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KAIST, Production Temperature ↓ by 500°C, Power Output ↑ 2x… Next-Generation Ceramic Electrochemical Cell Reborn
<(Top row, from left) Professor Kang Taek Lee, Ph.D candidate Yejin Kang, Dr. Dongyeon Kim, (Bottom row, from left) M.S candidate Mincheol Lee, Ph.D candidate Seeun Oh, Ph.D candidate Seungsoo Jang, Ph.D candidate Hyeonggeun Kim>
As power demand surges in the AI era, the “protonic ceramic electrochemical cell (PCEC),” which can simultaneously produce electricity and hydrogen, is gaining attention as a next-generation energy technology. However, this cell has faced the technical limitation of requiring an ultra-high production temperature of 1,500°C. A KAIST research team has succeeded in establishing a new manufacturing process that lowers this limit by more than 500°C for the first time in the world.
KAIST (President Kwang Hyung Lee) announced on the 4th of December that Professor Kang Taek Lee’s research team in the Department of Mechanical Engineering developed a new process that enables the fabrication of high-performance protonic ceramic electrochemical cells at temperatures more than 500°C lower than before, using “microwave + vapor control technology” that leverages microwave heating principles and the diffusion environment of chemical vapor generated from specific chemical components.
The electrolyte—the key material of protonic ceramic electrochemical cells—contains barium (Ba), and barium easily evaporates at temperatures above 1,500°C, which has been the main cause of performance degradation. Therefore, the ability to harden the ceramic electrolyte at a lower temperature has been the core issue that determines cell performance.
As power demand surges in the AI era, the “protonic ceramic electrochemical cell (PCEC),” which can simultaneously produce electricity and hydrogen, is gaining attention as a next-generation energy technology. However, this cell has faced the technical limitation of requiring an ultra-high production temperature of 1,500°C. A KAIST research team has succeeded in establishing a new manufacturing process that lowers this limit by more than 500°C for the first time in the world.
KAIST (President Kwang Hyung Lee) announced on the 4th of December that Professor Kang Taek Lee’s research team in the Department of Mechanical Engineering developed a new process that enables the fabrication of high-performance protonic ceramic electrochemical cells at temperatures more than 500°C lower than before, using “microwave + vapor control technology” that leverages microwave heating principles and the diffusion environment of chemical vapor generated from specific chemical components.
The electrolyte—the key material of protonic ceramic electrochemical cells—contains barium (Ba), and barium easily evaporates at temperatures above 1,500°C, which has been the main cause of performance degradation. Therefore, the ability to harden the ceramic electrolyte at a lower temperature has been the core issue that determines cell performance.
To solve this, the research team devised a new heat-treatment method called “vapor-phase diffusion.” This technique places a special auxiliary material (a vapor source) next to the cell and irradiates it with microwaves to quickly diffuse vapor. When the temperature reaches approximately 800°C, the vapor released from the auxiliary material moves toward the electrolyte and tightly bonds the ceramic particles. Thanks to this technology, a process that previously required 1,500°C can now be completed at just 980°C. In other words, a world-first ceramic electrochemical cell fabrication technology has been created that produces high-performance electricity at a “low temperature” without damaging the electrolyte.
A cell fabricated with this process produced 2 W of power stably from a 1 cm² cell (roughly the size of a fingernail) at 600°C and generated 205 mL of hydrogen per hour at 600°C (about the volume of a small paper cup, among the highest in the industry). It also maintained stability without performance degradation during 500 hours of continuous operation.
In other words, this technology reduces the production temperature (−500°C), lowers the operating temperature (600°C), doubles performance (2 W/cm²), and extends the lifespan (500-hour stability), achieving world-class performance in ceramic cell technology.
The research team also enhanced the reliability of the technology by using digital twins (virtual simulations) to analyze gas-transport phenomena occurring in the microscopic internal structure of the cell − phenomena that are difficult to observe in actual experiments.
<Figure 1. (a) Schematic of the vapor-diffusion-based process; (b) Surface microstructure of the electrolyte; (c) Internal barium composition ratio of the electrolyte according to processing conditions; (d) Comparison of power-generation performance with previous studies>
< Figure 2. (a) Three-dimensional reconstructed image of the protonic ceramic electrochemical cell fuel electrode according to processing conditions (b) Pore structure (c) Gas-transport simulation results >
Professor Kang Taek Lee emphasized, “This study is the world’s first case of using vapor to lower the heat-treatment temperature by more than 500°C while still producing a high-performance, high-stability cell.” He added, “It is expected to become a key manufacturing technology that addresses the power challenges of the AI era and accelerates the hydrogen society.”
Dongyeon Kim (KAIST PhD) and Yejin Kang (KAIST PhD candidate) participated as co–first authors. The research results were published in Advanced Materials (IF: 26.8), one of the world’s leading journals in energy and materials science, and were selected as the Inside Front Cover article on October 29.
(Paper title: “Sub-1000°C Sintering of Protonic Ceramic Electrochemical Cells via Microwave-Driven Vapor Phase Diffusion,” DOI: https://doi.org/10.1002/adma.202506905)
This research was supported by the MSIT’s Mid-career Researcher Program and the H2 Next Round Program.
