Category Archives: energy

How memristors retain information without a power source? A mystery solved

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A September 10, 2024 news item on ScienceDaily provides a technical explanation of how memristors, without a power source, can retain information,

Phase separation, when molecules part like oil and water, works alongside oxygen diffusion to help memristors — electrical components that store information using electrical resistance — retain information even after the power is shut off, according to a University of Michigan led study recently published in Matter.

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A September 11, 2024 University of Michigan press release (also on EurekAltert but published September 10, 2024), which originated the news item, delves further into the research,

Up to this point, explanations have not fully grasped how memristors retain information without a power source, known as nonvolatile memory, because models and experiments do not match up.

“While experiments have shown devices can retain information for over 10 years, the models used in the community show that information can only be retained for a few hours,” said Jingxian Li, U-M doctoral graduate of materials science and engineering and first author of the study.

To better understand the underlying phenomenon driving nonvolatile memristor memory, the researchers focused on a device known as resistive random access memory or RRAM, an alternative to the volatile RAM used in classical computing, and are particularly promising for energy-efficient artificial intelligence applications. 

The specific RRAM studied, a filament-type valence change memory (VCM), sandwiches an insulating tantalum oxide layer between two platinum electrodes. When a certain voltage is applied to the platinum electrodes, a conductive filament forms a tantalum ion bridge passing through the insulator to the electrodes, which allows electricity to flow, putting the cell in a low resistance state representing a “1” in binary code. If a different voltage is applied, the filament is dissolved as returning oxygen atoms react with the tantalum ions, “rusting” the conductive bridge and returning to a high resistance state, representing a binary code of “0”. 

It was once thought that RRAM retains information over time because oxygen is too slow to diffuse back. However, a series of experiments revealed that previous models have neglected the role of phase separation. 

“In these devices, oxygen ions prefer to be away from the filament and will never diffuse back, even after an indefinite period of time. This process is analogous to how a mixture of water and oil will not mix, no matter how much time we wait, because they have lower energy in a de-mixed state,” said Yiyang Li, U-M assistant professor of materials science and engineering and senior author of the study.

To test retention time, the researchers sped up experiments by increasing the temperature. One hour at 250°C is equivalent to about 100 years at 85°C—the typical temperature of a computer chip.

Using the extremely high-resolution imaging of atomic force microscopy, the researchers imaged filaments, which measure only about five nanometers or 20 atoms wide, forming within the one micron wide RRAM device.  

“We were surprised that we could find the filament in the device. It’s like finding a needle in a haystack,” Li said. 

The research team found that different sized filaments yielded different retention behavior. Filaments smaller than about 5 nanometers dissolved over time, whereas filaments larger than 5 nanometers strengthened over time. The size-based difference cannot be explained by diffusion alone.

Together, experimental results and models incorporating thermodynamic principles showed the formation and stability of conductive filaments depend on phase separation. 

The research team leveraged phase separation to extend memory retention from one day to well over 10 years in a rad-hard memory chip—a memory device built to withstand radiation exposure for use in space exploration. 

Other applications include in-memory computing for more energy efficient AI applications or memory devices for electronic skin—a stretchable electronic interface designed to mimic the sensory capabilities of human skin. Also known as e-skin, this material could be used to provide sensory feedback to prosthetic limbs, create new wearable fitness trackers or help robots develop tactile sensing for delicate tasks.

“We hope that our findings can inspire new ways to use phase separation to create information storage devices,” Li said.

Researchers at Ford Research, Dearborn; Oak Ridge National Laboratory; University at Albany; NY CREATES; Sandia National Laboratories; and Arizona State University, Tempe contributed to this study.

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Here’s a link to and a citation for the paper,

Thermodynamic origin of nonvolatility in resistive memory by Jingxian Li, Anirudh Appachar, Sabrina L. Peczonczyk, Elisa T. Harrison, Anton V. Ievlev, Ryan Hood, Dongjae Shin, Sangmin Yoo, Brianna Roest, Kai Sun, Karsten Beckmann, Olya Popova, Tony Chiang, William S. Wahby, Robin B. Jacobs-Godrim, Matthew J. Marinella, Petro Maksymovych, John T. Heron, Nathaniel Cady, Wei D. Lu, Suhas Kumar, A. Alec Talin, Wenhao Sun, Yiyang Li. Matter DOI: https://doi.org/10.1016/j.matt.2024.07.018 Published online: August 26, 2024

This paper is behind a paywall.

Early morning run could power your electrical wearables

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I don’t think this is going to be happening tomorrow but here’s a relatively recent news item on ScienceDaily from August 22, 2024 about bioenergy harvesting and wearable technology,

Your early morning run could soon help harvest enough electricity to power your wearable devices, thanks to new nanotechnology developed at the University of Surrey [UK].

Surrey’s Advanced Technology Institute (ATI) has developed highly energy-efficient, flexible nanogenerators, which demonstrate a 140-fold increase in power density when compared to conventional nanogenerators. ATI researchers believe that this development could pave the way for nano-devices that are as efficient as today’s solar cells.

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An August 21, 2024 University of Surrey press release (also on EurekAlert but published August 22, 2024), which originated the news item, provides more information about the research,

Surrey’s devices can convert small amounts of everyday mechanical energy, like motion, into a significantly higher amount of electrical power, similar to how an amplifier boosts sound in an electronic system. For instance, if a traditional nanogenerator produces 10 milliwatts of power, this new technology could increase that output to over 1,000 milliwatts, making it suitable for energy harvesting in various everyday applications. 

ATI’s nanogenerator works like a relay team – instead of one electrode (the runner) passing energy (charge) by itself. Each runner collects a baton (charge), adds more and then passes all batons to the next runner, boosting the overall energy that is collected in a process called the charge regeneration effect. 

Lead author of the study from the University of Surrey, Md Delowar Hussain, said: 

“The dream of nanogenerators is to capture and use energy from everyday movements, like your morning run, mechanical vibrations, ocean waves or opening a door. The key innovation with our nanogenerator is that we’ve fine-tuned the technology with 34 tiny energy collectors using a laser technique that can be scaled up for manufacture to increase energy efficiency further. 

