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Scientists revolutionise wireless communication with 3D processors

Fri, 08 Mar 2024 00:00:00 +1100

The innovation is poised to transform the landscape of wireless communication at a time when advances in AI are dramatically increasing demand.

Traditionally, wireless communication has relied on planar processors, which, while effective, are limited by their two-dimensional structure to operate within a limited portion of electromagnetic spectrum. The UF-designed approach leverages the power of semiconductor technology to propel wireless communication into a new dimension — quite literally.

Researchers have successfully transitioned from planar to three-dimensional processors, ushering in a new era of compactness and efficiency in data transmission.

Roozbeh Tabrizian, PhD, an associate professor in UF’s Department of Electrical and Computer Engineering, whose team developed the three-dimensional processor, said it marks a pivotal moment in the evolution of wireless communication as the world becomes increasingly reliant on seamless connectivity and real-time data exchange.

“The ability to transmit data more efficiently and reliably will open doors to new possibilities, fuelling advancements in areas such as smart cities, remote health care and augmented reality,” he said.

Currently, data in our cellphones and tablets are converted into electromagnetic waves that propagate back and forth among billions of users. Much like highway design and traffic lights ensure traffic flows efficiently through a city, filters, or spectral processors, move the data across different frequencies.

“A city’s infrastructure can only handle a certain level of traffic, and if you keep increasing the volume of cars, you have a problem,” Tabrizian said. “We’re starting to reach the maximum amount of data we can move efficiently. The planar structure of processors is no longer practical as they limit us to a very limited span of frequencies.”

With the advent of AI and autonomous devices, the increased demand will require a lot more traffic lights in the form of filters at numerous different frequencies to move the data to where it is intended.

“Think of it like lights on the road and in the air,” Tabrizian said. “It becomes a mess. One chip manufactured for just one frequency doesn’t make sense anymore.”

Tabrizian and his colleagues at the Herbert Wertheim College of Engineering use CMOS technology, or complementary metal-oxide-semiconductor fabrication process, to build the three-dimensional nanomechanical resonator.

“By harnessing the strengths of semiconductor technologies in integration, routing and packaging, we can integrate different frequency-dependent processors on the same chip,” Tabrizian said. “That’s a huge benefit.”

The three-dimensional processors occupy less physical space while delivering enhanced performance and have indefinite scalability, meaning they can accommodate growing demands.

“This entirely new type of spectral processor, which integrates different frequencies on one monolithic chip, is truly a game changer,” said David Arnold, associate chair for faculty affairs in the Department of Electrical and Computer Engineering. “Dr Tabrizian’s new approach for multi-band, frequency-agile radio chipsets not only solves a huge manufacturing challenge, but it also allows designers to imagine entirely new communication strategies in an increasingly congested wireless world. Put more simply, our wireless devices will work better, faster and more securely.”

The team of researchers, which included Tabrizian, Faysal Hakim, Nicholas Rudawski and Troy Tharpe, began work on this new approach to the processor in 2019. They received funding from the Defense Advanced Research Projects Agency, a U.S. Department of Defense agency that invests in breakthrough technologies for national security.

Image credit: iStock.com/Ignatiev

A leap towards computers with light-speed capabilities

Wed, 06 Mar 2024 00:00:00 +1100

Technologies in these emerging fields that operate at the atomic level are already realising big benefits for drug discovery and other small-scale applications.

In the future, large-scale quantum computers promise to be able to solve complex problems that would be impossible for today’s computers.

Lead researcher Professor Alberto Peruzzo from RMIT University in Australia said the team’s processor — a photonics device that used light particles to carry information — could help enable successful quantum computations, by minimising ‘light losses’.

“Our design makes the quantum photonic quantum computer more efficient in terms of light losses, which is critical for being able to keep the computation going,” said Peruzzo, who heads the ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) node at RMIT.

“If you lose light, you have to restart the computation.”

Other potential advances included improved data transmission capabilities for ‘unhackable’ communications systems and enhanced sensing applications in environmental monitoring and health care, Peruzzo said.

What did the team achieve?

The team reprogrammed a photonics processor in a range of experiments, achieving a performance equivalent to 2500 devices, by applying varying voltages. Their results and analysis are published in Nature Communications.

“This innovation could lead to a more compact and scalable platform for quantum photonic processors,” Peruzzo said.

Yang Yang, lead author and RMIT PhD scholar, said the device was “fully controllable”, enabled fast reprogramming with reduced power consumption and replaced the need for making many tailored devices.

“We experimentally demonstrated different physical dynamics on a single device,” he said.

“It’s like having a switch to control how particles behave, which is useful for both understanding the quantum world and creating new quantum technologies.”

Professor Mirko Lobino from the University of Trento in Italy made the innovative photonic device, using a crystal called lithium niobate, and Professor Yogesh Joglekar from Indiana University Purdue University Indianapolis in the United States brought his expertise in condensed matter physics.

Lithium niobate has unique optical and electro-optic properties, making it ideal for various applications in optics and photonics.

“My group was involved in the fabrication of the device, which was particularly challenging because we had to miniaturise a large number of electrodes on top of the waveguides to achieve this level of reconfigurability,” Lobino said.

Image caption: Professor Mirko Lobino from the University of Trento in Italy. Image credit: Daniel Peace.

“Programmable photonic processors offer a new route to explore a range of phenomena in these devices that will potentially unlock incredible advancements in technology and science,” Joglekar said.

Another quantum leap?

Meanwhile, Peruzzo’s team has also developed a world-first hybrid system that combines machine learning with modelling to program photonic processors and help control the quantum devices.

Peruzzo said the control of a quantum computer was crucial to ensure the accuracy and efficiency of data processing.

“One of the biggest challenges to the device’s output accuracy is noise, which describes the interference in the quantum environment that impacts how qubits perform,” he said.

Qubits are the basic units of quantum computing.

“There are a whole range of industries that are developing full-scale quantum computing, but they are still fighting against the errors and inefficiencies caused by noise,” Peruzzo said.

Attempts to control qubits typically relied on assumptions about what noise was and what caused it, Peruzzo said.

“Rather than make assumptions, we developed a protocol that uses machine learning to study the noise while also using modelling to predict what the system does in response to the noise,” he said.

With the use of the quantum photonic processors, Peruzzo said this hybrid method could help quantum computers perform more precisely and efficiently, impacting how we control quantum devices in the future.

“We believe our new hybrid method has the potential to become the mainstream control approach in quantum computing,” Peruzzo said.

Image caption: The team’s reprogrammable light-based processor. Image credit: Will Wright, RMIT University.

Lead author Dr Akram Youssry, from RMIT, said the results of the newly developed approach showed significant improvement over the traditional methods of modelling and control, and could be applied to other quantum devices beyond photonic processors.

“The method helped us uncover and understand aspects of our devices that are beyond the known physical models of this technology,” he said.

“This will help us design even better devices in the future.”

This work is published in Npj Quantum Information.

Next steps

Peruzzo said startup companies in quantum computing could be created around his team’s photonic device design and quantum control method, which they would continue to study in terms of applications and their “full potential”.

“Quantum photonics is one of the most promising quantum industries, because the photonics industry and manufacturing infrastructure are very well established,” he said.

“Quantum machine-learning algorithms have potential advantages over other methods in certain tasks, especially when dealing with large datasets.

“Imagine a world where computers work millions of times faster than they do today, where we can send information securely without any fear of it being intercepted and where we can solve problems in seconds that would currently take years.

“This isn’t just fantasy – it’s the potential future powered by quantum technologies, and research like ours is paving the way.”

Top image caption: The team’s reprogrammable light-based processor. Image credit: Will Wright, RMIT University.

Sound-powered sensors stand to save millions of batteries

Wed, 21 Feb 2024 00:00:00 +1100

The energy for this usually comes from batteries, which are replaced as soon as they are empty. This creates a huge waste problem. An EU study forecasts that in 2025, 78 million batteries will end up in the rubbish every day.

A new type of mechanical sensor, developed by researchers led by Marc Serra-Garcia and ETH geophysics professor Johan Robertsson, could now provide a remedy. Its creators have already applied for a patent for their invention and have now presented the principle in the journal Advanced Functional Materials.

Certain sound waves cause the sensor to vibrate

“The sensor works purely mechanically and doesn’t require an external energy source. It simply utilises the vibrational energy contained in sound waves,” Robertsson says.

Whenever a certain word is spoken or a particular tone or noise is generated, the sound waves emitted — and only these — cause the sensor to vibrate. This energy is then sufficient to generate a tiny electrical pulse that switches on an electronic device that has been switched off.

The prototype that the researchers developed in Robertsson’s lab at the Switzerland Innovation Park Zurich in Dübendorf has already been patented. It can distinguish between the spoken words “three” and “four”. Because the word “four” has more sound energy that resonates with the sensor compared to the word “three”, it causes the sensor to vibrate, whereas “three” does not. That means the word “four” could switch on a device or trigger further processes. Nothing would happen with “three”.

Newer variants of the sensor should be able to distinguish between up to 12 different words, such as standard machine commands like “on”, “off”, “up” and “down”. Compared to the palm-sized prototype, the new versions are also much smaller — about the size of a thumbnail — and the researchers are aiming to miniaturise them further.

Metamaterial without problematic substances

The sensor is what is known as a metamaterial: it’s not the material used that gives the sensor its special properties, but rather the structure. “Our sensor consists purely of silicone and contains neither toxic heavy metals nor any rare earths, as conventional electronic sensors do,” Serra-Garcia says.

The sensor comprises dozens of identical or similarly structured plates that are connected to each other via tiny bars. These connecting bars act like springs. The researchers used computer modelling and algorithms to develop the special design of these microstructured plates and work out how to attach them to each other. It is the springs that determine whether or not a particular sound source sets the sensor in motion.

Monitoring infrastructure

Potential use cases for these battery-free sensors include earthquake or building monitoring. They could, for example, register when a building develops a crack that has the right sound or wave energy.

There is also interest in battery-free sensors for monitoring decommissioned oil wells. Gas can escape from leaks in boreholes, producing a characteristic hissing sound. Such a mechanical sensor could detect this hissing and trigger an alarm without constantly consuming electricity — making it far cheaper and requiring much less maintenance.

Newer models of the sensor are highly miniaturised and fit on a fingertip. Image credit: Marc Serra-Garcia/Amolf.

Sensor for medical implants

Serra-Garcia also sees applications in medical devices, such as cochlear implants. These prostheses for the deaf require a permanent power supply for signal processing from batteries. Their power supply is located behind the ear, where there is no room for large battery packs. That means the wearers of such devices must replace the batteries every 12 hours. The novel sensors could also be used for the continuous measurement of eye pressure. “There isn’t enough space in the eye for a sensor with a battery,” he says.