2025.12.05 View 215 -
KAIST Develops Room-Temperature 3D Printing Technology for ‘Electronic Eyes’—Miniaturized Infrared Sensors
<(From Left) Professor Ji Tae Kim of the Department of Mechanical Engineering, Professor Soong Ju Oh of Korea University and Professor Tianshuo Zhao of the University of Hong Kong>
The “electronic eyes” technology that can recognize objects even in darkness has taken a step forward. Infrared sensors, which act as the “seeing” component in devices such as LiDAR for autonomous vehicles, 3D face recognition systems in smartphones, and wearable healthcare devices, are regarded as key components in next-generation electronics. Now, a research team at KAIST and their collaborators have developed the world’s first room-temperature 3D printing technology that can fabricate miniature infrared sensors in any desired shape and size.
KAIST (President Kwang Hyung Lee) announced on the 3rd of November that the research team led by Professor Ji Tae Kim of the Department of Mechanical Engineering, in collaboration with Professor Soong Ju Oh of Korea University and Professor Tianshuo Zhao of the University of Hong Kong, has developed a 3D printing technique capable of fabricating ultra-small infrared sensors—smaller than 10 micrometers (µm)—in customized shapes and sizes at room temperature.
Infrared sensors convert invisible infrared signals into electrical signals and serve as essential components in realizing future electronic technologies such as robotic vision. Accordingly, miniaturization, weight reduction, and flexible form-factor design have become increasingly important.
Conventional semiconductor fabrication processes were well suited for mass production but struggled to adapt flexibly to rapidly changing technological demands. They also required high-temperature processing, which limited material choices and consumed large amounts of energy.
To overcome these challenges, the research team developed an ultra-precise 3D printing process that uses metal, semiconductor, and insulator materials in the form of liquid nanocrystal inks, stacking them layer by layer within a single printing platform.
This method enables direct fabrication of core components of infrared sensors at room temperature, allowing for the realization of customized miniature sensors of various shapes and sizes.
Particularly, the researchers achieved excellent electrical performance without the need for high-temperature annealing by applying a “ligand-exchange” process, where insulating molecules on the surface of nanoparticles are replaced with conductive ones.
As a result, the team successfully fabricated ultra-small infrared sensors measuring less than one-tenth the thickness of a human hair (under 10 µm).
<Figure 1. 3D printing of infrared sensors.a. Room-temperature printing process for the electrodes and photoactive layer that make up the infrared sensor.b. Structure and chemical composition of the printed infrared microsensor. c.Printed infrared sensor micropixel array.>
Professor Ji Tae Kim commented, “The developed 3D printing technology not only advances the miniaturization and lightweight design of infrared sensors but also paves the way for the creation of innovative new form-factor products that were previously unimaginable. Moreover, by reducing the massive energy consumption associated with high-temperature processes, this approach can lower production costs and enable eco-friendly manufacturing—contributing to the sustainable development of the infrared sensor industry.”
The research results were published online in Nature Communications on October 16, 2025, under the title “Ligand-exchange-assisted printing of colloidal nanocrystals to enable all-printed sub-micron optoelectronics” (DOI: https://doi.org/10.1038/s41467-025-64596-4).
This research was supported by the Ministry of Science and ICT of Korea through the Excellent Young Researcher Program (RS−2025−00556379), the National Strategic Technology Material Development Program (RS−2024−00407084), and the International Cooperation Research Program for Original Technology Development (RS−2024−00438059).
2025.11.03 View 1951 -
3D Printing Becomes Stronger and More Economical with Light and AI
<(Front) Ph.D. candidate Jisoo Nam, (Back row, from left) Ph.D. candidate Boxin Chen, Professor Miso Kim>
Photocurable 3D printing, widely used for everything from dental treatments to complex prototype manufacturing, is fast and precise but has the limitation of being fragile and easily broken by impact. A KAIST research team has developed a new technology to overcome this weakness, paving the way for the more robust and economical production of everything from medical implants to precision machine parts.
KAIST (President Kwang Hyung Lee) announced on the 29th that Professor Miso Kim's research team in the Department of Mechanical Engineering has developed a new technology that fundamentally resolves the durability limitations of photocurable 3D printing.
Digital Light Processing (DLP)-based 3D printing is a technique that uses light to solidify liquid resin (polymer) to rapidly manufacture precise structures, used in various fields such as dentistry and precision machinery. While traditional injection molding offers excellent durability, it requires significant time and cost for mold fabrication. In contrast, photocurable 3D printing allows for flexible shape realization but has a durability drawback.
Professor Kim's team solved this problem by combining two key elements:
A new photocurable resin material that absorbs shock and vibration while allowing for a wide range of properties from rubber to plastic.
A machine learning-based design technology that automatically assigns optimal strength to each part of the structure.
