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Distinguished Professor Sang Yup Lee Honored with the 23rd NAEK Award
(Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering)
Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering was honored to be the laureate of the 23rd NAEK Award.
The NAEK (National Academy of Engineering of Korea) Award was instituted in 1997 to honor and recognize engineers who have made significant contributions to the development of the engineering and technology field at universities, industries, and institutions. Every year, it is conferred to only one person who has achieved original and world-leading research that has led to national development.
Distinguished Professor Lee is a pioneering scholar of the field of systems metabolic engineering and he was recognized for his significant achievements in the biochemical industry by developing novel microbial bioprocesses. In particular, he is globally renowned for biological plastic synthesis, making or decomposing polymers with microorganisms instead of using fossil resources.
He has produced numerous high-quality research breakthroughs in metabolic and systems engineering. In 2016, he produced an easily degradable plastic with Escherichia coli (E. coli). In 2018, he successfully produced aromatic polyesters, the main material for PET (poly ethylene terephthalate) from E. coli strains. He also identified microorganism structures for PET degradation and improved its degradability with a novel variant.
His research was ranked number one in the research and development division of Top Ten Science and Technology News 2018 announced by Korean Federation of Science & Technology Societies. He is one of highly cited researchers (HCR) ranked in the top 1% by citations for their field by the Clarivate Analytics.
2019.03.21 View 8562 -
Wafer-Scale Multilayer Fabrication of Silk Fibroin-Based Microelectronics
A KAIST research team developed a novel fabrication method for the multilayer processing of silk-based microelectronics. This technology for creating a biodegradable silk fibroin film allows microfabrication with polymer or metal structures manufactured from photolithography. It can be a key technology in the implementation of silk fibroin-based biodegradable electronic devices or localized drug delivery through silk fibroin patterns.
Silk fibroins are biocompatible, biodegradable, transparent, and flexible, which makes them excellent candidates for implantable biomedical devices, and they have also been used as biodegradable films and functional microstructures in biomedical applications. However, conventional microfabrication processes require strong etching solutions and solvents to modify the structure of silk fibroins.
To prevent the silk fibroin from being damaged during the process, Professor Hyunjoo J. Lee from the School of Electrical Engineering and her team came up with a novel process, named aluminum hard mask on silk fibroin (AMoS), which is capable of micropatterning multiple layers composed of both fibroin and inorganic materials, such as metal and dielectrics with high-precision microscale alignment. The AMoS process can make silk fibroin patterns on devices, or make patterns on silk fibroin thin films with other materials by using photolithography, which is a core technology in the current microfabrication process.
The team successfully cultured primary neurons on the processed silk fibroin micro-patterns, and confirmed that silk fibroin has excellent biocompatibility before and after the fabrication process and that it also can be applied to implanted biological devices.
Through this technology, the team realized the multilayer micropatterning of fibroin films on a silk fibroin substrate and fabricated a biodegradable microelectric circuit consisting of resistors and silk fibroin dielectric capacitors in a silicon wafer with large areas.
They also used this technology to position the micro-pattern of the silk fibroin thin film closer to the flexible polymer-based brain electrode, and confirmed the dye molecules mounted on the silk fibroin were transferred successfully from the micropatterns.
Professor Lee said, “This technology facilitates wafer-scale, large-area processing of sensitive materials. We expect it to be applied to a wide range of biomedical devices in the future. Using the silk fibroin with micro-patterned brain electrodes can open up many new possibilities in research on brain circuits by mounting drugs that restrict or promote brain cell activities.”
This research, in collaboration with Dr. Nakwon Choi from KIST and led by PhD candidate Geon Kook, was published in ACS AMI (10.1021/acsami.8b13170) on January 16, 2019.
Figure 1. The cover page of ACS AMI
Figure 2. Fibroin microstructures and metal patterns on a fibroin produced by using the AMoS mask.
Figure 3. Biocompatibility assessment of the AMoS Process. Top: Schematics image of a) fibroin-coated silicon b) fibroin-pattered silicon and c) gold-patterned fibroin. Bottom: Representative confocal microscopy images of live (green) and dead (red) primary cortical neurons cultured on the substrates.