“There’s a great deal of interest in zero-energy sensors in industry, too,” Serra-Garcia adds. He no longer works at ETH but at AMOLF, a public research institute in the Netherlands, where he and his team are refining the mechanical sensors. Their aim is to launch a solid prototype by 2027. “If we haven’t managed to attract anyone’s interest by then, we might found our own startup.”

Top image caption: The prototype of the sound sensor is relatively large. Image credit: Astrid Robertsson/ETH Zurich.

This is a modified version of a news item published by ETH Zurich under CC BY-NC-SA 4.0. This version is similarly licensed under CC BY-NC-SA 4.0. The original version of the news item can be accessed here.

Fast-charging lithium battery seeks to eliminate "range anxiety"

Fri, 16 Feb 2024 00:00:00 +1100

The breakthrough could alleviate “range anxiety” among drivers who worry electric vehicles cannot travel long distances without a time-consuming recharge.

“Range anxiety is a greater barrier to electrification in transportation than any of the other barriers, like cost and capability of batteries, and we have identified a pathway to eliminate it using rational electrode designs,” said Lynden Archer, Cornell’s James A. Friend Family Distinguished Professor of Engineering and Dean of Cornell Engineering, who oversaw the project. “If you can charge an EV battery in five minutes, I mean, gosh, you don’t need to have a battery that’s big enough for a 300-mile range. You can settle for less, which could reduce the cost of EVs, enabling wider adoption.”

The team’s paper, ‘Fast-Charge, Long-Duration Storage in Lithium Batteries’, was published in Joule. The lead author is Shuo Jin, a doctoral student in chemical and biomolecular engineering.

Lithium-ion batteries are among the most popular means of powering electric vehicles and smartphones. The batteries are lightweight, reliable and relatively energy-efficient. However, they take hours to charge, and lack the capacity to handle large surges of current.

“Our goal was to create battery electrode designs that charge and discharge in ways that align with daily routine,” Jin said. “In practical terms, we desire our electronic devices to charge quickly and operate for extended periods. To achieve this, we have identified a unique indium anode material that can be effectively paired with various cathode materials to create a battery that charges rapidly and discharges slowly.”

Archer’s lab previously approached battery design by focusing on how ions move in electrolytes and crystallise at interfaces of metal anodes, then used this knowledge to manipulate the electrode morphology to make safer anodes for long-duration storage.

For their new lithium battery, the researchers took a different tack and focused on the kinetics of electrochemical reactions, specifically employing a chemical engineering concept termed the “Damköhler number”. This is essentially a measure of the rate at which chemical reactions occur, relative to the rate at which material is transported to the reaction site.

Identifying battery electrode materials with inherently fast solid-state transport rates, and hence low Damköhler numbers, helped the researchers pinpoint indium as an exceptionally promising material for fast-charging batteries. Indium is a soft metal, mostly used to make indium tin oxide coatings for touch-screen displays and solar panels. It is also used as a replacement for lead in low-temperature solder.

The new study shows indium has two crucial characteristics as a battery anode: an extremely low migration energy barrier, which sets the rate at which ions diffuse in the solid state; and a modest exchange current density, which is related to the rate at which ions are reduced in the anode. The combination of those qualities — rapid diffusion and slow surface reaction kinetics — is essential for fast charging and long-duration storage.

“The key innovation is we’ve discovered a design principle that allows metal ions at a battery anode to freely move around, find the right configuration and only then participate in the charge storage reaction,” Archer said. “The end result is that in every charging cycle, the electrode is in a stable morphological state. It is precisely what gives our new fast-charging batteries the ability to repeatedly charge and discharge over thousands of cycles.”

That technology, paired with wireless induction charging on roadways, would shrink the size — and the cost — of batteries, making electric transportation a more viable option for drivers.

However, that doesn’t mean indium anodes are perfect, or even practical.

“While this result is exciting, in that it teaches us how to get to fast-charge batteries, indium is heavy,” Archer said. “Therein lies an opportunity for computational chemistry modelling, perhaps using generative AI tools, to learn what other lightweight materials chemistries might achieve the same intrinsically low Damköhler numbers. For example, are there metal alloys out there that we’ve never studied, which have the desired characteristics? That is where my satisfaction comes from, that there’s a general principle at work that allows anyone to design a better battery anode that achieves faster charge rates than the state-of-the art technology.”

Image credit: iStock.com/Cinefootage Visuals

Portable antenna could help restore communication after disasters

Thu, 08 Feb 2024 00:00:00 +1100

Researchers at Stanford University and the American University of Beirut (AUB) have developed a portable antenna that could be quickly deployed in disaster-prone areas or used to set up communications in underdeveloped regions. The antenna, described recently in Nature Communications, packs down to a small size and can easily shift between two configurations to communicate either with satellites or devices on the ground without using additional power.

“The state-of-the-art solutions typically employed in these areas are heavy, metallic dishes. They’re not easy to move around, they require a lot of power to operate and they’re not particularly cost-effective,” said Maria Sakovsky, an assistant professor of aeronautics and astronautics at Stanford. “Our antenna is lightweight, low-power and can switch between two operating states. It’s able to do more with as little as possible in these areas where communications are lacking.”

Two functions in one antenna

The researchers developed the antenna with an approach typically used to design devices that are being deployed in space. Because of fuel and space limitations, technology being sent into orbit must be very lightweight and packaged as small as possible. Once the items are in orbit, they unfold into the proper shape for use. The researchers wanted their antenna to be similarly collapsible and lightweight.

The antenna designed by Sakovsky and her colleagues at AUB, including Joseph Costantine, Youssef Tawk and Rosette Maria Bichara, is made of fibre composites (a material often used in satellites) and resembles a child’s finger-trap toy, with multiple strips of material crossing in spirals. Just like any helix-based antenna, conductive material running through the antenna sends out signals, but thanks to its unique structure, the researchers can adjust the pattern and power of those signals in the new antenna by pulling it into longer shapes or shorter shapes.

“Because we wanted the antenna to be able to collapse into a packable shape, we started with this structure that led us to a very untraditional antenna design,” Sakovsky said. “We’re using shapes that have never been used on helical antennas before, and we’ve shown that they work.”

At its most compact, the antenna is a hollow ring that stands just over 1 inch tall and about 5 inches across — not much larger than a bracelet — and weighs 1.4 ounces. In this shape, it’s able to reach satellites with a high-power signal sent in a particular direction. When stretched out to about a foot tall, the antenna sends a lower power signal in all directions, more like a Wi-Fi router.

Shifting between these two states is as simple as pulling or pushing on the antenna. These movements don’t even need to be particularly precise, because once the antenna is moved past a certain point, the structure snaps to the right position. The specific size and shape of the antenna design will determine which frequencies those two states communicate across.

“The frequency you want to operate at will dictate how large the antenna needs to be, but we’ve been able to show that no matter what frequency you operate at, you can scale this design principle to achieve the same performance,” Sakovsky said.

The fabricated prototype was tested for deployment and structural performance at Stanford and its electromagnetic radiation characteristics at the antenna measurement facilities at AUB.

Image caption: The bi-stable deployable quadrifilar helix antenna passively reconfigures its radiation characteristics in terms of pattern and polarisation. Image credit: Reconfigurable & Active Structures Lab, Stanford University.

Applications in orbit

To be deployed in the field, the antenna would need to be paired with a transceiver to send and receive signals, a ground plane to reflect radio waves and other electronics, but the whole package would still only weigh about 2 pounds, Sakovsky said. And the antenna’s unique dual functionality means that it could replace multiple heavier antennas in areas where deployment is a challenge.

That includes uses in disaster-struck and underdeveloped areas, but also, potentially, in space. Sakovsky and her colleagues are considering adapting their design for satellite communications, allowing satellites to use the same antenna to talk to each other and to talk to the ground.

“We don’t have a lot of spare operating power, volume or mass on our spacecraft either,” Sakovsky said. “This holds a lot of potential for replacing multiple antennas on a satellite with a single one.”

Top image caption: Assistant Professor Maria Sakovsky co-designed a portable antenna that can communicate with satellites and devices on the ground, making it easier to coordinate rescue and relief efforts in disaster-prone areas. Top image credit: Andrew Brodhead, Stanford University.

The evolution of GPS

Fri, 02 Feb 2024 00:00:00 +1100

Global positioning systems turned 50 years old last year with the ‘golden’ anniversary of the US Air Force being given approval in 1973 to develop the Navstar GPS.

GPS has since become a vital component of everyday life that is largely taken for granted by the billions of people who use it for positioning, navigation and timing every single day.

But that increasing reliance also causes greater risks and experts are warning of the dangers if this important technology can be hacked, jammed or even knocked out completely by a natural disaster such as a huge geomagnetic storm.

That’s why developments continue apace in the world of GPS — including Australia and New Zealand’s very own multibillion-dollar positioning system called SouthPAN, which is already active and with more and more services set to be made available in the coming months and years.

Here, UNSW academics Professor Andrew Dempster and Dr Craig Roberts give a sneak peek into what people can expect from GPS over the next 50 years.

Australasia gets its own ‘GPS’ system

What most people generally call GPS is actually a specific system owned by the United States government and now operated by the United States Space Force. It was started in 1973.

However, other countries have since developed their own systems and there are currently three major alternatives: Russia’s GLONASS, China’s BeiDou Navigation Satellite System and the Galileo system developed by the European Union. Collectively they are called global navigation satellite systems (GNSS).

India and Japan have also been developing separate systems that are not global. Augmentation systems have been introduced by the US, Europe, Japan and others to overcome some GNSS shortcomings using geostationary satellites (satellites that are always in the same place in the sky).

Australia and New Zealand have now added themselves to the list by joining forces to launch the SouthPAN system — designed to meet global performance requirements under the region’s unique service area and space weather conditions.

“SouthPAN is technically a satellite-based augmentation system, which means it is still relying on receiving signals from other satellite systems but then utilises a number of ground stations to process all the data and then correct some of the errors, making it more accurate. The stated aim is that by 2028 you will be able to use this system via your mobile phone and it will tell you within 10 centimetres exactly where you are,” Dempster, Director of ACSER, said.

In recent times uncorrected GPS signals in Australia have only been accurate to within around three to five metres.

The effect of SouthPAN, therefore, will be that every major industry across Australia and New Zealand, from transport and construction to resources and agriculture, will gain significant positioning and navigation benefits.

How GPS can continue to improve agriculture

You may not know that global navigation satellite systems have become vital in the agricultural industry to reduce costs and improve yields.

GPS is used to plan farming areas, map farms and track the yields of crops from different locations, as well as helping farmers to work in more challenging conditions including even in darkness.

So making GPS information even more accurate, available and reliable over the next 50 years will only improve crop production.

“On a basic level it’s good to know exactly where you are when you are a farmer in your combined harvester because you don’t want to be inefficient and waste time or fuel, and also you don’t want to drive over your crop and damage it,” said Roberts, from UNSW’s School of Civil and Environmental Engineering.

“The more automated it is, via an accurate GPS system, the more productive the process as farmers can reduce fatigue.

