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EV Group (EVG), a supplier of wafer bonding and lithography equipment for the MEMS, nanotechnology and semiconductor markets, and Leti, an institute of CEA Tech, announced today that Leti has ordered a HERCULES NIL track system from EV Group. The HERCULES NIL system will be installed in Leti’s cleanroom facility in Grenoble, where it will augment the process-development and demonstration capabilities available to participants in the collaborative EVG-Leti INSPIRE program.

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More than an industrial partnership to develop NIL process solutions, the INSPIRE program was launched by Leti and EVG in June 2015 to demonstrate the cost-of-ownership benefits of NIL for a wide range of application areas, such as photonics, plasmonics, lighting, photovoltaics, wafer-level optics and bio technology. Through INSPIRE, Leti and EVG are supporting the development of new applications from the feasibility-study stage to the first manufacturing steps on EVG platforms, as well as transferring integrated process solutions to their industrial partners. The result of this effort is to significantly lower the barriers for adopting NIL technology for use in manufacturing novel products.

“Nanoimprint lithography has shown significant potential as a low-cost, high-resolution patterning solution for emerging and growing applications outside the semiconductor industry,” said Laurent Pain, patterning program manager, Leti. “The INSPIRE program launched by Leti and EVG is designed to accelerate the adoption of this promising technology in high-volume manufacturing. Installing this tool supports our goal of expanding and accelerating the scope of INSPIRE and demonstrating the benefits of this versatile, powerful nano-patterning technology.”

“We are extremely pleased with the success of the INSPIRE program since Leti and EVG launched it one year ago,” stated Markus Wimplinger, corporate technology development and IP director, EV Group. “To date, this program is supporting the development of NIL solutions for several customers thanks to the combined expertise and capabilities provided by both organizations. With the addition of EVG’s HERCULES NIL track system–which has already been installed in multiple high-volume manufacturing sites–we expect INSPIRE’s success to continue to grow.”

HERCULES NIL is a fully integrated track system that combines cleaning, resist coating and baking pre-processing steps with EVG’s proprietary SmartNIL large-area NIL process in a single platform. It can imprint structures in sizes ranging from tens of nanometers up to several micrometers while offering unmatched throughput (40 wph for 200-mm wafers). The system is built on a highly configurable and modular platform that accommodates a variety of imprint materials and structure sizes–providing a high degree of flexibility in addressing customers’ manufacturing needs. The fully integrated approach also minimizes the risk of particle contamination.

Thorlabs has expanded its piezoelectric line to include new types of piezoelectric actuators, low‐voltage piezoelectric chips, and discrete stacks with through holes, enabling a higher level of flexibility when integrating the actuators into other devices. These chips are ideal for laser tuning, micro‐ dispensing, and life‐science applications.

The chips can be manufactured with or without pre‐attached wires, with holes ranging from Ø2.0 mm to Ø6.0 mm, cross sections ranging from 5.0 mm × 5.0 mm to 10.0 mm × 10.0 mm, and thicknesses under 5.0 mm. Stacks are available in lengths from 5 mm to 100 mm, providing free stroke displacements up to 100 μm. Their in‐house manufacturing facility can also be deployed to provide custom dimensions, voltage ranges, and coatings upon request.

The piezoelectric chips are driven under a maximum voltage of 150 V, providing maximum free stroke displacements from 1.8 μm to 3.0 μm with sub‐millisecond response time. Through a precision grinding process, the accuracy of the design height is ensured to better than ±5 μm. The high accuracy makes it significantly easier to design devices around our piezoelectric chips, as it allows the users to have a loose tolerance when choosing their other components, and helps guarantee a better parallelism when employing multiple chips between two substrates.

“Reliability and durability of multilayer piezoelectric actuators are becoming increasingly important as the piezo application fields expand,” commented Cary Zhang, Piezo Product Line Manager. “Thorlabs’ multilayer piezo actuators are based on modified PZT‐5H ceramics, which are sintered at low temperatures (<1000 °C) to possess improved characteristics such as low electrical capacity, large displacement, and high stiffness.”