“What’s really exciting is that our little device with high energy harvesting density could one day rival the power of solar panels and could be used to run anything from self-powered sensors to smart home systems that run without ever needing a battery change.” 

The device is a triboelectric nanogenerator (TENG) – a device that can capture and turn the energy from simple, everyday movements into electricity. They work by using materials that become electrically charged when they come into contact and then separate – similar to when you rub a balloon on your hair, and it sticks due to static electricity.  

Dr Bhaskar Dudem, co-author of the study from the University of Surrey, said:  

“We are soon going to launch a company focused on self-powered, non-invasive healthcare sensors using triboelectric technology. Innovations like these will enable us to drive new spin-out activities in sustainable health tech, improve sensitivity, and emphasize industrial scalability.” 

Professor Ravi Silva, co-author of the study and Director of the Advanced Technology Institute at the University of Surrey, said: 

“With the ever-increasing technology around us, it is predicted that we will have over 50 billion Internet of Things (IoT) devices in the next few years that will need energy to be powered. Local green energy solutions are needed, and this could be a convenient wireless technology that harnesses energy from any mechanical movements to power small devices. It offers an opportunity for the scientific and engineering community to find innovative and sustainable solutions to global challenges.” 

“We are incredibly excited about the potential of these nanogenerators to transform how we think about energy. You could also imagine these devices being used in IoT-based self-powered smart systems like autonomous wireless operations, security monitoring, and smart home systems, or even for supporting dementia patients, an area in which the University of Surrey has great expertise.” 

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Here’s a link to and a citation for the paper,

Exploring charge regeneration effect in interdigitated array electrodes-based TENGs for a more than 100-fold enhanced power density by Md Delowar Hussain, Bhaskar Dudem, Dimitar I. Kutsarov, S. Ravi P. Silva. Nano Energy Volume 130, November 2024, 110112 DOI: https://doi.org/10.1016/j.nanoen.2024.110112 Available online 13 August 2024, Version of Record 21 August 2024

This paper is open access under a Creative Commons license.

Multifunctional smart windows that lower indoor temperatures without consuming power and can generate electricity from raindrops

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Caption: Figure 1: The main functions of the multifunctional smart windows for implementing Plus Energy (transparent radiative cooling, power generation, and fog and frost removal technology). Credit: © Seoul National University College of Engineering

I’m always a sucker for a ‘smart window’ story and this one from Korea with its reference to harvesting energy from raindrops seems particularly intriguing. From an August 13, 2024 Seoul National University (SNU) press release, also on EurekAlert but published August 22, 2024,

■ Research Necessity

o Recently, with the significant increase in cooling demand due to global warming, a vast amount of energy is being consumed for heat management inside buildings. Existing windows, which have a high solar absorption rate and low reflectance, lead to considerable energy loss. Therefore, energy-saving windows are emerging as a practical solution to global challenges such as responding to climate change and ensuring energy sustainability. These windows not only provide optimal thermal comfort to occupants but also contribute to economic development by reducing dependence on conventional cooling systems.

o For windows to effectively save energy in buildings, it is necessary to adopt energy-efficient cooling technology (Zero Energy) and further ensure energy harvesting methods (Plus Energy) that guarantee sustainable power supply. Additionally, windows must maintain high transparency, which is their fundamental function, even on cold or foggy days.

■ Research Achievements / Expected Effects

o The multifunctional smart windows developed in this research demonstrate their effectiveness as next-generation energy-saving devices by implementing three main functions.

o First, they provide radiative cooling that lowers indoor temperature on sunny days without energy input. Second, they generate electricity using raindrops on rainy days. Third, they implement a transparent heater function to quickly remove frost from the windows on cold days.

■ Research Details 

□ Research Content Overview

o The research team led by Professor Seung Hwan Ko from the Department of Mechanical Engineering at Seoul National University has developed “multifunctional smart window technology” that lowers indoor temperatures without electricity consumption and generates power using the frictional electricity from raindrops. This research is significant in that it pioneers new possibilities for Plus Energy technology, surpassing Zero Energy to contribute to improving energy self-sufficiency in response to global warming.

□ Background

o Recently, implementing Plus Energy Buildings (PEBs) that surpass Zero Energy has become a key task for achieving energy self-sufficiency in buildings. Next-generation PEBs are buildings that go beyond minimizing energy loads and can autonomously produce energy. Buildings inherently consume a massive amount of energy for heat management, and with the rise in cooling demand due to global warming, energy usage has surged dramatically. Furthermore, existing windows with high solar absorption and low reflectivity result in substantial energy losses during cooling. Therefore, to realize economically efficient next-generation Plus Energy Buildings, it is necessary to develop multifunctional smart windows equipped with transparent cooling technology (Zero Energy-based) and further energy-harvesting technology (Plus Energy-based) that ensures sustainable power supply.
o To address these issues, researchers worldwide are focusing on the development of smart windows that maximize energy savings. Smart windows are often thought to adjust internal temperatures by changing color to control sunlight. However, this method has limitations since the windows become opaque during the cooling process, thus failing to maintain high transparency, which is the window’s primary function.

