Tag Archives: Korea Advanced Institute of Science and Technology (KAIST)

Next-generation neuromorphic, semiconductor-based, ultra-small computing chip learns and corrects itself

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This is yet another of my memristor posts. Researchers from Korea Advanced Institute of Science and Technology (KAIST) have some exciting news according to a January 21, 2025 news item on ScienceDaily,

Existing computer systems have separate data processing and storage devices, making them inefficient for processing complex data like AI. A KAIST research team has developed a memristor-based integrated system similar to the way our brain processes information. It is now ready for application in various devices including smart security cameras, allowing them to recognize suspicious activity immediately without having to rely on remote cloud servers, and medical devices with which it can help analyze health data in real time.

KAIST (President Kwang Hyung Lee) announced on the 17th of January [2025] that the joint research team of Professor Shinhyun Choi and Professor Young-Gyu Yoon of the School of Electrical Engineering has developed a next-generation neuromorphic semiconductor-based ultra-small computing chip that can learn and correct errors on its own.

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A January 17, 2025 KAIST press release (also on EurekAlert but published January 20, 2025), which originated the news item, provides more information,

What is special about this computing chip is that it can learn and correct errors that occur due to non-ideal characteristics that were difficult to solve in existing neuromorphic devices. For example, when processing a video stream, the chip learns to automatically separate a moving object from the background, and it becomes better at this task over time.

This self-learning ability has been proven by achieving accuracy comparable to ideal computer simulations in real-time image processing. The research team’s main achievement is that it has completed a system that is both reliable and practical, beyond the development of brain-like components.

The research team has developed the world’s first memristor-based integrated system that can adapt to immediate environmental changes, and has presented an innovative solution that overcomes the limitations of existing technology.

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At the heart of this innovation is a next-generation semiconductor device called a memristor*. The variable resistance characteristics of this device can replace the role of synapses in neural networks, and by utilizing it, data storage and computation can be performed simultaneously, just like our brain cells.

*Memristor: A compound word of memory and resistor, next-generation electrical device whose resistance value is determined by the amount and direction of charge that has flowed between the two terminals in the past.

The research team designed a highly reliable memristor that can precisely control resistance changes and developed an efficient system that excludes complex compensation processes through self-learning. This study is significant in that it experimentally verified the commercialization possibility of a next-generation neuromorphic semiconductor-based integrated system that supports real-time learning and inference.

This technology will revolutionize the way artificial intelligence is used in everyday devices, allowing AI tasks to be processed locally without relying on remote cloud servers, making them faster, more privacy-protected, and more energy-efficient.

“This system is like a smart workspace where everything is within arm’s reach instead of having to go back and forth between desks and file cabinets,” explained KAIST researchers Hakcheon Jeong and Seungjae Han, who led the development of this technology. “This is similar to the way our brain processes information, where everything is processed efficiently at once at one spot.”

The research was conducted with Hakcheon Jeong and Seungjae Han, the students of Integrated Master’s and Doctoral Program at KAIST School of Electrical Engineering being the co-first authors, the results of which was published online in the international academic journal, Nature Electronics, on January 8, 2025.

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

Self-supervised video processing with self-calibration on an analogue computing platform based on a selector-less memristor array by Hakcheon Jeong, Seungjae Han, See-On Park, Tae Ryong Kim, Jongmin Bae, Taehwan Jang, Yoonho Cho, Seokho Seo, Hyun-Jun Jeong, Seungwoo Park, Taehoon Park, Juyoung Oh, Jeongwoo Park, Kwangwon Koh, Kang-Ho Kim, Dongsuk Jeon, Inyong Kwon, Young-Gyu Yoon & Shinhyun Choi. Nature Electronics volume 8, pages 168–178 (2025) DOI: https://doi.org/10.1038/s41928-024-01318-6 Published: 08 January 2025 Issue Date: February 2025

This paper is behind a paywall.

Novel visible light communication encryption technology using chiral nanoparticles

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One of the most intriguing (yes, it’s a pun) encryption stories (for me) is centuries old and concerns Mary Queen of Scots, from a February 10, 2023 article by Meilan Solly for Smithsonian Magazine, Note: Links have been removed,

Over the course of her 19 years in captivity, Mary, Queen of Scots, wrote thousands of letters to ambassadors, government officials, fellow monarchs and conspirators alike. Most of these missives had the same underlying goal: securing the deposed Scottish queen’s freedom. After losing her throne in 1567, Mary had fled to England, hoping to find refuge at her cousin Elizabeth I’s court. (Mary’s paternal grandmother, Margaret Tudor, was the sister of Elizabeth’s father, Henry VIII.) Instead, the English queen imprisoned Mary, keeping her under house arrest for nearly two decades before ordering her execution in 1587.

Mary’s letters have long fascinated scholars and the public, providing a glimpse into her relentless efforts to secure her release. But the former queen’s correspondence often raises more questions than it answers, in part because Mary took extensive steps to hide her messages from the prying eyes of Elizabeth’s spies. In addition to folding the pages with a technique known as letterlocking, she employed ciphers and codes of varying complexity.

