materials
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High Speed Nanomanufacturing Process Developed using Laser
Dr. Yeo Jun Yeop from KAIST’s Department of Mechanical Engineering, in a joint research project with Prof. Seung Hwan Ko, has developed a technology that speeds up the nanomanufacturing process by using lasers. Their research is published in the frontispiece of Advanced Functional Materials (July 9th issue).
Fig. The frontispiece of Advanced Functional Materials(July 9th issue)
The research group put a nanomaterial precursor on the board, illuminated it with a continuous-wave laser in the green wavelength range, and succeeded in synthesizing a nanowire at the point they wanted for the first time in the world.
Currently nanomaterials are difficult to mass produce and commercialize due to their complex and costly manufacturing processes which also use toxic gases. However, their new technology simplified the process and so reduced the manufacturing time from some hours to five minutes (1/10th times reduced).
Furthermore, this technology will apply regardless of the type of the board. Such nanometerials can be synthesized at any point on a flexible plastic board or even in three dimensional structures by illuminating them with a simple laser. Academics and industries expect mass production and commercialization of nanomaterials in near future.
Dr. Yeo said he intends to research further to promote early commercialization of multifunctional electronic devices by combining various nanomaterials
This research is sponsored by the National Research Foundation of Korea, the Ministry of Trade, Industry and Energy and KAIST EEWS
Fig. A nanomaterial synthesized after illuminated by lasers
Fig. A nanomaterial synthesized on a three dimensional structure using the developed technology
Fig. Functional electron device manufactured by using the synthesized nanomaterials
2013.08.02 View 9125 -
Nanofiber sensor detects diabetes or lung cancer faster and easier
Metal-oxide nanofiber based chemiresistive gas sensors offer greater usability for portable real-time breath tests that can be available on smart phones or tablet PCs in the near future.
Daejeon, Republic of Korea, June 11, 2013 -- Today"s technological innovation enables smartphone users to diagnose serious diseases such as diabetes or lung cancer quickly and effectively by simply breathing into a small gadget, a nanofiber breathing sensor, mounted on the phones.
Il-Doo Kim, Associate Professor of Materials Science and Engineering Department at the Korea Advanced Institute of Science and Technology (KAIST), and his research team have recently published a cover paper entitled "Thin-Wall Assembled SnO2 Fibers Functionalized by Catalytic Pt Nanoparticles and their Superior Exhaled Breath-Sensing Properties for the Diagnosis of Diabetes," in an academic journal, Advanced Functional Materials (May 20th issue), on the development of a highly sensitive exhaled breath sensor by using hierarchical SnO2 fibers that are assembled from wrinkled thin SnO2 nanotubes.
In the paper, the research team presented a morphological evolution of SnO2 fibers, called micro phase-separations, which takes place between polymers and other dissolved solutes when varying the flow rate of an electrospinning solution feed and applying a subsequent heat treatment afterward.
The morphological change results in nanofibers that are shaped like an open cylinder inside which thin-film SnO2 nanotubes are layered and then rolled up. A number of elongated pores ranging from 10 nanometers (nm) to 500 nm in length along the fiber direction were formed on the surface of the SnO2 fibers, allowing exhaled gas molecules to easily permeate the fibers. The inner and outer wall of SnO2 tubes is evenly coated with catalytic platinum (Pt) nanoparticles. According to the research team, highly porous SnO2 fibers, synthesized by eletrospinning at a high flow rate, showed five-fold higher acetone responses than that of the dense SnO2 nanofibers created under a low flow rate. The catalytic Pt coating shortened the fibers" gas response time dramatically as well.
The breath analysis for diabetes is largely based on an acetone breath test because acetone is one of the specific volatile organic compounds (VOC) produced in the human body to signal the onset of particular diseases. In other words, they are biomarkers to predict certain diseases such as acetone for diabetes, toluene for lung cancer, and ammonia for kidney malfunction. Breath analysis for medical evaluation has attracted much attention because it is less intrusive than conventional medical examination, as well as fast and convenient, and environmentally friendly, leaving almost no biohazard wastes.
Various gas-sensing techniques have been adopted to analyze VOCs including gas chromatography-mass spectroscopy (GC-MS), but these techniques are difficult to incorporate into portable real-time gas sensors because the testing equipment is bulky and expensive, and their operation is more complex. Metal-oxide based chemiresistive gas sensors, however, offer greater usability for portable real-time breath sensors.