<Figure 1. Schematic of a new manufacturing technology for high-durability photocurable 3D printing using light-controlled gradient structures. This approach integrates the development of stiffness-controllable viscoelastic polyurethane acrylate (PUA) materials, machine learning-based property gradient optimization, and grayscale DLP 3D printing. The technology enhances damping performance and alleviates stress concentration, providing an integrated solution for high reliability, durability, and customized manufacturing. It demonstrates potential applications in structural components subjected to repetitive loads such as joints, automotive interior parts, and precision machinery components>
The research team developed a Polyurethane Acrylate (PUA) material incorporating dynamic bonds, which significantly increases shock and vibration absorption capability compared to existing materials. Furthermore, they successfully applied 'grayscale DLP' technology, which controls the light intensity to achieve different strengths from a single resin composition, thereby assigning customized strength to specific areas within the structure. This concept is inspired by the harmonious and different roles played by bone and cartilage in the human body.
A machine learning algorithm automatically proposes the optimal strength distribution by analyzing the structure and load conditions. This organically connects material development and structural design, enabling customized strength distribution.
The economic efficiency is also noteworthy. Previously, expensive 'multi-material printing' technology was required to achieve diverse material properties, but this new technology yields the same effect with a single material and a single process, significantly reducing production costs. It eliminates the need for complex equipment or material management, and the AI-based structural optimization shortens research and development time and product design costs.
Professor Miso Kim explained, "This technology simultaneously expands the degrees of freedom in material properties and structural design. Patient-specific implants will become more durable and comfortable, and precision machine parts can be manufactured more robustly." She added, "The fact that it secures economic viability by realizing various strengths with a single material and single process is highly significant," and "We anticipate its utilization across various industrial fields such as biomedical, aerospace, and robotics."
The research was spearheaded by Professor Miso Kim's team at the KAIST Department of Mechanical Engineering, with Ph.D. candidate Jisoo Nam as the first author. Boxin Chen, a student from Sungkyunkwan University, also contributed to the collaborative research. The findings were published online on July 16 in the world-renowned journal in materials science, Advanced Materials (IF 26.8). Recognizing the research's excellence, it was also selected for the journal's Frontispiece.
Paper Title: Machine Learning-Driven Grayscale Digital Light Processing for Mechanically Robust 3D-Printed Gradient Materials
DOI: 10.1002/adma.202504075
The achievements of this research have brought Professor Miso Kim significant international attention, as she simultaneously received the 'Wiley Rising Star Award' and the 'Wiley Women in Materials Science Award' in July 2025, hosted by the international academic publisher Wiley.
The Wiley Rising Star Award is given to emerging researchers with the potential for academic leadership, and the Wiley Women in Materials Science Award is a prestigious honor established to celebrate outstanding female scientists in the field of materials science.
<Figure 2. Frontispiece image (scheduled for Issue 42). Multi-property structure fabricated using a photocurable 3D printer. By varying the projector light intensity by location, stronger light creates rigid regions while weaker light forms flexible ones. AI designs an optimized pattern for the structural shape to prevent fracture and reinforce the overall strength.>
This research was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (Nos. NRF-2021R1A2C2095767, RS-2023-00254689, and RS-2024-00433654).
2025.09.30 View 1444 -
KAIST to Foster a 'Robot Valley' in Daejeon with $10 Million Initiative
<Group Photo of Kick-off Meeting>
On September 3, KAIST announced the official launch of the "2025 Deep Tech Scale-up Valley Nurturing Project" with a kick-off meeting at the KAIST Department of Mechanical Engineering.
KAIST was selected for this project by the Ministry of Science and ICT and the Research and Development Special District Foundation. With this selection, the university plans to create a "Robot Valley".
Over the next three and a half years, KAIST will receive a total of 13.65 billion won (approximately $10 million) in funding. The university's goal is to intensively nurture globally competitive, innovative robotics companies based on foundational technologies and to develop Daejeon into a global hub for the robotics industry.
The initiative will leverage Daejeon's exceptional research talent and its startup and investment ecosystem to create a model for regional revitalization and to cultivate the robotics industry as a next-generation strategic sector.
KAIST's vision for this project is to develop "Human-Friendly Robots (HFR)" that are more than just automated machines; they are collaborative partners that share space, roles, and emotions with people.
The project will implement a multi-stage strategy that includes promoting the commercialization of robotics technology, supporting the startup ecosystem, securing global technological competitiveness, and developing robot commercialization platforms. This will establish a virtuous cycle of technology development, startup and investment growth, and reinvestment.
Unlike traditional startup support and scale-up programs, this project aims for the simultaneous growth of the entire robotics industry, not just individual companies. A key element is an open innovation model where leading robotics firms like Angel Robotics Inc. and EuRoBotics Inc. (led by Professor Byung-ho Yu and Professor Hyun Myung) will share common core technologies related to actuators, circuits, AI, and standardized data. This will allow startups to focus on developing robot products that directly meet customer needs.