More than 400 years after Mary’s death, a chance discovery by a trio of code breakers is offering new insights into the queen’s final years. As the researchers write in the journal Cryptologia, they originally decided to examine a cache of coded notes housed at the National Library of France as part of a broader push to “locate, digitize, transcribe, decipher and analyze” historic ciphers. Those pages turned out to be 57 of Mary’s encrypted letters, the majority of which were sent to Michel de Castelnau, the French ambassador to England, between 1578 and 1584. All but seven were previously thought to be lost.

Interspersed with a collection of early 16th-century Italian papers, the documents were written in mysterious symbols that offered no clues “as to their sender, recipients or date,” lead author George Lasry, a computer scientist and cryptographer based in Israel, tells Smithsonian magazine. It was only when the scholars spotted the word “Walsingham”—the last name of Elizabeth’s spymaster, Francis Walsingham—that they realized the letters’ significance.

“This was the ‘bingo moment,’” Lasry says. “We were very excited.”

Before getting too excited, the trio set out to confirm whether the letters were already known to historians. While they found copies of a few in British archives, “50 or so are new to historians—and a real gold mine for them,” says Lasry. In total, the letters contain 50,000 words of deciphered material.

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Fascinating, non?

An October 10, 2024 news item on Nanowerk sheds light (more wordplay) on a contemporary approach to encryption,

Seoul National University(SNU) College of Engineering announced that a joint research team led by Professor Ki Tae Nam from the Department of Materials Science and Engineering at SNU and Professor Junil Choi from the Korea Advanced Institute of Science and Technology (KAIST) has developed a novel visible light communication encryption technology with high security using chiral nanoparticles.

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A September 30, 2024 Seoul National University (SNU) press release (also on EurekAlert but published on October 10, 2024), which originated the news item, describes the research in more detail,

Just as a lighthouse provides a guiding beam in the vast darkness of the sea, light-based information transmission has been a crucial means of communication throughout human history. Recently, next-generation communication technology based on visible light, which possesses high frequencies and linearity, has gained attention. It offers advantages such as integration with lighting systems and is free from the electromagnetic interference associated with conventional communication networks. With high security and fast transmission speeds, visible light communication is particularly suitable for local communication systems, especially in military operations involving vehicles, drones, and personnel.

In addition to intensity and wavelength (color), light can carry a vast amount of information through polarization. For instance, 3D movies use polarized filters to deliver two different polarized images to the viewer’s eyes, creating a sense of depth. Recently, efforts have been made to improve the security and performance of visible light communication, including the incorporation of technologies related to polarization, such as quantum information communication based on the superposition of polarization.

The SNU-KAIST joint research team focused on how light polarization can be significantly modulated through interaction with nanomaterials. In this study, they developed an innovative visible light communication encryption technology based on new materials. The core of this technology lies in chiral nanomaterials, which exhibit a symmetric structure when viewed in a mirror but do not overlap. These materials can significantly adjust the tilt of the polarization axis or its rotational properties. Having previously published two papers in 2018 and 2022 in the prestigious journal Nature on “the synthesis and optical device application of chiral nanoparticles with world-class polarization control performance,” the research team has now introduced a visible light communication encryption technology that cannot be replicated or intercepted without detailed information about the nanoparticles.

The chiral nanoparticles used in this technology are created by twisting their crystal structure using biomolecules like proteins and DNA, which possess natural chirality. The optical properties of these nanoparticles cannot be replicated without complete sequence information of the biomolecules used in their synthesis. Therefore, chiral nanoparticles function like fingerprints or unclonable keys in visible light communication, allowing only the receiver with the actual nanoparticles to correctly decode the information. This encryption technology is expected to have significant utility in secure point-to-point communication systems, such as those used in military operations involving drones.

Furthermore, the research team developed a spatiotemporal polarization control device capable of transmitting encrypted polarization information. By combining quantum nanorods, which efficiently emit polarized light, with nanowire materials that provide rotational properties to the light, they used 3D printing to fabricate a polarization control device with hundreds of micrometers of spatial resolution and nanoseconds of temporal resolution, allowing all polarization states to be represented without restriction. The transmitting unit can encrypt and transmit polarization information in a form suited to the polarization control properties of the nanoparticles using this device. This technology is expected to be the foundation for mass production of devices that can control spatiotemporal polarization without being constrained by form factor.

Professor Ki Tae Nam from SNU’s Department of Materials Science and Engineering said, “This research, which actively combines new material technologies with communication technologies, played a crucial role in developing the world’s first and only visible light communication encryption technology. We expect this technology to not only contribute to national defense but also be commercialized rapidly in industrial fields like display technology.” Professor Junil Choi from KAIST’s School of Electrical Engineering added, “This outstanding research result was achieved through joint efforts between material science and electrical engineering experts. In the future, we aim to further develop visible light communication technology based on nanoparticles to create communication systems that are fundamentally impossible to eavesdrop on.” Co-first author Jeong Hyun Han also stated, “We anticipate that this encryption system will act as a platform with great scalability and impact in the field of optical information transmission based on polarization.”