2019.03.15 View 22623 -
1g-Ultrasound System for the Brain Stimulation of a Freely-moving Mouse
A KAIST research team developed a light-weight capacitive micromachined ultrasonic transducer (CMUT) and succeeded in the ultrasound brain stimulation of a freely-moving mouse. With this lightweight and compact system, researchers can conduct a versatile set of in vivo experiments.
Conventional methods for stimulating a specific brain region, such as deep brain stimulation (DBS) and optogenetics technology, are highly invasive because they have to insert probes into a target brain, which makes them difficult to use for clinical application. While transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) are noninvasive, they have a wide range of stimulation and problems with in-depth stimulation, which makes them problematic for target-specific treatment.
Therefore, noninvasive and focused ultrasound stimulation technology is gaining a great deal of attention as a next-generation brain stimulation alternative. Since it is delivered noninvasively, it can be applied safely in humans as well as animal experiments. Focused ultrasound stimulation is more advantageous than conventional methods in terms of providing both local and deep stimulation.
Animal behavior experiments are essential for brain stimulation research; however, ultrasonic brain stimulation technology is currently in the early stages of development. So far, only research outcomes with fixed anesthetized mice have been studied because of the heavy ultrasonic device.
Professor Hyunjoo J. Lee from the School of Electrical Engineering and her team reported a technology that can provide ultrasound stimulation to the brain of a freely-moving mouse through a microminiaturized ultrasound device.
The team studied miniaturization and ultra-lightweight CMUTs through microelectromechanical systems (MEMS) technology and designed a device suitable for behavior experiments. The device weighing less than 1g (around 0.05% of the mouse’s weight) has the center frequency, size, focal length, and ultrasonic intensity to fit a mouse’s dimensions.
To evaluate the performance of the ultrasonic device, the team stimulated the motor cortex of the mouse brain and observed the movement reaction of its forefoot. They also measured the electromyography (EMG) of the trapezius.
As a result, the team confirmed that their ultrasonic device can deliver ultrasound to a depth of 3-4mm in the mouse brain and stimulate an area of the mouse brain that represents 25% of its total size.
Based on this research, the team is investigating the effects of ultrasound on sleep by stimulating the brain of sleeping mice.
Professor Lee said, “Going beyond experimenting on fixed anesthetized mice, this research succeeded in the brain stimulation of a freely-moving mouse. We are planning to study mice with diseases, such as Parkinson’s disease, dementia, depression, and epilepsy. I believe that this basic research can contribute to treating human brain-related diseases through ultrasound brain stimulation.
This research, led by Masters candidates Hyunggug Kim and Seongyeon Kim, was published in Brain Stimulation (10.1016/j.brs.2018.11.007) on November 17, 2018.
Figure 1. The miniature transducer for the transcranial ultrasound of a freely-moving mouse
Figure 2. Its structure and simulated 2D beam profile in the axial ad radial directions
2019.03.13 View 9520 -
Blue-enriched White Light to Wake You Up in the Morning
(from left: Professor Hyun Jung Chung, Professor Hyeon-Jeong Suk, Taesu Kim and Professor Kyungah Choi)
Here is a good news for those of who have difficulty with morning alertness. A KAIST research team proposed that a blue-enriched LED light can effectively help people overcome morning drowsiness. This study will provide the basis for major changes in future lighting strategies and thereby help create better indoor environments.
Considerable research has been devoted to unmasking circadian rhythms. The 2017 Nobel Prize in Physiology or Medicine went to Jeffrey C. Hall, Michael Rosbash, and Michael W. Young for unveiling the molecular mechanisms that control circadian rhythms. In particular, the relationship between light and its physiological effects has been investigated since the discovery of a novel, third type of photoreceptor in the human retina in the early 2000s. Rods and cones regulate visual effects, while the third type, photosensitive retinal ganglion cells, regulate a large variety of biological and behavioral processes including melatonin and cortisol secretion, alertness, and functional magnetic resonance imaging (fMRI).
Initial studies on light sources have shown that blue monochromatic, fully saturated lights are effective for stimulating physiological responses, but the relative effectiveness of commercially available white light sources is less well understood. Moreover, the research was more focused on the negative effects of blue light; for instance, when people are exposed to blue light at night, they have trouble achieving deep sleep because the light restrains melatonin secretion.