Besides the newly released piezo chips/stacks, Thorlabs manufactures a wide range of high quality piezo actuators, including chips, stacks, tubes, shear piezo and bimorphs. Modular, screw, and replaceable‐tip piezo actuators, including single axis, multi‐axis, closed‐loop and open‐loop actuators are also available.

Thorlabs, a vertically integrated photonics products manufacturer, was founded in 1989 to serve the laser and electro‐optics research market.

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Nanoelectronics research center imec announces that Kris Myny, one of its young scientists, has been awarded an ERC Starting Grant. The grant of 1.5 million euros is earmarked to open up new research horizons in the field of thin-film transistor technology. This will allow a leap forward compared to current state-of-the-art and enable breakthrough applications in e.g. healthcare and the Internet-of-Things (IoT). ERC Starting Grants are awarded by the European Research Council to support excellent researchers at the stage at which they are starting their own independent research team after a stringent selection procedure; they are among the most prestigious of European research grants.

With his research, Kris Myny wants to realize a breakthrough in thin-film transistor technology, a technology used to create the large-area, flexible circuits that e.g. drive today’s flat-panel displays.

Specifically, he wants to introduce design innovations of unipolar n-type transistor circuits based on amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) as semiconductor. These are currently acknowledged as the most promising transistors for next-generation curved, flexible, or even rollable electronic applications.

Kris Myny said, “My goal is to use these transistors to introduce a new logic family for building digital circuits that will drastically decrease the power consumption compared to current flexible circuits. And this of course without compromising the speed of the electronics. At the same time, we will also make the transistors smaller, in a way that is compatible with large-area manufacturing. In addition, I will also look at new techniques to design ultralow-power systems in the new logic style. These will allow building next-generation large-area flexible applications such as displays, IoT sensors, or wearable healthcare sensor patches.”

In a recent press release, the European Commission announced that in 2017 it would invest a record 1.8 billion in its ERC grant scheme. A sizable part of the budget is earmarked for Starting Grants, reserved for young scientists with two to seven years of post-PhD experience. Jo De Boeck, imec’s CTO says “We congratulate Kris Myny for all his valuable research culminating in this grant. Imec goes to great lengths to select and foster our young scientists and provide them with a world-class infrastructure. These ERC Starting Grants show that their work indeed meets the highest standards, comparable to any in Europe.”

The researchers in Jonathan Claussen’s lab at Iowa State University (who like to call themselves nanoengineers) have been looking for ways to use graphene and its amazing properties in their sensors and other technologies.

Iowa State engineers are developing real-world, low-cost applications for graphene. CREDIT: Photos by Christopher Gannon/Iowa State University.

Iowa State engineers are developing real-world, low-cost applications for graphene. Credit: Photos by Christopher Gannon/Iowa State University.

Graphene is a wonder material: The carbon honeycomb is just an atom thick. It’s great at conducting electricity and heat; it’s strong and stable. But researchers have struggled to move beyond tiny lab samples for studying its material properties to larger pieces for real-world applications.

Recent projects that used inkjet printers to print multi-layer graphene circuits and electrodes had the engineers thinking about using it for flexible, wearable and low-cost electronics. For example, “Could we make graphene at scales large enough for glucose sensors?” asked Suprem Das, an Iowa State postdoctoral research associate in mechanical engineering and an associate of the U.S. Department of Energy’s Ames Laboratory.

But there were problems with the existing technology. Once printed, the graphene had to be treated to improve electrical conductivity and device performance. That usually meant high temperatures or chemicals – both could degrade flexible or disposable printing surfaces such as plastic films or even paper.

Das and Claussen came up with the idea of using lasers to treat the graphene. Claussen, an Iowa State assistant professor of mechanical engineering and an Ames Laboratory associate, worked with Gary Cheng, an associate professor at Purdue University’s School of Industrial Engineering, to develop and test the idea.

And it worked: They found treating inkjet-printed, multi-layer graphene electric circuits and electrodes with a pulsed-laser process improves electrical conductivity without damaging paper, polymers or other fragile printing surfaces.

“This creates a way to commercialize and scale-up the manufacturing of graphene,” Claussen said.