This research was supported by the Future Defense Technology Development Program of the Agency for Defense Development, the Basic Research Laboratory Program of the National Research Foundation of Korea, and private support from LG Display. The research outcome, which has been recognized for its significance, was published in the prestigious multidisciplinary journal Nature Communications on September 27 [2024].

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

Spatiotemporally modulated full-polarized light emission for multiplexed optical encryption by Jiawei Lv, Jeong Hyun Han, Geonho Han, Seongmin An, Seung Ju Kim, Ryeong Myeong Kim, Jung‐El Ryu, Rena Oh, Hyuckjin Choi, In Han Ha, Yoon Ho Lee, Minje Kim, Gyeong-Su Park, Ho Won Jang, Junsang Doh, Junil Choi & Ki Tae Nam. Nature Communications volume 15, Article number: 8257 (2024) DOI: https://doi.org/10.1038/s41467-024-52358-7 Published: 27 September 2024

This paper is open access.

Striking similarity between memory processing of artificial intelligence (AI) models and hippocampus of the human brain

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A December 18, 2023 news item on ScienceDaily shifted my focus from hardware to software when considering memory in brainlike (neuromorphic) computing,

An interdisciplinary team consisting of researchers from the Center for Cognition and Sociality and the Data Science Group within the Institute for Basic Science (IBS) [Korea] revealed a striking similarity between the memory processing of artificial intelligence (AI) models and the hippocampus of the human brain. This new finding provides a novel perspective on memory consolidation, which is a process that transforms short-term memories into long-term ones, in AI systems.

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A November 28 (?), 2023 IBS press release (also on EurekAlert but published December 18, 2023, which originated the news item, describes how the team went about its research,

In the race towards developing Artificial General Intelligence (AGI), with influential entities like OpenAI and Google DeepMind leading the way, understanding and replicating human-like intelligence has become an important research interest. Central to these technological advancements is the Transformer model [Figure 1], whose fundamental principles are now being explored in new depth.

The key to powerful AI systems is grasping how they learn and remember information. The team applied principles of human brain learning, specifically concentrating on memory consolidation through the NMDA receptor in the hippocampus, to AI models.

The NMDA receptor is like a smart door in your brain that facilitates learning and memory formation. When a brain chemical called glutamate is present, the nerve cell undergoes excitation. On the other hand, a magnesium ion acts as a small gatekeeper blocking the door. Only when this ionic gatekeeper steps aside, substances are allowed to flow into the cell. This is the process that allows the brain to create and keep memories, and the gatekeeper’s (the magnesium ion) role in the whole process is quite specific.

The team made a fascinating discovery: the Transformer model seems to use a gatekeeping process similar to the brain’s NMDA receptor [see Figure 1]. This revelation led the researchers to investigate if the Transformer’s memory consolidation can be controlled by a mechanism similar to the NMDA receptor’s gating process.

In the animal brain, a low magnesium level is known to weaken memory function. The researchers found that long-term memory in Transformer can be improved by mimicking the NMDA receptor. Just like in the brain, where changing magnesium levels affect memory strength, tweaking the Transformer’s parameters to reflect the gating action of the NMDA receptor led to enhanced memory in the AI model. This breakthrough finding suggests that how AI models learn can be explained with established knowledge in neuroscience.

C. Justin LEE, who is a neuroscientist director at the institute, said, “This research makes a crucial step in advancing AI and neuroscience. It allows us to delve deeper into the brain’s operating principles and develop more advanced AI systems based on these insights.”

CHA Meeyoung, who is a data scientist in the team and at KAIST [Korea Advanced Institute of Science and Technology], notes, “The human brain is remarkable in how it operates with minimal energy, unlike the large AI models that need immense resources. Our work opens up new possibilities for low-cost, high-performance AI systems that learn and remember information like humans.”

What sets this study apart is its initiative to incorporate brain-inspired nonlinearity into an AI construct, signifying a significant advancement in simulating human-like memory consolidation. The convergence of human cognitive mechanisms and AI design not only holds promise for creating low-cost, high-performance AI systems but also provides valuable insights into the workings of the brain through AI models.

Fig. 1: (a) Diagram illustrating the ion channel activity in post-synaptic neurons. AMPA receptors are involved in the activation of post-synaptic neurons, while NMDA receptors are blocked by magnesium ions (Mg²⁺) but induce synaptic plasticity through the influx of calcium ions (Ca²⁺) when the post-synaptic neuron is sufficiently activated. (b) Flow diagram representing the computational process within the Transformer AI model. Information is processed sequentially through stages such as feed-forward layers, layer normalization, and self-attention layers. The graph depicting the current-voltage relationship of the NMDA receptors is very similar to the nonlinearity of the feed-forward layer. The input-output graph, based on the concentration of magnesium (α), shows the changes in the nonlinearity of the NMDA receptors. Courtesy: IBS

This research was presented at the 37th Conference on Neural Information Processing Systems (NeurIPS 2023) before being published in the proceedings, I found a PDF of the presentation and an early online copy of the paper before locating the paper in the published proceedings.