However, Professor Hyeon-Jeong Suk and Professor Kyungah Choi from the Department of Industrial Design and their team argue that the effects of blue-enriched morning light on physiological responses are time dependent, and that it has positive effects on melatonin levels and the subjective perception of alertness, mood, and visual comfort compared with warm white light.
The team conducted an experiment with 15 university students. They investigated whether an hour of morning light exposure with different chromaticity would affect their physiological and subjective responses differently. The decline of melatonin levels was significantly greater after the exposure to blue-enriched white light in comparison with warm white light.
Professor Suk said, “Light takes a huge part of our lives since we spend most of our time indoors. Light is one of the most powerful tools to affect changes in how we perceive and experience the environment around us.”
Professor Choi added, “When we investigate all of the psychological and physiological effects of light, we see there is much more to light than just efficient quantities. I believe that human-centric lighting strategies could be applied to a variety of environments, including residential areas, learning environments, and working spaces to improve our everyday lives.”
This research was collaborated with Professor Hyun Jung Chung from the Graduate School of Nanoscience and Technology and was published in Scientific Reports (10.1038/s41598-018-36791-5) on January 23, 2019.
Figure 1. Changes in melatonin secretion during day and night time
2019.03.06 View 11724 -
New Catalyst for Synthesizing Chiral Molecules Selectively
(from left: Dr. Yoonsu Park and Professor Sukbok Chang from the Department of Chemistry)
Molecules in nature often have “twin” molecules that look identical. In particular, the twin molecules that look like mirror images to each other are called enantiomers. However, even though they have the same type and number of elements, these twin molecules exhibit completely different properties.
Professor Sukbok Chang and Dr. Yoonsu Park from the Department of Chemistry developed a new catalyst capable of selectively synthesizing only one of the two enantiomers. Using this catalyst, the have succeeded in manufacturing the chiral lactam, an essential ingredient in pharmaceuticals, from a hydrocarbon compound.
Enantiomerism or chirality is considered very important for drug development. Biomaterials, such as DNAs and proteins also have chiral properties, but they exhibit different physiological activities depending on the types of drugs. One type of the enantiomer could be useful while the other is toxic. Hence, the technology for selective synthesizing (i.e. asymmetric synthesis) is required, but it is still regarded as a great challenge faced by modern chemistry to date.
The researchers solved this problem by developing a new catalyst. Earlier they presented their research on developing an iridium catalyst that converts hydrocarbons into high value γ-lactam compounds, and published it in Science in March 2018. However, the developed catalyst still had a limitation that both types of enantiomers are obtained without selectivity.
In this study, they found that among dozens of other catalyst candidates, iridium catalysts with chiral diamine scaffolds were able to select the correct enantiomer with a selectivity of 99% or more. This novel catalyst can be used to synthesize the various chiral γ-lactam as required. A left-handed γ-lactam and a right-handed γ-lactam can be produced using a left-handed iridium catalyst and a right-handed iridium catalyst, respectively.
They analyzed the reason for the high selectivity through computational chemistry simulations. They identified that temporal hydrogen bonding occurred between the chiral diamine catalysts and the hydrocarbon compound during the reaction. As a result of the hydrogen bonding, the formation of the left-handed lactam was boosted.
With their new catalyst, they also succeeded in synthesizing chiral lactam compounds with different structures. By using inexpensive and readily available feedstock hydrocarbons, the researchers produced a group of chiral lactams in different shapes. As their chirality and diverse structures enable lactams to function as an active compound in the body for antibiotic, anti-inflammatory, or anti-tumoral functions, this study may facilitate the development of potential drugs in a more efficient and cheaper way.
Professor Chang said, “We hope that our research on selectively producing core units of effective drugs will lead to developing new drugs that demonstrate fewer side-effects and higher efficacy. There are also economic advantages of this research because it uses hydrocarbon compounds, which can be abundantly found in nature, to produce high-value raw materials.
This research was published in Nature Catalysis(10.1038/s41929-019-0230-x) on February 19, 2019.