The findings are featured on the front cover of the journal Nanoscale‘s issue 35. Claussen and Cheng are lead authors and Das is first author. Additional Iowa State co-authors are Allison Cargill, John Hondred and Shaowei Ding, graduate students in mechanical engineering. Additional Purdue co-authors are Qiong Nian and Mojib Saei, graduate students in industrial engineering.

Two major grants are supporting the project and related research: a three-year grant from the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 11901762 and a three-year grant from the Roy J. Carver Charitable Trust. Iowa State’s College of Engineering and department of mechanical engineering are also supporting the research.

The Iowa State Research Foundation Inc. has filed for a patent on the technology.

“The breakthrough of this project is transforming the inkjet-printed graphene into a conductive material capable of being used in new applications,” Claussen said.

Those applications could include sensors with biological applications, energy storage systems, electrical conducting components and even paper-based electronics.

To make all that possible, the engineers developed computer-controlled laser technology that selectively irradiates inkjet-printed graphene oxide. The treatment removes ink binders and reduces graphene oxide to graphene – physically stitching together millions of tiny graphene flakes. The process makes electrical conductivity more than a thousand times better.

“The laser works with a rapid pulse of high-energy photons that do not destroy the graphene or the substrate,” Das said. “They heat locally. They bombard locally. They process locally.”

That localized, laser processing also changes the shape and structure of the printed graphene from a flat surface to one with raised, 3-D nanostructures. The engineers say the 3-D structures are like tiny petals rising from the surface. The rough and ridged structure increases the electrochemical reactivity of the graphene, making it useful for chemical and biological sensors.

All of that, according to Claussen’s team of nanoengineers, could move graphene to commercial applications.

“This work paves the way for not only paper-based electronics with graphene circuits,” the researchers wrote in their paper, “it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells and (medical) devices.”

Last March, the artificial intelligence (AI) program AlphaGo beat Korean Go champion LEE Se-Dol at the Asian board game.

“The game was quite tight, but AlphaGo used 1200 CPUs and 56,000 watts per hour, while Lee used only 20 watts. If a hardware that mimics the human brain structure is developed, we can operate artificial intelligence with less power,” points out Professor YU Woo Jong.

In the junctions (synapses) between neurons, signals are transmitted from one neuron to the next. TRAM is made by a stack of different layers: A semiconductor molybdenum disulfide (MoS2) layer with two electrodes (drain and source), an insulating hexagonal boron nitride (h-BN) layer and graphene layer. This two-terminal architecture simulates the two neurons that made up to the synaptic structure. When the difference in the voltage of the drain and the source is sufficiently high, electrons from the drain electrode tunnel through the insulating h-BN and reach the graphene layer. Memory is written when electrons are stored in the graphene layer, and it is erased by the introduction of positive charges in the graphene layer. CREDIT: IBS

In the junctions (synapses) between neurons, signals are transmitted from one neuron to the next. TRAM is made by a stack of different layers: A semiconductor molybdenum disulfide (MoS2) layer with two electrodes (drain and source), an insulating hexagonal boron nitride (h-BN) layer and graphene layer. This two-terminal architecture simulates the two neurons that made up to the synaptic structure. When the difference in the voltage of the drain and the source is sufficiently high, electrons from the drain electrode tunnel through the insulating h-BN and reach the graphene layer. Memory is written when electrons are stored in the graphene layer, and it is erased by the introduction of positive charges in the graphene layer. CREDIT: IBS

In collaboration with Sungkyunkwan University, researchers from the Center for Integrated Nanostructure Physics within the Institute for Basic Science (IBS), have devised a new memory device inspired by the neuron connections of the human brain. The research, published in Nature Communications, highlights the devise’s highly reliable performance, long retention time and endurance. Moreover, its stretchability and flexibility makes it a promising tool for the next-generation soft electronics attached to clothes or body.