PDF of presentation: Transformer as a hippocampal memory consolidation model based on NMDAR-inspired nonlinearity

PDF copy of paper:

Transformer as a hippocampal memory consolidation model based on NMDAR-inspired nonlinearity by Dong-Kyum Kim, Jea Kwon, Meeyoung Cha, C. Justin Lee.

This paper was made available on OpenReview.net:

OpenReview is a platform for open peer review, open publishing, open access, open discussion, open recommendations, open directory, open API and open source.

It’s not clear to me if this paper is finalized or not and I don’t know if its presence on OpenReview constitutes publication.

Finally, the paper published in the proceedings,

Transformer as a hippocampal memory consolidation model based on NMDAR-inspired nonlinearity by Dong Kyum Kim, Jea Kwon, Meeyoung Cha, C. Justin Lee. Part of Advances in Neural Information Processing Systems 36 (NeurIPS 2023) Main Conference Track

This link will take you to the abstract, access the paper by clicking on the Paper tab.

A graphene-inorganic-hybrid micro-supercapacitor made of fallen leaves

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I wonder if this means the end to leaf blowers. That is almost certainly wishful thinking as the researchers don’t seem to be concerned with how the leaves are gathered.

The schematic illustration of the production of femtosecond laser-induced graphene. Courtesy of KAIST

A January 27, 2022 news item on Nanowerk announces the work (Note: A link has been removed),

A KAIST [Korea Advanced Institute of Science and Technology] research team has developed graphene-inorganic-hybrid micro-supercapacitors made of fallen leaves using femtosecond laser direct laser writing (Advanced Functional Materials, “Green Flexible Graphene-Inorganic-Hybrid Micro-Supercapacitors Made of Fallen Leaves Enabled by Ultrafast Laser Pulses”).

A January 27, 2022 KAIST press release (also on EurekAlert but published January 26, 2022), which originated the news item, delves further into the research,

The rapid development of wearable electronics requires breakthrough innovations in flexible energy storage devices in which micro-supercapacitors have drawn a great deal of interest due to their high power density, long lifetimes, and short charging times. Recently, there has been an enormous increase in waste batteries owing to the growing demand and the shortened replacement cycle in consumer electronics. The safety and environmental issues involved in the collection, recycling, and processing of such waste batteries are creating a number of challenges.

Forests cover about 30 percent of the Earth’s surface and produce a huge amount of fallen leaves. This naturally occurring biomass comes in large quantities and is completely biodegradable, which makes it an attractive sustainable resource. Nevertheless, if the fallen leaves are left neglected instead of being used efficiently, they can contribute to fire hazards, air pollution, and global warming.

To solve both problems at once, a research team led by Professor Young-Jin Kim from the Department of Mechanical Engineering and Dr. Hana Yoon from the Korea Institute of Energy Research developed a novel technology that can create 3D porous graphene microelectrodes with high electrical conductivity by irradiating femtosecond laser pulses on the leaves in ambient air. This one-step fabrication does not require any additional materials or pre-treatment. 

They showed that this technique could quickly and easily produce porous graphene electrodes at a low price, and demonstrated potential applications by fabricating graphene micro-supercapacitors to power an LED and an electronic watch. These results open up a new possibility for the mass production of flexible and green graphene-based electronic devices.

Professor Young-Jin Kim said, “Leaves create forest biomass that comes in unmanageable quantities, so using them for next-generation energy storage devices makes it possible for us to reuse waste resources, thereby establishing a virtuous cycle.” 

This research was published in Advanced Functional Materials last month and was sponsored by the Ministry of Agriculture Food and Rural Affairs, the Korea Forest Service, and the Korea Institute of Energy Research.

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

Green Flexible Graphene–Inorganic-Hybrid Micro-Supercapacitors Made of Fallen Leaves Enabled by Ultrafast Laser Pulses by Truong-Son Dinh Le, Yeong A. Lee, Han Ku Nam, Kyu Yeon Jang, Dongwook Yang, Byunggi Kim, Kanghoon Yim, Seung-Woo Kim, Hana Yoon, Young-Jin Kim. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202107768 First published: 05 December 2021

This paper is behind a paywall.

Self-assembling salt-crystal nanoscale ‘origami’ balls

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This November 4, 2021 news item on Nanowerk features research from the Korea Advanced Institute of Science and Technology (KAIST),

Researchers have developed a technique whereby they can spontaneously encapsulate microscopic droplets of water and oil emulsion in a tiny sphere made of salt crystals—sort of like a minute, self-constructing origami soccer ball filled with liquid. The process, which they are calling ‘crystal capillary origami,’could be used in a range of fields from more precise drug delivery to nanoscale medical devices.

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A November 4, 2021 KAIST press release (also on EurekAlert), which originated the news item, goes on to provide technical detail,

Capillary action, or ‘capillarity,’ will be familiar to most people as the way that water or other liquids can move up narrow tubes or other porous materials seemingly in defiance of gravity (for example within the vascular systems of plants, or even more simply, the drawing up of paint between the hairs of a paintbrush). This effect is due to the forces of cohesion (the tendency of a liquid’s molecules to stick together), which results in surface tension, and adhesion (their tendency to stick to the surface of other substances). The strength of the capillarity depends on the chemistry of the liquid, the chemistry of the porous material, and on the other forces acting on them both. For example, a liquid with lower surface tension than water would not be able to hold up a water strider insect. 

