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Fabrication of Shape-conformable Batteries with 3D-Printing
(from left: Dr. Bok Yeop Ahn, Dr. Chanhoon Kim, Professor Il-Doo Kim and Professor Jennifer A. Lewis)
Flexible, wireless electronic devices are rapidly emerging and have reached the level of commercialization; nevertheless, most of battery shapes are limited to either spherical and/or rectangular structures, which results in inefficient space use. Professor Il-Doo Kim’s team from the Department of Materials Science at KAIST has successfully developed technology to significantly enhance the variability of battery design through collaboration research with Professor Jennifer A. Lewis and her team from the School of Engineering and Applied Sciences at Harvard University.
Most of the battery shapes today are optimized for coin cell and/or pouch cells. Since the battery as an energy storage device occupies most of the space in microelectronic devices with different designs, new technology to freely change the shape of the battery is required.
The KAIST-Harvard research collaboration team has successfully manufactured various kinds of battery shapes, such as ring-type, H, and U shape, using 3D printing technology. And through the research collaboration with Dr. Youngmin Choi at the Korea Research Institute of Chemical Technology (KRICT), 3D-printed batteries were applied to small-scale wearable electronic devices (wearable light sensor rings).
The research group has adopted environmentally friendly aqueous Zn-ion batteries to make customized battery packs. This system, which uses Zn2+ instead of Li+ as charge carriers, is much safer compared with the conventional lithium rechargeable batteries that use highly inflammable organic electrolytes. Moreover, the processing conditions of lithium-ion batteries are very complicated because organic solvents can ignite upon exposure to moisture and oxygen.
As the aqueous Zn-ion batteries adopted by the research team are stable upon contact with atmospheric moisture and oxygen, they can be fabricated in the ambient air condition, and have advantages in packaging since packaged plastic does not dissolve in water even when plastic packaging is applied using a 3D printer.
To fabricate a stable cathode that can be modulated in various forms and allows high charge-discharge, the research team fabricated a carbon fiber current collector using electrospinning process and uniformly coated electrochemically active polyaniline conductive polymer on the surface of carbon fiber for a current collector-active layer integrated cathode. The cathode, based on conductive polyaniline consisting of a 3D structure, exhibits very fast charging speeds (50% of the charge in two minutes) and can be fabricated without the detachment of active cathode materials, so various battery forms with high mechanical stability can be manufactured.
Prof. Kim said, “Zn-ion batteries employing aqueous electrolytes have the advantage of fabrication under ambient conditions, so it is easy to fabricate the customized battery packs using 3D printing.”
“3D-printed batteries can be easily applied for niche applications such as wearable, personalized, miniaturized micro-robots, and implantable medical devices or microelectronic storage devices with unique designs,” added Professor Lewis.
With Dr. Chanhoon Kim in the Department of Materials Science and Engineering at KAIST and Dr. Bok Yeop Ahn School of Engineering and Applied Sciences at Harvard University participating as equally contributing first authors, this work was published in the December issue of ACS Nano.
This work was financially supported by the Global Research Laboratory (NRF-2015K1A1A2029679) and Wearable Platform Materials Technology Center (2016R1A5A1009926).
Figure 1.Fabrication of shape-conformable batteries based on 3D-printing technology and the application of polyaniline carbon nanofiber cathodes and wearable electronic devices
Figure 2.Fabricated shape-conformable batteries based on a 3D-printing method
Meanwhile, Professor Il-Doo Kim was recently appointed as an Associate Editor of ACS Nano, a highly renowned journal in the field of nanoscience.
Professor Kim said, “It is my great honor to be an Associate Editor of the highly renowned journal ACS Nano, which has an impact factor reaching 13.709 with 134,596 citations as of 2017. Through the editorial activities in the fields of energy, I will dedicate myself to improving the prominence of KAIST and expanding the scope of Korea’s science and technology. I will also contribute to carrying out more international collaborations with world-leading research groups.”