Figure 1. Asymmetric formation of chiral γ-lactam
Figure 2. Outline of research outcome
2019.03.05 View 7570 -
Brain-inspired Artificial Intelligence in Robots
(from left: PhD candidate Su Jin An, Dr. Jee Hang Lee and Professor Sang Wan Lee)
Research groups in KAIST, the University of Cambridge, Japan’s National Institute for Information and Communications Technology, and Google DeepMind argue that our understanding of how humans make intelligent decisions has now reached a critical point in which robot intelligence can be significantly enhanced by mimicking strategies that the human brain uses when we make decisions in our everyday lives.
In our rapidly changing world, both humans and autonomous robots constantly need to learn and adapt to new environments. But the difference is that humans are capable of making decisions according to the unique situations, whereas robots still rely on predetermined data to make decisions.
Despite the rapid progress being made in strengthening the physical capability of robots, their central control systems, which govern how robots decide what to do at any one time, are still inferior to those of humans. In particular, they often rely on pre-programmed instructions to direct their behavior, and lack the hallmark of human behavior, that is, the flexibility and capacity to quickly learn and adapt.
Applying neuroscience in robotics, Professor Sang Wan Lee from the Department of Bio and Brain Engineering, KAIST and Professor Ben Seymour from the University of Cambridge and Japan’s National Institute for Information and Communications Technology proposed a case in which robots should be designed based on the principles of the human brain. They argue that robot intelligence can be significantly enhanced by mimicking strategies that the human brain uses during decision-making processes in everyday life.
The problem with importing human-like intelligence into robots has always been a difficult task without knowing the computational principles for how the human brain makes decisions –in other words, how to translate brain activity into computer code for the robots’ ‘brains’.
However, researchers now argue that, following a series of recent discoveries in the field of computational neuroscience, there is enough of this code to effectively write it into robots. One of the examples discovered is the human brain’s ‘meta-controller’, a mechanism by which the brain decides how to switch between different subsystems to carry out complex tasks. Another example is the human pain system, which allows them to protect themselves in potentially hazardous environments. “Copying the brain’s code for these could greatly enhance the flexibility, efficiency, and safety of robots,” Professor Lee said.
The team argued that this inter-disciplinary approach will provide just as many benefits to neuroscience as to robotics. The recent explosion of interest in what lies behind psychiatric disorders such as anxiety, depression, and addiction has given rise to a set of sophisticated theories that are complex and difficult to test without some sort of advanced situation platform.
Professor Seymour explained, “We need a way of modelling the human brain to find how it interacts with the world in real-life to test whether and how different abnormalities in these models give rise to certain disorders. For instance, if we could reproduce anxiety behavior or obsessive-compulsive disorder in a robot, we could then predict what we need to do to treat it in humans.”
The team expects that producing robot models of different psychiatric disorders, in a similar way to how researchers use animal models now, will become a key future technology in clinical research.
The team also stated that there may also be other benefits to humans and intelligent robots learning, acting, and behaving in the same way. In future societies in which humans and robots live and work amongst each other, the ability to cooperate and empathize with robots might be much greater if we feel they think like us.
Professor Seymour said, “We might think that having robots with the human traits of being a bit impulsive or overcautious would be a detriment, but these traits are an unavoidable by-product of human-like intelligence. And it turns out that this is helping us to understand human behavior as human.”
The framework for achieving this brain-inspired artificial intelligence was published in two journals, Science Robotics (10.1126/scirobotics.aav2975) on January 16 and Current Opinion in Behavioral Sciences (10.1016/j.cobeha.2018.12.012) on February 6, 2019.
Figure 1. Overview of neuroscience - robotics approach for decision-making. The figure details key areas for interdisciplinary study (Current Opinion in Behavioral Sciences)
Figure 2. Brain-inspired solutions to robot learning. Neuroscientific views on various aspects of learning and cognition converge and create a new idea called prefrontal metacontrol, which can inspire researchers to design learning agents that can address various key challenges in robotics such as performance-efficiency-speed, cooperation-competition, and exploration-exploitation trade-offs (Science Robotics)
2019.02.20 View 6219 -
Kimchi Toolkit by Costa Rican Summa Cum Laude Helps Make the Best Flavor
(Maria Jose Reyes Castro with her kimchi toolkit application)
Every graduate feels a special attachment to their school, but for Maria Jose Reyes Castro who graduated summa cum laude in the Department of Industrial Design this year, KAIST will be remembered for more than just academics. She appreciates KAIST for not only giving her great professional opportunities, but also helping her find the love of her life.