Less well known is a related phenomenon, elasto-capillarity, that takes advantage of the relationship between capillarity and the elasticity of a very tiny flat sheet of a solid material. In certain circumstances, the capillary forces can overcome the elastic bending resistance of the sheet. 

This relationship can be exploited to create ‘capillary origami,’ or three-dimensional structures. When a liquid droplet is placed on the flat sheet, the latter can spontaneously encapsulate the former due to surface tension. Capillary origami can take on other forms including wrinkling, buckling, or self-folding into other shapes. The specific geometrical shape that the 3D capillary origami structure ends up taking is determined by both the chemistry of the flat sheet and that of the liquid, and by carefully designing the shape and size of the sheet.

There is one big problem with these small devices, however. “These conventional self-assembled origami structures cannot be completely spherical and will always have discontinuous boundaries, or what you might call ‘edges,’ as a result of the original two-dimensional shape of the sheet,” said Kwangseok Park, a lead researcher on the project. He added, “These edges could turn out to be future defects with the potential for failure in the face of increased stress.” Non-spherical particles are also known to be more disadvantageous than spherical particles in terms of cellular uptake. 

Professor Hyoungsoo Kim from the Department of Mechanical Engineering explained, “This is why researchers have long been on the hunt for substances that could produce a fully spherical capillary origami structure.” 

The authors of the study have demonstrated such an origami sphere for the first time. They showed how instead of a flat sheet, the growth of salt-crystals can perform capillary origami action in a similar manner. What they call ‘crystal capillary origami’ spontaneously constructs a smooth spherical shell capsule from these same surface tension effects, but now the spontaneous encapsulation of a liquid is determined by the elasto-capillary conditions of growing crystals.

Here, the term ‘salt’ refers to a compound of one positively charged ion and another negatively charged. Table salt, or sodium chloride, is just one example of a salt. The researchers used four other salts: calcium propionate, sodium salicylate, calcium nitrate tetrahydrate, and sodium bicarbonate to envelop a water-oil emulsion. Normally, a salt such as sodium chloride has a cubical crystal structure, but these four salts form plate-like structures as crystallites or ‘grains’ (the microscopic shape that forms when a crystal first starts to grow) instead. These plates then self-assemble into perfect spheres.

Using scanning electron microscopy and X-ray diffraction analysis, they investigated the mechanism of such formation and concluded that it was ‘Laplace pressure’ that drives the crystallite plates to cover the emulsion surface. Laplace pressure describes the pressure difference between the interior and exterior of a curved surface caused by the surface tension at the interface between the two substances, in this case between the salt water and the oil.

The researchers hope that these self-assembling nanostructures can be used for encapsulation applications in a range of sectors, from the food industry and cosmetics to drug delivery and even tiny medical devices.

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

Crystal capillary origami capsule with self-assembled nanostructures by
Kwangseok Park and Hyoungsoo Kim. Nanoscale, 2021, 13, 14656-14665 DOI: https://doi.org/10.1039/D1NR02456F First published 19 Jul 2021

This paper is behind a paywall.

Highly scalable neuromorphic (brainlike) computing hardware

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This work comes from Korea (or South Korea, if you prefer). An August 5, 2021 news item on ScienceDaily announces a step forward in the future production of neuromorphic hardware,

KAIST [The Korea Advanced Institute of Science and Technology] researchers fabricated a brain-inspired highly scalable neuromorphic hardware by co-integrating single transistor neurons and synapses. Using standard silicon complementary metal-oxide-semiconductor (CMOS) technology, the neuromorphic hardware is expected to reduce chip cost and simplify fabrication procedures.

Caption: Single transistor neurons and synapses fabricated using a standard silicon CMOS process. They are co-integrated on the same 8-inch wafer. Credit: KAIST

An August 5, 2021 The Korea Advanced Institute of Science and Technology (KAIST) press release (also on EurekAlert), which originated the news item, provides more detail about the research,

The research team led by Yang-Kyu Choi and Sung-Yool Choi produced a [sic] neurons and synapses based on single transistor for highly scalable neuromorphic hardware and showed the ability to recognize text and face images. This research was featured in Science Advances on August 4 [2021].

Neuromorphic hardware has attracted a great deal of attention because of its artificial intelligence functions, but consuming ultra-low power of less than 20 watts by mimicking the human brain. To make neuromorphic hardware work, a neuron that generates a spike when integrating a certain signal, and a synapse remembering the connection between two neurons are necessary, just like the biological brain. However, since neurons and synapses constructed on digital or analog circuits occupy a large space, there is a limit in terms of hardware efficiency and costs. Since the human brain consists of about 1011 neurons and 1014 synapses, it is necessary to improve the hardware cost in order to apply it to mobile and IoT devices.