The project team includes key KAIST robotics researchers. The project leader is Professor Jung Kim (President of the Korea Robotics Society) from the Department of Mechanical Engineering. Other participating professors include Geon-Jae Lee from the Department of Materials Science and Engineering (human augmentation sensors), Hyun Myung from the School of Electrical Engineering (winner of the QRC 2023 quadruped robot autonomous walking competition at IEEE ICRA), Kyung-Chul Kong from the Department of Mechanical Engineering (two-time champion of the Cybathlon International Competition and founder of Angel Robotics), and Suk-Hyung Bae from the Department of Industrial Design (winner of the ACM SIGGRAPH robot sketching competition).
In addition, the KAIST Technology Commercialization Office, KAIST Holdings, Global Techno Valley Lab (GTLAB), and the Daejeon Center for Creative Economy and Innovation will manage technology commercialization and valley construction. The Daejeon Technopark will also participate to provide comprehensive commercialization support.
"The strategic cooperation between Daejeon City's robotics industry nurturing plan and KAIST was the driving force behind the selection for this project," said Geon-Jae Lee, Director of the KAIST Technology Commercialization Office. "We will create a robotics innovation ecosystem based in Daejeon and systematically foster global companies to rival the likes of ABB in Switzerland and KUKA in Germany, which are considered among the top three robotics companies in the world."
< Kick-off Meeting Scene>
Project leader Jung Kim stated, "We will spearhead efforts to discover and nurture over 15 future unicorn companies by promoting the commercialization of deep-tech robotics developed at KAIST. The entire KAIST robotics research team will dedicate its full efforts to ensure that our research and development achievements lead to real-world industries and startups."
KAIST President Kwang-Hyung Lee emphasized, "As Korea's leading research-oriented university, KAIST will actively support Daejeon's growth into a global robotics hub. This project is more than just research and development; it will be a turning point for KAIST to stand at the center of the global robotics ecosystem and create a new growth engine for the region and the nation."
In collaboration with Daejeon City, KAIST plans to form an "HFR Valley Innovation Council" to share and review project outcomes, ultimately building a self-sustaining ecosystem. This initiative aims to establish Daejeon as a world-class robotics industry hub.
2025.09.03 View 2468 -
Artificial Muscles Bloom, Dance, and Wave
Wearing a flower brooch that blooms before your eyes sounds like magic. KAIST researchers have made it real with robotic muscles.
Researchers have developed an ultrathin, artificial muscle for soft robotics. The advancement, recently reported in the journal Science Robotics, was demonstrated with a robotic blooming flower brooch, dancing robotic butterflies and fluttering tree leaves on a kinetic art piece.
The robotic equivalent of a muscle that can move is called an actuator. The actuator expands, contracts or rotates like muscle fibers using a stimulus such as electricity. Engineers around the world are striving to develop more dynamic actuators that respond quickly, can bend without breaking, and are very durable. Soft, robotic muscles could have a wide variety of applications, from wearable electronics to advanced prosthetics.
The team from KAIST’s Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering developed a very thin, responsive, flexible and durable artificial muscle. The actuator looks like a skinny strip of paper about an inch long. They used a particular type of material called MXene, which is class of compounds that have layers only a few atoms thick.
Their chosen MXene material (T3C2Tx) is made of thin layers of titanium and carbon compounds. It was not flexible by itself; sheets of material would flake off the actuator when bent in a loop. That changed when the MXene was “ionically cross-linked” — connected through an ionic bond — to a synthetic polymer. The combination of materials made the actuator flexible, while still maintaining strength and conductivity, which is critical for movements driven by electricity.
Their particular combination performed better than others reported. Their actuator responded very quickly to low voltage, and lasted for more than five hours moving continuously.
To prove the tiny robotic muscle works, the team incorporated the actuator into wearable art: an origami-inspired brooch mimics how a narcissus flower unfolds its petals when a small amount of electricity is applied. They also designed robotic butterflies that move their wings up and down, and made the leaves of a tree sculpture flutter.
“Wearable robotics and kinetic art demonstrate how robotic muscles can have fun and beautiful applications,” said Il-Kwon Oh, lead paper author and professor of mechanical engineering. “It also shows the enormous potential for small, artificial muscles for a variety of uses, such as haptic feedback systems and active biomedical devices.”
The team next plans to investigate more practical applications of MXene-based soft actuators and other engineering applications of MXene 2D nanomaterials.
2019.08.22 View 28902 -
Wearable Robot 'WalkON Suit' Off to Cybathlon 2020
Standing upright and walking alone are very simple but noble motions that separate humans from many other creatures. Wearable and prosthetic technologies have emerged to augment human function in locomotion and manipulation. However, advances in wearable robot technology have been especially momentous to Byoung-Wook Kim, a triplegic for 22 years following a devastating car accident.
Kim rejoiced after standing upright and walking again by putting on the ‘WalkON Suit,’ the wearable robot developed by Professor Kyoungchul Kong’s team. Even more, Kim won third prize in the powered exoskeleton race at Cybathlon 2016, an international cyborg Olympics hosted by ETH Zurich.
Now Kim and Professor Kong’s team are all geared up for the Cybathlon Championship 2020. Professor Kong and his startup, Angel Robotics, held a kickoff ceremony for Cybathlon 2020 at KAIST on June 24. The 2020 championship will take place in Switzerland.
