Category Archives: MEMS

A new design for solar cells that uses inexpensive, commonly available materials could rival and even outperform conventional cells made of silicon.

A tandem perovskite solar cell boosts efficiency by absorbing high- and low-energy photons from the sun. Credit: Rongrong Cheacharoen/Stanford University

A tandem perovskite solar cell boosts efficiency by absorbing high- and low-energy photons from the sun. Credit: Rongrong Cheacharoen/Stanford University

Writing in the Oct. 21 edition of Science, researchers from Stanford and Oxford describe using tin and other abundant elements to create novel forms of perovskite – a photovoltaic crystalline material that’s thinner, more flexible and easier to manufacture than silicon crystals.

“Perovskite semiconductors have shown great promise for making high-efficiency solar cells at low cost,” said study co-author Michael McGehee, a professor of materials science and engineering at Stanford. “We have designed a robust, all-perovskite device that converts sunlight into electricity with an efficiency of 20.3 percent, a rate comparable to silicon solar cells on the market today.”

The new device consists of two perovskite solar cells stacked in tandem. Each cell is printed on glass, but the same technology could be used to print the cells on plastic, McGehee added.

“The all-perovskite tandem cells we have demonstrated clearly outline a roadmap for thin-film solar cells to deliver over 30 percent efficiency,” said co-author Henry Snaith, a professor of physics at Oxford. “This is just the beginning.”

Tandem technology

Previous studies showed that adding a layer of perovskite can improve the efficiency of silicon solar cells. But a tandem device consisting of two all-perovskite cells would be cheaper and less energy-intensive to build, the authors said.

“A silicon solar panel begins by converting silica rock into silicon crystals through a process that involves temperatures above 3,000 degrees Fahrenheit (1,600 degrees Celsius),” said co-lead author Tomas Leijtens, a postdoctoral scholar at Stanford. “Perovskite cells can be processed in a laboratory from common materials like lead, tin and bromine, then printed on glass at room temperature.”

But building an all-perovskite tandem device has been a difficult challenge. The main problem is creating stable perovskite materials capable of capturing enough energy from the sun to produce a decent voltage.

A typical perovskite cell harvests photons from the visible part of the solar spectrum. Higher-energy photons can cause electrons in the perovskite crystal to jump across an “energy gap” and create an electric current.

A solar cell with a small energy gap can absorb most photons but produces a very low voltage. A cell with a larger energy gap generates a higher voltage, but lower-energy photons pass right through it.

An efficient tandem device would consist of two ideally matched cells, said co-lead author Giles Eperon, an Oxford postdoctoral scholar currently at the University of Washington.

“The cell with the larger energy gap would absorb higher-energy photons and generate an additional voltage,” Eperon said. “The cell with the smaller energy gap can harvest photons that aren’t collected by the first cell and still produce a voltage.”

The smaller gap has proven to be the bigger challenge for scientists. Working together, Eperon and Leijtens used a unique combination of tin, lead, cesium, iodine and organic materials to create an efficient cell with a small energy gap.

“We developed a novel perovskite that absorbs lower-energy infrared light and delivers a 14.8 percent conversion efficiency,” Eperon said. “We then combined it with a perovskite cell composed of similar materials but with a larger energy gap.”

The result: A tandem device consisting of two perovskite cells with a combined efficiency of 20.3 percent.

“There are thousands of possible compounds for perovskites,” Leijtens added, “but this one works very well, quite a bit better than anything before it.”

Seeking stability

One concern with perovskites is stability. Rooftop solar panels made of silicon typically last 25 years or more. But some perovskites degrade quickly when exposed to moisture or light. In previous experiments, perovskites made with tin were found to be particularly unstable.

To assess stability, the research team subjected both experimental cells to temperatures of 212 degrees Fahrenheit (100 degrees Celsius) for four days.

“Crucially, we found that our cells exhibit excellent thermal and atmospheric stability, unprecedented for tin-based perovskites,” the authors wrote.

“The efficiency of our tandem device is already far in excess of the best tandem solar cells made with other low-cost semiconductors, such as organic small molecules and microcrystalline silicon,” McGehee said. “Those who see the potential realize that these results are amazing.”