The brain is able to learn and memorize thanks to a huge number of connections between neurons. The information you memorize is transmitted through synapses from one neuron to the next as an electro-chemical signal. Inspired by these connections, IBS scientists constructed a memory called two-terminal tunnelling random access memory (TRAM), where two electrodes, referred to as drain and source, resemble the two communicating neurons of the synapse. While mainstream mobile electronics, like digital cameras and mobile phones use the so-called three-terminal flash memory, the advantage of two-terminal memories like TRAM is that two-terminal memories do not need a thick and rigid oxide layer. “Flash memory is still more reliable and has better performance, but TRAM is more flexible and can be scalable,” explains Professor Yu.

TRAM is made up of a stack of one-atom-thick or a few atom-thick 2D crystal layers: One layer of the semiconductor molybdenum disulfide (MoS2) with two electrodes (drain and source), an insulating layer of hexagonal boron nitride (h-BN) and a graphene layer. In simple terms, memory is created (logical-0), read and erased (logical-1) by the flowing of charges through these layers. TRAM stores data by keeping electrons on its graphene layer. By applying different voltages between the electrodes, electrons flow from the drain to the graphene layer tunnelling through the insulating h-BN layer. The graphene layer becomes negatively charged and memory is written and stored and vice versa, when positive charges are introduced in the graphene layer, memory is erased.

IBS scientists carefully selected the thickness of the insulating h-BN layer as they found that a thickness of 7.5 nanometers allows the electrons to tunnel from the drain electrode to the graphene layer without leakages and without losing flexibility.

Flexibility and stretchability are indeed two key features of TRAM. When TRAM was fabricated on flexible plastic (PET) and stretachable silicone materials (PDMS), it could be strained up to 0.5% and 20%, respectively. In the future, TRAM can be useful to save data from flexible or wearable smartphones, eye cameras, smart surgical gloves, and body-attachable biomedical devices.

Last but not least, TRAM has better performance than other types of two-terminal memories known as phase-change random-access memory (PRAM) and resistive random-access memory (RRAM).

A leading South Korean research university has successfully integrated two Advanced Vacuum plasma processing systems from Plasma-Therm into its nanotechnology fabrication lab, which supports multiple users engaged in wide-ranging nanotechnology research.

Seoul National University lab researchers recently installed two Apex SLR systems with the well-proven inductively coupled plasma (ICP) source technology from Plasma-Therm. One system is configured for dry etching, and the second system is configured for high-density plasma chemical vapor deposition (HDPCVD).

Jong-Seung Park, Team Manager/Fab. Operations of Seoul National University, said the university’s cleanroom facility serves many users who are employing the Apex SLR® systems’ etch and deposition capabilities.

“We are pleased to provide a good reference for these systems and their support,” Park said. “Both systems operate as we expected and deliver reproducible results over the last more than 16 months. The systems are reliable and we are pleased to be a customer of Plasma-Therm.”

Park said the Apex SLR ICP system utilizes chlorine-based chemistries for etching various materials, with an emphasis on aluminum interconnects. The Apex SLR® HDPCVD system has been employed for a wide range of silicon oxide and silicon nitride deposition processes, such as trench or gap filling for device fabrication.

Dr. David Lishan, Director, Technical Marketing for Plasma-Therm, said that Apex SLR systems are ideally suited for corporate R&D and academic research settings. “The Apex SLR, with its very strong and successful processing history, excellent uniformity and reproducibility, has proven highly productive in research environments.” Dr. Lishan continued, “The ability for facilities like SNU’s to task Apex SLR systems and quickly achieve process specs for multiple users are big reasons for selection of Apex SLR over products that are less capable and more expensive.”

Advanced Vacuum Apex SLR systems are highly versatile, small-footprint, field-proven tools for all plasma processing applications. Apex SLR ICP is capable of etching a wide range of materials for semiconductor devices and other types of nanotechnology. Apex SLR HDPCVD performs deposition of high-quality thin films at relatively low temperatures for applications such as optical coatings, semiconductor device passivation layers, and other nano-electronic fabrication processes with limited thermal budgets.

Researchers at the Faculty of Physics at the University of Warsaw, using the liquid crystal elastomer technology, originally developed in the LENS Institute in Florence, demonstrated a bioinspired micro-robot capable of mimicking caterpillar gaits in natural scale. The 15-millimeter long soft robot harvests energy from green light and is controlled by spatially modulated laser beam. Apart from travelling on flat surfaces, it can also climb slopes, squeeze through narrow slits and transport loads.