Only pilots with complete paralysis of the legs resulting from spinal cord injuries are eligible to participate in the Cybathlon, which takes place every four years. Pilots compete against each other while completing everyday tasks using technical assistance systems in six different disciplines: a brain-computer interface race, a functional electrical stimulation bike race, a powered arm prosthesis race, a powered leg prosthesis race, a powered exoskeleton race, and a powered wheelchair race. The 2016 championship drew 66 pilots from 56 teams representing 25 countries.
In the powered exoskeleton race, pilots complete everyday activities such as getting up from a sofa and overcoming obstacles such as stairs, ramps, or slopes and up to four pilots compete simultaneously on tracks to solve six tasks; and the pilot that solves the most tasks in the least amount of time wins the race.
(Kim, a triplegic for 22 years demonstrates walking and climbing the stairs (below photo) wearing the WalkOn Suit during the media day on June 21 at KAIST.)
Kim, who demonstrated walking and climbing the stairs wearing the WalkON Suit during the media day for the Cybathlon 2020 kickoff ceremony on June 21 at KAIST, said, “I have been confined to a wheelchair for more than 20 years. I am used to it so I feel like the wheelchair is one of my body parts. Actually, I don’t feel any big difficulties in doing everyday tasks in wheelchair. But whenever I face the fact that I will never be able to stand up with my own two legs again, I am so devastated.” He continued, “I still remember the day when I stood up with my own two legs by myself after 22 years. It was beyond description.”
The market for wearable robots, especially for exoskeleton robots, is continuing to grow as the aging population has been a major challenge in almost every advanced country. The global market for these robots expects to see annual growth of 41.2% to 8.3 billion US dollars by 2025. Healthcare wearable robots for the elderly and rehabilitation take up the half of the market share followed by wearable robots for industrial and defense purposes.
Professor Kong from the Department of Mechanical Engineering and his colleagues have developed two wearable robot systems in 2014: The "WalkON Suit" for complete paraplegics and “Angel Suit” for those with partial impairment in walking ability such as the elderly and rehabilitation patients.
Professor Kong said after 15 years of basic research, the team is now able to develop its own distinct technologies. He said their robots are powered by non-resistant precision drives with algorithms recognizing the user’s moving intention. Incorporated with prosthetic devices technology from the Severance Rehabilitation Hospital, their control technology has led to the production of a customizable robot suit optimized for each user’s physical condition.
The WalkON Suit, which boasts a maximum force of 250 Nm and maximum rotation speed of 45 RPM, gives the user high-energy efficiency modeled after the physiology of the human leg. It allows users to walk on flat ground and down stairs, climb up and down inclines, and sit and lie down. Currently the battery lasts five to six hours for locomotion and the approximate 25 kg of robot weight still remains a technical challenge to upgrade.
Professor Kong’s team has grafted AR glass technology into the WalkOn Suit that one of his pilots put on for the torch relay of the PyongChang Paralympics in 2018. His team is now upgrading the WalkON Suit 4.0 for next year’s competition. Severance Rehabilitation Hospital will help the seven pilots with their training.
Professor Kong said his goal is to make robots that can make people with disabilities much more independent. He stressed, “Wearable robots should be designed for each single user. We provide a very good graphical user interface so that we can design, check, and also verify our optimized design for users’ best performance.”
(Seven pilots and Professor Kong (fifth from left in second row) pose with guests who joined the Cybathlon 2020 kickoff ceremony. President Shin (fifth from right) made a congratulatory remarks during the ceremony.)
2019.06.25 View 46701 -
On-chip Drug Screening for Identifying Antibiotic Interactions in Eight Hours
(from left: Seunggyu Kimand Professor Jessie Sungyun Jeon)
A KAIST research team developed a microfluidic-based drug screening chip that identifies synergistic interactions between two antibiotics in eight hours. This chip can be a cell-based drug screening platform for exploring critical pharmacological patterns of antibiotic interactions, along with potential applications in screening other cell-type agents and guidance for clinical therapies.
Antibiotic susceptibility testing, which determines types and doses of antibiotics that can effectively inhibit bacterial growth, has become more critical in recent years with the emergence of antibiotic-resistant pathogenic bacteria strains.
To overcome the antibiotic-resistant bacteria, combinatory therapy using two or more kinds of antibiotics has been gaining considerable attention. However, the major problem is that this therapy is not always effective; occasionally, unfavorable antibiotic pairs may worsen results, leading to suppressed antimicrobial effects. Therefore, combinatory testing is a crucial preliminary process to find suitable antibiotic pairs and their concentration range against unknown pathogens, but the conventional testing methods are inconvenient for concentration dilution and sample preparation, and they take more than 24 hours to produce the results.
To reduce time and enhance the efficiency of combinatory testing, Professor Jessie Sungyun Jeon from the Department of Mechanical Engineering, in collaboration with Professor Hyun Jung Chung from the Department of Biological Sciences, developed a high-throughput drug screening chip that generates 121 pairwise concentrations between two antibiotics.