“In addition, there is a lot of technical agricultural information that can be paired with the GPS data. For example, grain can be analysed to show the exact protein levels, and if you know precisely where that grain was harvested from you get some very useful knowledge.

“And they can do the same for soil moisture and fertiliser usage for each specific location, which over time helps to maximise the yields.”

The need for more robust security

A huge number of technological systems would be affected if global positioning systems were hacked or jammed on a major scale — from airliners to electric grids, from stock markets to ATMs, and any other system that relies on GPS to time its operations.

Such events might be caused deliberately by bad actors in the geopolitical sphere or by a natural phenomenon such as a geomagnetic storm. Many fear a repeat of the Carrington Event of 1859 would knock out every high-level Earth-orbiting satellite in an instant by frying their electronics.

“The problem is that we’re now wedded to GNSS and satellite positioning, but it’s really vulnerable. The goal for the future is to keep utilising the systems, but be less vulnerable,” Dempster said.

“There have been studies done that show that every single sector of the economy that can be considered critical infrastructure relies on GNSS. So many things need accurate positioning, or accurate timing.

“If you take out a major GPS system then there is an awful lot that can go wrong. But people are becoming more aware of the issue and resilience is becoming a bigger thing.

“There is a lot of work being done on the assumption that at some point a major GPS system will go down.”

One solution is for navigation services to be provided by satellites in low-Earth orbits (LEO). These would sit at around 500–1000 km above the Earth — as opposed to the current satellites which are around 20,000 km high — and would therefore be more protected by the Earth’s own atmosphere should significant geomagnetic activity from space occur.

Another benefit is the signals are 20 times stronger than traditional GPS systems, although the low orbit means that each satellite’s antenna covers a smaller radius of the Earth’s surface and so more of them are required to provide the same coverage.

“When those signals are more robust from satellites in LEO there are a few benefits,” Roberts said.

“Firstly, the signals become harder to jam or spoof and so there is an extra layer of security.

“The second is that emergency services may be able to benefit more from more robust positioning systems. When signals have to travel 20,000 km up and down from Earth, they can be very weak, and that is why GPS does not really work indoors.

“But with new systems with closer satellites and much stronger signals, the potential for accurate GPS inside of buildings increases and there are possible important applications there for those involved with search and rescue.”

Image credit: iStock.com/DancingMan

New dirt-powered fuel cell can 'run forever'

Wed, 24 Jan 2024 00:00:00 +1100

Approximately the size of a standard paperback book, the fully soil-powered technology could fuel underground sensors used in precision agriculture and green infrastructure. This could offer a sustainable, renewable alternative to batteries, which hold toxic, flammable chemicals that leach into the ground and contribute to electronic waste.

To test the new fuel cell, the researchers used it to power sensors measuring soil moisture and detecting touch. To enable wireless communications, the researchers equipped the soil-powered sensor with a tiny antenna to transmit data to a neighbouring base station by reflecting existing radio frequency signals. Not only did the fuel cell work in wet and dry conditions, its power also outlasted similar technologies by 120%.

The device's 3D-printed cap sticks out of the ground. Image credit: Bill Yen/Northwestern University.

The research was published in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies. The study authors will also release all designs, tutorials and simulation tools to the public, so others may use and build upon the research. Lead researcher and Northwestern alumnus Bill Yen said the number of devices in the Internet of Things (IoT) is constantly growing.

“If we imagine a future with trillions of these devices, we cannot build every one of them out of lithium, heavy metals and toxins that are dangerous to the environment. We need to find alternatives that can provide low amounts of energy to power a decentralised network of devices. In a search for solutions, we looked to soil microbial fuel cells, which use special microbes to break down soil and use that low amount of energy to power sensors. As long as there is organic carbon in the soil for the microbes to break down, the fuel cell can potentially last forever,” Yen said.

George Wells, a senior author on the study, said the microbes are ubiquitous, as they live in soil everywhere. “We can use very simple engineered systems to capture their electricity. We’re not going to power entire cities with this energy. But we can capture minute amounts of energy to fuel practical, low-power applications,” Wells said.

In recent years, precision agriculture has been adopted worldwide as a strategy to improve crop yields. This tech-driven approach relies on measuring precise levels of moisture, nutrients and contaminants in soil to make decisions that enhance crop health. This requires a widespread network of electronic devices to continuously collect environmental data.

“If you want to put a sensor out in the wild, in a farm or in a wetland, you are constrained to putting a battery in it or harvesting solar energy. Solar panels don’t work well in dirty environments because they get covered with dirt, do not work when the sun isn’t out and take up a lot of space. Batteries also are challenging because they run out of power. Farmers are not going to go around a 100-acre farm to regularly swap out batteries or dust off solar panels,” Yen said.

To address this challenge, the researchers wondered if they could instead harvest energy from the soil that farmers are monitoring anyway.

‘Stymied efforts’

Initially developed in 1911, soil-based microbial fuel cells (MFCs) operate like a battery, with an anode, cathode and electrolyte. But instead of using chemicals to generate electricity, MFCs harvest energy from bacteria that naturally donate electrons to nearby conductors. When these electrons flow from the anode to the cathode, it creates an electric circuit. However, in order for microbial fuel cells to operate, they need to stay hydrated and oxygenated, which can be difficult when buried underground within dry dirt.

“Although MFCs have existed as a concept for more than a century, their unreliable performance and low output power have stymied efforts to make practical use of them, especially in low-moisture conditions,” Yen said.

With these challenges in mind, the researchers spent two years developing a practical and reliable soil-based MFC. Yen’s research included creating — and comparing — four different versions. First, the researchers collected nine months of data on the performance of each design. Then, they tested their final version in an outdoor garden.

The best-performing prototype worked well in dry conditions as well as within a water-logged environment. The prototype was successful because of its geometry; instead of using a traditional design (in which the anode and cathode are parallel to one another), the prototype fuel cell leveraged a perpendicular design. Made of carbon felt (an inexpensive and ubiquitous conductor to capture the microbes’ electrodes), the anode is horizontal to the ground’s surface. Made of an inert, conductive metal, the cathode sits vertically atop the anode.

This schematic shows an “exploded view” of the device. Image credit: Bill Yen/Northwestern University.

Although the device is buried, the vertical design ensures that the top end is flush with the ground’s surface. A 3D printed cap rests on top of the device to prevent debris from falling inside, while a hole on top and an empty air chamber running alongside the cathode enable consistent air flow. The lower end of the cathode is buried beneath the surface, ensuring that it stays hydrated from the moist, surrounding soil — even when the soil dries out in the sunlight. The researchers also coated part of the cathode with waterproofing material to allow it to breathe during a flood, while its vertical design enables the cathode to dry out gradually rather than all at once.

On average, the resulting fuel cell generated 68 times more power than needed to operate its sensors. It was also robust enough to withstand changes in soil moisture — from somewhat dry (41% water by volume) to completely underwater.

Making computing accessible

The researchers plan to develop a soil-based MFC made from fully biodegradable materials, to bypass complicated supply chains and avoid using conflict materials. Josiah Hester, co-author of the study, said the researchers want to build devices that use local supply chains and low-cost materials so that computing is accessible for all communities. “With the COVID-19 pandemic, we all became familiar with how a crisis can disrupt the global supply chain for electronics,” Hester said.

Top image credit: iStock.com/jittawit.21

The power of vibrational spectroscopy

Fri, 12 Jan 2024 00:00:00 +1100

This has led to a constant demand for higher capacity energy storage in ever-smaller formats, driving the development of new materials that can bolster device performance. However, any tweaks to electrode composition must be thoroughly characterised and tested under operating conditions before they can be cleared for use in commercial products, which can be both time consuming and expensive. Additionally, many of the analytical technologies traditionally used in this process require highly skilled personnel to interpret the results, limiting the pool of qualified operators and slowing the rate at which novel battery components can be developed and cleared for manufacture. Fortunately, modern vibrational spectroscopy solutions — such as Raman and Fourier transform infrared (FTIR) instruments — are becoming increasingly intuitive, allowing a greater number of individuals to quickly become proficient in their operation. This can help to lighten the workload for more experienced team members, as well as speed up analyses for increased plant throughput.

What is Raman?

Raman spectroscopy is a non-destructive technique that relies on the inelastic scattering of incident photons, from ultraviolet through to visible and near-infrared, to determine a sample’s spectral fingerprint. In battery development, it can be used to identify compound constituents, characterise molecular structures, evaluate morphologies, and monitor dynamic processes in cathodes, anodes and electrolytes. Raman imaging takes this concept a step further, allowing users to make thousands of spectral measurements over an area of interest in quick succession to create a 2D snapshot of a surface, rather than just capturing data from a single point.

In situ inspection

Whether used for single- or multi-point analysis, Raman technologies play an important role in battery R&D, especially for in situ and operando applications, where battery components are studied within an assembled cell under a variety of operating conditions. This allows their performance to be evaluated over entire charge and discharge cycles — assessing everything from ionic dispersion to electrolyte degradation — giving researchers added confidence that their novel designs will stand up to the rigours of everyday use. In situ measurements are particularly helpful in the investigation of lithiation and delithiation, two opposing processes that describe the movement of lithium ions within the battery during charging and discharging cycles. Raman spectral data is also proving invaluable in the search for alternative carbon allotropes that can be substituted for graphite, helping researchers to determine everything from the number of sheets in a graphene stack to the diameters of single-wall nanotubes, as well as providing vital information about structural defects or disorders. Furthermore, it can be used to study the degree of association of electrolyte ions in solutions and polymers, a factor that directly affects battery performance.

Vibrational versatility

In addition to excelling in the measurement of solids and solutions, Raman is also capable of monitoring gaseous emissions during in situ battery tests, providing an early warning of cell damage prior to any visible signs appearing. This can help to establish a battery’s susceptibility to overheating, overvoltage and mechanical stresses, informing the development of safer, more resilient products. Thanks to the versatility of Raman techniques, they are not limited solely to product development applications, and can also be used to determine the purity of raw materials used in the manufacturing process. Many state-of-the-art instruments feature their own material libraries that facilitate the detection of contaminants, bolstering production QC by minimising the chances of downstream defects.

Infrared insights

A complementary technology often employed alongside Raman in many battery R&D and manufacturing applications is FTIR spectroscopy. Like Raman, FTIR is also a non-destructive technique, making it ideal for examining the behaviour of various regions of battery cells while in situ, aiding the rapid identification of changes that could affect product lifespan and safety. It can also be applied during raw material QC to assess incoming goods, and is widely used for ex situ characterisation of lithium salts, electrolyte formulations and catalytic systems. FTIR again comes into play during final product QC, helping to confirm that regulatory and stakeholder specifications have been met.