□ Key Research Methods

o The research team is actively working on developing new technologies that improve energy efficiency while preserving the transparency of windows. As part of this effort, Professor Ko’s research team developed a Zero Energy-based “transparent radiative cooling technology” that maintains transparency while enabling cooling without using electricity. Additionally, they developed energy-harvesting technology that produces electricity through the friction generated when raindrops contact the window surface, introducing a Plus Energy-based smart window technology that surpasses Zero Energy. The team also developed a transparent heater technology that quickly clears frost from windows on cold or foggy days, thereby implementing three functions—radiative cooling, power generation, and frost removal—simultaneously in a single device for the first time in the world.
o The research team achieved these three functionalities in a single device by fabricating windows with a layered structure of silver and ITO (Indium Tin Oxide), materials with excellent electrical conductivity and unique optical properties. First, the “transparent radiative cooling technology” minimizes the absorption of sunlight entering indoors while emitting radiant heat outdoors to lower the temperature. Unlike conventional air conditioning systems that use refrigerants, this radiative cooling technology offers cooling performance without consuming electrical energy. The research team focused on allowing only the visible light spectrum from sunlight to pass through the window while selectively reflecting near-infrared sunlight to lower indoor temperatures and maximize cooling. Second, the “frictional electricity-based power generation technology” generates electricity when raindrops contact the window surface on rainy days. For this purpose, an electrode material covering the window surface is necessary, and thanks to the excellent electrical conductivity of the layered silver and ITO structure, the smart window can generate electricity through frictional electricity. Lastly, through “Joule heating,” the transparent electrodes also serve as a heater that quickly removes frost or ice from the window, ensuring clear visibility on cold days. The multifunctional smart windows developed by the research team can provide transparent radiative cooling on sunny days, generate power on rainy days, and remove frost or ice on cold days.

□ Results

o The research team led by Professor Seung Hwan Ko confirmed that the smart windows they developed maintained a temperature approximately 7 degrees lower than regular windows in hot environments under direct sunlight. In an experiment simulating rainy conditions, the smart windows generated 8.3 W m-2 of power with just a single raindrop, while also clearing frost from the window twice as fast as regular windows through Joule heating, demonstrating both high performance and multifunctionality.

□ Expected Effects

o Professor Seung Hwan Ko stated, “This achievement of presenting next-generation smart window technology optimized for responding to the depletion of fossil fuels and global warming offers valuable insights into the technological advancements for Plus Energy buildings and the eco-friendly electric vehicle industry. Smart windows are expected to be applied across various industries because they address environmental pollution, reduce cooling energy, and overcome the limitations of conventional battery technologies through self-power generation.”

□ Achievements

o This research was supported by the Basic Science Research Program through the National Research Foundation of Korea, and it has gained global attention, being published in the October 2024 issue of the prestigious journal Nano Energy (Impact factor: 16.8, Top 5.3%) under the title: “Energy-saving window for versatile multimode of radiative cooling, energy harvesting, and defrosting functionalities.”

o Meanwhile, Dr. Yeongju Jung, the lead author of this study, is currently conducting follow-up research at Professor Ko’s laboratory in the Department of Mechanical Engineering at Seoul National University and is preparing for a postdoctoral research fellowship abroad.

□ Introduction to the SNU College of Engineering

Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of ‘fostering leaders for global industry and society.’ In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.

Here’s a link to and a citation for the paper,

Energy-saving window for versatile multimode of radiative cooling, energy harvesting, and defrosting functionalities by Yeongju Jung, Ji-Seok Kim, Junhyuk Bang, Seok Hwan Choi, Kangkyu Kwon, Min Jae Lee, Il-Kwon Oh, Jaeman Song, Jinwoo Lee, Seung Hwan Ko. Nano Energy DVolume 129, Part A, October 2024, 110004 DOI: https://doi.org/10.1016/j.nanoen.2024.110004 Available online 25 July 2024, Version of Record 25 July 2024

This paper is behind a paywall.

Soundscapes comprised of underground acoustics can help amplify soil health

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For anyone who doesn’t like cartoons, this looks a lot cuter than the information it conveys,

An August 16, 2024 news item on ScienceDaily announces the work,

Barely audible to human ears, healthy soils produce a cacophony of sounds in many forms—a bit like an underground rave concert of bubble pops and clicks.

Special recordings made by Flinders University ecologists in Australia show that this chaotic mixture of soundscapes can be a measure of the diversity of tiny living animals in the soil, which create sounds as they move and interact with their environment.

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An August 16, 2024 Flinders University press release (also on EurekAlert), which originated the news item, describes a newish (more about newish later) field of research ‘eco-acoustics’ and technical details about the researchers’ work, Note: A link has been removed,

With 75% of the world’s soils degraded, the future of the teeming community of living species that live underground face a dire future without restoration, says microbial ecologist Dr Jake Robinson, from the Frontiers of Restoration Ecology Lab in the College of Science and Engineering at Flinders University.

This new field of research aims to investigate the vast, teeming hidden ecosystems where almost 60% of the Earth’s species live, he says.

“Restoring and monitoring soil biodiversity has never been more important.

“Although still in its early stages, ‘eco-acoustics’ is emerging as a promising tool to detect and monitor soil biodiversity and has now been used in Australian bushland and other ecosystems in the UK.

“The acoustic complexity and diversity are significantly higher in revegetated and remnant plots than in cleared plots, both in-situ and in sound attenuation chambers.

“The acoustic complexity and diversity are also significantly associated with soil invertebrate abundance and richness.”

The latest study, including Flinders University expert Associate Professor Martin Breed and Professor Xin Sun from the Chinese Academy of Sciences, compared results from acoustic monitoring of remnant vegetation to degraded plots and land that was revegetated 15 years ago. 

The passive acoustic monitoring used various tools and indices to measure soil biodiversity over five days in the Mount Bold region in the Adelaide Hills in South Australia. A below-ground sampling device and sound attenuation chamber were used to record soil invertebrate communities, which were also manually counted.   

“It’s clear acoustic complexity and diversity of our samples are associated with soil invertebrate abundance – from earthworms, beetles to ants and spiders – and it seems to be a clear reflection of soil health,” says Dr Robinson.

“All living organisms produce sounds, and our preliminary results suggest different soil organisms make different sound profiles depending on their activity, shape, appendages and size.

“This technology holds promise in addressing the global need for more effective soil biodiversity monitoring methods to protect our planet’s most diverse ecosystems.”

This is a copy of the research paper’s graphical abstract,

Caption: Acoustic monitoring was carried out on soil in remnant vegetation as well as degraded plots and land that was revegetated 15 years ago. Credit: Flinders University

Here’s a link to and a citation for the paper,

Sounds of the underground reflect soil biodiversity dynamics across a grassy woodland restoration chronosequence by Jake M. Robinson, Alex Taylor, Nicole Fickling, Xin Sun, Martin F. Breed. Journal of Applied Ecology Volume 61, Issue 9 September 2024 Pages 2047-2060 DOI: https://doi.org/10.1111/1365-2664.14738 First published online: 15 August 2024

This paper is open access.