(Associate Editor of ACS Nano Professor Il-Doo Kim)
2018.12.20 View 11338 -
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 8691 -
Vietnamese Alumni of Korean S&T Universities Gather in Hanoi
(Vietnamese KAIST alumni gather in Hanoi on November 24.)
(Dr.Huong Minh Nguyen at the Institute of Biotechnology in the Vietnam Academy of Science and Technology (VAST). She is the representative of Vietnamese KAIST alumni.)
Some came from Ho Chi Minh and some even flew in from Singapore. For those KAIST alumni who gathered in Hanoi, the trip was well worth it. More than 100 Vietnamese alumni of KAIST, GIST, and UST attended the reunion in Hanoi on November 24. Presidents and vice president from three universities welcomed them and celebrated their successful careers after returning home or starting careers in other countries.
The reunion was co-hosted by KAIST, UST, and GIST in an effort to make a platform for continued networking for scientists who have studied at Korea’s science and technology universities. This joint reunion will be expected to include other science and technology universities and institutes in the future.
Among 1,873 international KAIST alumni from 106 countries, the number of Vietnamese graduates is the most dominant with 262 alumni, 14% of the total international alumni. Welcoming them, KAIST Vice President Soohyun Kim said that he was very impressed that all of the alumni are making a very impressive stride in their fields.
“You will be a big asset to make your country grow. You will also be a bridge for future collaborations with your institutions and KAIST and Korea. Vietnam holds great potential for future prosperity especially in science and technology and we look forward to seeing this network continue to benefit both countries.” Vice President Kim said all of the presidents shared the idea to make this gathering a regular event. “Other S&T universities will join to hold joint reunions in other countries in the future,” he added.
Dr. Huong Minh Nguyen at the Institute of Biotechnology in the Vietnam Academy of Science and Technology (VAST) is one of 22 KAIST alumni who joined the reunion and supported the idea. She is also the representative of Vietnamese KAIST alumni. Dr. Nguyen, who earned her MS and PhD in the Department of Biological Sciences in 2013, spent five and half years at KAIST. “All the members at the lab were taking care of each other. When I joined the lab back then, they treated me as a ‘baby sister’ in a family and our relationship grew like a sister and brotherhood. I still appreciate the bonding relationship we could make with our colleagues.”
She cites a supporting culture, a competent educational system that places a focus on practicality, and rich resources that help researchers try whatever they want as the distinct advantages of a KAIST education.
“I never heard my professor saying “No” to any of my suggestions in conducting research. Professors and lab members put all their efforts, resources, and facilities to getting my research started. They helped me obtain all the resources that I needed. It was a huge encouragement to me,” she added.
She started her Masters, along with four Vietnamese colleagues, right after graduating from the Hanoi University of Natural Sciences, a top science university in Vietnam. Their experience at KAIST during a 4-week exchange program during undergraduates made them decide their academic destination without any doubt. All of them finished their PhDs in 2013. Two of them moved back home and the two others are now in the US and Germany as postdoctoral fellows.
“At that time, I could go to other countries for my further studies. But I already experienced KAIST for a month when I was an undergraduate, so I was not hesitant to go to KAIST. All of the classes are in English so, for students who do not speak in Korean, language does not bring any problems in studying and conducting research.”
She said that KAIST alumni are enjoying very successful careers in Vietnam and many foreign countries. “We do not have any problems choosing our careers back home and other countries we wanted to work in.”
However, like many PhD candidates who feel pressure about their studies and an uncertain future, her days at KAIST also included challenging times while adjusting to Korean culture. She took Korean classes for three semesters voluntarily at the KAIST Language Center to better understand Korea and her lab members. Her efforts paid off well. She could easily communicate with her colleagues and felt she became a real part of the inner group. But the stress remained to prove herself in research and she still had to deal with some bias.