Keeping pace

QC in battery applications is becoming more important than ever, as manufacturers look to squeeze every last drop of efficiency out of existing energy storage solutions, as well as looking ahead to emerging technologies. This has led to vibrational spectroscopy becoming a mainstay of development and production lines around the globe, offering unparalleled insights into the characteristics of novel materials, while also enabling the early detection of impurities and defects during the manufacturing process. With production pressures only likely to increase as time goes by, lithium-ion battery manufacturers must be sure to include Raman and FTIR technologies in their arsenals if they are to produce high-quality products in the vast quantities needed to keep pace with market demands.

Top image credit: iStock.com/KanawatTH

Lasers map electrons "going ballistic" in graphene

Thu, 11 Jan 2024 00:00:00 +1100

The observations, made at the University of Kansas’s Ultrafast Laser Lab, could lead to breakthroughs in governing electrons in semiconductors, fundamental components in most information and energy technology.

Lead author Ryan Scott said that generally, electron movement is interrupted by collisions with other particles in solids. “These collisions are rather frequent — about 10 to 100 billion times per second. They slow down the electrons, cause energy loss and generate unwanted heat. Without collisions, an electron would move uninterrupted within a solid, similar to cars on a freeway or ballistic missiles through air. We refer to this as ‘ballistic transport’,” Scott said.

Scott performed the lab experiments under the mentorship of Hui Zhao, professor of physics & astronomy at KU. They were joined in the work by former KU doctoral student Pavel Valencia-Acuna. Zhao said electronic devices utilising ballistic transport could potentially be faster, more powerful and more energy efficient.

“Current electronic devices, such as computers and phones, utilise silicon-based field-effect transistors. In such devices, electrons can only drift with a speed on the order of centimetres per second due to the frequent collisions they encounter. The ballistic transport of electrons in graphene can be utilised in devices with fast speed and low energy consumption,” Zhao said.

The researchers observed the ballistic movement in graphene, a promising material for next-generation electronic devices. Graphene is made of a single layer of carbon atoms forming a hexagonal lattice structure — somewhat like a soccer net.

“Electrons in graphene move as if their ‘effective’ mass is zero, making them more likely to avoid collisions and move ballistically,” Scott said. “Previous electrical experiments, by studying electrical currents produced by voltages under various conditions, have revealed signs of ballistic transport. However, these techniques aren’t fast enough to trace the electrons as they move.”

According to the researchers, electrons in graphene (or any other semiconductor) are like students sitting in a full classroom, who can’t freely move around because the desks are full. The laser light can free electrons to momentarily vacate a desk, or ‘hole’ as physicists call them.

“Light can provide energy to an electron to liberate it so that it can move freely. This is similar to allowing a student to stand up and walk away from their seat. However, unlike a charge-neutral student, an electron is negatively charged. Once the electron has left its ‘seat’, the seat becomes positively charged and quickly drags the electron back, resulting in no more mobile electrons — like the student sitting back down,” Zhao said.

Because of this effect, the super-light electrons in graphene can only stay mobile for about one-trillionth of a second before falling back to their seats. This short time presents a challenge to observing the movement of the electrons. To address this problem, the researchers designed and fabricated a four-layer artificial structure with two graphene layers separated by two other single-layer materials, molybdenum disulphide and molybdenum diselenide.

“With this strategy, we were able to guide the electrons to one graphene layer while keeping their ‘seats’ in the other graphene layer. Separating them with two layers of molecules, with a total thickness of just 1.5 nanometres, forces the electrons to stay mobile for about 50-trillionths of a second, long enough for the researchers, equipped with lasers as fast as 0.1-trillionth of a second, to study how they move,” Scott said.

The researchers used a tightly focused laser spot to liberate some electrons in their sample. They traced these electrons by mapping out the “reflectance” of the sample, or the percentage of light they reflect.

“We see most objects because they reflect light to our eyes,” Scott said. “Brighter objects have larger reflectance. On the other hand, dark objects absorb light, which is why dark clothes become hot in the summer. When a mobile electron moves to a certain location of the sample, it makes that location slightly brighter by changing how electrons in that location interact with light. The effect is very small — even with everything optimised, one electron only changes the reflectance by 0.1 part per million.”

To detect such a small change, the researchers liberated 20,000 electrons at once, using a probe laser to reflect off the sample and measure this reflectance, repeating the process 80 million times for each data point. They found the electrons on average move ballistically for about 20-trillionths of a second with a speed of 22 kilometres per second before running into something that terminates their ballistic motion.

Zhao said the researchers are now working to refine their material design to guide electrons more efficiently to the desired graphene layer, and trying to find ways to make them move longer distances ballistically.

Image caption: Ultrafast Laser Lab. Image credit: KU Marketing Communications

More range for EV batteries on the horizon

Tue, 09 Jan 2024 00:00:00 +1100

An EV’s mileage depends on the deliverable energy from each of the constituent cells of its battery pack. For lithium-ion cells, both the cell-level energy capacity and the cell cost are bottlenecked by the positive electrode, or cathode.

Now that bottleneck might be opening up, thanks to an innovative, cost-effective approach for synthesising single-crystal, high-energy, nickel-rich cathodes that was recently published in Energy Storage Materials.

The nickel-rich battery vision

Cathodes for conventional EV batteries use a cocktail of metal oxides — lithium nickel manganese cobalt oxides (LiNi_1/3Mn_1/3Co_1/3O₂), abbreviated NMC. When more nickel is incorporated into a cathode, it greatly increases the battery’s ability to store energy, and thus, the range of the EV. As a result, nickel-rich NMC (such as NMC811, where the “8” denotes 80% nickel) is of great interest and importance.

However, high-nickel NMC cathodes formed using the standard method are agglomerated into polycrystal structures that are rough and lumpy. This meatball-like texture has its advantages for regular NMC. For NMC811 and beyond, though, the bulbous polycrystal fissures are prone to splitting apart, causing material failure. This renders batteries made using these nickel-rich cathodes susceptible to cracking; they also begin to produce gases and decay faster than cathodes with less nickel.

Challenges of synthesising single-crystal NMC811

One strategy to fix this problem: convert that lumpy, polycrystal NMC into a smooth, single-crystal form by eliminating the problematic boundaries between the crystals — but this conversion is easier said than done. In laboratories, single crystals are grown in environments such as molten salts or hydrothermal reactions that produce smooth crystal surfaces. However, these environments are not practical for real-world cathode manufacturing, where lower-cost, solid-state methods are preferred.

In these more typical solid-state approaches, an NMC cathode is prepared by mixing a metal hydroxide precursor with lithium salt, directly mixing and heating those hydroxides — and producing the agglomerated (lumpily clustered) polycrystal NMC. Using a multiple-step heating process results in micron-sized crystals — but they are still agglomerated, so the undesirable side effects persist.

PNNL’s solution

Led by PNNL battery experts, and in collaboration with Albemarle Corporation, the research team solved these issues by introducing a pre-heating step that changes the structure and chemical properties of the transition metal hydroxide. When the pre-heated transition metal hydroxide reacts with lithium salt to form the cathode, it creates a uniform single-crystal NMC structure that looks smooth, even under magnification.

“The one-step heating process of precursors seems straightforward, but there is a lot of interesting atomic-level phase transition involved to make the single crystal segregation possible,” said Yujing Bi, first author of the paper. “It is also convenient for industry to adopt.”

The researchers are now scaling up this single-crystal NMC811 to kilogram level by using lithium salt provided by Albemarle. The scaled single crystals were tested in realistic 2 Ah lithium-ion pouch cells, using a standard graphite anode to make sure that the battery’s performance was mainly dictated by the new cathode.

The first prototype battery equipped with the scaled single crystals was stable, even after 1000 charge and discharge cycles. When the researchers looked at the microscopic structure of the crystals after 1000 cycles, they found no defects and a perfectly aligned electronic structure.

“This is an important breakthrough that will allow the highest energy density lithium batteries to be used without degradation,” said Stan Whittingham, a Nobel Laureate and distinguished professor of chemistry at Binghamton University. “In addition, this breakthrough on long-lived batteries will be critical to their use in vehicles that can be tethered to the grid to make it more resilient and to support clean renewable energy sources.”

The synthesis method for the single-crystal, nickel-rich cathode is both innovative and cost-efficient. It is also easy to scale up, as it is a drop-in approach that allows cathode manufacturers to use existing production facilities to conveniently produce single-crystal NMC811 — and even cathodes with more than 80% nickel.

“This is a fundamentally new direction for large-scale production of single crystal cathode materials,” said Jie Xiao, the principal investigator of the project and a Battelle Fellow at PNNL. “This work is only part of the cathode technology we are developing at PNNL. In collaboration with Albemarle, we are addressing the scientific challenges in synthesis and scale-up of single crystals and reducing the manufacturing cost starting from raw materials.”

Rapid deployment of EV battery technology

In the research phase, set to begin in early 2024, PNNL, teaming up with industry and university partners, will work to realise commercial-scale synthesis and testing with an eye toward production.

To accomplish this so quickly, they will use conventional manufacturing equipment and techniques that have been industrially adapted to include PNNL’s scale-up approach (as well as a few other innovations that further reduce costs and waste generation).

“During single-crystal synthesis at the kilogram level, we have identified a brand new world full of science and engineering challenges and opportunities. We are excited to apply this new knowledge to accelerate the commercial-scale manufacturing process,” Xiao said.

This article was originally published by Pacific Northwest National Laboratory.

Image credit: iStock.com/Kulpreya Chaichatpornsuk

Researchers develop brain-like transistor

Fri, 05 Jan 2024 00:00:00 +1100

Designed by researchers at Northwestern University, Boston College and the Massachusetts Institute of Technology (MIT), the device processes and stores information like the human brain. Experiments demonstrate that the transistor goes beyond simple machine-learning tasks to categorise data and is capable of performing associative learning.

While previous studies have leveraged similar strategies to develop brain-like computing devices, those transistors cannot function outside cryogenic temperatures. The new device, however, is stable at room temperatures and also operates at fast speeds, consumes very little energy and retains stored information even when power is removed. The research findings have been published in the journal Nature.

Mark C. Hersam, who co-led the research, said the brain has a fundamentally different architecture from a digital computer. “In a digital computer, data move back and forth between a microprocessor and memory, which consumes a lot of energy and creates a bottleneck when attempting to perform multiple tasks at the same time. On the other hand, in the brain, memory and information processing are co-located and fully integrated, resulting in orders-of-magnitude higher energy efficiency. Our synaptic transistor similarly achieves concurrent memory and information processing functionality to more faithfully mimic the brain,” Hersam said.

Recent advances in artificial intelligence (AI) have motivated researchers to develop computers that operate more like the human brain. Conventional, digital computing systems have separate processing and storage units, causing data-intensive tasks to use up large amounts of energy. With smart devices continuously collecting vast quantities of data, researchers are looking for ways to uncover new ways to process it all without consuming an increasing amount of power.