During her master’s course, she completed an electronic kimchi toolkit, which optimizes kimchi’s flavor. Her kit uses a mobile application and smart sensor to find the fermentation level of kimchi by measuring its pH level, which is closely related to its fermentation. A user can set a desired fermentation level or salinity on the mobile application, and it provides the best date to serve it.
Under the guidance of Professor Daniel Saakes, she conducted research on developing a kimchi toolkit for beginners (Qualified Kimchi: Improving the experience of inexperienced kimchi makers by developing a monitoring toolkit for kimchi).
“I’ve seen many foreigners saying it’s quite difficult to make kimchi. So I chose to study kimchi to help people, especially those who are first-experienced making kimchi more easily,” she said. She got recipes from YouTube and studied fermentation through academic journals. She also asked kimchi experts to have a more profound understanding of it.
Extending her studies, she now works for a startup specializing in smart farms after starting last month. She conducts research on biology and applies it to designs that can be used practically in daily life.
Her tie with KAIST goes back to 2011 when she attended an international science camp in Germany. She met Sunghan Ro (’19 PhD in Nanoscience and Technology), a student from KAIST and now her husband. He recommended for her to enroll at KAIST because the school offers an outstanding education and research infrastructure along with support for foreign students.
At that time, Castro had just begun her first semester in electrical engineering at the University of Costa Rica, but she decided to apply to KAIST and seek a better opportunity in a new environment. One year later, she began her fresh start at KAIST in the fall semester of 2012.
Instead of choosing her original major, electrical engineering, she decided to pursue her studies in the Department of Industrial Design, because it is an interdisciplinary field where students get to study design while learning business models and making prototypes.
She said, “I felt encouraged by my professors and colleagues in my department to be creative and follow my passion. I never regret entering this major.”
When Castro was pursuing her master’s program in the same department, she became interested in interaction designs with food and biological designs by Professor Saakes, who is her advisor specializing in these areas.
After years of following her passion in design, she now graduates with academic honors in her department.
It is a bittersweet moment to close her journey at KAIST, but “I want to thank KAIST for the opportunity to change my life for the better. I also thank my parents for being supportive and encouraging me. I really appreciate the professors from the Department of Industrial Design who guided and shaped who I am,” she said.
Figure 1. The concept of the kimchi toolkit
Figure 2. The scenario of the kimchi toolkit
2019.02.19 View 5568 -
Kenya-KAIST Kicks off with a 95-Million USD Funding from the Korean Government
KAIST, founded through a six-million USD loan from USAID in 1971, to provide turnkey-based education consultancy for Kenya’s first advanced science and technology institute.
KAIST and the Konza Technopolis Development Authority (KoTDA) announced the official establishment of Kenya-KAIST by 2021 during a kickoff ceremony on February 12 in Kenya. The KAIST delegation headed by President Sung-Chul Shin and Kenyan cabinet members and dignitaries including Minister of Education Amina Mohamed, the Chairman of the KoTDA Reuben Mutiso, and the CEO of KoTDA John Tanui attended the ceremony.
With this kickoff held at Konza Technopolis Malili, KAIST, the first and top science and technology university in Korea, will participate in Kenya’s strategic economic development plan with the provision of a turnkey-based science and technology education consultancy for the establishment of Kenya’s first advanced institute of science and technology. KAIST, which won preferred bidder status in consortium with Samwoo and Sunjin architecture and engineering companies, signed the contract with the KoTDA last November.
Korea Eximbank will offer a 95-million USD economic development cooperation fund loan to the Kenyan government. The campus will be constructed in the Konza Techno City located near Nairobi by 2021, with the first batch of 200 graduate students starting classes in 2022.
KAIST will develop academic curricula for six initial departments (Mechanical Engineering, Electrical/Electronic Engineering, ICT Engineering, Chemical Engineering, Civil Engineering, and Agricultural Biotechnology), which will lay the groundwork for engineering research and education in Kenya to meet emerging socioeconomic demands. In addition, KAIST will provide education in the basic science areas of math, physics, chemistry, and biology for students.
