental insight into understanding the influence temperature exerts on the dynamics of freestanding graphene. This may drive future applications of the flexible circuits of consumer devices such as cell phones and digital cameras.

While freestanding graphene offers promise as a replacement for silicon and other materials in microprocessors and next-generation energy devices, much remains unknown about its mechanical and thermal properties.

The research team published its findings on Wednesday, Sept. 17, in a paper titled “Thermal mirror buckling in freestanding graphene locally controlled by scanning tunneling microscopy” in the online journal Nature Communications, a publication of the journal Nature.

Previously, scientists have used electric voltage to cause large movements and sudden changes in the curvature of the ripples in freestanding graphene, said Paul Thibado, professor of physics at the University of Arkansas. In this paper, the team showed that an alternative method, thermal load, can be used to control these movements.

“Imagine taking a racquetball and cutting it in half,” said Thibado, an expert in experimental condensed matter physics. “You could invert it by pressing on it. That’s what we did here with a cross-section of a single ripple of freestanding graphene at the nanometer scale. Most materials expand when you heat them. Graphene contracts which is very unusual. So when we heated this cross-section, instead of expanding, it contracted, and that thermal stress caused it to buckle in the opposite direction.”

Graphene, discovered in 2004, is a one-atom-thick sheet of graphite. Electrons moving through graphite have mass and encounter resistance, while electrons moving through graphene are massless, and therefore travel much more freely. This makes graphene an excellent candidate material for use in meeting future energy needs and the fabrication of quantum computers, which make enormous calculations with little energy use.

The study was led by Peng Xu, formerly a postdoctoral research associate in the Department of Physics at the University of Arkansas and currently a postdoctoral research associate at the University of Maryland.

Xu and Thibado used scanning tunneling microscopy, which produces images of individual atoms on a surface, combined with large-scale molecular dynamic simulations to demonstrate the thermal mirror buckling.

In the paper, the third published in a major journal by the research team in 2014, they propose a concept for a new instrument that capitalizes on the control of the mirror buckling: a nanoscale electro-thermal-mechanical device.

Such a device would provide an alternative to microelectromechanical systems, which are tiny machines that are activated electrically. The advantage of this nanoscale electro-thermal-mechanical device would be the ability to change its output using electricity or heat. In addition, thermal loads can provide a significantly larger force.

The study, funded by the Office of Naval Research and the National Science Foundation, was conducted primarily through a research partnership between the University of Arkansas and the University of Antwerp in Belgium.

The results were obtained through a collaborative effort with University of Arkansas physics graduate students Steven D. Barber, James Kevin Schoelz and Matthew L. Ackerman; Mehdi Neek-Amal of the University of Antwerp and Shahid Rajaee Teacher Training University in Iran, Ali Sadeghi of the University of Basel in Switzerland and Francois Peeters of the University of Antwerp.

Intending to improve the smallest audio component found in smartphones, wearables and Internet of Things (IoT) devices, a new Boston-based sensor company called Vesper has designed a microphone that will enhance consumers’ acoustic experience with voice capture and sound recording. Though such microphones are virtually invisible to consumers, the market for the highest-performance devices is huge: the research firm IHS predicts that it will reach $718 million by 2017i.

Vesper’s microphone technology offers the highest signal-to-noise ratio (SNR) in ultra-compact form factors for consumer microphones: 70 db SNR, which is the key determining factor in acoustic performance.

Boosting Acoustic Performance

Consumers demand a better acoustic experience with their mobile devices. However, current MEMS microphone technology has been lacking, limiting the quality of always-on voice command, which is prone to high rates of error, and high-fidelity sound recording, particularly in noisy environments.

“Acoustics have not kept pace with other innovations in consumer electronics,” said Matt Crowley, CEO, Vesper. “They’ve been eclipsed by advances in display, processing, connectivity and camera. Our technology will improve always-on voice command, even at a distance. That’s particularly useful for applications such as Google Now. It’s also going to enhance the quality of sound recording, even in loud environments where ambient noise is a problem.”