Hersam said that for many decades, the paradigm in electronics has been to build everything out of transistors and use the same silicon architecture. Much progress has been made by packing more and more transistors into integrated circuits, but this consumes a lot of power, particularly in the current era of big data where digital computing is on track to overwhelm the grid. “We have to rethink computing hardware, especially for AI and machine-learning tasks,” Hersam said.

Hersam and his team explored new advances in the physics of moiré patterns, a type of geometrical design that arises when two patterns are layered on top of one another. When two-dimensional materials are stacked, new properties emerge that do not exist in one layer alone. And when those layers are twisted to form a moiré pattern, the tunability of electronic properties becomes possible.

For the new device, the researchers combined two types of atomically thin materials: bilayer graphene and hexagonal boron nitride. When stacked and twisted, the materials formed a moiré pattern. By rotating one layer relative to another, the researchers achieved different electronic properties in each graphene layer even though they are separated by only atomic-scale dimensions. With the right choice of twist, the researchers harnessed moiré physics for neuromorphic functionality at room temperature.

“With twist as a new design parameter, the number of permutations is vast. Graphene and hexagonal boron nitride are very similar structurally but just different enough that you get exceptionally strong moiré effects,” Hersam said.

Image caption: A schematic showing the different layers within the new technology. Image credit: Mark C. Hersam/Northwestern University

To test the transistor, the researchers trained it to recognise similar — but not identical — patterns. First, the researchers showed the device one pattern: 000 (three zeroes in a row). Then, they asked the AI to identify similar patterns, such as 111 or 101. “If we trained it to detect 000 and then gave it 111 and 101, it knows 111 is more similar to 000 than 101. 000 and 111 are not exactly the same, but both are three digits in a row. Recognising that similarity is a higher-level form of cognition known as associative learning,” Hersam said.

In experiments, the synaptic transistor recognised similar patterns, displaying its associative memory. Even when the researchers threw curveballs — like giving it incomplete patterns — it still successfully demonstrated associative learning.

Top image credit: iStock.com/BlackJack3D

A micro-ring resonator with big potential

Wed, 13 Dec 2023 00:00:00 +1100

This pioneering work, led by Professor Camille Brès and postdoctoral researcher Marco Clementi from EPFL’s School of Engineering, represents a significant advance in the field of photonics, with implications for telecommunications, metrology and other high-precision applications.

The study, published in the journal Light: Science & Applications, reveals how the researchers, in collaboration with the Laboratory of Photonics and Quantum Measurements, have integrated semiconductor lasers with silicon nitride photonic circuits containing microresonators. This integration results in a hybrid device capable of emitting highly uniform and precise light in both near-infrared and visible ranges, filling a technological gap that has long challenged the industry.

“Semiconductor lasers are ubiquitous in modern technology, found in everything from smartphones to fibre optic communications. However, their potential has been limited by a lack of coherence and the inability to generate visible light efficiently,” Brès said. “Our work not only improves the coherence of these lasers but also shifts their output towards the visible spectrum, opening up new avenues for their use.”

Coherence, in this context, refers to the uniformity of the phases of the light waves emitted by the laser. High coherence means the light waves are synchronised, leading to a beam with a very precise colour or frequency. This property is crucial for applications where precision and stability of the laser beam are paramount, such as time keeping and precision sensing.

Increased accuracy and improved functionality

The team’s approach involves coupling commercially available semiconductor lasers with a silicon nitride chip. This tiny chip is created with industry-standard, cost-efficient CMOS technology. Thanks to the material’s low-loss properties, there is little to no light that is absorbed or escapes. The light from the semiconductor laser flows through microscopic waveguides into extremely small cavities, where the beam is trapped. These cavities, called micro-ring resonators, are intricately designed to resonate at specific frequencies, selectively amplifying the desired wavelengths while attenuating others, thereby achieving enhanced coherence in the emitted light.

The other significant achievement is the hybrid system’s ability to double the frequency of the light coming from the commercial semiconductor laser — enabling a shift from the near-infrared spectrum to the visible light spectrum. The relationship between frequency and wavelength is inversely proportional, meaning that if the frequency is doubled, the wavelength is reduced by half. While the near infrared spectrum is exploited for telecommunications, higher frequencies are essential for building smaller, more efficient devices where shorter wavelengths are needed, such as in atomic clocks and medical devices.

These shorter wavelengths are achieved when the trapped light in the cavity undergoes a process called all-optical poling, which induces what is known as second-order nonlinearity in the silicon nitride. Nonlinearity in this context means that there is a significant shift, a jump in magnitude, in the light's behaviour that is not directly proportional to its frequency, arising from its interaction with the material. Silicon nitride does not normally incur this specific second order nonlinear effect, and the team performed an elegant engineering feat to induce it: The system takes advantage of the light’s capacity, when resonating within the cavity, to produce an electromagnetic wave that provokes the nonlinear properties in the material.

An enabling technology for future applications

“We are not just improving existing technology but also pushing the boundaries of what’s possible with semiconductor lasers. By bridging the gap between telecom and visible wavelengths, we’re opening the door to new applications in fields like biomedical imaging and precision timekeeping,” said Marco Clementi, who played a key role in the project.

One of the most promising applications of this technology is in metrology, particularly in the development of compact atomic clocks. The history of navigational advancements hinges on the portability of accurate timepieces — from determining longitude at sea in the 16th century to ensuring the accurate navigation of space missions and achieving better geo-localisation today. “This significant advancement lays the groundwork for future technologies, some of which are yet to be conceived,” Clementi said.

The team’s understanding of photonics and material science could lead to smaller and lighter devices and lower the energy consumption and production costs of lasers. Their ability to take a fundamental scientific concept and translate it into a practical application using industry standard fabrication underscores the potential of solving complex technological challenges that can lead to unforeseen advances.

Image caption: The micro-resonator being activated by a semi-conductor laser. Image credit: EPFL/Alain Herzog

'Doughnut' beams reveal secrets of tiny electronics

Thu, 07 Dec 2023 00:00:00 +1100

The new technique could help scientists improve the inner workings of a range of ‘nanoelectronics’, including the miniature semiconductors in computer chips. The discovery was highlighted in a special issue of Optics & Photonics News called Optics in 2023.

The research is the latest advance in the field of ptychography, a difficult to pronounce (the “p” is silent) but powerful technique for viewing very small things. Unlike traditional microscopes, ptychography tools don’t directly view small objects. Instead, they shine lasers at a target, then measure how the light scatters away — a bit like the microscopic equivalent of making shadow puppets on a wall.

So far, the approach has worked remarkably well, with one major exception, said study senior author and Distinguished Professor of physics Margaret Murnane.

“Until recently, it has completely failed for highly periodic samples, or objects with a regularly repeating pattern,” said Murnane, fellow at JILA, a joint research institute of CU Boulder and the National Institute of Standards and Technology (NIST). “It’s a problem because that includes a lot of nanoelectronics.

She noted that many important technologies like some semiconductors are made up of atoms like silicon or carbon joined together in regular patterns like a small grid or mesh. To date, those structures have proved tricky for scientists to view up close using ptychography.

In the new study, however, Murnane and her colleagues came up with a solution. Instead of using traditional lasers in their microscopes, they produced beams of extreme ultraviolet light in the shape of doughnuts.

The team’s novel approach can collect accurate images of tiny and delicate structures that are roughly 10 to 100 nanometres in size, or many times smaller than a millionth of an inch. In the future, the researchers expect to zoom in to view even smaller structures. The doughnut, or optical angular momentum, beams also won’t harm tiny electronics in the process — as some existing imaging tools, like electron microscopes, sometimes can.

“In the future, this method could be used to inspect the polymers used to make and print semiconductors for defects, without damaging those structures in the process,” Murnane said.

Bin Wang and Nathan Brooks, who earned their doctoral degrees from JILA in 2023, were first authors of the new study.

Image caption: Doughnut-shaped beams of light scatter away from two incredibly small structures with different repeating patterns. Image credit: Wang, et al., 2023, “Optica”.

Pushing the limits of microscopes

The research, Murnane said, pushes the fundamental limits of microscopes: because of the physics of light, imaging tools using lenses can only see the world down to a resolution of about 200 nanometres — which isn’t accurate enough to capture many of the viruses, for example, that infect humans. Scientists can freeze and kill viruses to view them with powerful cryo-electron microscopes, but can’t yet capture these pathogens in action and in real time.

Ptychography, which was pioneered in the mid-2000s, could help researchers push past that limit.

To understand how, go back to those shadow puppets. Imagine that scientists want to collect a ptychographic image of a very small structure, perhaps letters spelling out “CU”. To do that, they first zap a laser beam at the letters, scanning them multiple times. When the light hits the “C” and the “U” (in this case, the puppets), the beam will break apart and scatter, producing a complex pattern (the shadows). Employing sensitive detectors, scientists record those patterns, then analyse them with a series of mathematical equations. With enough time, Murnane explained, they recreate the shape of their puppets entirely from the shadows they cast.

“Instead of using a lens to retrieve the image, we use algorithms,” Murnane said.

She and her colleagues have previously used such an approach to view submicroscopic shapes like letters or stars.

But the approach won’t work with repeating structures like those silicon or carbon grids. If you shine a regular laser beam on a semiconductor with such regularity, for example, it will often produce a scatter pattern that is incredibly uniform — ptychographic algorithms struggle to make sense of patterns that don’t have much variation in them.

The problem has left physicists scratching their heads for close to a decade.

Doughnut microscopy

In the new study, however, Murnane and her colleagues decided to try something different. They didn’t make their shadow puppets using regular lasers. Instead, they generated beams of extreme ultraviolet light, then employed a device called a spiral phase plate to twist those beams into the shape of a corkscrew, or vortex. (When such a vortex of light shines on a flat surface, it makes a shape like a doughnut.)

The doughnut beams didn’t have pink glaze or sprinkles, but they did the trick. The team discovered that when these types of beams bounced off repeating structures, they created much more complex shadow puppets than regular lasers.

To test out the new approach, the researchers created a mesh of carbon atoms with a tiny snap in one of the links. The group was able to spot that defect with precision not seen in other ptychographic tools.

“If you tried to image the same thing in a scanning electron microscope, you would damage it even further,” Murnane said.

Moving forward, her team wants to make their doughnut strategy even more accurate, allowing them to view smaller and even more fragile objects — including, one day, the workings of living, biological cells.

Top image credit: iStock.com/AegeanBlue

Diamond device for next-gen semiconductors

Wed, 29 Nov 2023 00:00:00 +1100

Researchers at the University of Illinois Urbana-Champaign have developed a semiconductor device made using diamond that has the highest breakdown voltage and lowest leakage current compared to previously reported diamond devices. Such a device will enable more efficient technologies needed as the world transitions to renewable energies.

It is estimated that currently, 50% of the world’s electricity is controlled by power devices, and in less than a decade, it is expected that that number will increase to 80%, while simultaneously, the demand for electricity will increase by 50% by 2050.