To solve the problem, the research team mimicked the behavior of biological neurons and synapses with a single transistor, and co-integrated them onto an 8-inch wafer. The manufactured neuromorphic transistors have the same structure as the transistors for memory and logic that are currently mass-produced. In addition, the neuromorphic transistors proved for the first time that they can be implemented with a ‘Janus structure’ that functions as both neuron and synapse, just like coins have heads and tails.

Professor Yang-Kyu Choi said that this work can dramatically reduce the hardware cost by replacing the neurons and synapses that were based on complex digital and analog circuits with a single transistor. “We have demonstrated that neurons and synapses can be implemented using a single transistor,” said Joon-Kyu Han, the first author. “By co-integrating single transistor neurons and synapses on the same wafer using a standard CMOS process, the hardware cost of the neuromorphic hardware has been improved, which will accelerate the commercialization of neuromorphic hardware,” Han added.This research was supported by the National Research Foundation (NRF) and IC Design Education Center (IDEC). 

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

Cointegration of single-transistor neurons and synapses by nanoscale CMOS fabrication for highly scalable neuromorphic hardware by Joon-Kyu Han, Jungyeop Oh, Gyeong-Jun Yun, Dongeun Yoo, Myung-Su Kim, Ji-Man Yu, Sung-Yool Choi, and Yang-Kyu Choi. Science Advances 04 Aug 2021: Vol. 7, no. 32, eabg8836 DOI: 10.1126/sciadv.abg8836

This article appears to be open access.

Smart film lets windows switch autonomously

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This work from Korean research scientists gives me some hope that smart windows will one day be the norm. From a June 2, 2020 Korea Advanced Institute of Science and Technology (KAIST) press release (also on EurekAlert),

Researchers have developed a new easy-to-use smart optical film technology that allows smart window devices to autonomously switch between transparent and opaque states in response to the surrounding light conditions.

The proposed 3D hybrid nanocomposite film with a highly periodic network structure has empirically demonstrated its high speed and performance, enabling the smart window to quantify and self-regulate its high-contrast optical transmittance. As a proof of concept, a mobile-app-enabled smart window device for Internet of Things (IoT) applications has been realized using the proposed smart optical film with successful expansion to the 3-by-3-inch scale. This energy-efficient and cost-effective technology holds great promise for future use in various applications that require active optical transmission modulation.

Flexible optical transmission modulation technologies for smart applications including privacy-protection windows, zero-energy buildings, and beam projection screens have been in the spotlight in recent years. Conventional technologies that used external stimuli such as electricity, heat, or light to modulate optical transmission had only limited applications due to their slow response speeds, unnecessary color switching, and low durability, stability, and safety.

The optical transmission modulation contrast achieved by controlling the light scattering interfaces on non-periodic 2D surface structures that often have low optical density such as cracks, wrinkles, and pillars is also generally low. In addition, since the light scattering interfaces are exposed and not subject to any passivation, they can be vulnerable to external damage and may lose optical transmission modulation functions. Furthermore, in-plane scattering interfaces that randomly exist on the surface make large-area modulation with uniformity difficult.

Inspired by these limitations, a KAIST research team led by Professor Seokwoo Jeon from the Department of Materials Science and Engineering and Professor Jung-Wuk Hong of the Civil and Environmental Engineering Department used proximity-field nanopatterning (PnP) technology that effectively produces highly periodic 3D hybrid nanostructures, and an atomic layer deposition (ALD) technique that allows the precise control of oxide deposition and the high-quality fabrication of semiconductor devices.

The team then successfully produced a large-scale smart optical film with a size of 3 by 3 inches in which ultrathin alumina nanoshells are inserted between the elastomers in a periodic 3D nanonetwork.

This “mechano-responsive” 3D hybrid nanocomposite film with a highly periodic network structure is the largest smart optical transmission modulation film that exists. The film has been shown to have state-of-the-art optical transmission modulation of up to 74% at visible wavelengths from 90% initial transmission to 16% in the scattering state under strain. Its durability and stability were proved by more than 10,000 tests of harsh mechanical deformation including stretching, releasing, bending, and being placed under high temperatures of up to 70°C. When this film was used, the transmittance of the smart window device was adjusted promptly and automatically within one second in response to the surrounding light conditions. Through these experiments, the underlying physics of optical scattering phenomena occurring in the heterogeneous interfaces were identified. Their findings were reported in the online edition of Advanced Science on April 26 [2020]. KAIST Professor Jong-Hwa Shin’s group and Professor Young-Seok Shim at Silla University also collaborated on this project.

Donghwi Cho, a PhD candidate in materials science and engineering at KAIST and co-lead author of the study, said, “Our smart optical film technology can better control high-contrast optical transmittance by relatively simple operating principles and with low energy consumption and costs.”

“When this technology is applied by simply attaching the film to a conventional smart window glass surface without replacing the existing window system, fast switching and uniform tinting are possible while also securing durability, stability, and safety. In addition, its wide range of applications for stretchable or rollable devices such as wall-type displays for a beam projection screen will also fulfill aesthetic needs,” he added.