Il-Doo Kim said, "Catalyst-loaded metal oxide nanofibers synthesized by electrospinning have a great potential for future exhaled breath sensor applications. From our research, we obtained the results that Pt-coated SnO2 fibers are able to identify promptly and accurately acetone or toluene even at very low concentration less than 100 parts per billion (ppb)."
The exhaled acetone level of diabetes patients exceeds 1.8 parts per million (ppm), which is two to six-fold higher than that (0.3-0.9 ppm) of healthy people. Therefore, a highly sensitive detection that responds to acetone below 1 ppm, in the presence of other exhaled gases as well as under the humid environment of human breath, is important for an accurate diagnosis of diabetes. In addition, Professor Kim said, "a trace concentration of toluene (30 ppb) in exhaled breath is regarded to be a distinctive early symptom of lung cancer, which we were able to detect with our prototype breath tester."
The research team has now been developing an array of breathing sensors using various catalysts and a number of semiconducting metal oxide fibers, which will offer patients a real-time easy diagnosis of diseases.
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Youtube Link: http://www.youtube.com/watch?v=t_Hr11dRryg
For further inquires:
Il-Doo Kim, Professor of Materials Science and Engineering, KAIST
Advanced Nanomaterials and Energy Laboratory
Tel: +82-42-350-3329
Email: idkim@kaist.ac.kr
Clockwise from left to right: left upper shows a magnified SEM image of a broken thin-wall assembled SnO2 fiber. Left below is an array of breath sensors (Inset is an actual size of a breath sensor). The right is the cover of Advanced Functional Materials (May 20th issue) in which a research paper on the development of a highly sensitive exhaled breath sensor by using SnO2 fibers is published.
This is the microstructural evolution of SnO2 nanofibers as a function of flow rate during electrospinning.
2013.06.20 View 14353 -
New Technology Will Enable the Commercialization of Plasmon Displays
-- Enhancements in the penetration ratios of color filters are expected by applying nano-surface plasmon effects. --
-- Color filter technology will be applicable to large-area OLED and LCD. --
The fabrication technology to commercialize display color filters using plasmon effects has been discovered.
A joint research team headed by Professor Kyung Cheol Choi from the Department of Electrical Engineering of the Korea Advanced Institute for Science and Technology and Prof. Byeong-Kwon Ju from the School of Electrical Engineering of Korea University has developed the technology to design and produce a display color filter by applying nano-surface plasmon effects.
Color filters are core components used to express colors in CMOS image sensors found in LCD/OLED displays or digital cameras. The current color filters have penetration ratios of 20~30%, but the objective of the joint research team is to raise this penetration ratio by over 40% to facilitate the mass production of energy-efficient plasmonic displays.
Currently available plasmonic color filters are limited to applications on micrometer scales. However, outcomes of the newest research extend the size of the applications up to 2.5 cm by using laser interference lithography. The academic and industrial sectors agree that it is now possible to mass-produce displays using plasmonic color filters.
The researchers built a nanohole array to large scale by using laser interference lithography, a technology that forms nanostructures with laser light interferences. They also suggested a new manufacturing process that can optimize the features of color filters while compensating for defects arising from the fabrication stages.
The new manufacturing process of applying laser interference lithography is expected to overcome the shortcomings of traditional color filters by simplifying production and, enabling them to be produced at lower costs.
“There were limitations to industrial applications of plasmon effect due to production costs, time, and yields,” explained Yun Seon Do, a Ph. D. candidate in the Department of Electrical Engineering of KAIST. “The new technology can reduce fabrication time and cost to the extent that it would be advisable to replace dye-based and pigment-based color filter technology."
“This research can be applied to large-scale displays, such as TV screens, by using laser-interference lithography,” said Jung-Ho Park, a Ph. D. candidate in the School of Electrical Engineering of Korea University. “The research outcome is expected to be widely applied in advanced nano-manufacturing processes as it does not restrict the types of circuit boards."
The research outcome, led by doctoral candidates Do and Park, appeared on the front cover of the second issue of Advanced Optical Materials, a highly regarded academic journal in the field of nanotechnologies, and the team has applied for six related patents.
2013.03.13 View 9098 -
The control of light at the nano-level
Professor Min Bumki
Professor Min Bumki’s research team from the Department of Mechanical Engineering at KAIST have successfully gained control of the transmittance of light in optical devices using graphene* and artificial 2-dimensional metamaterials**.