The team utilized a microfluidic chip with a sample volume of a few tens of microliters. This chip enabled 121 pairwise concentrations of two antibiotics to be automatically formed in only 35 minutes.
They loaded a mixture of bacterial samples and agarose into the microchannel and injected reagents with or without antibiotics into the surrounding microchannel. The diffusion of antibiotic molecules from the channel with antibiotics to the one without antibiotics resulted in the formation of two orthogonal concentration gradients of the two antibiotics on the bacteria-trapping agarose gel.
The team observed the inhibition of bacterial growth by the antibiotic orthogonal gradients over six hours with a microscope, and confirmed different patterns of antibiotic pairs, classifying the interaction types into either synergy or antagonism.
Professor Jeon said, “The feasibility of microfluidic-based drug screening chips is promising, and we expect our microfluidic chip to be commercialized and utilized in near future.”
This study, led by Seunggyu Kim, was published in Lab on a Chip (10.1039/c8lc01406j) on March 21, 2019.
Figure 1. Back cover image for the “Lab on a Chip”.
Figure 2. Examples of testing results using the microfluidic chips developed in this research.
2019.04.18 View 33912 -
Technology to Control Near-Field Thermal Radiation
(from left clockwise: Professor Seung Seob Lee, Professor Bong Jae Lee, PhD Mikyung Lim and PhD candidate Jaeman Song)
A KAIST research team succeeded in measuring and controlling the near-field thermal radiation between metallo-dielectric (MD) multilayer structures.
Their thermal radiation control technology can be applied to next-generation semiconductor packaging, thermophotovoltaic cells and thermal management systems. It also has the potential to be applied to a sustainable energy source for IoT sensors.
In the nanoscale gaps, thermal radiation between objects increases greatly with closer distances. The amount of heat transfer in this scale was found to be from 1,000 to 10,000 times greater than the blackbody radiation heat transfer, which was once considered the theoretical maximum for the rate of thermal radiation. This phenomenon is called near-field thermal radiation. With recent developments in nanotechnology, research into near-field thermal radiation between various materials has been actively carried out.
Surface polariton coupling generated from nanostructures has been of particular interest because it enhances the amount of near-field thermal radiation between two objects, and allows the spectral control of near-field thermal radiation. This advantage has motivated much of the recent theoretical research on the application of near-field thermal radiation using nanostructures, such as thin films, multilayer nanostructures, and nanowires. Nevertheless, thus far, most of the studies have focused on measuring near-field thermal radiation between isotropic materials.
A joint team led by Professor Bong Jae Lee and Professor Seung Seob Lee from the Department of Mechanical Engineering succeeded in measuring near-field thermal radiation according to the vacuum distance between MD multilayer nanostructures by using a custom MEMS (Micro-Electro-Mechanical Systems)-device-integrated platform with three-axis nanopositioner.
MD multilayer nanostructures refer to structures in which metal and dielectric layers with regular thickness alternate. The MD single-layer pair is referred to as a unit cell, and the ratio of the thickness occupied by the metal layer in the unit cell is called the fill factor.
By measuring the near-field thermal radiation with a varying number of unit cells and the fill factor of the multilayer nanostructures, the team demonstrated that the surface plasmon polariton coupling enhances near-field thermal radiation greatly, and allows spectral control over the heat transfer.
Professor B. J. Lee said, “The isotropic materials that have so far been studied experimentally had limited spectral control over the near-field thermal radiation. Our near-field thermal radiation control technology using multilayer nanostructures is expected to become the first step toward developing various near-field thermal radiation applications.”
This research, led by PhD Mikyung Lim and PhD candidate Jaeman Song, was published in Nature Communications on October 16.
Figure 1. Experimental setup for measuring near-field thermal radiation between MD multilayers
Figure 2. Investigation of manipulated near-field heat flux by modifying the surface conditions with MD multilayers
2019.01.04 View 8328 -
Characteristics of Submesoscale Geophysical Turbulence Reported
A KAIST research team has reported some of unique characteristics and driving forces behind submesoscale geophysical turbulence. Using big data analysis on ocean surface currents and chlorophyll concentrations observed using coastal radars and satellites has brought better understanding of oceanic processes in space and time scales of O(1) kilometer and O(1) hour. The outcomes of this work will lead to improved tracking of water-borne materials and performance in global and regional climate prediction models.
In 2012, United States National Aeronautics and Space Administration (NASA) released a movie clip called “Perpetual Oceans”, which visualized ocean circulation obtained from satellite altimeter-derived sea surface height observations over two and a half years. When the movie was released to the public, it received a great deal of attention because the circulation patterns were strikingly similar to “The Starry Night” by Vincent van Gogh.
“Perpetual Oceans” is full of vortical flow patterns describing the oceanic turbulent motions at mesoscale (a scale of 100 km or larger). Meanwhile, Professor Sung Yong Kim from the Department of Mechanical Engineering and his team focused on the study of the oceanic turbulence at sub-mesoscale (space and time scales of 1 to 100 km and hours).