Caterpillar micro-robot sitting on a finger tip. Credit: Source: FUW

Caterpillar micro-robot sitting on a finger tip. Credit: Source: FUW

For decades scientists and engineers have been trying to build robots mimicking different modes of locomotion found in nature. Most of these designs have rigid skeletons and joints driven by electric or pneumatic actuators. In nature, however, a vast number of creatures navigate their habitats using soft bodies – earthworms, snails and larval insects can effectively move in complex environments using different strategies. Up to date, attempts to create soft robots were limited to larger scale (typically tens of centimeters), mainly due to difficulties in power management and remote control.

Liquid Crystalline Elastomers (LCEs) are smart materials that can exhibit large shape change under illumination with visible light. With the recently developed techniques, it is possible to pattern these soft materials into arbitrary three dimensional forms with a pre-defined actuation performance. The light-induced deformation allows a monolithic LCE structure to perform complex actions without numerous discrete actuators.

Researchers from the University of Warsaw with colleagues from LESN (Italy) and Cambridge (UK) have now developed a natural-scale soft caterpillar robot with an opto-mechanical liquid crystalline elastomer monolithic design. The robot body is made of a light sensitive elastomer stripe with patterned molecular alignment. By controlling the travelling deformation pattern the robot mimics different gaits of its natural relatives. It can also walk up a slope, squeeze through a slit and push objects as heavy as ten times its own mass, demonstrating its ability to perform in challenging environments and pointing at potential future applications.

– Designing soft robots calls for a completely new paradigm in their mechanics, power supply and control. We are only beginning to learn from nature and shift our design approaches towards these that emerged in natural evolution – says Piotr Wasylczyk, head of the Photonic Nanostructure Facility at the Faculty of Physics of the University of Warsaw, Poland, who led the project.

Researchers hope that rethinking materials, fabrication techniques and design strategies should open up new areas of soft robotics in micro- and millimeter length scales, including swimmers (both on-surface and underwater) and even fliers.

ams AG (SIX: AMS), a provider of high performance sensors and analog ICs, has launched the smallest ever optical sensor module that delivers a combination of colour (RGB), ambient light and proximity sensing, providing OEMs with design flexibility and the ability to provide a better display viewing experience.

The TMD3700 footprint, at 4.00 x 1.75mm, is the smallest footprint available in the market, and with height of 1.00mm, its low-profile is ideal for next-generation mobile phones with extremely tight layout and mechanical design constraints. Its wide 45 degree field-of-view, ambient light sensing accuracy of +/-10% and operating range of 200mlux to 60Klux behind dark glass enable smartphones to measure the surrounding light environment and automatically adjust display colour and brightness for optimal viewing.

The TMD3700 colour sensor channels each have UV and IR blocking filters and a dedicated converter allowing simultaneous data capture necessary for accurate measurements. The combination of photopic colour and ambient light sensing enables smartphones to perform real-time adjustment of the display properties, such as white point, colour gamut and colour saturation, to achieve the best visual colour accuracy.

The TMD3700 features allow dynamic elimination of both electrical and optical crosstalk producing reliable proximity detection, a function used by smartphone manufacturers to disable the touchscreen display when it is held close to the user’s face. In addition, the module’s integrated IR LED is calibrated for maximum performance and consistent operation.

“Smartphone OEMs are continually condensing their product profiles while seeking ways to improve display performance for the best visual appeal. The availability of the TM3700 light sensing and proximity detection performance in a compact package enables innovative display management for today’s space-constrained smartphones,” said Darrell Benke, Strategic Program Director for Advanced Optical Solutions at ams.

Researchers from Moscow Institute of Physics and Technology (MIPT), Skolkovo Institute of Science and Technology (Skoltech), the Technological Institute for Superhard and Novel Carbon Materials (TISNCM), the National University of Science and Technology MISiS (Russia), and Rice University (USA) used computer simulations to find how thin a slab of salt has to be in order for it to break up into graphene-like layers. Based on the computer simulation, they derived the equation for the number of layers in a crystal that will produce ultrathin films with applications in nanoelectronics. Their findings were in The Journal of Physical Chemistry Letters (which has an impact factor of 8.54).