“I know some people think Vietnam is behind Korea. Many people think that we are not as good as Korean students because we are from Vietnam. I desperately wanted to prove that I am as good as my peers.” Studying together with Korean and other international PhD candidates, she realized that everyone has their own purposes and pressures. “Even though there are minor differences, every PhD candidate has the same issues with their uncertain futures. It was quite comforting when we shared that it’s not only my problem. To understand that it’s a problem we all share comforts us a lot and we came to support each other.
To better help students release such pressure and stress, she said the university needs to create more diverse institutional channels to communicate with them. “Looking back, I was younger and less competent to speak up about when we were stressed and needed to ask for help. I hope students can begin to release their pressure and stress through diverse channels and resolve the problems,” she said.
Asked about her future plans, she replied, “I don’t think I can do anything better than what I am doing now. I enjoy what I am doing now at my institute. But in the near very future, I want to visit Korea and KAIST again.”
2018.11.27 View 4249 -
OUIC Presents the Six Most Promising Techs Transferrable to Local SMEs
KAIST will showcase the six most promising technologies for small and medium enterprises (SMEs) on November 14 in the Academic Cultural Complex. To strengthen the competitive edge of local SMEs in Daejeon, the Office of University-Industry made a survey of their technological needs and came up with the six most promising technologies. Developers will introduce their technologies during the session.Besides the introduction of the promising technologies, the session will also provide a program named University to Business (U2B) to match up technologies according to the SMEs’ needs. SMEs who wish to engage in technology transfers can receive counseling and other support programs during the session.First, Professor Seok-Hyung Bae from the Department of Industrial Design will present a technology for controlling cooperation robots. Professor Bae inserted flexible materials between the controllers to allow robots to use both hands stably and operate more accurately and swiftly. It can be applied to automatic robots, industrial robots, and service robots.Professor Hyun Myung from the Department of Civil & Environmental Engineering will demonstrate a robot navigation system in a dynamic indoor and outdoor environment, which can be applied to robotics in logistics, smart factories, and autonomous vehicles. Providing robust simultaneous localization and mapping systems, this technology shows high-performing navigation with low-cost sensors.Meanwhile, Professor Siyoung Choi from the Department of Chemical and Biomolecular Engineering will introduce a technology for forming stable adhesive emulsions. An emulsion is a stable mixture of water and oil. Conventionally, a small amount of surfactant is added to stabilize an emulsion. Here, Professor Choi developed a stable emulsion system without using any chemical substances. This technology can be applied to various fields, including the cosmetics, pharmaceutical, semiconductor, and painting industries. The session will also present smart IoTs platform technology developed by Professor Jinhong Yang from the KAIST Institute for IT Convergence. His technology minimizes errors occurring when multiple IoT devices are connected simultaneously. Professor Yong Keun Park from the Department of Physics will introduce a technology for measuring glycated hemoglobin by using the optical properties of red blood cells. This technology can be applied to make low-cost, small-sized measuring equipment. It can also be used for vitro diagnoses including diabetes, cardiovascular disorders, tumors, kidney disease, and infectious diseases. Professor Yong Man Ro from the School of Electrical Engineering will show technology for biometric access control. Conventional technologies for face recognition fall behind other biometrics. Professor Ro and his team developed a facial dynamics interpreting network which allows very accurate facial recognition by interpreting the relationships between facial local dynamics and estimating facial traits. This technology can be applied to security and communication in finance, computers, and information system.KAIST President Sung-Chul Shin said, “KAIST will continue to support SMEs to have stronger competitiveness in the market. Through technology transfer, we will drive innovation in technological commercialization where a university’s research and development creates economic value.”
2018.11.13 View 9954 -
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 8368 -
A Novel Biosensor to Advance Diverse High-Level Production of Microbial Cell Factories
A research group at KAIST presented a novel biosensor which can produce diverse, high-level microbial cell factories. The biosensor monitors the concentration of products and even intermediates when new strains are being developed. This strategy provides a new platform for manufacturing diverse natural products from renewable resources. The team succeeded in creating four natural products of high-level pharmaceutical importance with this strategy.