* Graphene : a thin membrane composed of pure carbon, with atoms arranged in a regular hexagonal pattern
** Metamaterials : artificial materials engineered to have properties that may not be found in nature
The research results were published in the recent online edition (September 30th) of Nature Materials, a sister journal of the world renowned Nature journal, under the title ‘Terahertz waves with gate-controlled active graphene metamaterials’
Since the discovery of graphene in 2004 by Professors Novoselov and Geim from the University of Manchester (2010 Nobel Prize winners in Physics), it has been dubbed “the dream material” because of its outstanding physical properties.
Graphene has been especially praised for its ability to absorb approximately 2.3% of near infrared and visible rays due to its characteristic electron structure. This property allows graphene to be used as a transparent electrode, which is a vital electrical component used in touch screens and solar batteries. However, graphene’s optical transmittance was largely ignored by researchers due to its limited control using electrical methods and its small optical modulation in data transfer.
Professor Min’s team combined 0.34 nanometer-thick graphene with metamaterials to allow a more effective control of light transmittance and greater optical modulation. This graphene metamaterial can be integrated in to a thin and flexible macromolecule substrate which allows the control of transmittance using electric signals.
This research experimentally showed that graphene metamaterials can not only effective control optical transmittance, but can also be used in graphene optical memory devices using electrical hysteresis.
Professor Min said that “this research allows the effective control of light at the nanometer level” and that “this research will help in the development of microscopic optical modulators or memory disks”.
figure 1. The working drawing of graphene metamaterials
figure 2. Conceptual diagram (Left) and microscopic photo (right) of graphene metamaterials
2012.11.23 View 10742 -
Professor Yoon Dong Ki becomes first Korean to Receive the Michi Nakata Prize
Professor Yoon Dong Ki (Graduate School of Nano Science and Technology) became the first Korean to receive the Michi Nakata Prize from the International Liquid Crystal Society.
The Awards Ceremony was held on the 23rd of August in Mainz, Germany in the 24th Annual International Liquid Crystal Conference.
The Michi Nakata Prize was initiated in 2008 and is rewarded every two years to a young scientist that made a ground breaking discovery or experimental result in the field of liquid crystal. Professor Yoon is the first Korean recipient of the Michi Nakata Prize.
Professor Yoon is the founder of the patterning field that utilizes the defect structure formed by smectic displays. He succeeded in large scale patterning complex chiral nano structures that make up bent-core molecules.
Professor Yoon’s experimental accomplishment was published in the Advanced Materials magazine and the Proc. Natl. Acad. Sci. U.S.A. and also as the cover dissertation of Liquid Crystals magazine.
Professor Yoon is currently working on Three Dimensional Nano Patterning of Supermolecular Liquid Crystal and is part of the World Class University organization.
2012.09.11 View 12437
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KAIST researchers verify and control the mechanical properties of graphene
KAIST researchers have successfully verified and controlled the mechanical properties of graphene, a next-generation material. Professor Park Jung Yong from the EEWS Graduate School and Professor Kim Yong Hyun from the Graduate School of Nanoscience and Technology have succeeded in fluorinating a single atomic-layered graphene sample and controlling its frictional and adhesive properties. This is the first time the frictional properties of graphene have been examined at the atomic level, and the technology is expected to be applied to nano-sized robots and microscopic joints.
Graphene is often dubbed “the dream material” because of its ability to conduct high amounts of electricity even when bent, making it the next-generation substitute for silicon semiconductors, paving the way for flexible display and wearable computer technologies. Graphene also has high potential applications in mechanical engineering because of its great material strength, but its mechanical properties remained elusive until now.
Professor Park’s research team successfully produced individual graphene samples with fluorine-deficiency at the atomic level by placing the samples in Fluoro-xenon (XeF2) gas and applying heat. The surface of the graphene was scanned using a micro probe and a high vacuum atomic microscope to measure its dynamic properties.
The research team found that the fluorinated graphene sample had 6 times more friction and 0.7 times more adhesiveness than the original graphene. Electrical measurements confirmed the fluorination process, and the analysis of the findings helped setup the theory of frictional changes in graphene.
Professor Park stated that “graphene can be used for the lubrication of joints in nano-sized devices” and that this research has numerous applications such as the coating of graphene-based microdynamic devices.