‘Newish’ eco-acoustics

Like a lot of newish scientific terms, eco-acoustics, appears to be evolving. A search for the term led me to the Acoustic ecology entry on Wikipedia, Note: Links have been removed,

Acoustic ecology, sometimes called ecoacoustics or soundscape studies, is a discipline studying the relationship, mediated through sound, between human beings and their environment.[1] Acoustic ecology studies started in the late 1960s with R. Murray Schafer a musician, composer and former professor of communication studies at Simon Fraser University (Vancouver, British Columbia, Canada) with the help of his team there[2] as part of the World Soundscape Project. The original WSP team included Barry Truax and Hildegard Westerkamp, Bruce Davies and Peter Huse, among others. The first study produced by the WSP was titled The Vancouver Soundscape. This innovative study raised the interest of researchers and artists worldwide, creating enormous growth in the field of acoustic ecology. In 1993, the members of the by now large and active international acoustic ecology community formed the World Forum for Acoustic Ecology.[3]

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Soundscapes are composed of the anthrophony, geophony and biophony of a particular environment. They are specific to location and change over time.[12] Acoustic ecology aims to study the relationship between these things, i.e. the relationship between humans, animals and nature, within these soundscapes. These relationships are delicate and subject to disruption by natural or man-made means.[9]

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The acoustic niche hypothesis, as proposed by acoustic ecologist Bernie Krause in 1993,[23] refers to the process in which organisms partition the acoustic domain, finding their own niche in frequency and/or time in order to communicate without competition from other species. The theory draws from the ideas of niche differentiation and can be used to predict differences between young and mature ecosystems. Similar to how interspecific competition can place limits on the number of coexisting species that can utilize a given availability of habitats or resources, the available acoustic space in an environment is a limited resource that is partitioned among those species competing to utilize it.[24]

In mature ecosystems, species will sing at unique bandwidths and specific times, displaying a lack of interspecies competition in the acoustic environment. Conversely, in young ecosystems, one is more likely to encounter multiple species using similar frequency bandwidths, which can result in interference between their respective calls, or a complete lack of activity in uncontested bandwidths. Biological invasions can also result in interference in the acoustic niche, with non-native species altering the dynamics of the native community by producing signals that mask or degrade native signals. This can cause a variety of ecological impacts, such as decreased reproduction, aggressive interactions, and altered predator-prey dynamics.[25] The degree of partitioning in an environment can be used to indicate ecosystem health and biodiversity.

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Earlier bioacoustic research at Flinders University has been mentioned in a June 14, 2023 posting “The sound of dirt.” Finally, whether you spell it eco-acoustics or ecoacoustics or call it acoustic ecology, it is a fascinating way of understanding the natural and not-so-natural world we live in.

Mayonnaise and nuclear fusion research?

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Intriguing, eh? An August 6, 2023 news item on ScienceDaily announces an innovative approach to studying nuclear fusion energy,

Researchers are using mayonnaise to study and address the stability challenges of nuclear fusion by examining the phases of Rayleigh-Taylor instability. Their innovative approach aims to inform the design of more stable fusion capsules, contributing to the global effort to harness clean fusion energy. Their most recent paper explores the critical transitions between elastic and plastic phases in these conditions.

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An August 6, 2024 Lehigh University (Pennsylvania, US) news release, which originated the news item, elaborates on the mayonnaise-fusion connection,

Mayonnaise continues to help researchers better understand the physics behind nuclear fusion.

“We’re still working on the same problem, which is the structural integrity of fusion capsules used in inertial confinement fusion, and Hellmann’s Real Mayonnaise is still helping us in the search for solutions,” says Arindam Banerjee, the Paul B. Reinhold Professor of Mechanical Engineering and Mechanics at Lehigh University and Chair of the MEM department in the P.C. Rossin College of Engineering and Applied Science. 

In simple terms, fusion reactions are what power the sun. If the process could be harnessed on earth, scientists believe it could offer a nearly limitless and clean energy source for humanity. However, replicating the sun’s extreme conditions is an incredibly complex challenge. Researchers across science and engineering disciplines, including Banerjee and his team, are examining the problem from a multitude of perspectives.

Inertial confinement fusion is a process that initiates nuclear fusion reactions by rapidly compressing and heating capsules filled with fuel, in this case, isotopes of hydrogen. When subjected to extreme temperatures and pressure, these capsules melt and form plasma, the charged state of matter that can generate energy. 

“At those extremes, you’re talking about millions of degrees Kelvin and gigapascals of pressure as you’re trying to simulate conditions in the sun,” says Banerjee. “One of the main problems associated with this process is that the plasma state forms these hydrodynamic instabilities, which can reduce the energy yield.”

In their first paper on the topic back in 2019, Banerjee and his team examined that problem, known as Rayleigh-Taylor instability. The condition occurs between materials of different densities when the density and pressure gradients are in opposite directions, creating an unstable stratification. 

“We use mayonnaise because it behaves like a solid, but when subjected to a pressure gradient, it starts to flow,” he says. Using the condiment also negates the need for high temperatures and pressure conditions, which are exceedingly difficult to control.

Banerjee’s team used a custom-built, one-of-a-kind rotating wheel facility within Banerjee’s Turbulent Mixing Laboratory to mimic the flow conditions of the plasma. Once the acceleration crossed a critical value, the mayo started to flow. 

One of the things they figured out during that initial research was that before the flow became unstable, the soft solid, i.e., the mayo, went through a couple of phases.  

“As with a traditional molten metal, if you put a stress on mayonnaise, it will start to deform, but if you remove the stress, it goes back to its original shape,” he says. “So there’s an elastic phase followed by a stable plastic phase. The next phase is when it starts flowing, and that’s where the instability kicks in.”