Malonyl-CoA is a major building block for many value-added chemicals including diverse natural products with pharmaceutical importance. However, due to the low availability of malonyl-CoA in bacteria, many malonyl-CoA-derived natural products have been produced by chemical synthesis or extraction from natural resources that are harmful to the environment and are unsustainable. For the sustainable biological production of malonyl-CoA-derived natural products, increasing the intracellular malonyl-CoA pool is necessary. To this end, the development of a robust and efficient malonyl-CoA biosensor was required to monitor the concentration of intracellular malonyl-CoA abundance as new strains are developed.
Metabolic engineering researchers at KAIST addressed this issue. This research reports the development of a simple and robust malonyl-CoA biosensor by repurposing a type III polyketide synthase (also known as RppA), which produces flaviolin, a colorimetric indicator of malonyl-CoA. Subsequently, the RppA biosensor was used for the rapid and efficient colorimetric screening of gene manipulation targets enabling enhanced malonyl-CoA abundance. The screened beneficial gene targets were employed for the high-level production of four representative natural products derived from malonyl-CoA. Compared with the previous strategies, which were expensive and time-consuming, the new biosensor could be easily applied to industrially relevant bacteria including Escherichia coli, Pseudomonas putida, and Corynebacterium glutamicum to enable a one-step process.
The study employs synthetic small regulatory RNA (sRNA) technology to rapidly and efficiently reduce endogenous target gene expression for improved malonyl-CoA production. The researchers constructed an E. coli genome-scale synthetic sRNA library targeting 1,858 genes covering all major metabolic genes in E. coli. This library was employed with the RppA biosensor to screen for gene targets which are believed to be beneficial for enhancing malonyl-CoA accumulation upon their expression knockdown.
From this colorimetric screening, 14 gene targets were selected, all of which were successful at significantly increasing the production of four natural products (6-methylsalicylic acid, aloesone, resveratrol, and naringenin). Although specific examples are demonstrated in E. coli as a host, the researchers showed that the biosensor is also functional in P. putida and C. glutamicum, industrially important representative gram-negative and gram-positive bacteria, respectively. The malonyl-CoA biosensor developed in this research will serve as an efficient platform for the rapid development of strains capable of producing natural products crucial for the pharmaceutical, chemical, cosmetics, and food industries.
An important aspect of this work is that the high-performance strains constructed in this research were developed rapidly and easily by utilizing the simple approach of colorimetric screening, without involving extensive metabolic engineering approaches. 6-Methylsalicylic acid (an antibiotic) could be produced to the highest titer reported for E. coli, and the microbial production of aloesone (a precursor of aloesin, an anti-inflammatory agent/whitening agent) was achieved for the first time.
“A sustainable process for producing diverse natural products using renewable resources is of great interest. This study represents the development of a robust and efficient malonyl-CoA biosensor generally applicable to a wide range of industrially important bacteria. The capability of this biosensor for screening a large library was demonstrated to show that the rapid and efficient construction of high-performance strains is feasible. This research will be useful for further accelerating the development process of strains capable of producing valuable chemicals to industrially relevant levels,” said Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering, who led the research.
This study entitled “Repurposing type III polyketide synthase as a malonyl-CoA biosensor for metabolic engineering in bacteria,” was published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on October 02.
PhD students Dongsoo Yang and Won Jun Kim, MS student Shin Hee Ha, research staff Mun Hee Lee, Research Professor Seung Min Yoo, and Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering and Dr. Jong Hyun Choi of the Applied Microbiology Research Center at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) participated in this research.
Figure: Type III polyketide synthase (RppA) as a malonyl-CoA biosensor. RppA converts five molecules of malonyl-CoA into one molecule of red-colored flaviolin. This schematic diagram shows the overall conceptualization of the malonyl-CoA biosensor by indicating that higher malonyl-CoA abundance leads to higher production and secretion of flaviolin, resulting in a deeper red color of the culture. This system was employed for the enhanced production of four representative natural products (6-methylsalicylic acid, aloesone, resveratrol, and naringenin) from engineered E. coli strains.