This research was published in the online June edition of Nano Letters and was supported by the Ministry of Science, Technology, and Education and the National Research Foundation as part of the World Class University (WCU) program.
2012.07.24 View 16047 -
Biomimetic reflective display technology developed
Professor Shin Jung Hoon
The bright colors of a rainbow or a peacock are produced by the reflection and interference of light in transparent periodic structures, producing what is called a structural color. These colors are very bright and change according to the viewing angle. On the other hand, the wings of a morpho-butterfly also have structural colors but are predominantly blue over a wide range of angles. This is because the unique structure of the morpho-butterfly’s wings contains both order and chaos.
Professor Shin Jung Hoon’s team from the Department of Physics and the Graduate School of Nanoscience and Technology at KAIST produced a display that mimics the structure of the morpho-butterfly’s wings using glass beads.
This research successfully produced a reflective display (one that reflects external light to project images), which could be used to make very bright displays with low energy consumption. This technology can also be used to make anti-counterfeit bills, as well as coating materials for mobile phones and wallets.
The structure of the morpho-butterfly’s wings seems to be in periodic order at the 1-micrometer level, but contains disorder at the 100-nanometer level. So far, no one had succeeded in reproducing a structure with both order and disorder at the nanometer level.
Professor Shin’s team randomly aligned differently sized glass beads of a few hundred nanometers to create chaos and placed a thin periodic film on top of it using the semiconductor deposition method, thereby creating the morpho-butterfly-like structure over a large area.
This new development produced better color and brightness than the morpho-butterfly wing and even exhibited less color change according to angle. The team sealed the film in thin plastic, which helped to maintain the superior properties whilst making it more firm and paper-like.
Professor Shin emphasized that the results were an exemplary success in the field of biomimetics and that structural colors could have other applications in sensors and fashion, for example.
The results were first introduced on May 3rd in Nature as one of the Research Highlights and will be published in the online version of the material science magazine, Advanced Materials.
This research was jointly conducted by Professor Shin Jung Hoon (Department of Physics / Graduate School of Nanoscience and Technology at KAIST), Professor Park NamKyoo (Department of Electrical and Computer Engineering at Seoul National University), and Samsung Advanced Institute of Technology. The funding was provided by the National Research Foundation of Korea and the Ministry of Education, Science and Technology as part of the World Class University (WCU) project.
Figure 2. The biomimetic film can express many different colors
Figure 3. The biomimetic diplay and a morpho-butterfly
2012.05.07 View 14972 -
Paving the Way to Next Generation Display
A new type of LCD that does not require polymer orientation films has been developed by researchers within the country. This technology will enable the creation of thiner and higher definition display.
Prof. Hee Tae Jung form KAIST’s biochemical engineering department led the research and Hyun Soo Jung, Hwan Jin Jeon doctoral students (1st co-authors), Doctor Yun Ho Kim from Korea Chemistry Research Center, and Prof. Shin Woong Kang from Jeon Buk University ( co-author) have participated in this research. This research has been funded by the WCU program and middle-grade researcher support program. The results of the research has been published as the online update of ‘‘Nature Asia Materials(NPG Asia Materials)” which is a sister magazine of the world renowned academic magazine ‘Nature’.
The flat display industry is the core industry leading the 21st century’s IT industry. The LCD is the main area of research. Korea is the leader of this industry, holding more than 50% of the world market. Many technologies are combined to make the electro-optic devices of the LCD function. The most important technology, which determines the indicating element’s quality and function is the technology to align the liquid crystals in one direction.
Currently, all LCD products are created by mechanically cutting into the surface of the polymer film and orienting the liquid crystal material along these cuts. However, the creation of polymer orientation films cost much time and money, and the high temperature processes necessary to stabilize the polymers does not allow for the free selection of circuit boards, and thus does not allow for the use in flexible display.
Prof. Hee Tae Jung devised a method to orient liquid display without the use of a polymer film using ITOs. Prof. Jung’s base technology has been tested on ITOs to maintain the necessary transparency and conductivity after forming a pattern with high decomposition rates and slenderness ratios.
The technology developed by the research team can horizontally or vertically align the transparent conductors without the use of polymer orientation films. Thus, the manufacturing processes have become much shortened and the LCDs can be made in much thinner from a few micrometers to a few centimeters. Also, it has a lower functioning voltage and faster response speed, showing the prospects of a high definition ultra-fast screen display development. Furthermore, this technology can be used for any type of board, and can be adjusted to a nanometer scale. This enables for its use in LCD based flexible or multi-domain modes.