Understanding this transition between the elastic phase and the stable plastic phase is critical, he says, because knowing when the plastic deformation starts might tip off researchers as to when the instability would occur, Banerjee says. Then, they’d look to control the condition in order to stay within this elastic or stable plastic phase.

Here’s a link to and a citation for the latest paper,

Transition to plastic regime for Rayleigh-Taylor instability in soft solids by Aren Boyaci and Arindam Banerjee. Phys. Rev. E 109, 055103 – Published 15 May 2024 DOI: https://doi.org/10.1103/PhysRevE.109.055103

This paper is behind a paywall.

Jennifer Ouellette’s August 9, 2024 article for Ars Technica offers information that augments what can be learned from the news release, Note 1: For anyone who’s not a physicist is more accessible than the paper; Note 2: Links have been removed,

Inertial confinement fusion is one method for generating energy through nuclear fusion, albeit one plagued by all manner of scientific challenges (although progress is being made). Researchers at Lehigh University are attempting to overcome one specific bugbear with this approach by conducting experiments with mayonnaise placed in a rotating figure-eight contraption. They described their most recent findings in a new paper published in the journal Physical Review E with an eye toward increasing energy yields from fusion.

The work builds on prior research in the Lehigh laboratory of mechanical engineer Arindam Banerjee, who focuses on investigating the dynamics of fluids and other materials in response to extremely high acceleration and centrifugal force. In this case, his team was exploring what’s known as the “instability threshold” of elastic/plastic materials. Scientists have debated whether this comes about because of initial conditions, or whether it’s the result of “more local catastrophic processes,” according to Banerjee. The question is relevant to a variety of fields, including geophysics, astrophysics, explosive welding, and yes, inertial confinement fusion.

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If you’re interested in learning more about inertial confinement fusion, Ouellette’s August 9, 2024 article will help.

As for fusion energy, there are many articles here; just use the search engine.

Proposed platform for brain-inspired computing

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Researchers at the University of California at Santa Barbara (UCSB) have proposed a more energy-efficient architecture for neuromorphic (brainlike or brain-inspored) computing according to a June 25, 2024 news item on ScienceDaily,

Computers have come so far in terms of their power and potential, rivaling and even eclipsing human brains in their ability to store and crunch data, make predictions and communicate. But there is one domain where human brains continue to dominate: energy efficiency.

“The most efficient computers are still approximately four orders of magnitude — that’s 10,000 times — higher in energy requirements compared to the human brain for specific tasks such as image processing and recognition, although they outperform the brain in tasks like mathematical calculations,” said UC Santa Barbara electrical and computer engineering Professor Kaustav Banerjee, a world expert in the realm of nanoelectronics. “Making computers more energy efficient is crucial because the worldwide energy consumption by on-chip electronics stands at #4 in the global rankings of nation-wise energy consumption, and it is increasing exponentially each year, fueled by applications such as artificial intelligence.” Additionally, he said, the problem of energy inefficient computing is particularly pressing in the context of global warming, “highlighting the urgent need to develop more energy-efficient computing technologies.”

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A June 24, 2024 UCSB news release (also on Eurekalert), which originated the news item, delves further into the subject,

Neuromorphic (NM) computing has emerged as a promising way to bridge the energy efficiency gap. By mimicking the structure and operations of the human brain, where processing occurs in parallel across an array of low power-consuming neurons, it may be possible to approach brain-like energy efficiency. In a paper published in the journal Nature Communications, Banerjee and co-workers Arnab Pal, Zichun Chai, Junkai Jiang and Wei Cao, in collaboration with researchers Vivek De and Mike Davies from Intel Labs propose such an ultra-energy efficient platform, using 2D transition metal dichalcogenide (TMD)-based tunnel-field-effect transistors (TFETs). Their platform, the researchers say, can bring the energy requirements to within two orders of magnitude (about 100 times) with respect to the human brain.

Leakage currents and subthreshold swing

The concept of neuromorphic computing has been around for decades, though the research around it has intensified only relatively recently. Advances in circuitry that enable smaller, denser arrays of transistors, and therefore more processing and functionality for less power consumption are just scratching the surface of what can be done to enable brain-inspired computing. Add to that an appetite generated by its many potential applications, such as AI and the Internet-of-Things, and it’s clear that expanding the options for a hardware platform for neuromorphic computing must be addressed in order to move forward.

Enter the team’s 2D tunnel-transistors. Emerging out of Banerjee’s longstanding research efforts to develop high-performance, low-power consumption transistors to meet the growing hunger for processing without a matching increase in power requirement, these atomically thin, nanoscale transistors are responsive at low voltages, and as the foundation of the researchers’ NM platform, can mimic the highly energy efficient operations of the human brain. In addition to lower off-state currents, the 2D TFETs also have a low subthreshold swing (SS), a parameter that describes how effectively a transistor can switch from off to on. According to Banerjee, a lower SS means a lower operating voltage, and faster and more efficient switching.

“Neuromorphic computing architectures are designed to operate with very sparse firing circuits,” said lead author Arnab Pal, “meaning they mimic how neurons in the brain fire only when necessary.” In contrast to the more conventional von Neumann architecture of today’s computers, in which data is processed sequentially, memory and processing components are separated and which continuously draw power throughout the entire operation, an event-driven system such as a NM computer fires up only when there is input to process, and memory and processing are distributed across an array of transistors. Companies like Intel and IBM have developed brain-inspired platforms, deploying billions of interconnected transistors and generating significant energy savings.

However, there’s still room for energy efficiency improvement, according to the researchers.

“In these systems, most of the energy is lost through leakage currents when the transistors are off, rather than during their active state,” Banerjee explained. A ubiquitous phenomenon in the world of electronics, leakage currents are small amounts of electricity that flow through a circuit even when it is in the off state (but still connected to power). According to the paper, current NM chips use traditional metal-oxide-semiconductor field-effect transistors (MOSFETs) which have a high on-state current, but also high off-state leakage. “Since the power efficiency of these chips is constrained by the off-state leakage, our approach — using tunneling transistors with much lower off-state current — can greatly improve power efficiency,” Banerjee said.