2018.10.11 View 10458 -
Permanent, Wireless Self-charging System Using NIR Band
(Professor Jung-Yong Lee from the Graduate School of Energy, Environment, Water and Sustainability)
As wearable devices are emerging, there are numerous studies on wireless charging systems. Here, a KAIST research team has developed a permanent, wireless self-charging platform for low-power wearable electronics by converting near-infrared (NIR) band irradiation to electrical energy. This novel technology can be applied to flexible, wearable charging systems without needing any attachments.
Colloidal-quantum-dots (CQDs) are promising materials for manufacturing semiconductors; in particular, PbS-based CQDs have facile optical tunability from the visible to infrared wavelength region. Hence, they can be applied to various devices, such as lighting, photovoltaics (PVs), and photodetectors.
Continuous research on CQD-based optoelectronic devices has increased their power conversion efficiency (PCE) to 12%; however, applicable fields have not yet been found for them. Meanwhile, wearable electronic devices commonly face the problem of inconvenient charging systems because users have to constantly charge batteries attached to an energy source.
A joint team led by Professor Jung-Yong Lee from the Graduate School of Energy, Environment, Water and Sustainability and Jang Wok Choi from Seoul National University decided to apply CQD PVs, which have high quantum efficiency in NIR band to self-charging systems on wearable devices.
They employed a stable and efficient NIR energy conversion strategy. The system was comprised of a PbS CQD-based PV module, a flexible interdigitated lithium-ion battery, and various types of NIR-transparent films.
The team removed the existing battery from the already commercialized wearable healthcare bracelet and replaced it with the proposed self-charging system. They confirmed that the system can be applied to a low power wearable device via the NIR band.
There have been numerous platforms using solar irradiation, but the newly developed platform has more advantages because it allows conventional devices to be much more comfortable to wear and charged easily in everyday life using various irradiation sources for constant charging.
With this aspect, the proposed platform facilitates more flexible designs, which are the important component for actual commercialization. It also secures higher photostability and efficient than existing structures.
Professor Lee said, “By using the NIR band, we proposed a new approach to solve charging system issues of wearable devices. I believe that this platform will be a novel platform for energy conversion and that its application can be further extended to various fields, including mobiles, IoTs, and drones.”
This research, led by PhD Se-Woong Baek and M.S. candidate Jungmin Cho, was published in Advanced Materials on May 11.
Figure 1. a) Conceptual NIR-driven self-charging system including a flexible CQD PVs module and an interdigitatedly structured LIB. b) Photographic images of a conventional wearable healthcare bracelet and a self-charging system-integrated wearable device.
Figure 2. Illustration of the CQD PVs structure and performance of the wireless self-charging platform.
2018.10.08 View 8937 -
Engineered E. coli Using Formic Acid and CO2 As a C1-Refinery Platform Strain
(Figure: Formic acid and CO2 assimilation pathways consisting of the reconstructed THF cycle and reverse glycine cleavage reaction. This schematic diagram shows the formic acid and CO2 assimilation procedure through the pathway. Plasmids used in this study and the genetic engineering performed in this study are illustrated.)
A research group at KAIST has developed an engineered E. coli strain that converts formic acid and CO2 to pyruvate and produces cellular energy from formic acid through reconstructed one-carbon pathways. The strategy described in this study provides a new platform for producing value-added chemicals from one-carbon sources.
Formic acid is a carboxylic acid composed of one carbon. Formic acid was produced from CO2 by the chemical method. Recently, the C1 Gas Refinery R&D Center has successfully developed a biological process that produces formic acid from carbon monoxide for the first time. Formic acid is in a liquid state when at room temperature and atmospheric pressure. In addition, it is chemically stable and less toxic, thus, easy to store and transport. Therefore, it can be used as an alternative carbon source in the microbial fermentation process. In order to produce value-added chemicals using formic acid, a metabolic pathway that converts formic acid into cellular molecules composed of multiple carbons is required. However, a metabolic pathway that can efficiently convert formic acid into cellular molecules has not been developed. This acted as an obstacle for the production of value-added chemicals using formic acid
A research group of Ph.D. student Junho Bang and Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering addressed this issue. This study, entitled “Assimilation of Formic Acid and CO2 by Engineered Escherichia coli Equipped with Reconstructed One-Carbon Assimilation Pathways”, has been published online in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on September 18.