The next step is to optimize the composition of the materials to absorb more light and generate an even higher current, Snaith said.

“The versatility of perovskites, the low cost of materials and manufacturing, now coupled with the potential to achieve very high efficiencies, will be transformative to the photovoltaic industry once manufacturability and acceptable stability are also proven,” he said.

University of Alabama at Birmingham researchers will use pressures greater than those found at the center of the Earth to potentially create as yet unknown new materials. In the natural world, such immense forces deep underground can turn carbon into diamonds, or volcanic ash into slate.

Credit: UAB

Credit: UAB

The ability to produce these pressures depends on tiny nanocrystalline-diamond anvils built in a UAB clean room manufacturing facility. Each anvil head is just half the width of an average human hair. The limits of their pressure have not yet been reached as the first 27 prototypes are being tested.

“We have achieved 75 percent of the pressure found at the center of the Earth, or 264 gigapascals, using lab-grown nanocrystalline-diamond micro-anvil,” said Yogesh Vohra, Ph.D., a professor and university scholar of physics in the UAB College of Arts and Sciences. “But the goal is one terapascal, which is the pressure close to the center of Saturn. We are one-quarter of the way there.”

One terapascal, a scientific measure of pressure, is equal to 147 million pounds per square inch.

One key to high pressure is to make the point of the anvil, where the pressure is applied, very narrow. This magnifies the pressure applied by a piston above the micro-anvil, much like the difference of being stepped on by a spiked high heel rather than a loafer.

A more difficult task is how to make an anvil that is able to survive this ultra-high pressure. The solution for the Vohra team is to grow a nanocrystalline pillar of diamond — 30 micrometers wide and 15 micrometers tall — on the culet of a gem diamond. The culet is the flat surface at the bottom of a gemstone.

“We didn’t know that we could grow nanocrystalline diamonds on a diamond base,” Vohra said. “This has never been done before.”

In the 264-gigapascal pressure test at Argonne National Laboratory in Lemont, Illinois, the nanocrystalline diamond showed no sign of deformation. Vohra and colleagues recently reported this result in the American Institute of Physics journal AIP Advances.

“The structure did not collapse when we applied pressure,” Vohra said. “Nanocrystalline diamond has better mechanical properties than gem diamonds. The very small-sized grain structure makes it really tough.”

As more micro-anvils are tested and improved, they will be used to study how transition metals, alloys and rare earth metals behave under extreme conditions. Just as graphitic carbon that is subjected to high pressure and temperature can turn into diamond, some materials squeezed by the micro-anvils may gain novel crystal modifications with enhanced physical and mechanical properties — modifications that are retained when the pressure is released. Such new materials have potential applications in the aerospace, biomedical and nuclear industries.

The micro-anvils are made in a Class 7000 clean room in the UAB Diamond Microfabrication Lab, using maskless lithography and microwave plasma chemical vapor deposition.

Vohra says his research team wants to generate smaller grain sizes in the nanocrystalline diamond, which may make it even stronger; understand how the nanocrystalline diamond is bonded to the gem diamond; and use ion beams to machine the top of the micro-anvil to a hemispherical shape. That shape will mean an even narrower contact point, thus increasing the pressure.

Testing is done at Argonne because it has a very bright synchrotron X-ray source that can probe crystal structure of micron-sized materials under pressure. Vohra and two graduate students travel to Argonne about four times a year.

STMicroelectronics (NYSE: STM) today announced that its LSM6DSM 6-axis Inertial Measurement Unit (IMU) has earned certification for use in next-generation mobile devices running Google Daydream, a high-performance virtual-reality platform, and Tango, a platform that maps 3D space and enables it to be overlaid with virtual objects.

Announced at the Google I/O Developer Conference 2016, Daydream is being built into the newest generation of smartphones and other mobile devices and will operate along with a controller and a viewer to provide an amazing immersive virtual reality experience for exploring new worlds, enjoying entertainment with your own personal cinema and gaming.

Well suited to Daydream, Tango, and other mobile applications, ST’s 6-axis IMU, which integrates a 3-axis gyroscope and a 3-axis accelerometer, enables “always-on” sensing that maximizes battery life to stay on. The IMU’s efficient power-management techniques include an enhanced gyroscope design, energy-efficient data batching, and ST’s ultra-low-power process technology.