With today’s smartphones embedding up to five microphones in arrays, designers are looking for better microphone solutions. Arrays of low-power, very high SNR microphones, such as Vesper’s, will address the issues with existing microphones in several ways:

  • Higher SNR microphones enable far field audio, dramatically improving sound capture even at longer distances
  • They provide ambient noise cancellation for recording, or for speaking on the phone, enhancing clarity and intelligibility
  • “Audio Zoom” capability focuses on a single sound source when recording, enabling more accurate sound-selection

“At the top performance level, very high SNR microphones feature a signal-to-noise ratio level of greater than, or equal to, 64 dB. These are the microphones projected to have the greatest growth in the coming years, with an estimated five-year revenue CAGR of 40 percent from 2012 to 2017,” said Marwan Boustany, senior analyst, MEMS & Sensors, IHS. “A robust MEMS microphone achieving 70 dB SNR at a small form factor would be well placed to provide a rich consumer experience with voice calls, voice commands and sound recording. This bodes well for companies that are targeting this space with very high SNR microphones.”

An inter­dis­ci­pli­nary team of researchers led by North­eastern Uni­ver­sity has devel­oped a novel method for con­trol­lably con­structing pre­cise inter-​​nanotube junc­tions and a variety of nanocarbon struc­tures in carbon nan­otube arrays. The method, the researchers say, is facile and easily scal­able, which will allow them to tailor the phys­ical prop­er­ties of nan­otube net­works for use in appli­ca­tions ranging from elec­tronic devices to CNT-​​reinforced com­posite mate­rials found in every­thing from cars to sports equipment.

Their find­ings were pub­lished on Monday in the journal Nature Com­mu­ni­ca­tions. The paper—titled “Sculpting carbon bonds for allotropic trans­for­ma­tion through solid-​​state re-​​engineering of –sp2 carbon”—was co-​​authored by post­docs, stu­dents, and leading CNT researchers from North­eastern Uni­ver­sity, the Mass­a­chu­setts Insti­tute of Tech­nology, and the Korea Advanced Insti­tute of Sci­ence and Tech­nology whose exper­tise runs from physics and mechan­ical engi­neering to mate­rials sci­ence and elec­trical engineering.

The chief archi­tect of the team’s novel method for re-​​engineering carbon bonds was Hyun­y­oung Jung, the paper’s lead author and a post­doc­toral fellow in the lab of co-​​author Yung Joon Jung, a nano-​​manufacturing expert and an asso­ciate pro­fessor of mechan­ical and indus­trial engi­neering.

Hyun­y­oung found that applying con­trolled, alter­nating voltage pulses across single-​​walled carbon nan­otube net­works trans­formed them into larger-​​diameter single-​​walled CNTs; multi-​​walled CNTs of dif­ferent mor­pholo­gies; or multi-​​layered graphene nanorribbons.

The new recon­struc­tion method—unlike pre­vious attempts to meld nanotubes—eschews harsh chem­i­cals and extremely high tem­per­a­tures, making the solid-​​state engi­neering tech­nique emi­nently con­ducive to scal­a­bility. What’s more, the new method pro­duces mol­e­c­ular junc­tions whose elec­trical and thermal con­duc­tiv­i­ties are far supe­rior com­pared to the junction-​​free assem­bled CNT network.

Their robust phys­ical prop­er­ties, the researchers say, make these inter-​​nanotube junc­tions per­fect for rein­forcing com­posite mate­rials that require mechan­ical tough­ness, including tennis rac­quets, golf clubs, cars, and even air­planes, where carbon fibers are cur­rently being used.

“Using these mate­rials for mechan­ical com­po­nents could lighten cars or other mechan­ical struc­tures without sac­ri­ficing strength,” Yung Joon explained.

The researchers described the utility of their ground­breaking work through the use of a metaphor in which carbon nan­otubes were wall-​​building bricks. Fashion a wall by stacking single bricks atop each other, they said, and watch the wall come tum­bling down. But build a wall by placing cement between the bricks and marvel at the indomitable strength of the larger, single unit.

“We have filled in the gaps with cement,” said co-​​author Swastik Kar, an assis­tant pro­fessor of physics at North­eastern, in keeping with the metaphor. “We started with single-​​walled carbon nan­otubes,” he added, “and then used this pio­neering method to bring them together.”

In addi­tion to Kar, Hyun­y­oung, and Yung Joon, the paper’s North­eastern co-​​authors com­prised Younglae Kim, an ex-​​graduate stu­dent, and Sanghyung Hong, a doc­toral can­di­date in Yung Joon Jung’s lab. “Pro­fessor Kar’s and our groups have had a very strong col­lab­o­ra­tion for many years,” Yung Joon said. “This research brings together experts from a number of dis­ci­plines to not only pro­duce a high-​​impact paper but also to gen­erate intel­lec­tual property.”

The team’s research was sup­ported by the National Sci­ence Foun­da­tion and the Min­istry of Industry in the Republic of Korea.