The Kenyan government plans to transform Kenya into a middle-income country under Vision 2030 through the promotion of science, technology, and innovation for national economic growth. Nicknamed Africa’s Silicon Savannah, Konza Techno City is a strategic science and technology hub constructed to realize this vision. To this end, the medium-term plan set a goal to provide specialized research and training in various cutting-edge engineering and advanced science fields.
It is also notable that the Kenyan government asked to develop an industry-academy cooperation program in the Konza Techno City. This reflects the high expectations for Kenya-KAIST and its role as a growth engine in the center of the Konza Technopolis. It is anticipated that the technopolis will create 16,675 jobs in the medium term and over 200,000 upon completion, positioning Kenya as an ICT hub within the region.
Saying that the partnership through Kenya-KAIST will bring a new future to Kenya as well as KAIST at the ceremony, President Shin reflected that the project will be a significant milestone for KAIST’s history and global competitiveness. He added, “With this Kenya project, we come to share the past, present, and future of KAIST. And I am very pleased to celebrate our shared vision: the empowerment of science, technology, and education.”
In particular, President Shin was accompanied by Dr. Kun-Mo Chung, a founding provost who served as the Minister of Science and Technology in Korea twice. He now serves as an advisor to Kenyan President Uhuru Kenyatta.
Dr. Chung had played a crucial role in securing a six-million USD loan from US AID to the Korean government to establish KAIST in 1971. He proposed the idea to establish an advanced science and technology institute in Korea to Dr. John Hannah, then the director of US AID.
The seed that was sowed five decades ago in Korea by Dr. Chung has now fully bloomed in Kenya. In only a half century, KAIST has become a donor institution that passes on science and technology education systems including the construction of campuses to developing countries.
KAIST has been acclaimed as US AID’s most successful foreign aid project. A report from the National Academy of Sciences in the US described KAIST as an exemplary case in which a former recipient of international aid has grown to become a science, technology and innovation leader.
The kickoff of Kenya-KAIST drew the attention of both media and local universities in Kenya, attesting to their strong interest to drive economic growth through advanced science and technology.
The University of Nairobi also hosted a special lecture by President Shin, asking him to share the recipe for the success of KAIST in Korea. In a lecture titled “A Crucial Engine for Rapid National Development,” President Shin presented the vision, innovation, and passion of the Korean people that led to the phenomenal results we can see today.
The successful case of KAIST has been benchmarked by many countries for years. For instance, KAIST set up the curriculum for the nuclear engineering program at the Khalifa University of Science and Technology in UAE in 2010. Since 2015, Chongquing University of Technology in China has been running its electrical engineering and computer science programs based on the educational systems and curricula offered by KAIST.
Last October, KAIST also signed an MOU with the Prince Mohammad Bin Salman College of Cyber Security, AI, and Advanced Technologies in Saudi Arabia to provide the undergraduate program for robotics.
Among all these programs benchmarking KAIST, Kenya-KAIST clearly stands out, as it carries out a turnkey-based project that encompasses every aspect of institution building, ranging from educational curricular development to campus construction and supervision.
Figure 1. KAIST President Sung-Chul Shin and Principal Secretary of Ministry of Education Collette A. Suda
Figure 2. Kickoff Ceremony of Kenya-KAIST
Figure 3. Conceptual image of Kenya KAIST
2019.02.13 View 7766 -
New LSB with Theoretical Capacity over 90%
(Professor Hee-Tak Kim and Hyunwon Chu)
A KAIST research team has developed a lithium sulfur battery (LSB) that realizes 92% of the theoretical capacity and an areal capacity of 4mAh/cm2.
LSBs are gaining a great deal of attention as an alternative for lithium ion batteries (LIBs) because they have a theoretical energy density up to six to seven times higher than that of LIBs, and can be manufactured in a more cost-effective way.
However, LSBs face the obstacle of having a capacity reaching its theoretical maximum because they are prone to uncontrolled growth of lithium sulfide on the electrodes, which leads to blocking electron transfer.