Transition from a cubic arrangement into several hexagonal layers. Credit: Authors of the study

Transition from a cubic arrangement into several hexagonal layers. Credit:
Authors of the study

From 3D to 2D

Unique monoatomic thickness of graphene makes it an attractive and useful material. Its crystal lattice resembles a honeycombs, as the bonds between the constituent atoms form regular hexagons. Graphene is a single layer of a three-dimensional graphite crystal and its properties (as well as properties of any 2D crystal) are radically different from its 3D counterpart. Since the discovery of graphene, a large amount of research has been directed at new two-dimensional materials with intriguing properties. Ultrathin films have unusual properties that might be useful for applications such as nano- and microelectronics.

Previous theoretical studies suggested that films with a cubic structure and ionic bonding could spontaneously convert to a layered hexagonal graphitic structure in what is known as graphitisation. For some substances, this conversion has been experimentally observed. It was predicted that rock salt NaCl can be one of the compounds with graphitisation tendencies. Graphitisation of cubic compounds could produce new and promising structures for applications in nanoelectronics. However, no theory has been developed that would account for this process in the case of an arbitrary cubic compound and make predictions about its conversion into graphene-like salt layers.

For graphitisation to occur, the crystal layers need to be reduced along the main diagonal of the cubic structure. This will result in one crystal surface being made of sodium ions Na? and the other of chloride ions Cl?. It is important to note that positive and negative ions (i.e. Na? and Cl?)–and not neutral atoms–occupy the lattice points of the structure. This generates charges of opposite signs on the two surfaces. As long as the surfaces are remote from each other, all charges cancel out, and the salt slab shows a preference for a cubic structure. However, if the film is made sufficiently thin, this gives rise to a large dipole moment due to the opposite charges of the two crystal surfaces. The structure seeks to get rid of the dipole moment, which increases the energy of the system. To make the surfaces charge-neutral, the crystal undergoes a rearrangement of atoms.

Experiment vs model

To study how graphitisation tendencies vary depending on the compound, the researchers examined 16 binary compounds with the general formula AB, where A stands for one of the four alkali metals lithium Li, sodium Na, potassium K, and rubidium Rb. These are highly reactive elements found in Group 1 of the periodic table. The B in the formula stands for any of the four halogens fluorine F, chlorine Cl, bromine Br, and iodine I. These elements are in Group 17 of the periodic table and readily react with alkali metals.

All compounds in this study come in a number of different structures, also known as crystal lattices or phases. If atmospheric pressure is increased to 300,000 times its normal value, an another phase (B2) of NaCl (represented by the yellow portion of the diagram) becomes more stable, effecting a change in the crystal lattice. To test their choice of methods and parameters, the researchers simulated two crystal lattices and calculated the pressure that corresponds to the phase transition between them. Their predictions agree with experimental data.

Just how thin should it be?

The compounds within the scope of this study can all have a hexagonal, “graphitic”, G phase (the red in the diagram) that is unstable in 3D bulk but becomes the most stable structure for ultrathin (2D or quasi-2D) films. The researchers identified the relationship between the surface energy of a film and the number of layers in it for both cubic and hexagonal structures. They graphed this relationship by plotting two lines with different slopes for each of the compounds studied. Each pair of lines associated with one compound has a common point that corresponds to the critical slab thickness that makes conversion from a cubic to a hexagonal structure energetically favourable. For example, the critical number of layers was found to be close to 11 for all sodium salts and between 19 and 27 for lithium salts.

Based on this data, the researchers established a relationship between the critical number of layers and two parameters that determine the strength of the ionic bonds in various compounds. The first parameter indicates the size of an ion of a given metal–its ionic radius. The second parameter is called electronegativity and is a measure of the ? atom’s ability to attract the electrons of element B. Higher electronegativity means more powerful attraction of electrons by the atom, a more pronounced ionic nature of the bond, a larger surface dipole, and a lower critical slab thickness.