When integrated into a neuromorphic circuit, which emulates the firing and reset of neurons, the TFETs proved themselves more energy efficient than state-of-the-art MOSFETs, particularly the FinFETs (a MOSFET design that incorporates vertical “fins” as a way to provide better control of switching and leakage). TFETs are still in the experimental stage, however the performance and energy efficiency of neuromorphic circuits based on them makes them a promising candidate for the next generation of brain-inspired computing.

According to co-authors Vivek De (Intel Fellow) and Mike Davies (Director of Intel’s Neuromorphic Computing Lab), “Once realized, this platform can bring the energy consumption in chips to within two orders of magnitude with respect to the human brain — not accounting for the interface circuitry and memory storage elements. This represents a significant improvement from what is achievable today.”

Eventually, one can realize three-dimensional versions of these 2D-TFET based neuromorphic circuits to provide even closer emulation of the human brain, added Banerjee, widely recognized as one of the key visionaries behind 3D integrated circuits that are now witnessing wide scale commercial proliferation.

Here’s a link to and a citation for the latest paper,

An ultra energy-efficient hardware platform for neuromorphic computing enabled by 2D-TMD tunnel-FETs by Arnab Pal, Zichun Chai, Junkai Jiang, Wei Cao, Mike Davies, Vivek De & Kaustav Banerjee. Nature Communications volume 15, Article number: 3392 (2024) DOI: https://doi.org/10.1038/s41467-024-46397-3 Published: 22 April 2024

This paper is open access.

Using copper to mitigate climate change?

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A July 4, 2024 news item on phys.org announces research into copper that mitigates climate change,

Carbon in the atmosphere is a major driver of climate change. Now researchers from McGill University have designed a new catalyst for converting carbon dioxide (CO2) into methane—a cleaner source of energy—using tiny bits of copper called nanoclusters. While the traditional method of producing methane from fossil fuels introduces more CO2 into the atmosphere, the new process, electrocatalysis, does not.

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A July 4, 2024 Canadian Light Source (CLS) news release (also received via email) by Rowan Hollinger, which originated the news item, delves further into the research, Note: A link has been removed,

“On sunny days you can use solar power, or when it’s a windy day you can use that wind to produce renewable electricity, but as soon as you produce that electricity you need to use it,” says Mahdi Salehi, Ph.D. candidate at the Electrocatalysis Lab at McGill University. “But in our case, we can use that renewable but intermittent electricity to store the energy in chemicals like methane.”

By using copper nanoclusters, says Salehi, carbon dioxide from the atmosphere can be transformed into methane and once the methane is used, any carbon dioxide released can be captured and “recycled” back into methane. This would create a closed “carbon loop” that does not emit new carbon dioxide into the atmosphere. The research, published recently in the journal Applied Catalysis B: Environment and Energy, was enabled by the Canadian Light Source (CLS) at the University of Saskatchewan (USask).

“In our simulations, we used copper catalysts with different sizes, from small ones with only 19 atoms to larger ones with 1000 atoms,” says Salehi. “We then tested them in the lab, focusing on how the sizes of the clusters influenced the reaction mechanism.”

“Our top finding was that extremely small copper nanoclusters are very effective at producing methane,” continues Salehi. “This was a significant discovery, indicating that the size and structure of the copper nanoclusters play a crucial role in the reaction’s outcome.”

The team plans to continue refining their catalyst to make it more efficient and investigate its large-scale, industrial applications. Their hope is that their findings will open new avenues for producing clean, sustainable energy.

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Researcher Mahdi Salehi describes his work in a video provided by the Canadian Light Source (CLS),

Here’s a link to and a citation for the paper,

Copper nanoclusters: Selective CO2 to methane conversion beyond 1 A/cm² by Mahdi Salehi, Hasan Al-Mahayni, Amirhossein Farzi, Morgan McKee, Sepideh Kaviani, Elmira Pajootan, Roger Lin, Nikolay Kornienko, Ali Seifitokaldani. Applied Catalysis B: Environment and Energy Volume 353, 15 September 2024, 124061 DOI: https://doi.org/10.1016/j.apcatb.2024.124061 Available online 9 April 2024, Version of Record 12 April 2024.

This paper is open access. Under a Creative Commons license

Maxwell’s demon at Simon Fraser University (Vancouver, Canada)

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James Clerk Maxwell (1831 – 1879), a Scottish physicist, is famous for many scientific breakthroughs (see Maxwell’s Wikipedia entry) and also for a thought experiment known as Maxwell’s demon. This graphical abstract illustrates a paper from three Simon Fraser University (SFU) physicists that advances the ‘demon’s’ possibiliteis,

Graphical Abstract: Energy flows in conventional and information engines used to displace a bead. Credit: Advances in Physics: X (2024). DOI: 10.1080/23746149.2024.2352112

A June 6, 2024 news item on phys.org describes Maxwell’s thought experiment and announces a possible breakthrough, Note: Links have been removed,

The molecules that make up the matter around us are in constant motion. What if we could harness that energy and put it to use?

Over 150 years ago, Maxwell theorized that if molecules’ motion could be measured accurately, this information could be used to power an engine. Until recently this was a thought experiment, but technological breakthroughs have made it possible to build working information engines in the lab.

SFU Physics professors John Bechhoefer and David Sivak teamed up to build an information engine and test its limits. Their work has greatly advanced our understanding of how these engines function, and a paper led by postdoctoral fellow Johan du Buisson and published recently in Advances in Physics: X summarizes the findings made during their collaboration.

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A June 5, 2024 SFU news release (also on EurekAlert but published June 6, 2024) by Erin Brown-John, which originated the news item, describes the breakthrough in more detail,

“We live in a world full of extra unused energy that potentially could be used,” says Bechhoefer. Understanding how information engines function can not only help us put that energy to work, it can also suggest ways that existing engines could be redesigned to use energy more efficiently, and help us learn how biological motors work in organisms and the human body.