There has been increasing interest in utilizing formic acid as an alternative carbon source for the production of value-added chemicals. This research reports the development of an engineered E. coli strain that can convert formic acid and CO2 to pyruvate and produce cellular energy from formic acid through the reconstructed one-carbon pathways.
The metabolic pathway that efficiently converts formic acid and CO2 into pyruvate was constructed by the combined use of the tetrahydrofolate cycle and reverse glycine cleavage reaction. The tetrahydrofolate cycle was reconstructed by utilizing Methylobacterium extorquens formate-THF ligase, methenyl-THF cyclohydrolase, and methylene-THF dehydrogenase. The glycine cleavage reaction was reversed by knocking out the repressor gene (gcvR) and overexpressing the gcvTHP genes that encode enzymes related with the glycine cleavage reaction. Formic acid and CO2 conversion to pyruvate was increased via metabolic engineering of the E. coli strain equipped with the one-carbon assimilation pathway.
In addition, in order to reduce glucose consumption and increase formic acid consumption, Candida boidnii formate dehydrogenase was additionally introduced to construct a cellular energy producing pathway from formic acid. This reduces glucose consumption and increases formic acid consumption.
The reconstructed one-carbon pathways can supply cellular molecules and cellular energies from the formic acid and CO2. Thus, the engineered E. coli strain equipped with the formic acid and CO2 assimilation pathway and cellular energy producing pathway from formic acid showed cell growth from formic acid and CO2 without glucose. Cell growth was monitored and 13C isotope analysis was performed to confirm E. coli growth from the formic acid and CO2. It was found that the engineered E. coli strain sustained cell growth from the formic acid and CO2 without glucose.
Professor Lee said, “To construct the C1-refinery system, a platform strain that can convert one-carbon materials to higher carbon materials needs to be developed. In this report, a one-carbon pathway that can efficiently convert formic acid and CO2 to pyruvate was developed and a cellular energy producing pathway from formic acid was introduced. This resulted in an engineered E. coli strain that can efficiently utilize formic acid as a carbon source while glucose consumption was reduced. The reconstructed one-carbon pathways in this research will be useful for the construction of the C1-refinery system.”
This work was supported by the C1 Gas Refinery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2016M3D3A1A01913250). For further information: Sang Yup Lee, Distinguished Professor of Chemical and Biomolecular Engineering, KAIST (leesy@kaist.ac.kr, Tel: +82-42-350-3930)
2018.09.18 View 7327 -
Transfering Nanowires onto a Flexible Substrate
(from left: PhD Min-Ho Seo and Professor Jun-Bo Yoon)
Boasting excellent physical and chemical properties, nanowires (NWs) are suitable for fabricating flexible electronics; therefore, technology to transfer well-aligned wires plays a crucial role in enhancing performance of the devices. A KAIST research team succeeded in developing NW-transfer technology that is expected to enhance the existing chemical reaction-based NW fabrication technology that has this far showed low performance in applicability and productivity.
NWs, one of the most well-known nanomaterials, have the structural advantage of being small and lightweight. Hence, NW-transfer technology has drawn attention because it can fabricate high-performance, flexible nanodevices with high simplicity and throughput.
A conventional nanowire-fabrication method generally has an irregularity issue since it mixes chemically synthesized nanowires in a solution and randomly distributes the NWs onto flexible substrates. Hence, numerous nanofabrication processes have emerged, and one of them is master-mold-based, which enables the fabrication of highly ordered NW arrays embedded onto substrates in a simple and cost-effective manner, but its employment is limited to only some materials because of its chemistry-based NW-transfer mechanism, which is complex and time consuming. For the successful transfer, it requires that adequate chemicals controlling the chemical interfacial adhesion between the master mold, NWs, and flexible substrate be present.