Sub-mesoscale processes are important because they contribute to the vertical transport of oceanic tracers, mass, buoyancy, and nutrients and rectify both the mixed layer structure and upper ocean stratification. These process studies have been primarily based on numerical simulations because traditional in situ ocean measurements can be limited in their capability to resolve the detailed horizontal and vertical structures of these processes.
The team conducted big data analysis on hourly observations of one-year ocean surface current maps and five-year chlorophyll concentration maps, obtained from remote sensing instruments such as coastal high-frequency radars (HFRs) and geostationary ocean color imagery (GOCI) to examine the unique characteristics of oceanic submesoscale processes.
The team analyzed the slope change of the wavenumber energy spectra of the observations in terms of season and sampling directions. Through the analysis, the team proved that energy cascade (a phenomenon in which large-scale energy transfers to small-scale energy or vice-versa during the turbulent energy transit) occurs in the spatial scale of 10 km in the forward and inverse directions. This is driven by baroclinic instability as opposed to the mesoscale eddy-driven frontogenesis at the O(100) km scale based on the observed regional submesoscale circulations.
This work will contribute to the parameterization of physical phenomenon of sub-mesoscale in the field of global high-resolution modeling within ocean physics and atmospheric as well as climate change. Based on the understanding of the principle of sub-mesoscale surface circulation, practical applications can be further derived for radioactivity, oil spill recovery, and marine pollutant tracking.
Moreover, the data used in this research was based on long-term observations on sub-mesoscale surface currents and concentrations of chlorophyll, which may reflect the submesoscale processes actively generated in the subpolar front off the east coast of Korea. Hence, this study can potentially be beneficial for integrated big data analyses using high-resolution coastal radar-derived surface currents and satellite-derived products and motivate interdisciplinary research between ocean physics and biology.
This research was published as two companion papers in the Journal of Geophysical Research: Oceans on August 6, 2018. (doi:10.1002/2016JC012517; doi:10.1002/2017JC013732)
Figure 1.'The Starry Night' of Van Gogh and the 'Perpetual Ocean' created by NASA's Goddard Space Flight Center.
Figure 2. A schematic diagram of the energy cascades in forward and backward directions and the spatial scale where the energy is injected.
Figure 3. A snapshot of the chlorophyll concentration map derived from geostationary ocean color imagery (GOCI) off the east coast of Korea presenting several examples of sub-mesoscale turbulent flows.
Figure 4. Energy spectra of the HFR-derived surface currents and GOCI-derived chlorophyll concentrations and the temporal variability of spectral decay slopes in the cross-shore and along-shore directions.
2018.12.13 View 6992 -
Reducing the Drag Force of a Moving Body Underwater
(from left: Professor Yeunwoo Cho and PhD Jaeho Chung)
Professor Yeunwoo Cho and his team from the Department of Mechanical Engineering developed new technology that reduces the drag force of a moving body in a still fluid by using the supercavitation phenomenon.
When a body moves in air, the frictional drag is lower than that of the same body moving in water. Therefore, the body that moves in water can reduce the drag significantly when it is completely enveloped in a gaseous cavity.
The team used compressed air to create so-called supercavitation, which is a phenomenon created by completely enveloping a body in a single large gaseous cavity. The drag force exerted on the body is then measured.
As a result, the team confirmed that the drag force for a moving body enveloped in air is about 25% of the drag force for a moving body without envelopment.
These results can be applied for developing high-speed underwater vehicles and the development of air-lubricated, high-speed vessels.
The team expects that the results can be applied for developing high-speed underwater vehicles and the development of air lubrication for a ship’s hull.
This research, led by PhD Jaeho Chung, was published in the Journal of Fluid Mechanics as a cover article on November 10, 2018.
Figure 1. The cover article of the Journal of Fluid Mechanics Vol. 854
2018.12.04 View 5828 -
From Concept to Reality: Changing Color of Light Using a Spatiotemporal Boundary
(from left: Professor Bumki Min, PhD candidate Jaehyeon Son and PhD Kanghee Lee)
A KAIST team developed an optical technique to change the color (frequency) of light using a spatiotemporal boundary. The research focuses on realizing a spatiotemporal boundary with a much higher degree of freedom than the results of previous studies by fabricating a thin metal structure on a semiconductor surface. Such a spatiotemporal boundary is expected to be applicable to an ultra-thin film type optical device capable of changing the color of light.
The optical frequency conversion device plays a key role in precision measurement and communication technology, and the device has been developed mainly based on optical nonlinearity.
If the intensity of light is very strong, the optical medium responds nonlinearly so the nonlinear optical phenomena, such as frequency doubling or frequency mixing, can be observed. Such optical nonlinear phenomena are realized usually by the interaction between a high-intensity laser and a nonlinear medium.
As an alternative method frequency conversion is observed by temporally modifying the optical properties of the medium through which light travels using an external stimulus. Since frequency conversion in this way can be observed even in weak light, such a technique could be particularly useful in communication technology.