“Certification of ST’s 6-axis motion-sensing device for operation with Daydream and Tango for amazing virtual- and augmented-reality experiences demonstrates our abilities to design and deliver an exceptionally accurate and power-efficient IMU,” said Aymeric Gisselbrecht, Vice President Global Key Accounts Sales, STMicroelectronics. “Our long-term developments in sensing and actuation, along with our work with Google, are contributing to making mobile applications incredibly immersive and even more fun.”

In 2015, the Company’s net revenues were $6.90 billion, serving more than 100,000 customers worldwide.

Samsung Electronics Co., Ltd. today announced that it has commenced mass production of System-on-Chip (SoC) products with 10-nanometer (nm) FinFET technology for which would make it first in the industry.

Following the successful mass production of the industry’s first FinFET mobile application processor (AP) in January, 2015, Samsung extends its leadership in delivering leading-edge process technology to the mass market with the latest offering.

“The industry’s first mass production of 10nm FinFET technology demonstrates our leadership in advanced process technology,” said Jong Shik Yoon, Executive Vice President, Head of Foundry Business at Samsung Electronics. “We will continue our efforts to innovate scaling technologies and provide differentiated total solutions to our customers.”

Samsung’s new 10nm FinFET process (10LPE) adopts an advanced 3D transistor structure with additional enhancements in both process technology and design enablement compared to its 14nm predecessor, allowing up to 30-percent increase in area efficiency with 27-percent higher performance or 40-percent lower power consumption. In order to overcome scaling limitations, cutting edge techniques such as triple-patterning to allow bi-directional routing are also used to retain design and routing flexibility from prior nodes.

Following the introduction of Samsung’s first-generation 10nm process (10LPE), its second generation process (10LPP) with performance boost is targeted for mass production in the second half of 2017. The company plans to continue its leadership with a variety of derivative processes to meet the needs of a wide range of applications.

Through close collaboration with customers and partners, Samsung also aims to cultivate a robust 10nm foundry ecosystem that includes reference flow verification, IPs and libraries.

Production level process design kits (PDK) and IP design kits are currently available for design starts.

SoCs with 10nm process technology will be used in digital devices launching early next year and are expected to become more widely available throughout 2017.

A new type of atomic force microscope (AFM) uses nanowires as tiny sensors. Unlike standard AFM, the device with a nanowire sensor enables measurements of both the size and direction of forces. Physicists at the University of Basel and at the EPF Lausanne have described these results in the recent issue of Nature Nanotechnology.

A nanowire sensor measures size and direction of forces. Credit: University of Basel, Department of Physics

A nanowire sensor measures size and direction of forces. Credit: University of Basel, Department of Physics

Nanowires are extremely tiny filamentary crystals which are built-up molecule by molecule from various materials and which are now being very actively studied by scientists all around the world because of their exceptional properties.

The wires normally have a diameter of 100 nanometers and therefore possess only about one thousandth of a hair thickness. Because of this tiny dimension, they have a very large surface in comparison to their volume. This fact, their small mass and flawless crystal lattice make them very attractive in a variety of nanometer-scale sensing applications, including as sensors of biological and chemical samples, and as pressure or charge sensors.

Measurement of direction and size

The team of Argovia Professor Martino Poggio from the Swiss Nanoscience Institute (SNI) and the Department of Physics at the University of Basel has now demonstrated that nanowires can also be used as force sensors in atomic force microscopes. Based on their special mechanical properties, nanowires vibrate along two perpendicular axes at nearly the same frequency. When they are integrated into an AFM, the researchers can measure changes in the perpendicular vibrations caused by different forces. Essentially, they use the nanowires like tiny mechanical compasses that point out both the direction and size of the surrounding forces.

Image of the two-dimensional force field

The scientists from Basel describe how they imaged a patterned sample surface using a nanowire sensor. Together with colleagues from the EPF Lausanne, who grew the nanowires, they mapped the two-dimensional force field above the sample surface using their nanowire “compass”. As a proof-of-principle, they also mapped out test force fields produced by tiny electrodes.