The team’s information engine consists of a tiny bead in a water bath that is held in place with an optical trap. When fluctuations in the water cause the bead to move in the desired direction, the trap can be adjusted to prevent the bead from returning to the place where it was before. By taking accurate measurements of the bead’s location and using that information to adjust the trap, the engine is able to convert the heat energy of the water into work.

To understand how fast and efficient the engine could be, the team tested multiple variables such as the mass of the bead and sampling frequency, and developed algorithms to reduce the uncertainty of their measurements.

“Stripped down to its simplest essence, we can systematically understand how things like temperature and the size of the system changes the things we can take advantage of,” Sivak says. “What are the strategies that work best? How do they change with all those different properties?”

The team was able to achieve the fastest speed recorded to date for an information engine, approximately ten times faster than the speed of E. coli, and comparable to the speed of motile bacteria found in marine environments.

Next, the team wanted to learn if an information engine could harvest more energy than it costs to run. “In equilibrium, that’s always a losing game,” Bechhoefer says. “The costs of gathering the information and processing it will always exceed what you’re getting out of it, but when you have an environment that has extra energy, [molecules doing] extra jiggling around, then that can change the balance if it’s strong enough.”

They found that in a non-equilibrium environment, where the engine was in a heat bath with a higher temperature than the measuring apparatus, it could output significantly more power than it cost to run.

All energy on Earth comes from the sun, and it eventually radiates out into space. That directional flow of energy manifests itself in many different ways, such as wind or ocean currents that can be harvested. Understanding the principles behind information engines can help us make better use of that energy.

“We’re coming at [energy harvesting] from a very different point of view, and we hope that this different perspective can lead to some different insights about how to be more efficient,” Bechhoefer says.

The pair is looking forward to working together on other projects in the future. “We were lucky to get a joint grant together. That really helped with the collaboration,” says Bechhoefer.

Sivak, a theorist, and Bechhoefer, an experimentalist, bring complementary approaches to their work, and they have been able to attract trainees who want to work with both. “We have different styles in terms of how we go about mentoring and leading a group,” says Sivak. “Our students and post-docs can benefit from both approaches.”

Here’s a link to and a citation for the paper,

Performance limits of information engines by Johan du Buisson, David A. Sivak, & John Bechhoefer. Advances in Physics: X Volume 9, 2024 – Issue 1 Article: 2352112 DOI: https://doi.org/10.1080/23746149.2024.2352112 Published online: 21 May 2024

This paper is open access.

A kintsugi approach to fusion energy: seeing the beauty (strength) in your flaws

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Kintsugi is the Japanese word for a type of repair that is also art. “Golden joinery” is the literal meaning of the word, from the Traditional Kyoto. Culture_Kintsugi webpage,

Caption: An example of kintsugi repair by David Pike. (Photo courtesy of David Pike) [downloaded from https://traditionalkyoto.com/culture/kintsugi/]

A March 5, 2024 news item on phys.org links the art of kintsugi to fusion energy, specifically, managing plasma, Note: Links have been removed,

In the Japanese art of Kintsugi, an artist takes the broken shards of a bowl and fuses them back together with gold to make a final product more beautiful than the original.

That idea is inspiring a new approach to managing plasma, the super-hot state of matter, for use as a power source. Scientists are using the imperfections in magnetic fields that confine a reaction to improve and enhance the plasma in an approach outlined in a paper in the journal Nature Communications.

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A March 5, 2024 Princeton Plasma Physics Laboratory (PPPL) news release (also on EurekAlert), which originated the news item, describes the research in more detail, Note: Links have been removed,

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“This approach allows you to maintain a high-performance plasma, controlling instabilities in the core and the edge of the plasma simultaneously. That simultaneous control is particularly important and difficult to do. That’s what makes this work special,” said Joseph Snipes of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL). He is PPPL’s deputy head of the Tokamak Experimental Science Department and was a co-author of the paper.

PPPL Physicist Seong-Moo Yang led the research team, which spans various institutions in the U.S. and South Korea. Yang says this is the first time any research team has validated a systematic approach to tailoring magnetic field imperfections to make the plasma suitable for use as a power source. These magnetic field imperfections are known as error fields. 

“Our novel method identifies optimal error field corrections, enhancing plasma stability,” Yang said. “This method was proven to enhance plasma stability under different plasma conditions, for example, when the plasma was under conditions of high and low magnetic confinement.”

Errors that are hard to correct

Error fields are typically caused by minuscule defects in the magnetic coils of the device that holds the plasma, which is called a tokamak. Until now, error fields were only seen as a nuisance because even a very small error field could cause a plasma disruption that halts fusion reactions and can damage the walls of a fusion vessel. Consequently, fusion researchers have spent considerable time and effort meticulously finding ways to correct error fields.

“It’s quite difficult to eliminate existing error fields, so instead of fixing these coil irregularities, we can apply additional magnetic fields surrounding the fusion vessel in a process known as error field correction,” Yang said. 

In the past, this approach would have also hurt the plasma’s core, making the plasma unsuitable for fusion power generation. This time, the researchers were able to eliminate instabilities at the edge of the plasma and maintain the stability of the core. The research is a prime example of how PPPL researchers are bridging the gap between today’s fusion technology and what will be needed to bring fusion power to the electrical grid. 

“This is actually a very effective way of breaking the symmetry of the system, so humans can intentionally degrade the confinement. It’s like making a very tiny hole in a balloon so that it will not explode,” said SangKyeun Kim, a staff research scientist at PPPL and paper co-author. Just as air would leak out of a small hole in a balloon, a tiny quantity of plasma leaks out of the error field, which helps to maintain its overall stability.

Managing the core and the edge of the plasma simultaneously

One of the toughest parts of managing a fusion reaction is getting both the core and the edge of the plasma to behave at the same time. There are ideal zones for the temperature and density of the plasma in both regions, and hitting those targets while eliminating instabilities is tough.

This study demonstrates that adjusting the error fields can simultaneously stabilize both the core and the edge of the plasma. By carefully controlling the magnetic fields produced by the tokamak’s coils, the researchers could suppress edge instabilities, also known as edge localized modes (ELMs), without causing disruptions or a substantial loss of confinement.