According to a report from the National Academies of Sciences, Engineering, and Medicine, “Perhaps the single greatest technological danger to a successful energy transition is the risk that the nation fails to site, modernise, and build out the electrical grid. Without increased transmission capacity, renewables deployment would be delayed, and the net result could be at least a temporary increase in fossil fuel emissions, preventing the nation from achieving its emission reduction goals.”

Electrical and computer engineering professor Can Bayram said it is important that we move away from conventional materials, like silicon, to new materials that are being adopted today, like silicon carbide and the new generation of semiconductors — ultra-wide bandgap materials — such as aluminium nitride, diamond and related compounds, to meet these electricity demands. Bayram led this research, along with graduate student Zhuoran Han. The results of this work were published in the journal IEEE Electron Device Letters.

Beyond silicon

Most semiconductors are built using silicon and, thus far, have met society’s electrical needs. But as Bayram points out, “We want to make sure that we have enough resources for everyone, while our needs are evolving. Right now, we are using more and more bandwidth, we are creating more data (that also comes with more storage) and we are using more power, more electricity and more energy in general. The question is: is there a way we can make all of this more efficient, rather than generating more energy and building more power plants?”

Why diamond?

Diamond is an ultra-wide gap semiconductor with the highest thermal conductivity, which is the ability of a material to transfer heat. Due to these properties, diamond semiconductor devices can operate at much higher voltages and currents (with less material) and will still dissipate the heat without causing a reduction in electrical performance, compared to traditional semiconductor materials like silicon. “To have an electricity grid where you need high current and high voltage, which makes everything more efficient for applications such as solar panels and wind turbines, then we need a technology that has no thermal limit. That’s where diamond comes in,” Bayram said.

Although many people associate diamond with expensive jewellery, diamond can be made more affordably and sustainably in the lab, making it a viable and important semiconductor alternative. Natural diamond is formed deep below Earth’s surface under immense pressure and heat, but since it is essentially just carbon — of which there is an abundance — artificially synthesised diamond can be made in weeks rather than billions of years, while also producing fewer carbon emissions.

Image caption: Diamond semiconductor device (4 x 4 mm in size). Image credit: University of Illinois Urbana-Champaign

In this work, Bayram and Han show that their diamond device can sustain high voltage, approximately 5 kV, although the voltage was limited by set-up of measurement and not from the device itself. In theory, the device can sustain up to 9 kV. Besides the highest breakdown voltage, the device also demonstrates the lowest leakage current, which can be thought of like a leaking faucet but with energy. Leakage current affects the overall efficiency and reliability of the device.

“We built an electronic device better suited for high-power, high-voltage applications for the future electric grid and other power applications. And we built this device on an ultra-wide bandgap material, synthetic diamond, which promises better efficiency and better performance than current generation devices. Hopefully, we will continue optimising this device and other configurations so that we can approach the performance limits of diamond’s material potential,” Han said.

Top image credit: iStock.com/avagyanlevon

The GPS constellation is made up of 24 satellites positioned around 20,000 kilometres above the Earth. The arrangement of the constellation ensures at least four satellites can be observed at any point on the planet. A GPS receiver picks up the signals from the satellites which provide their locations, status and the precise time from onboard atomic clocks. The receiver notes the arrival time of the signal and then determines the distance to each satellite from the difference in time between signal transmission and reception, and then multiplying by the speed of light. Information from four satellites fixes the receiver’s position to a unique point.

Billions of people rely on GNSS daily to help them determine where they are on the Earth’s surface. GNSS is also now providing a foundation for many IoT applications in the logistics and transportation sectors helping keep track of valuable assets that might otherwise go missing. This is why for asset tracking and other applications, Nordic’s cellular IoT solution, the nRF9160 SiP, incorporates GNSS capability.

Satellite signal lost

Despite its impressive technical foundation, GNSS is not flawless. Some problems do occur with the satellites, such as inaccuracies with the onboard clocks resulting in timing errors. To mitigate such drift errors, GNSS systems compare multiple satellites and use algorithms to determine which clocks are in error and then reset them compared with an earthbound reference.

Other problems occur because the relatively weak signal between satellites and earthbound receivers can easily be disrupted. For example, ‘urban canyons’ — formed by rows of tall buildings — can obstruct the signal. And there’s little chance of GNSS signals penetrating buildings.

But even if the signal does get through, so-called multipath errors can occur when it reflects off buildings before reaching the receiver. That can result in timing errors which in turn lead to incorrect positional information. Other errors can occur because of anomalies in the Earth’s atmosphere that can delay or distort the GNSS signal. Electromagnetic interference (EMI) from other radio sources can also cause timing errors. To mitigate these problems, receivers use techniques such as filtering, correlation and signal power measurement, and for the atmospheric challenges, methods such as ionosphere and troposphere modelling are employed.

Another challenge with a GNSS modem is that it can take several minutes to fix the location of a group of satellites from a cold start. That uses significant battery capacity. One solution, used by Nordic’s nRF9160 together with the company’s nRF Cloud Location Services, is Assisted- and Predicted-GPS (A-GPS and P-GPS). These methods use satellite assistance data stored in a database which is relayed to the nRF9160 via the LTE-M or NB-IoT network — saving significant power compared to an extended first fix. When required, the IoT device can then find the satellites in seconds, saving further energy. The P-GPS technique builds on A-GPS by providing over two weeks of assistance data to the IoT device resulting in even greater power savings.

A partner nRF9160 SiP forwards the SSID (and other useful information) from the nRF70 Series companion IC to nRF Cloud using cellular connectivity. Image credit: Nordic Semiconductor.

Even with power saving techniques, GNSS can still extract a heavy toll from batteries; that’s an important consideration for things like wearables or asset trackers which are typically equipped with modest batteries yet are expected to deliver long battery life.

Complementing GNSS

If high accuracy is needed then the battery trade-off of GNSS is worth it, but if less accurate locationing is acceptable there are ways to save power. One option to overcome the power consumption of GNSS — and which is also supported by the nRF9160 SiP and nRF Cloud Location Services — is to use the known location of cellular base stations to narrow down the position of the receiver. The single-cell location method relies on identifying in which cell the tracked device is situated and then referencing the cell identification against a database of known base station locations. The technique offers accuracy down to kilometre level while only modestly impacting the receiver’s battery life.

Multi-cell location builds on the single-cell technique by referencing the position of several nearby base stations instead of just one, to offer accuracy down to a few hundred metres while keeping power consumption low.

An interesting locationing technique which complements GNSS — and which can also be used to trade-off location precision against battery life — is Wi-Fi Service Set Identifier (SSID) scanning. Every Wi-Fi access point (AP) network is identified with an SSID — a technical reference for the AP’s name. With knowledge of the network’s SSID it’s possible to cross-reference against databases that will detail its location.

SSID locationing is supported by Nordic’s nRF70 Series of companion ICs. When used for Wi-Fi locationing, the nRF70 Series devices scan any nearby Wi-Fi AP for its SSID; a partner nRF9160 SiP then forwards the SSID (and other useful information) to nRF Cloud using cellular connectivity. nRF Cloud then checks one or more Wi-Fi SSID databases and returns the SSID’s location, plus a degree of uncertainty for that location, to the nRF9160, or elsewhere as directed.

SSID locationing is supported by Nordic’s nRF70 Series of companion ICs. Image credit: Nordic Semiconductor.

It’s hard to beat the precision of GNSS. But when precision of tens of metres is acceptable and battery life is critical, or when the GNSS signal is interrupted, Wi-Fi SSID locationing is an excellent alternative as it consumes significantly less power than GNSS. If it’s only necessary to determine the location of an asset to within a kilometre and battery life is critical, cell-based locationing is the answer. With Nordic’s nRF91, nRF70 Series and nRF Cloud Location Services it’s simple to switch seamlessly between all three methods to optimally trade-off location precision against battery life. With this locationing tech there is now no reason for valuable assets to ever be lost again.

Need to know

SSID information is found in the packet header of each communication transmitted over a Wi-Fi network and is distinct from the payload of the packet. The data is publicly broadcasted by every Wi-Fi enabled device and is accessible by any other Wi-Fi device within range, regardless of whether the Wi-Fi network uses encryption.

Never to be seen again

You might think that owners of valuable assets would make very sure they look after them. But no, just like your keys or pocketbook, items worth thousands or even millions of dollars have a habit of just disappearing.

Some, like the 1816 containers lost from the container ship ONE Apus, are down to pure bad luck. As reported in Slash Gear, the unfortunate vessel met with disaster due to extreme weather conditions in the Pacific Ocean, about 3000 kilometres from Hawaii. $90 million worth of goods sank into the abyss. Others, such as the lost Nazi train of Walbrzych, said to have been loaded with 270 tonnes of gold, weapons, jewels and art, and which allegedly disappeared late in WWII between Breslau and Walbrzych, might just be the stuff of myth. An extensive search for the train revealed naught, leading many to believe it never set off in the first place. If the carriages ever turn out to be real, the gold alone would be worth a cool $19 billion at today’s prices.

But then there are the foolhardy. Reported in UK newspaper Metro, in 2009 IT worker James Howells got his hands on 7500 bitcoin which he stored on his PC’s hard drive. When Howells ditched the computer, the hard drive went with it to landfill, only for him to later realise the bitcoin therein were worth nearly $5 million. Weeks of grubbing among the trash left him empty-handed. And then there was British journalist Nigel Reynolds. He was one of the first journalists to interview author JK Rowling and received a first edition copy of Harry Potter and the Philosopher’s Stone for his trouble. Reynolds assumed the book would fall flat and threw it in the bin — yet today, similar copies sell for over $60,000.

And finally, there’s the downright incompetent. Popular Mechanics magazine reports over one million spare parts needed to keep F-35 fighter aircraft in the air have gone missing. The parts are believed to have a total value of at least $85 million, but no one really knows because of some questionable bookkeeping. One can only hope the government keeps the actual weaponry on a tighter leash.

This article is republished from Nordic Semiconductor’s Wireless Quarter with permission.

www.nordicsemi.com/News/Wireless-Quarter

Top image credit: iStock.com/simplehappyart

Laminates and prototype PCBs

Thu, 09 Nov 2023 00:00:00 +1100

Copper laminates

Individual PCBs are made using laminates, ie, sheets of plastic (usually epoxy glass) that are factory-coated with a homogenous layer of copper. Traces, solder pads and other PCB components are made by removing the conductive layer chemically or mechanically. The former technology is etching (more about it later), while the latter one involves the use of a CNC machine. There, a digitally controlled milling machine removes the copper so that only a computer-designed PCB layout is left on the laminate surface. For this kind of processing, adequately sized material is required — a thicker laminate board will be the optimal choice as it will provide tolerance in terms of the milling depth and, in addition, retain mechanical resistance (even if processed on both sides). The products available from the TME catalogue are up to 2.4 mm thick, so the customers will surely find the right items for their needs.