The most challenging technical aspect of the experiments was the realization of an apparatus that could simultaneously scan a nanowire above a surface and monitor its vibration along two perpendicular directions. With their study, the scientists have demonstrated a new type of AFM that could extend the technique’s numerous applications even further.

AFM – today widely used

The development of AFM 30 years ago was honored with the conferment of the Kavli-Prize beginning of September this year. Professor Christoph Gerber of the SNI and Department of Physics at the University of Basel is one of the awardees, who has substantially contributed to the wide use of AFM in different fields, including solid-state physics, materials science, biology, and medicine.

The various different types of AFM are most often carried out using cantilevers made from crystalline Si as the mechanical sensor. “Moving to much smaller nanowire sensors may now allow for even further improvements on an already amazingly successful technique”, Martino Poggio comments his approach.

SEMICON Europa 2016, opening in less than two weeks in Grenoble, will explore the issues facing Europe’s semiconductor and electronics industries, including processes, materials, equipment and supply chain. SEMICON Europa (October 25-27) is a leading exhibition and conference dedicated to the future of electronics in Europe.

As semiconductor manufacturers target new high-growth European strength areas, SEMICON Europa connects the European ecosystem and the global manufacturing supply chain by offering new business opportunities like advanced packaging, MEMS, imaging, power electronics, flexible hybrid electronics, automotive, smart manufacturing, medtech and addressing the demands of the IoT.

Executive keynotes include:

  • GLOBALFOUNDRIES Dresden: “FDX and FinFET: Differentiated Technologies for Diverging Markets” presented by Dr. Rutger Wijburg, senior VP and GM
  • Intel Israel: “How Technology and Equipment March Forward Hand-in-Hand” presented by Maxine Fassberg, CEO
  • CEA-Leti: “European Chance in Industry and Technologies” presented by Marie-Noëlle Semeria, CEO

In addition, companies such as Infineon, STMicroelectronics, ABB, ASML, Applied Materials, SOITEC, imec and Fraunhofer, and hundreds more, will present the latest trends, technologies, processes and techniques in electronic applications, design and manufacturing.

This year for the first time, Iot Planet will co-locate with SEMICON Europa. The combined shows are expected to attract 7,000 professionals and more than 600 visiting companies, giving attendees the opportunity to conduct business up and down the supply chain.  New programs, like the B2B Matchmaking Event 2016, offer visitors and exhibitors an opportunity to prearrange appointments.

SEMICON Europa is co-located with 2016FLEX Europe which covers the field of large-scale electronics, with emphasis on printed, flexible and organic electronics and its convergence with conventional semiconductor manufacturing.

Register now and take advantage of our early pricing for conferences, forums, and select sessions. To register for SEMICON Europa 2016, please visit: www.semiconeuropa.org

Nature has inspired generations of people, offering a plethora of different materials for innovations. One such material is the molecule of the heritage, or DNA, thanks to its unique self-assembling properties. Researchers at the Nanoscience Center (NSC) of the University of Jyväskylä and BioMediTech (BMT) of the University of Tampere have now demonstrated a method to fabricate electronic devices by using DNA. The DNA itself has no part in the electrical function, but acts as a scaffold for forming a linear, pearl-necklace-like nanostructure consisting of three gold nanoparticles. The research was funded by the Academy of Finland.

The DNA itself has no part in the electrical function, but acts as a scaffold for forming a linear, pearl-necklace-like nanostructure consisting of three gold nanoparticles. Credit: the University of Jyväskylä

The DNA itself has no part in the electrical function, but acts as a scaffold for forming a linear, pearl-necklace-like nanostructure consisting of three gold nanoparticles. Credit: The University of Jyväskylä

The nature of electrical conduction in nanoscale materials can differ vastly from regular, macroscale metallic structures, which have countless free electrons forming the current, thus making any effect by a single electron negligible. However, even the addition of a single electron into a nanoscale piece of metal can increase its energy enough to prevent conduction. This kind of addition of electrons usually happens via a quantum-mechanical effect called tunnelling, where electrons tunnel through an energy barrier. In this study, the electrons tunnelled from the electrode connected to a voltage source, to the first nanoparticle and onwards to the next particle and so on, through the gaps between them.