And there’s more

Pavel Sorokin, Dr. habil., is head of the Laboratory of New Materials Simulation at TISNCM. He explains the importance of the study, ‘This work has already attracted our colleagues from Israel and Japan. If they confirm our findings experimentally, this phenomenon [of graphitisation] will provide a viable route to the synthesis of ultrathin films with potential applications in nanoelectronics.’

The scientists intend to broaden the scope of their studies by examining other compounds. They believe that ultrathin films of different composition might also undergo spontaneous graphitisation, yielding new layered structures with properties that are even more intriguing.

It may be clammy and inconvenient, but human sweat has at least one positive characteristic – it can give insight to what’s happening inside your body. A new study published in the ECS Journal of Solid State Science and Technology aims to take advantage of sweat’s trove of medical information through the development of a sustainable, wearable sensor to detect lactate levels in your perspiration.

“When the human body undergoes strenuous exercise, there’s a point at which aerobic muscle function becomes anaerobic muscle function,” says Jenny Ulyanova, CFD Research Corporation (CFDRC) researcher and co-author of the paper. “At that point, lactate is produce at a faster rate than it is being consumed. When that happens, knowing what those levels are can be an indicator of potentially problematic conditions like muscle fatigue, stress, and dehydration.”

Utilizing green technology

Using sweat to track changes in the body is not a new concept. While there have been many developments in recent years to sense changes in the concentrations of the components of sweat, no purely biological green technology has been used for these devices. The team of CFDRC researchers, in collaboration with the University of New Mexico, developed an enzyme-based sensor powered by a biofuel cell – providing a safe, renewable power source.

Biofuel cells have become a promising technology in the field of energy storage, but still face many issues related to short active lifetimes, low power densities, and low efficiency levels. However, they have several attractive points, including their ability to use renewable fuels like glucose and implement affordable, renewable catalysts.

“The biofuel cell works in this particular case because the sensor is a low-power device,” Ulyanova says. “They’re very good at having high energy densities, but power densities are still a work in progress. But for low-power applications like this particular sensor, it works very well.”

In their research, entitled “Wearable Sensor System Powered by a Biofuel Cell for Detection of Lactate Levels in Sweat,” the team powered the biofuel cells with a fuel based on glucose. This same enzymatic technology, where the enzymes oxidize the fuel and generate energy, is used at the working electrode of the sensor which allows for the detection of lactate in your sweat.

Targeting lactate

While the use of the biofuel cell is a novel aspect of this work, what sets it apart from similar developments in the field is the use of electrochemical processes to very accurately detect a specific compound in a very complex medium like sweat.

“We’re doing it electrochemically, so we’re looking at applying a constant load to the sensor and generating a current response,” Ulyanova says, “which is directly proportional to the concentration of our target analyte.”

Practical applications

Originally, the sensor was developed to help detect and predict conditions related to lactate levels (i.e. fatigue and dehydration) for military personnel.

“The sensor was designed for a soldier in training at boot camp,” says Sergio Omar Garcia, CFDRC researcher and co-author of the paper, “but it could be applied to people that are active and anyone participating in strenuous activity.”

As for commercial applications, the researchers believe the device could be used as a training aid to monitor lactate changes in the same way that athletes use heart rate monitors to see how their heart rate changes during exercise.

On-body testing

The team is currently working to redesign the physical appearance of the patch to move from laboratory research to on-body tests. Once the scientists optimize how the sensor adheres to the skin, its sweat sample delivery/removal, and the systems electronic components, volunteers will test its capabilities while exercising.

“We had actually talked about this idea to some local high school football coaches,” Ulyanova says, “and they seem to really like it and are willing to put forth the use of their players to beta test the idea.”

After initial data is gathered, the team will be able to work with other groups to interpret the data and relate it to the physical condition of the person. With this, predictive models could be built to potentially help prevent conditions related to individual overexertion.

Future plans for the device include implementing wireless transmission of results and the development of a suite of sensors (a hybrid sensor) that can detect various other biomolecules, indicative of physical or physiological stressors.