“We are trying to protect the device,” said PPPL Staff Research Physicist Qiming Hu, an author of the paper. 

Extending the research beyond KSTAR

The research was conducted using the KSTAR tokamak in South Korea, which stands out for its ability to adjust its magnetic error field configuration with great flexibility. This capability is crucial for experimenting with different error field configurations to find the most effective ones for stabilizing the plasma.

The researchers say their approach has significant implications for the design of future tokamak fusion pilot plants, potentially making them more efficient and reliable. They are currently working on an artificial intelligence (AI) version of their control system to make it more efficient.

“These models are fairly complex; they take a bit of time to calculate. But when you want to do something in a real-time control system, you can only afford a few milliseconds to do a calculation,” said Snipes. “Using AI, you can basically teach the system what to expect and be able to use that artificial intelligence to predict ahead of time what will be necessary to control the plasma and how to implement it in real-time.”

While their new paper highlights work done using KSTAR’s internal magnetic coils, Hu suggests future research with magnetic coils outside of the fusion vessel would be valuable because the fusion community is moving away from the idea of housing such coils inside the vacuum-sealed vessel due to the potential destruction of such components from the extreme heat of the plasma.

Researchers from the Korea Institute of Fusion Energy (KFE), Columbia University, and Seoul National University were also integral to the project.

The research was supported by: the U.S. Department of Energy under contract number DE-AC02-09CH11466; the Ministry of Science and ICT under the KFE R&D Program “KSTAR Experimental Collaboration and Fusion Plasma Research (KFE-EN2401-15)”; the National Research Foundation (NRF) grant No. RS-2023-00281272 funded through the Korean Ministry of Science, Information and Communication Technology and the New Faculty Startup Fund from Seoul National University; the NRF under grants No. 2019R1F1A1057545 and No. 2022R1F1A1073863; the National R&D Program through the NRF funded by the Ministry of Science & ICT (NRF-2019R1A2C1010757).

Here’s a link to and a citation for the paper,

Tailoring tokamak error fields to control plasma instabilities and transport by SeongMoo Yang, Jong-Kyu Park, YoungMu Jeon, Nikolas C. Logan, Jaehyun Lee, Qiming Hu, JongHa Lee, SangKyeun Kim, Jaewook Kim, Hyungho Lee, Yong-Su Na, Taik Soo Hahm, Gyungjin Choi, Joseph A. Snipes, Gunyoung Park & Won-Ha Ko. Nature Communications volume 15, Article number: 1275 (2024) DOI: https://doi.org/10.1038/s41467-024-45454-1 Published: 10 February 2024

This paper is open access.

Proof-of-concept for implantable batteries that run on body’s own oxygen

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Bioenergy harvesting may be here. Well maybe not yet but we are one step closer according to a March 27, 2024 news item on ScienceDaily,

From pacemakers to neurostimulators, implantable medical devices rely on batteries to keep the heart on beat and dampen pain. But batteries eventually run low and require invasive surgeries to replace. To address these challenges, researchers have devised an implantable battery that runs on oxygen in the body. The study shows in rats that the proof-of-concept design can deliver stable power and is compatible with the biological system.

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This is a dynamic image illustrating the device in action,

Caption: Implantable and bio-compatible Na-O2 battery. Credit: Chem/Lv et al.

A March 27, 2024 Cell Press news release on EurekAlert, which originated the news item, provides more detail about the -proof-of-concept device,

“When you think about it, oxygen is the source of our life,” says corresponding author Xizheng Liu, who specializes in energy materials and devices at Tianjin University of Technology. “If we can leverage the continuous supply of oxygen in the body, battery life won’t be limited by the finite materials within conventional batteries.”

To build a safe and efficient battery, the researchers made its electrodes out of a sodium-based alloy and nanoporous gold, a material with pores thousands of times smaller than a hair’s width. Gold has been known for its compatibility with living systems, and sodium is an essential and ubiquitous element in the human body. The electrodes undergo chemical reactions with oxygen in the body to produce electricity. To protect the battery, the researchers encased it within a porous polymer film that is soft and flexible.

The researchers then implanted the battery under the skin on the backs of rats and measured its electricity output. Two weeks later, they found that the battery can produce stable voltages between 1.3 V and 1.4 V, with a maximum power density of 2.6 µW/cm2. Although the output is insufficient to power medical devices, the design shows that harnessing oxygen in the body for energy is possible.

The team also evaluated inflammatory reactions, metabolic changes, and tissue regeneration around the battery. The rats showed no apparent inflammation. Byproducts from the battery’s chemical reactions, including sodium ions, hydroxide ions, and low levels of hydrogen peroxide, were easily metabolized by the body and did not affect the kidneys and liver. The rats healed well after implantation, with the hair on their back completely regrown after four weeks. To the researchers’ surprise, blood vessels also regenerated around the battery.

“We were puzzled by the unstable electricity output right after implantation,” says Liu. “It turned out we had to give the wound time to heal, for blood vessels to regenerate around the battery and supply oxygen, before the battery could provide stable electricity. This is a surprising and interesting finding because it means that the battery can help monitor wound healing.”

Next, the team plans to up the battery’s energy delivery by exploring more efficient materials for the electrodes and optimizing the battery structure and design. Liu also noted that the battery is easy to scale up in production and choosing cost-effective materials can further lower the price. The team’s battery may also find other purposes beyond powering medical devices.

“Because tumor cells are sensitive to oxygen levels, implanting this oxygen-consuming battery around it may help starve cancers. It’s also possible to convert the battery energy to heat to kill cancer cells,” says Liu. “From a new energy source to potential biotherapies, the prospects for this battery are exciting.”

Here’s a link to and a citation for the paper,

Implantable and bio-compatible Na-O2 battery by Yang Lv, Xizheng Liu, Jiucong Liu, Pingli Wu, Yonggang Wang, Yi Ding. Chem DOI: https://doi.org/10.1016/j.chempr.2024.02.012 In press, corrected proof Published online: March 27, 2024 Copyright © 2024 Elsevier Inc.

The paper appears to be open access.