“Such single-electron devices have been fabricated within the scale of tens of nanometres by using conventional micro- and nanofabrication methods for more than two decades,” says Senior Lecturer Jussi Toppari from the NSC. Toppari has studied these structures already in his PhD work.

“The weakness of these structures has been the cryogenic temperatures needed for them to work. Usually, the operation temperature of these devices scales up as the size of the components decreases. Our ultimate aim is to have the devices working at room temperature, which is hardly possible for conventional nanofabrication methods – so new venues need to be found.”

Modern nanotechnology provides tools to fabricate metallic nanoparticles with the size of only a few nanometres. Single-electron devices fabricated from these metallic nanoparticles could function all the way up to room temperature. The NSC has long experience of fabricating such nanoparticles.

“After fabrication, the nanoparticles float in an aqueous solution and need to be organised into the desired form and connected to the auxiliary circuitry,” explains researcher Kosti Tapio. “DNA-based self-assembly together with its ability to be linked with nanoparticles offer a very suitable toolkit for this purpose.”

Gold nanoparticles are attached directly within the aqueous solution onto a DNA structure designed and previously tested by the involved groups. The whole process is based on DNA self-assembly, and yields countless of structures within a single patch. Ready structures are further trapped for measurements by electric fields.

“The superior self-assembly properties of the DNA, together with its mature fabrication and modification techniques, offer a vast variety of possibilities,” says Associate Professor Vesa Hytönen.

Electrical measurements carried out in this study demonstrated for the first time that these scalable fabrication methods based on DNA self-assembly can be efficiently utilised to fabricate single-electron devices that work at room temperature.

The research builds on a long-term multidisciplinary collaboration between the research groups involved. In addition to the above persons, Dr Jenni Leppiniemi (BMT), Boxuan Shen (NSC), and Dr Wolfgang Fritzsche (IPHT, Jena, Germany) contributed to the research. The study was published on 13 October 2016 in Nano Letters. Collaborative travel funding was obtained from DAAD in Germany.

MEMS & Sensors Industry Group (MSIG)’s annual MEMS & Sensors Technology Showcase at MEMS & Sensors Executive Congress® 2016 (November 9-11, 2016 in Scottsdale, AZ) highlights some of the newest and most unique MEMS/sensors-enabled applications in the industry. MSIG today announced the shortlist of finalists who will compete for the title of winner at this year’s event.

i-BLADES’ Smartplatform
i-BLADES’ mobile Smartcase is a new modular accessory that dramatically accelerates time to market and reach for MEMS and Internet of Things (IoT) technologies. It lets new technologies quickly reach mass-market mobile consumers through one integrated smartphone accessory — a mobile phone case. It not only provides protection but also a Smartplatform that forms a “hard-wired” smartphone connection, enabling add-on MEMS and IoT technologies. Developers can add new sensors to Smartcase directly or through snap-on Smartblade modules.

With i-BLADES, technologies can quickly go onto hundreds of millions of smartphones as an after-market opportunity, making smartphones “smarter.” i-BLADES partnered with Bosch to deploy successfully the BME680 sensor faster than via other routes. For more information, visit: www.i-blades.com or watch video: https://www.youtube.com/watch?v=dVcOewMhopE&feature=youtu.be

Chirp Microsystems’ MEMS-Based Ultrasonic Sensing Solution
Today’s VR and gaming systems are limited by their reliance on complex computer vision techniques for controller tracking, resulting in higher cost, limited tracking area and lack of mobility due to high power consumption. Chirp Microsystems’ ultrasonic tracking technology addresses these limitations, offering solutions that enable truly mobile VR and AR systems at attractive price points suitable for multiple tiers of products.

Chirp Microsystems’ new ultrasonic time-of-flight (ToF) technology uses pulses of ultrasound to measure an object’s range with millimeter accuracy. This ultra-low power ultrasonic ToF technology enables low-latency, millimeter-accurate 6 degrees of freedom (DOF) inside-out controller tracking for VR/AR and gaming systems. This system solution is enabled by Chirp’s ultra-low power ultrasonic ToF sensor, which offers ultra-wide field-of-view, noise and light immunity, fast sample rate, and small package size. The ToF sensor is a system in package (SiP) that combines a MEMS ultrasound transducer with a power-efficient digital signal processor (DSP) on a custom integrated circuit. In wearable applications, Chirp’s ultrasonic SiP provides a transformative and intuitive touchless gesture interface. For more information, visit: www.chirpmicro.com