Image caption: Making a PCB with the use of a CNC milling machine. Image credit: Transfer Multisort Elektronik

‘Classic’ etching

PCB etching makes use of chemical reactions. One of the most popular methods is the oxidation of copper using sodium persulphate. Before immersing the PCB in the solution, the layout of the circuit is applied onto the board with the use of an insoluble substance that protects metal fragments from coming into contact with the etching agent.

There are several technologies for applying the protective layer. In fully amateur conditions, a toner transfer from a laser printout is used. Sometimes (in the case of the simplest circuits), drawing the traces with a special marker pen is enough. Both methods can produce satisfactory results, but their accuracy is limited. Any laminate (even 0.6 mm) can be used for such work, but the thickness of the copper layer has to be taken into account (there are products where this value ranges from 18 to 105 µm). The more solid the metal layer is, the longer the etching process will take, and such prolonged immersion in the solution may cause damage (‘over-etching’) to the smallest parts of the layout, eg, narrow traces.

‘Photo-transfer’

Electronic components are getting increasingly smaller, and some of them are only available in SMD packages. Nowadays, not only electronic device manufacturers, but also amateurs feel the need to make precise circuits characterised by tolerance of a few dozen, or even just a few micrometres. This is why the photo-transfer technology — which allows almost professional results to be achieved, but without the use of specialist machinery — is becoming increasingly popular.

Image caption: Film-protected photoresist-coated laminate. Image credit: Transfer Multisort Elektronik

Photo-transfer does not refer to a method of making PCBs as such (traces are made by etching, as described above), but to a technology of applying a protective layer to the laminate. First, the copper is coated with a photosensitive substance (photoresist) cured by using ultraviolet light (UV). The surface prepared in this way is covered with transparent film with a negative image of the circuit layout printed on it (it is advisable to darken the layout image as much as possible) and then exposed to light. In the unprinted areas, the photoresist covering the metallised layer is cured, while in the other areas it is rinsed off after it is immersed in a developer (developers are available in our range of chemicals, eg, UNI-DEV-22G). From now on, the process looks exactly the same as described above: the board is immersed in an oxidising solution which removes the copper from the laminate (except for the areas protected by the photoresist). The protective layer is then washed off with isopropyl alcohol or acetone.

One way to get a photosensitive layer on a PCB is to make it yourself; there are special means to do it. However, you can also purchase ready-made laminates with a machine-applied photosensitive substance. Such products bring the best and most consistent results (due to the homogenous coating with a strictly controlled concentration of photoresist). The coating is protected from light by a peel-off film so that the products can be stored for a longer period of time and mechanically processed before use. Such boards are available in a variety of formats: from 100 x 50 mm to 300 x 210 mm, the latter being equivalent to an A4 sheet.

Important characteristics of laminates

It should be noted that the range of laminates is very diverse. In addition to variants with dimensions of even 610 x 457 mm and single- and double-sided coppered variants, more specialised items are also available. While most boards are made with the use of FR4 (a flame-resistant combination of epoxy resin and fibreglass), selected products have been developed for high-power circuits and better heat dissipation — they contain a layer of aluminium. The offering also includes laminates without copper, which are used as materials for insulation, construction and for making non-standard circuits.

Universal and prototype PCBs

Laminates are used in the final stage of prototyping, eg, to test a designed circuit. Sometimes, they are used to produce one or a few pieces of a device, eg, if it is a custom order for a circuit with a very specific functionality. When planning circuits, making your own designs or testing design solutions, the PCB production stage can be completely excluded.

Universal PCBs are laminates with straight traces (or solder pads alone) and holes drilled at a standard spacing (usually 2.54 mm). Electronic components can be attached and soldered to them to facilitate the circuit production. In the case of PCBs with rows of interconnected solder pads, the traces are cut with a knife or reamed — in the case of PCBs that only have holes and solder pads, connections are made by solder bridging.

Since such PCBs are, by their nature, regularly perforated and often made from hard paper (rather than FR4), you can adjust their size to your needs by cutting and breaking, which will speed up your work significantly. However, it should be noted that universal PCBs are available in a wide variety of sizes, often with machine-made fixing holes, so in all likelihood such a treatment will not be needed at all.

Image caption: PCB acting as an adapter, designed to work with a variety of SMD components. Image credit: Transfer Multisort Elektronik

A special type of prototype PCB is a multi-adapter with pads for mounting components that are housed in a specific type of package. Multi-adapters facilitate, among other things, prototyping with the use of surface-mounted components, especially integrated circuits with multiple leads, such as multiplexers, drivers or microcontrollers. They are made in such a way that each SMT pad is connected to at least one THT hole, to which wires or pin headers can be easily soldered.

Prototyping with breadboards

The fastest method for demonstrating and prototyping circuits is to use breadboards. These are flat bodies made of plastic. They have holes at a standard pitch of 2.54 mm on top, suitable for fitting typical THT components. Underneath the holes, there are elongated metal contacts that provide connectivity between all points in each row (each row has a separate set of contacts). The fields placed on the sides of the PCB remain shorted over the entire length of the column, as they have been designed to act as power traces, shared by multiple components. Thanks to this layout, you can produce circuits (even complex ones) without using tools. THT components and connecting wires alone will be enough. Some products are delivered together with such connectors.

Image caption: A set of breadboards with a set of connecting cables. Image credit: Transfer Multisort Elektronik

TME offers a wide selection of breadboards — from the smallest (100 fields) to extensive models (3200 fields) placed on a loaded, shielded base and with holes for mounting banana plugs (for easy power connection). Such products are an excellent educational accessory, which invites users to experiment freely with electronics. Nevertheless, professionals are also eager to use them — for example to carry out a quick test of a design solution or to make a temporary replacement circuit. Apart from different sizes, the PCBs can also be distinguished by their colours. What is more, selected models have a modular design and can be connected to form larger boards.

TME offers a wide selection of universal PCBs, laminates and other products for the prototyping of electronic devices. The components are suitable for large companies and small manufacturers alike, as well as for students and even amateurs.

Top image credit: iStock.com/Jay_Zynism

A game changer for building robust distributed systems

Thu, 09 Nov 2023 00:00:00 +1100

Take the example of three servers that need to store three copies of data and keep track of any updates to information so that all three servers remain consistent. If one server fails, the remaining two must keep the data consistent and allow updates to continue normally as if there was no failure.

Current state-of-the-art consensus protocols to achieve consensus rely on one computer node being designated a leader at any given time, continually supervising and handling any updates to data. If the leader fails another node wakes up and takes over, but there’s a challenge. How long should another node wait before taking over from an unresponsive leader?

“If the leader fails or the network is bad, the problem with the classic consensus protocols is that there’s the very tricky question of how you decide how big or small the timeout should be,” explained Professor Bryan Ford, Head of the Decentralized and Distributed Systems Laboratory (DEDIS) in EPFL’s School of Computer and Communications Sciences (IC). “If you set it too big, then when a leader fails, you might be waiting a long time and the system is just dead. On the other hand, consider if you set the timeout too short — this is where the real disaster can happen.

“Suppose the old leader hasn’t failed, suppose the network is just a little slower than you thought it was, the next leader comes and tries to take over, but the way all the existing protocols work, the new leader’s actions will cancel what the old leader’s actions did so it can no longer finish what it was doing and all its work is wasted. These kinds of issues can cause major reliability problems and these leader-based protocols can fail entirely if there’s a deliberate denial of service attack,” he continued.

To overcome these challenges, DEDIS researchers have been investigating a rarely used class of consensus algorithms, known as asynchronous consensus protocols. Unlike current leader-based protocols, their asynchronous cousins are not vulnerable to leader failures and denial-of-service attacks. But there’s a big trade-off — prior asynchronous protocols are much less efficient under normal conditions, and that’s one reason they are almost never deployed.

For the first time, Ford said, their QuePaxa protocol changes this dynamic. “We’ve come up with a win-win. What is new and unique to QuePaxa is that it’s an asynchronous consensus protocol that finally achieves efficiency equivalent to the widely deployed leader-based protocols under normal network conditions. QuePaxa is just as fast, efficient, low latency and low cost in terms of network bandwidth, under normal conditions.”

The new algorithm is designed in such a way that one leader at a time is usually expected to lead the task of making progress, but a second leader can come in and help in the same round without interfering with the first one. A third leader could even join and help the other two finish the work more quickly. There will be some redundancy of effort, but the non-leaders don’t destructively interfere. Short delays don’t cause leaders to cancel each other’s work as with current protocols.

Another advantage of QuePaxa is that it is also extremely robust under bad conditions such as noisy networks, high communication delays, unpredictably- varying network delays or deliberate denial-of-service attacks.

“Under these conditions existing consensus protocols will just die completely. QuePaxa will keep going; it’s much more robust,” he continued. “In any place where there are significant concerns about performance, reliability or vulnerability to these kinds of attacks I believe this is a game changer for robustness reasons and this should be the new standard consensus protocol.”

The DEDIS team has already built an open source prototype of QuePaxa, which is available on the well-known GitHub repository. The new protocol has already gone through an artefact evaluation review process at SOSP, where peer reviewers have tested its capabilities.

Image credit: iStock.com/shulz

Robot performs autonomous experiments in the laboratory

Thu, 09 Nov 2023 00:00:00 +1100

With affordability and accessibility in mind, the researchers collaboratively created a benchtop robot that rapidly performs electrochemistry. Aptly named the Electrolab, this instrument greatly reduces the effort and time needed for electrochemical studies by automating many basic and repetitive laboratory tasks.

The Electrolab can be used to explore energy storage materials and chemical reactions that promote the use of alternative and renewable power sources like solar or wind energy, which are essential to combating climate change.

“We hope the Electrolab will allow new discoveries in energy storage while helping us share knowledge and data with other electrochemists — and non-electrochemists! We want them to be able to try things they couldn’t before,” said Joaquín Rodríguez-López, a professor in the Department of Chemistry at the University of Illinois Urbana-Champaign.

The interdisciplinary team was co-led by Rodríguez-López and Charles Schroeder, the James Economy professor in the Department of Materials Science and Engineering and a professor of chemical and biomolecular engineering at UIUC. Their work appears in the journal Device.

Electrochemistry is the study of electricity and its relation to chemistry. Chemical reactions release energy that can be converted into electricity — batteries used to power remote controllers or electric vehicles are perfect examples of this phenomenon.

In the opposite direction, electricity can also be used to drive chemical reactions. Electrochemistry can provide a green and sustainable alternative to many reactions that would otherwise require the use of harsh chemicals, and it can even drive chemical reactions that convert greenhouse gases such as carbon dioxide into chemicals that are useful in other industries. These are relatively simple demonstrations of electrochemistry, but the growing demand to generate and store massive amounts of energy on a much larger scale is currently a prominent challenge.