Here, Professor Jun-Bo Yoon and his team from the School of Electrical Engineering introduced a material-independent mechanical-interlocking-based nanowire-transfer (MINT) method to fabricate ultralong and fully aligned NWs on a large flexible substrate in a highly robust manner.
This method involves sequentially forming a nanosacrificial layer and NWs on a nanograting substrate that becomes the master mold for the transfer, then weakening the structure of the nanosacrificial layer through a dry etching process. The nanosacrificial layer very weakly holds the nanowires on the master mold. Therefore, when using a flexible substrate material, the nanowires are very easily transferred from the master mold to the substrate, just like a piece of tape lifting dust off a carpet.
This technology uses common physical vapor deposition and does not rely on NW materials, making it easy to fabricate NWs onto the flexible substrates.
Using this technology, the team was able to fabricate a variety of metal and metal-oxide NWs, including gold, platinum, and copper – all perfectly aligned on a flexible substrate. They also confirmed that it can be applied to creating stable and applicable devices in everyday life by successfully applying it to flexible heaters and gas sensors.
PhD Min-Ho Seo who led this research said, “We have successfully aligned various metals and semiconductor NWs with excellent physical properties onto flexible substrates and applied them to fabricated devices. As a platform-technology, it will contribute to developing high-performing and stable electronic devices.”
This research was published in ACS Nano on May 24.
Figure 1. Photograph of the fabricated wafer-scale fully aligned and ultralong Au nanowire array on a flexible substrate
2018.09.17 View 6656 -
Distinguished Professor Sang Yup Lee Announced as the Eni Award Recipient
(Distinguished Professor Sang Yup Lee)
Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering will be awarded the 2018 Eni Advanced Environmental Solutions Prize in recognition of his innovations in the fields of energy and environment. The award ceremony will take place at the Quirinal Palace, the official residence of Italian President Sergio Mattarella, who will also be attending on October 22.
Eni, an Italian multinational energy corporation established the Eni Award in 2008 to promote technological and research innovation of efficient and sustainable energy resources. The Advanced Environmental Solutions Prize is one of the three categories of the Eni Award. The other two categories are Energy Transition and Energy Frontiers. The Award for Advanced Environmental Solutions recognizes a researcher or group of scientists that has achieved internationally significant R&D results in the field of environmental protection and recovery. The Eni Award is referred to as the Nobel Award in the fields of energy and environment.
Professor Lee, a pioneering leader in systems metabolic engineering was honored with the award for his developing engineered bacteria to produce chemical products, fuels, and non-food biomass materials sustainably and with a low environmental impact. He has leveraged the technology to develop microbial bioprocesses for the sustainable and environmentally friendly production of chemicals, fuels, and materials from non-food renewable biomass.
The award committee said that they considered the following elements in assessing Professor Lee’s achievement: the scientific relevance and the research innovation level; the impact on the energy system in terms of sustainability as well as fairer and broader access to energy; and the adequacy between technological and economic aspects.
Professor Lee, who already won two other distinguished prizes such as the George Washington Carver Award and the PV Danckwerts Memorial Lecture Award this year, said, “I am so glad that the international academic community as well as global industry leaders came to recognize our work that our students and research team has made for decades.”
Dr. Lee’s lab has been producing a lot of chemicals in environmentally friendly ways. Among them, many were biologically produced for the first time and some of these processes have been already commercialized. “We will continue to strive for research outcomes with two objectives: First, to develop bio-based processes suitable for sustainable chemical industry. The other is to contribute to the human healthcare system through development of platform technologies integrating medicine and nutrition,” he added.
2018.09.12 View 8587 -
KAIST Core Technology Fair Accelerates Commercialization
(President Shin makes opening remarks at the KAIST Core Tech Transfer Day in Seoul.)