Integrated Device Technology’s Gas Sensor for Air Quality and Breath Detection
Integrated Device Technology’s (IDT’s) new highly sensitive gas sensor family based on the ZMOD3250 targets indoor air quality with a roadmap that includes environmental (outdoor) air quality and breath detection. The ZMOD3250 family detects total volatile organic compounds (VOCs) and odors, and can be used to selectively identify several VOCs, including formaldehyde, ethanol and toluene. The company is promoting several features and applications of this new gas sensor product line, including the off-gassing detection of chemicals from common home and office materials, odor detection, selective measurements among VOCs and detection of several breath components.

IDT’s flagship product, the ZMOD3250, features a unique silicon microhotplate with nanostructured sensing material that enables a highly sensitive measurement of gas. The accompanying ASIC provides a flexible solution for integration of the sensor with various consumer devices, including mobile phones, wearables and appliances. Packaged in a 12 pin LGA assembly (3.0 mm x 3.0 mm x 0.7 mm), the sensor emulates a sensor array with a single sensor element. Suitable for a wide range of applications, the sensor features programmable-measurement sequence and highly integrated CMOS design. To request more information about the ZMOD3250, visit: www.idt.com or watch video: http://www.idt.com/video/uv-sensor-and-gas-sensor-demonstration-idt

Valencell’s Biometric Gaming
Biometric input adds a new element to gaming. For example, fitness games can use heart rate as a key control measure, or action games can require users to hold their breath while their characters are swimming. Audio earbuds, headsets, armbands and wrist devices — all of which make good use of MEMS/sensors — are natural peripherals for gaming — and as well as for exercising.

Valencell has created a demonstration game that not only involves real-time biometric data to affect the gaming experience, but also collects meaningful health metrics in the background. This has implications not only for the gaming industry, but also for healthcare and medical markets. In fact, healthcare practitioners are integrating biometric game play into physical therapy and surgery recovery protocols to measure and manage recovery processes. Valencell will demonstrate the game as well as its biometric output and analysis. For more information, visit: www.valencell.com or watch video: https://www.youtube.com/watch?v=QMTJP6OBmjA

Vesper’s Wake-on Sound MEMS Microphone
Always-listening MEMS microphones may signal a new era of ubiquitous sensors that can run indefinitely on small batteries. That’s good news for developers of TV remote controls, smart speakers, smartphones, intelligent sensor nodes, hearables and other electronic devices. It’s even better news for consumers who want to cut the power cord but end up incessantly charging devices or replacing batteries, even when those devices aren’t in regular use.

Vesper — developer of the world’s only piezoelectric MEMS microphones — will demonstrate VM1010, the first quiescent-sensing MEMS microphone, during MEMS & Sensors Technology Showcase. VM1010 alleviates the heavy power consumption typical of speech recognition–which consumes up to 1000 µW or more. Because it supports wake-on sound at practically zero power draw (a mere 3 µA of current while in listening mode), VM1010 reduces standby power by two orders of magnitude and can increase standby time by a factor of 100.

Vesper will also demonstrate the extremely fast response time of VM1010, showing how it can go to full power within microseconds, quick enough to record what a user is saying and capture keywords and other acoustic event triggers. For more information, visit: www.vespermems.com or watch video: https://www.youtube.com/watch?v=KhFtrjbpffE

New research, led by the University of Southampton, has demonstrated that a nanoscale device, called a memristor, could be used to power artificial systems that can mimic the human brain.

First demonstration of brain-inspired device to power artificial systems. Credit: University of Southampton

First demonstration of brain-inspired device to power artificial systems. Credit: University of Southampton

Artificial neural networks (ANNs) exhibit learning abilities and can perform tasks which are difficult for conventional computing systems, such as pattern recognition, on-line learning and classification. Practical ANN implementations are currently hampered by the lack of efficient hardware synapses; a key component that every ANN requires in large numbers.

In the study, published in Nature Communications, the Southampton research team experimentally demonstrated an ANN that used memristor synapses supporting sophisticated learning rules in order to carry out reversible learning of noisy input data.