One type of battery, known as a redox-flow battery, is used for grid-level storage and can store and bring power to entire electrical grids. The batteries explored by this collaboration use organic molecules to store energy and can be easily altered or tuned by changing the structure of those molecules. A major drawback of exploring redox-flow battery conditions is that it takes a lot of time and effort to identify a system that works, said Michael Pence, a graduate student of the Rodríguez-López Laboratory and a 2023 Beckman Institute Graduate Fellow.

The Electrolab started as an idea between Rodríguez-López and Schroeder based on a collaborative project funded by the Joint Center for Energy Storage Research, an Energy Innovation Hub of the U.S. Department of Energy focused on advancing battery science and technology. Rodríguez-López and Schroeder put together an interdisciplinary team including programmers, engineers and electrochemists. Initially, the idea was to create a microfabricated design, but the team decided to prioritise accessibility and transferability.

After establishing the final design of the Electrolab, the research group successfully created and tested an affordable device that is highly adaptable, made from common parts, and costs about $1000 to build, which is key for its adoption by laboratories of all sizes. The team is openly sharing construction plans for this instrument, so that all researchers can benefit from it.

There are two main components of the Electrolab: hardware and software. The hardware consists of a standard 3D printer frame that was transformed into a solution-handling robot; microfabricated electrode arrays, or eChips; and electrochemical hardware. The frame allows the robot to move around within a designated area above electrochemical cells to dispense different liquids. The eChips measure electrical current which is necessary for understanding the electrochemical measurements.

The software component was created in Python (a free, open-source coding platform) that allows the user to connect with Electrolab to perform experiments. The software allows for fully automated data analysis, visual graphics and plotting. When paired with machine learning, the Electrolab transforms from a robot completing predetermined tasks to a robot that can make decisions about the direction of the experiment while it is happening. Typically, an electrochemist handpicks datasets of interest to move forward, but the Electrolab uses the data it is collecting and analysing in real time to make the next move. In other words, the Electrolab is making this science electro-fast.

The bottleneck of electrochemical characterisation is the time required for in-depth analysis and characterisation of new molecules and solutions. These are tasks like measuring voltages at which battery materials charge and discharge and figuring out the speed of side reactions. There are almost limitless ways to explore and tweak these systems but simply not enough time or bandwidth to explore every option.

The Electrolab is accelerating the discovery of new materials and will ultimately help combat climate change. Studying efficient energy conversion and exploring new energy storage materials used in redox-flow batteries would enable alternative energy sources like solar or wind energy to become more practical. At the heart of all that is electrochemistry, Pence said, and that is why Electrolab is so important.

In their paper, the research team describe the Electrolab’s function in detail and report the findings of two experiments used to test the accuracy and robustness of their robot. The Electrolab performed more than 200 experiments across multiple conditions, analysed the data and even cleaned up after itself in two hours. This experiment would have taken eight hours for the average electrochemist — depending on their caffeination level.

The second experiment tested the Electrolab’s ability to work as a specialist. Programmed to look at a next generation redox-flow battery material in a much more demanding type of experiment to find supporting electrolyte solutions, the Electrolab was modified with smaller, more sensitive electrodes and set to run entirely autonomously. It completed the tasks in less than four hours with no human interference, allowing researchers to work on other projects and reducing background noise that can often be seen in delicate electrochemical analyses.

Beyond exploring new battery materials, the Electrolab shows promise for exploring systems where electrochemistry is driving chemical reactions in a green and sustainable manner. As part of his Beckman research, Pence plans to use the Electrolab to screen conditions for oxidation of common biomass by-products, finding ways to transform waste materials into value-added chemicals.

Image credit: iStock.com/Ivan Bajic

Researchers design a pulsing nanomotor

Wed, 01 Nov 2023 00:00:00 +1100

It is driven by a clever mechanism and can perform pulsing movements. The researchers are now planning to fit it with a coupling and install it as a drive in complex machines. Their findings have appeared in the journal Nature Nanotechnology.

This novel type of motor is similar to a hand grip trainer that strengthens your grip when used regularly. However, the motor is around one million times smaller. Two handles are connected by a spring in a V-shaped structure.

In a hand grip trainer, you squeeze the handles together against the resistance of the spring. Once you release your grip, the spring pushes the handles back to their original position. “Our motor uses a very similar principle,” explained Professor Dr Michael Famulok from the Life and Medical Sciences (LIMES) Institute at the University of Bonn. “But the handles are not pressed together but rather pulled together.”

For this purpose, the researchers have repurposed a mechanism without which there would be no plants or animals. Every cell is equipped with a sort of library. It contains the blueprints for all types of proteins that the cell needs to perform its function. If the cell wants to produce a certain type of protein, it orders a copy of the respective blueprint. This transcript is produced by RNA polymerases.

RNA polymerases drive the pulsing movements

The original blueprint consists of long strands of DNA. The RNA polymerases move along these strands and copy the stored information letter by letter. “We took an RNA polymerase and attached it to one of the handles in our nanomachine,” explained Famulok, who is also a member of the transdisciplinary research areas ‘Life & Health’ and ‘Matter’ at the University of Bonn. “In close proximity, we also strained a DNA strand between the two handles. The polymerase grabs on to this strand to copy it. It pulls itself along the stand and the non-transcribed section becomes increasingly smaller. This pulls the second handle bit by bit towards the first one, compressing the spring at the same time.”

The DNA strand between the handles contains a particular sequence of letters shortly before its end. This so-called termination sequence signals to the polymerase that it should let go of the DNA. The spring can now relax again and moves the handles apart. This brings the start sequence of the strand near to the polymerase and the molecular copier can start a new transcription process: The cycle thus repeats. “In this way, our nanomotor performs a pulsing action,” said Mathias Centola from the research group headed by Famulok, who carried out a large proportion of the experiments.

An alphabet soup serves as fuel

This motor also needs energy just like any other type of motor. It is provided by the ‘alphabet soup’ from which the polymerase produces the transcripts. Every one of these letters (in technical terminology: nucleotides) has a small tail consisting of three phosphate groups — a triphosphate. In order to attach a new letter to an existing sentence, the polymerase has to remove two of these phosphate groups. This releases energy which it can use for linking the letters together. “Our motor thus uses nucleotide triphosphates as fuel,” said Famulok. “It can only continue to run when a sufficient number of them are available.”

By monitoring individual nanomotors, one of the cooperation partners based in the US state of Michigan was able to demonstrate that they actually carry out the expected movement. A research group in Arizona also simulated the process on high-speed computers. The results could be used, for example, to optimise the motor to work at a particular pulsation rate.

Furthermore, the researchers were able to demonstrate that the motor can be easily combined with other structures. This should make it possible for it to, for example, wander across a surface — similar to an inchworm that pulls itself along a branch in its own characteristic style. “We are also planning to produce a type of clutch that will allow us to only utilise the power of the motor at certain times and otherwise leave it to idle,” explained Famulok. In the long term, the motor could become the heart of a complex nanomachine. “However, there is still a lot of work to be done before we reach this stage.”

Image caption: The novel type of nanomotor — with an RNA polymerase, which pulls the two ‘handles’ together and then releases them again. This generates a pulsing movement. Image credit: Mathias Centola/Uni Bonn.

Preventing catastrophes with next-gen sensors

Fri, 20 Oct 2023 00:00:00 +1100

While this was only a test in a lab, the researchers are working to improve the way structures such as turbines, helicopter propellers and even bridges are monitored for wear and tear from the weather.

A changing climate is increasing the need for better erosion-corrosion monitoring in a wide range of industries from aviation to marine transportation and from renewable energy generation to construction, explained UBC Okanagan doctoral student Vishal Balasubramanian.

In many industries, wear-resistant coatings are used to protect a structure from erosive wear. However, these coatings have a limited service life and can wear out with time. As a result, these coated structures are periodically inspected for abrasion and breaches, which are then fixed by recoating the damaged areas.

Currently, these inspections are done manually using a probe, and Balasubramanian — one of several researchers working in UBC’s Okanagan Microelectronics and Gigahertz Applications (OMEGA) lab — is working to develop sensors that can be embedded directly into the coatings. This could take away any chance of human-caused errors and drastically reduce the inspection time. By integrating artificial intelligence (AI) and augmented reality (AR) into these embedded sensors the researchers can monitor in real time the wear and tear of protective mechanical coatings designed to prevent catastrophic failures.

“By leveraging AI technologies into our microwave resonator sensors, we’re able to detect not only surface-level coating erosion but we can also distinguish when an individual layer is being eroded within a multi-layer coating,” Balasubramanian, lead author of the research recently published in Nature Communications, said.

Some studies suggest that metal corrosion in the United States has a cost of nearly $300 billion a year — more than 3% of that country’s gross domestic product.

But it’s not just about money.

Erosion can cause irreversible damage to the exterior surfaces of bridges, aircraft, cars and naval infrastructure, explained Balasubramanian. History has a long list of disasters where erosion was identified as the primary reason for structural failures that have led to the loss of thousands of lives — including the 2018 Genoa bridge collapse in Italy, the 1984 Bhopal gas tragedy in India and the 2000 Carlsbad gas pipeline fire in Texas.

“Being able to proactively monitor and address equipment degradation — especially in harsh environments — can undoubtedly safeguard important infrastructure and reduce the effect on human life,” said Dr Mohammad Zarifi, an Associate Professor in UBCO’s School of Engineering and principal investigator at the OMEGA Lab. “For several years, we’ve been developing microwave-based sensors for ice detection and the addition of newer technologies like AI and AR can improve these sensors’ effectiveness exponentially.”

The newly developed sensors can detect and locate the eroding layer in multi-layered coatings and can also detect the total wear depth of protective coatings. This information is collected and can provide a detailed understanding for engineers and stakeholders of the potential damage and danger of failures.

In the lab, the differential network device interface system was tested at varying temperatures — extreme hot and cold — and different levels of humidity and UV exposure to mimic several harsh environments. The developed system was tested with different types of coatings and its response was monitored in four different types of experimental set-ups that performed the desired environmental parameter variations.

“We tested our sensors under some of the harshest environments including various temperatures, humidity and UV exposures,” Balasubramanian said. “We continue to push the limits of what these sensors are able to withstand in order to stay ahead of what’s transpiring around the world.”

For his work, Balasubramanian was recently recognised with an Award for Excellence in Microsystems CAD Tool & Design Methodology by CMC Microsystems and sponsored by COMSOL. The award recognises a graduate student who demonstrates a novel design technology advancement with the most potential for applicable improvements to microsystems manufacture and deployment.

The research was supported by funding from the Department of National Defence of Canada, the Natural Sciences and Engineering Research Council of Canada and the Canadian Foundation for Innovation.

Image credit: iStock.com/fokkebok

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A game changer for building robust distributed systems

Robot performs autonomous experiments in the laboratory

Researchers design a pulsing nanomotor

RNA polymerases drive the pulsing movements

An alphabet soup serves as fuel

Preventing catastrophes with next-gen sensors