However, rapid optical property modification of the medium by an external stimulus and subsequent light frequency conversion techniques have been researched only in the pertubative regime, and it has been difficult to realize these theoretical results in practical applications.
To realize such a conceptual idea, Professor Bumki Min from the Department of Mechanical Engineering and his team collaborated with Professor Wonju Jeon from the Department of Mechanical Engineering and Professor Fabian Rotermund from the Department of Physics. They developed an artificial optical material (metamaterial) by arranging a metal microstructure that mimics an atomic structure and succeeded in creating a spatiotemporal boundary by changing the optical property of the artificial material abruptly.
While previous studies only slightly modified the refractive index of the medium, this study provided a spatiotemporal boundary as a platform for freely designing and changing the spectral properties of the medium. Using this, the research team developed a device that can control the frequency of light to a large degree.
The research team said a spatiotemporal boundary, which was only conceptually considered in previous research and realized in the pertubative regime, was developed as a step that can be realized and applied.
Professor Min said, “The frequency conversion of light becomes designable and predictable, so our research could be applied in many optical applications. This research will present a new direction for time-variant media research projects in the field of optics.”
This research, led by PhD Kanghee Lee and PhD candidate Jaehyeon Son, was published online in Nature Photonics on October 8, 2018.
This work was supported by the National Research Foundation of Korea (NRF) through the government of Korea. The work was also supported by the Center for Advanced Meta-Materials (CAMM) funded by the Korea Government (MSIP) as the Global Frontier Project (NRF-2014M3A6B3063709).
Figure 1. The frequency conversion process of light using a spatiotemporal boundary.
Figure 2. The complex amplitude of light at the converted frequency with the variation of a spatiotemporal boundary.
2018.11.29 View 10781 -
Washing and Enrichment of Micro-Particles Encapsulated in Droplets
Researchers developed microfluidic technology for the washing and enrichment of in-droplet micro-particles. They presented the technology using a microfluidic chip based on surface acoustic wave (SAW)-driven acoustic radiation force (ARF).
The team demonstrated the first instance of acoustic in-droplet micro-particle washing with a particle recovery rate of approximately 90 percent. They further extended the applicability of the proposed method to in-droplet particle enrichment with the unprecedented abilities to increase the in-droplet particle quantity and exchange the droplet dispersed phase.
This proposed method enabled on-chip, label-free, continuous, and selective in-droplet micro-particle manipulation. The team demonstrated the first instance of in-droplet micro-particle washing between two types of alternating droplets in a simple microchannel, proving that the method can increase the particle quantity, which has not been achieved by previously reported methods.
The study aimed to develop an in-droplet micro-particle washing and enrichment method based on SAW-driven ARF. When a droplet containing particles is exposed to an acoustic field, both the droplet and suspended particles experience ARF arising from inhomogeneous wave scattering at the liquid-liquid and liquid-solid interfaces. Unlike previous in-droplet particle manipulation methods, this method allows simultaneous and precise control over the droplets and suspended particles. Moreover, the proposed acoustic method does not require labelled particles, such as magnetic particles, and employs a simple microchannel geometry.
Microfluidic sample washing has emerged as an alternative to centrifugation because the limitations of centrifugation-based washing methods can be addressed using continuous washing processes. It also has considerable potential and importance in a variety of applications such as single-cell/particle assays, high-throughput screening of rare samples, and cell culture medium exchange.
Compared to continuous flow-based microfluidic methods, droplet-based microfluidic sample washing has been rarely explored due to technological difficulties. On-chip, in-droplet sample washing requires sample transfer across the droplet interface composed of two immiscible fluids. This process involves simultaneous and precise control over the encapsulated sample and droplet interface during the medium exchange of the in-droplet sample.
Sample encapsulation within individual microscale droplets offers isolated microenvironments for the samples. Experimental uncertainties due to cross-contamination and Taylor dispersion between multiple reagents can be reduced in droplet-based microfluidics.
This is the first research achievement made by the Acousto-Microfluidics Research Center for Next-Generation Healthcare, the cross-generation collaborative lab KAIST opened in May. This novel approach pairs senior and junior faculty members for sustaining the research legacy even after the senior researcher retires. The research center, which paired Chair Professor Hyung Jin Sung and Professors Hyoungsoo Kim and Yeunwoo Cho, made a breakthrough in microfluidics along with PhD candidate Jinsoo Park. The study was featured as the cover of Lab on a Chip published by Royal Society of Chemistry.
Jinsoo Park, first author of the study, believes this technology will may serve as an in-droplet sample preparation platform with in-line integration of other droplet microfluidic components. Chair Professor Sung said, “The proposed acoustic method will offer new perspectives on sample washing and enrichment by performing the operation in microscale droplets.”
Figure 1. (a) A microfluidic device for in-droplet micro-particle washing and enrichment; (b) alternatingly produced droplets of two kinds at a double T-junction; (c) a droplet and encapsulated micro-particles exposed to surface acoustic wave-driven acoustic radiation force; (d-h) sequential processes of in-droplet micro-particle washing and enrichment operation.
2018.10.19 View 10285