Memristors are electrical components that limit or regulate the flow of electrical current in a circuit and can remember the amount of charge that was flowing through it and retain the data, even when the power is turned off.

Lead author Dr Alex Serb, from Electronics and Computer Science at the University of Southampton, said: “If we want to build artificial systems that can mimic the brain in function and power we need to use hundreds of billions, perhaps even trillions of artificial synapses, many of which must be able to implement learning rules of varying degrees of complexity. Whilst currently available electronic components can certainly be pieced together to create such synapses, the required power and area efficiency benchmarks will be extremely difficult to meet -if even possible at all- without designing new and bespoke ‘synapse components’.

“Memristors offer a possible route towards that end by supporting many fundamental features of learning synapses (memory storage, on-line learning, computationally powerful learning rule implementation, two-terminal structure) in extremely compact volumes and at exceptionally low energy costs. If artificial brains are ever going to become reality, therefore, memristive synapses have to succeed.”

Acting like synapses in the brain, the metal-oxide memristor array was capable of learning and re-learning input patterns in an unsupervised manner within a probabilistic winner-take-all (WTA) network. This is extremely useful for enabling low-power embedded processors (needed for the Internet of Things) that can process in real-time big data without any prior knowledge of the data.

Co-author Dr Themis Prodromakis, Reader in Nanoelectronics and EPSRC Fellow in Electronics and Computer Science at the University of Southampton, said: “The uptake of any new technology is typically hampered by the lack of practical demonstrators that showcase the technology’s benefits in practical applications. Our work establishes such a technological paradigm shift, proving that nanoscale memristors can indeed be used to formulate in-silico neural circuits for processing big-data in real-time; a key challenge of modern society.

“We have shown that such hardware platforms can independently adapt to its environment without any human intervention and are very resilient in processing even noisy data in real-time reliably. This new type of hardware could find a diverse range of applications in pervasive sensing technologies to fuel real-time monitoring in harsh or inaccessible environments; a highly desirable capability for enabling the Internet of Things vision.”

Scientists have created a material that could make reading biological signals, from heartbeats to brainwaves, much more sensitive.

Organic electrochemical transistors (OECTs) are designed to measure signals created by electrical impulses in the body, such as heartbeats or brainwaves. However, they are currently only able to measure certain signals.

Now researchers led by a team from Imperial College London have created a material that measures signals in a different way to traditional OECTs that they believe could be used in complementary circuits, paving the way for new biological sensor technologies.

Semiconducting materials can conduct electronic signals, carried by either electrons or their positively charged counterparts, called holes. Holes in this sense are the absence of electrons – the spaces within atoms that can be filled by them.

Electrons can be passed between atoms but so can holes. Materials that use primarily hole-driven transport are called ‘p-type’ materials, and those that use primarily electron-driven transport are called, and ‘n-type’ materials.

An ‘ambipolar’ material is the combination of both types, allowing the transport of holes and electrons within the same material, leading to potentially more sensitive devices. However, it has not previously been possible to create ambipolar materials that work in the body.

The current most sensitive OECTs use a material where only holes are transported. Electron transport in these devices however has not been possible, since n-type materials readily break down in water-based environments like the human body.

But in research published today in Nature Communications, the team have demonstrated the first ambipolar OECT that can conduct electrons as well as holes with high stability in water-based solutions.

The team overcame the seemingly inherent instability of n-type materials in water by designing new structures that prevent electrons from engaging in side-reactions, which would otherwise degrade the device.

These new devices can detect positively charged sodium and potassium ions, important for neuron activities in the body, particularly in the brain. In the future, the team hope to be able to create materials tuned to detect particular ions, allowing ion-specific signals to be detected.

Lead author Alexander Giovannitti, a PhD student under the supervision of Professor Iain McCulloch, from the Department of Chemistry and Centre for Plastic Electronics at Imperial said: “Proving that an n-type organic electrochemical transistor can operate in water paves the way for new sensor electronics with improved sensitivity.

“It will also allow new applications, particularly in the sensing of biologically important positive ions, which are not feasible with current devices. For example, these materials might be able to detect abnormalities in sodium and potassium ion concentrations in the brain, responsible for neuron diseases such as epilepsy.”