To address the problem of electrode passivation, researchers introduced additional conductive agent into the electrode; however, it drastically lowered the energy density of LSBs, making it difficult to exceed 70% of the theoretical capacity.
Professor Hee-Tak Kim from the Department of Chemical and Biomolecular Engineering and his team replaced the lithium salt anions used in conventional LSB electrolytes with anions with a high donor number. The team successfully induced the three-dimensional growth of lithium sulfide on electrode surfaces and efficiently delayed the electrode passivation.
Based on this electrolyte design, the research team achieved 92% of the theoretical capacity with their high-capacity sulfur electrode (4mAh/cm2), which is equivalent to that of conventional LIB cathode. Furthermore, they were able to form a stable passivation film on the surface of the lithium anode and exhibited stable operation over 100 cycles.
This technology, which can be flexibly used with various types of sulfur electrodes, can mark a new milestone in the battery industry.
Professor Kim said, “We proposed a new physiochemical principle to overcome the limitations of conventional LSBs. I believe our achievement of obtaining 90% of the LBSs’ theoretical capacity without any capacity loss after 100 cycles will become a new milestone.”
This research, first-authored by Hyunwon Chu and Hyungjun Noh, was published in Nature Communications on January 14, 2019. It was also selected in the editor’s highlight for its outstanding achievements.
Figure 1. Lithium sulfur growth and its deposition mechanism for different sulfide growth behaviors
Figure 2. Capacity and cycle life characteristics of the LSBs
2019.02.11 View 8090 -
Stretchable Multi-functional Fiber for Energy Harvesting and Strain Sensing
(from left: Professor Steve Park, Jeongjae Ryu and Professor Seungbum Hong)
Fiber-based electronics are expected to play a vital role in next-generation wearable electronics. Woven into textiles, they can provide higher durability, comfort, and integrated multi-functionality. A KAIST team has developed a stretchable multi-functional fiber (SMF) that can harvest energy and detect strain, which can be applied to future wearable electronics.
With wearable electronics, health and physical conditions can be assessed by analyzing biological signals from the human body, such as pulse and muscle movements. Fibers are highly suitable for future wearable electronics because they can be easily integrated into textiles, which are designed to be conformable to curvilinear surfaces and comfortable to wear. Moreover, their weave structures offer support that makes them resistant to fatigue. Many research groups have developed fiber-based strain sensors to sense external biological signals. However, their sensitivities were relatively low.
The applicability of wearable devices is currently limited by their power source, as the size, weight, and lifetime of the battery lessens their versatility. Harvesting mechanical energy from the human body is a promising solution to overcome such limitations by utilizing various types of motions like bending, stretching, and pressing. However, previously reported, fiber-based energy harvesters were not stretchable and could not fully harvest the available mechanical energy.
Professor Seungbum Hong and Professor Steve Park from the Department of Materials Science and Engineering and their team fabricated a stretchable fiber by using a ferroelectric layer composed of P(VDF-TrFE)/PDMS sandwiched between stretchable electrodes composed of a composite of multi-walled carbon nanotubes (MWCNT) and poly 3,4-ethylenedioxythiophene polystyrenesulfonate (PEDOT:PSS).
Cracks formed in MWCNT/PEDOT:PSS layer help the fiber show high sensitivity compared to the previously reported fiber strain sensors. Furthermore, the new fiber can harvest mechanical energy under various mechanical stimuli such as stretching, tapping, and injecting water into the fiber using the piezoelectric effect of the P(VDF-TrFE)/PDMS layer.
Professor Hong said, “This new fiber has various functionalities and makes the device simple and compact. It is a core technology for developing wearable devices with energy harvesting and strain sensing capabilities.”
This article, led by PhD candidate Jeongjae Ryu, was published in the January 2019 issue of Nano Energy.
Figure 1.Schematic illustration of an SMF fiber and its piezoelectric voltage output and response to strain.
Figure 2. Photographs of a stretchable multi-functional fiber being stretched by 100%, bent, and twisted.
2019.01.31 View 8853 -
Hierarchical Porous Titanium Nitride Synthesized by Multiscale Phase Separation for LSBs
(from left: Professor Jinwoo Lee and PhD candidate Won-Gwang Lim)
A KAIST research team developed ultra-stable, high-rate lithium-sulfur batteries (LSBs) by using hierarchical porous titanium nitride as a sulfur host, and achieved superior cycle stability and high rate performance for LSBs.