Here’s an image illustrating how the composite scatters light (I think),

Caption: Design concept of and fabrication procedures for the 3D scatterer. Credit: KAIST

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

High‐Contrast Optical Modulation from Strain‐Induced Nanogaps at 3D Heterogeneous Interfaces by Donghwi Cho, Prof. Young‐Seok Shim, Dr. Jae‐Wook Jung, Sang‐Hyeon Nam, Seokhwan Min, Dr. Sang‐Eon Lee, Youngjin Ham, Prof. Kwangjae Lee, Prof. Junyong Park, Prof. Jonghwa Shin, Prof. Jung‐Wuk Hong, and Prof. Seokwoo Jeon. Advanced Science DOI: https://doi.org/10.1002/advs.201903708 First published: 26 April 2020

This paper is open access.

Korean researchers extend food shelf *life* with nanomicrobial coating

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These Korean scientists have applied their new coating to food and to shoe insoles as they test various uses for their technology. From an Aug. 11, 2017 news item on Nanowerk,

The edible coating on produce has drawn a great deal of attention in the food and agricultural industry. It could not only prolong postharvest shelf life of produce against external changes in the environment but also provide additional nutrients to be useful for human health. However, most versions of the coating have had intrinsic limitations in their practical application.

First, highly specific interactions between coating materials and target surfaces are required for a stable and durable coating. Even further, the coating of bulk substrates, such as fruits, is time consuming or is not achievable in the conventional solution-based coating. In this respect, material-independent and rapid coating strategies are highly demanded.

The research team led by Professor Insung Choi of the Department of Chemistry developed a sprayable nanocoating technique using plant-derived polyphenol that can be applied to any surface.

An Aug. 10, 2017 KAIST (Korea Advanced Institute of Science and Technology) press release, which originated the news item, expands on the theme,

Polyphenols, a metabolite of photosynthesis, possess several hydroxyl groups and are found in a large number of plants showing excellent antioxidant properties. They have been widely used as a nontoxic food additive and are known to exhibit antibacterial, as well as potential anti-carcinogenic capabilities. Polyphenols can also be used with iron ions, which are naturally found in the body, to form an adhesive complex, which has been used in leather tanning, ink, etc.

The research team combined these chemical properties of polyphenol-iron complexes with spray techniques to develop their nanocoating technology. Compared to conventional immersion coating methods, which dip substrates in specialized coating solutions, this spray technique can coat the select areas more quickly. The spray also prevents cross contamination, which is a big concern for immersion methods. The research team has showcased the spray’s ability to coat a variety of different materials, including metals, plastics, glass, as well as textile fabrics. The polyphenol complex has been used to form antifogging films on corrective lenses, as well as antifungal treatments for shoe soles, demonstrating the versatility of their technique.

Furthermore, the spray has been used to coat produce with a naturally antibacterial, edible film. The coatings significantly improved the shelf life of tangerines and strawberries, preserving freshness beyond 28 days and 58 hours, respectively. (Uncoated fruit decomposed and became moldy under the same conditions). See the image below.

 

a –I, II: Uncoated and coated tangerines incubated for 14 and 28 days in daily-life settings

b –I: Uncoated and coated strawberries incubated for 58 hours in daily-life settings

b –II: Statistical investigation of the resulting edibility.

Professor Choi said, “Nanocoating technologies are still in their infancy, but they have untapped potential for exciting applications. As we have shown, nanocoatings can be easily adapted for several different uses, and the creative combination of existing nanomaterials and coating methods can synergize to unlock this potential.”

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

Antimicrobial spray nanocoating of supramolecular Fe(III)-tannic acid metal-organic coordination complex: applications to shoe insoles and fruits by Ji Park, Sohee Choi, Hee Moon, Hyelin Seo, Ji Kim, Seok-Pyo Hong, Bong Lee, Eunhye Kang, Jinho Lee, Dong Ryu, & Insung S. Choi. Scientific Reports 7, Article number: 6980 (2017) doi:10.1038/s41598-017-07257-x Published online: 01 August 2017

This paper is open access.

*’life’ added to correct headline on Sept. 4, 2017.

Graphene speakers for mobile devices?

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Credit: American Chemical Society

Credit: American Chemical Society

This speaker doesn’t look its ready for the marketplace yet but it does possess a rather nifty component, graphene aerogel. A Sept. 7, 2016 news item on phys.org briefly describes the scientists’ accomplishment,

Graphene has been hailed as a wonder material since it was first made more than a decade ago. It’s showing up in an increasing number of products, including coatings, sports equipment and even light bulbs. Now scientists are one step closer to making graphene audio speakers for mobile devices. They report in the journal ACS Applied Materials & Interfaces a simple way to fabricate once-elusive thermoacoustic speakers using the ultra-thin material.

A Sept. 7, 2016 American Chemical Society (ACS) news release (also on EurekAlert), which originated the news item, offers an explanation of how these new speakers differ from conventional speakers and a brief description of graphene aerogel (I once saw aerogel described as ‘solid smoke’),

Conventional speakers today rely on many mechanical parts that vibrate to create sound and must be encased in an acoustic cavity — essentially, in a box. But this approach complicates manufacturing and limits where listeners can put their speakers. Scientists have been pursuing ways around this by turning to a principle conceived of more than a century ago: thermoacoustics, the production of sound by rapidly heating and cooling a material rather than through vibrations. Science has caught up to this concept largely thanks to the development of graphene, which is highly conductive and durable. Some efforts to make graphene speakers have succeeded, but making them en masse would be challenging. Jung-Woo Choi, Byungjin Cho, Sang Ouk Kim and colleagues at Korea Advanced Institute of Science and Technology (KAIST) wanted to come up with a simpler approach.