Technology commercialization is the one of the innovation initiatives KAIST is strongly driving. KAIST showcased six core technologies developed by KAIST research teams during the 2018 KAIST Core Tech Transfer Day on September 10 at Coex in Seoul. More than 300 investors, buyers, and venture capitalists showed up for the fair. This is the second fair organized as one of the strategic innovation initiatives that KAIST is promoting.
Developers of key technologies selected in the fields of bio, nano, AI, and semiconductors presented their distinct technological prowess to the attendees. The technologies are highly relevant for the new industrial environment trends in the Fourth Industrial Revolution.
The 15-member committee comprised of patent attorneys, venture capitalists, and commercialization specialists selected the six core technologies based on their innovativeness, applicability, and marketability. The Office of University-Industry Cooperation (OUIC) plans to offer buyers various services for developing business models, business strategy analysis, and marketing at home and abroad. The six core technologies featured at the fair include:
- Novel technology of a nano patterning platform by Professor Hee Tae Chung from the Department of Chemical and Biomolecular Engineering
- Anticancer therapeutic candidate materials strengthening immune function by Professor Byung Sok Choi from the Department of Chemistry
- Biofuel mass production using micro-organisms by Distinguished Professor Sang-Yup Lee from the Department of Chemical and Biomolecular Engineering
- Compact single-shot hyperspectral camera technology by Min Hyuk Kim from the School of Computing
- AI-powered high speed ultra-high definition upscaling technology by Professor Munchurl Kim from the School of Electrical Engineering - A radiation strong MOSFET device by Hee Chul Lee from the School of Electrical Engineering
President Sung-Chul Shin stressed in his opening remarks that universities should make contributions to economic development through innovation. “Global leading universities are taking an instrumental role in creating new jobs and economic growth with their own technologies. KAIST, as the leading university in Korea, is accelerating the commercialization of technology produced internally to create a meaningful impact for the economy as well as the job market beyond Korea,” he said.
“We are aiming for the global market, not just in Korea. I want KAIST to be a global value creator that can contribute to the betterment of the world through our innovations,” he added.
2018.09.10 View 6923 -
Adding Smart to Science Museum
KAIST and the National Science Museum (NSM) created an Exhibition Research Center for Smart Science to launch exhibitions that integrate emerging technologies in the Fourth Industrial Revolution, including augmented reality (AR), virtual reality (VR), Internet of Things (IoTs), and artificial intelligence (AI).
There has been a great demand for a novel technology for better, user-oriented exhibition services. The NSM continuously faces the problem of not having enough professional guides. Additionally, there have been constant complaints about its current mobile application for exhibitions not being very effective.
To tackle these problems, the new center was founded, involving 11 institutes and universities. Sponsored by the National Research Foundation, it will oversee 15 projects in three areas: exhibition-based technology, exhibition operational technology, and exhibition content.
The group first aims to provide a location-based exhibition guide system service, which allows it to incorporate various technological services, such as AR/VR to visitors. An indoor locating system named KAILOS, which was developed by KAIST, will be applied to this service. They will also launch a mobile application service that provides audio-based exhibition guides.
To further cater to visitors’ needs, the group plans to apply a user-centered ecosystem, a living lab concept to create pleasant environment for visitors.
“Every year, hundred thousands of young people visit the National Science Museum. I believe that the exhibition guide system has to be innovative, using cutting-edge IT technology in order to help them cherish their dreams and inspirations through science,” Jeong Heoi Bae, President of Exhibition and Research Bureau of NSM, emphasized.
Professor Dong Soo Han from the School of Computing, who took the position of research head of the group, said, “We will systematically develop exhibition technology and contents for the science museum to create a platform for smart science museums. It will be the first time to provide an exhibition guide system that integrates AR/VR with an indoor location system.”
The center will first apply the new system to the NSM and then expand it to 167 science museums and other regional museums.
2018.09.04 View 10190