The control of large amounts of energy is required for use in an electric vehicle or smart grid system. In this sense, the development of next-generation secondary batteries is in high demand. Theoretically, LSBs have an energy density seven times higher than commercial lithium ion batteries (LIBs). Also, their production cost can be reduced dramatically since sulfur can be obtained at a low price.
Despite these positive aspects, there have been several issues impeding the commercialization of LSBs, such as the low electric conductivity of sulfur, the dissolution of active materials during operation, and sluggish conversion reactions. These issues decrease the cycle stability and rate capability of batteries.
To tackle those issues, Professor Jinwoo Lee from the Department of Chemical and Biomolecular Engineering and his team synthesized a well-developed hierarchical macro/mesoporous titanium nitride as a host material for sulfur. The titanium nitride has a high chemical affinity for sulfur and high electrical conductivity. As a result, it prevents the dissolution of active materials and facilitates the charge transfer. Moreover, the synergistic effect of macropore and mesopore structures allows the stable accommodation of large amounts of sulfur and facilitates the electrolyte penetration.
Previously reported polar inorganic materials have a high affinity for sulfur, but it was challenging to control the porous architecture suitable to the sulfur host. This work breaks such limitations by developing a synthetic route to easily control the porous architecture of inorganic materials, which led to obtaining superior cycle stability and high rate capabilities.
Professor Lee said, “Some problems still remain in commercializing LSBs as next-generation batteries. Hence, there should be a continued research on this matter to solve the issues. Through this research, we secured a key technology for ultrastable, high-rate LSBs.”
This research was led by PhD candidate Won-Gwang Lim and collaborated on by Jeong Woo Han from POSTECH. It was chosen as the cover article of Advanced Materials on January 15, 2019.
Figure 1. Schematic illustration for the synthetic route of co-continuous h-TiN
Figure 2. The hierarchical multiscale porous structure is still retained without any collapse after the conversion to h-TiN. The good retention of the porous structure is attributed to the thick pore wall of the h-TiO₂derived from the block copolymer self-assembly
Figure 3. The cover page of Advanced Materials
2019.01.28 View 7316 -
First Korean Member of OceanObs' Organizing Committee
Professor Sung Yong Kim from the Department of Mechanical Engineering became the first Korean to be elected as an organizing committee member of the international conference OceanObs’19’, specializing in the ocean observing field.
Professor Kim has been actively engaged in advisory panels, technical committees, and working groups for the North Pacific Marine Science Organization (PICES). Through numerous activities, he was recognized for his professionalism and academic achievements, which led him to be appointed as a member of the organizing committee.
The organizing committee is comprised of leading scholars and researchers from 20 countries, and Professor Kim will be the first Korean scientist to participate on the committee.
Since 1999, the conference has been held every decade. Global experts specializing in oceanic observation gather to discuss research directions for the next ten years by monitoring physical, biological, and chemical variables in regional, national, and global oceans and applying marine engineering.
This year, approximately 20 institutes including NASA’s Jet Propulsion Laboratory (JPL), the National Science Foundation, the National Oceanic and Atmospheric Administration, and the European Space Agency will support funds as well as high-tech equipment to the conference.
This year’s conference theme is the governance of global ocean observing systems such as underwater gliders, unmanned vehicles, remote sensing, and observatories. The conference will hold discussions on monitoring technology and information systems to ensure human safety as well as to develop and preserve food resources. Additionally, participants will explore ways to expand observational infrastructures and carry out multidisciplinary approaches.
There will also be collaborations with the Global Ocean Observing System (GOOS) and the Partnership for Observation of the Global Oceans (POGO) to organize ocean observing programs and discuss priorities.
Finally, they will set a long-term plan for solving major scientific issues, such as climate change, ocean acidification, energy, and marine pollution.
Professor Kim said, “Based on the outcomes drawn from the conference, I will carry out research on natural disasters and climate change monitoring by using unmanned observing systems. I will also encourage more multidisciplinary research in this field.”
2019.01.25 View 11297