The researchers developed a two-step (freeze-drying and reduction/doping) method for making a sound-emitting graphene aerogel. An array of 16 of these aerogels comprised a speaker that could operate on 40 Watts of power with a sound quality comparable to that of other graphene-based sound systems. The researchers say their fabrication method is practical and could lend itself to mass production for use in mobile devices and other applications. Because the speaker is thin and doesn’t vibrate, it could fit snugly against walls and even curved surfaces.

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

Application of N-Doped Three-Dimensional Reduced Graphene Oxide Aerogel to Thin Film Loudspeaker by Choong Sun Kim, Kyung Eun Lee, Jung-Min Lee, Sang Ouk Kim, Byung Jin Cho, and Jung-Woo Choi. ACS Appl. Mater. Interfaces, 2016, 8 (34), pp 22295–22300 DOI: 10.1021/acsami.6b03618 Publication Date (Web): August 17, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Korea Advanced Institute of Science and Technology (KAIST) at summer 2016 World Economic Forum in China

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From the Ideas Lab at the 2016 World Economic Forum at Davos to offering expertise at the 2016 World Economic Forum in Tanjin, China that is taking place from June 26 – 28, 2016.

Here’s more from a June 24, 2016 KAIST news release on EurekAlert,

Scientific and technological breakthroughs are more important than ever as a key agent to drive social, economic, and political changes and advancements in today’s world. The World Economic Forum (WEF), an international organization that provides one of the broadest engagement platforms to address issues of major concern to the global community, will discuss the effects of these breakthroughs at its 10th Annual Meeting of the New Champions, a.k.a., the Summer Davos Forum, in Tianjin, China, June 26-28, 2016.

Three professors from the Korea Advanced Institute of Science and Technology (KAIST) will join the Annual Meeting and offer their expertise in the fields of biotechnology, artificial intelligence, and robotics to explore the conference theme, “The Fourth Industrial Revolution and Its Transformational Impact.” The Fourth Industrial Revolution, a term coined by WEF founder, Klaus Schwab, is characterized by a range of new technologies that fuse the physical, digital, and biological worlds, such as the Internet of Things, cloud computing, and automation.

Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department will speak at the Experts Reception to be held on June 25, 2016 on the topic of “The Summer Davos Forum and Science and Technology in Asia.” On June 27, 2016, he will participate in two separate discussion sessions.

In the first session entitled “What If Drugs Are Printed from the Internet?” Professor Lee will discuss the future of medicine being impacted by advancements in biotechnology and 3D printing technology with Nita A. Farahany, a Duke University professor, under the moderation of Clare Matterson, the Director of Strategy at Wellcome Trust in the United Kingdom. The discussants will note recent developments made in the way patients receive their medicine, for example, downloading drugs directly from the internet and the production of yeast strains to make opioids for pain treatment through systems metabolic engineering, and predicting how these emerging technologies will transform the landscape of the pharmaceutical industry in the years to come.

In the second session, “Lessons for Life,” Professor Lee will talk about how to nurture life-long learning and creativity to support personal and professional growth necessary in an era of the new industrial revolution.

During the Annual Meeting, Professors Jong-Hwan Kim of the Electrical Engineering School and David Hyunchul Shim of the Aerospace Department will host, together with researchers from Carnegie Mellon University and AnthroTronix, an engineering research and development company, a technological exhibition on robotics. Professor Kim, the founder of the internally renowned Robot World Cup, will showcase his humanoid micro-robots that play soccer, displaying their various cutting-edge technologies such as imaging processing, artificial intelligence, walking, and balancing. Professor Shim will present a human-like robotic piloting system, PIBOT, which autonomously operates a simulated flight program, grabbing control sticks and guiding an airplane from take offs to landings.

In addition, the two professors will join Professor Lee, who is also a moderator, to host a KAIST-led session on June 26, 2016, entitled “Science in Depth: From Deep Learning to Autonomous Machines.” Professors Kim and Shim will explore new opportunities and challenges in their fields from machine learning to autonomous robotics including unmanned vehicles and drones.

Since 2011, KAIST has been participating in the World Economic Forum’s two flagship conferences, the January and June Davos Forums, to introduce outstanding talents, share their latest research achievements, and interact with global leaders.

KAIST President Steve Kang said, “It is important for KAIST to be involved in global talks that identify issues critical to humanity and seek answers to solve them, where our skills and knowledge in science and technology could play a meaningful role. The Annual Meeting in China will become another venue to accomplish this.”

I mentioned KAIST and the Ideas Lab at the 2016 Davos meeting in this Nov. 20, 2015 posting and was able to clear up my (and possible other people’s) confusion as to what the Fourth Industrial revolution might be in my Dec. 3, 2015 posting.