Also, the transparent conductor patterning technology devised by the research team can be used not only for displays, but also for touch panels with highly increased sensitivity.
Prof. Jung said, “It was a long desire of the industry and academia to find a way to replace the polymer orientation film. This new technology does not need any polymer orientation films, and we can still use the original boards used for LCDs. This mean a lot to the industry. Also, this technology will increase the sensitivity of the touch panels for tablet PCs and smart phones. It can be used in many areas of future electronics base technology.”
2012.04.04 View 10866
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Biomimetic Carbon Nanotube Fiber Synthesis Technology Developed
The byssus of the mussel allows it to live in harsh conditions where it is constantly battered by crashing waves by allowing the mussel to latch onto the seaside rocks. This particular characteristic of the mussel is due to the unique structure and high adhesiveness of the mussel’s byssus.
KAIST’s Professor Hong Soon Hyung (Department of Material Science and Engineering) and Professor Lee Hae Shin (Department of Chemistry) and the late Professor Park Tae Kwan (Department of Bio Engineering) were able to reproduce the mussel’s byssus using carbon nanotubes.
The carbon nanotube, since its discovery in 1991, was regarded as the next generation material due to its electrical, thermal, and mechanical properties. However due to its short length of several nanometers, its industrial use was limited.
The KAIST research team referred to the structure of the byssus of the mussel to solve this problem.
The byssus is composed of collagen fibers and Mefp-1 protein which are in a cross-linking structure. The Mefp-1 protein has catecholamine that allows it to bind strongly with the collagen fiber.
In the artificial structure, the carbon nanotube took on the role of the collagen fibers and the macromolecular adhesive took on the role of the catecholamine. The result was a fiber that was ultra-light and ultra-strong.
The results of the experiment were published in the Advanced Materials magazine and is patent registered both domestically and internationally.
2011.06.20 View 13065
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From Pencil Lead to Batteries: the Unlimited Transformation of Carbon
Those materials, like lead or diamond, made completely up of Carbon are being used in numerous ways as materials or parts. Especially with the discovery of carbon nanotubes, graphemes, and other carbon based materials in nanoscale, the carbon based materials are receiving a lot of interest in both fields of research and industry.
The carbon nanotubes and graphemes are considered as the ‘dream material’ and have a structure of a cross section of a bee hive. Such structure allows the material to have strength higher than that of a diamond and still be able to bend, be transparent and also conduct electricity. However the problem up till now was that these carbon structures appeared in layers and in bunches and were therefore hard to separate to individual layers or tubes.
Professor Kim Sang Wook’s research team developed the technology that can assemble the grapheme and carbon nanotubes in a three dimensional manner.
The team was able to assemble the grapheme ad carbon nanotubes in an entirely new three dimensional structure. In addition, the team was able to efficiently extract single layered grapheme from cheap pencil lead.
Professor Kim is scheduled to give a guest lecture in the “Materials Research Society” in San Francisco and the paper was published in ‘Advanced Functional Materials’ magazine as an ‘Invited Feature Article’.
2011.05.11 View 11476
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Artificial Photosynthesis Technology Developed using Solar Cell Material
Humanity is facing global warming and the exhaustion of fossil fuel. In order to remedy these problems, efforts to produce fuel without the production of carbon dioxide using solar energy continues constantly.
KAIST’s Professor Park Chan Beom and Professor Ryu Jeong Ki’s research teams of the department of Material Science and Engineering has developed an artificial photosynthesis system that mimics the photosynthesis in nature using solar cell technology.
The development of the technology is sure to pave the way to ‘Eco-Friendly Green Biological Process’.
Photosynthesis is the process by which a biological entity produces chemical products like carbohydrates using physical and chemical reactions using solar energy as its energy source.
Professor Park’s team was able to develop the artificial photosynthesis technology with a biological catalyst as its basis.
The result of the experiment was published in ‘Advanced Materials’ magazine on the 26th of April edition and has been patented.
2011.05.11 View 11132
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KAIST paves the way to commercialize flexible display screens
Source: IDTechEX, Feb. 28, 2011
KAIST paves the way to commercialize flexible display screens
28 Feb 2011
Transparent plastic and glass cloths, which have a limited thermal expansion needed for the production of flexible display screens and solar power cells, were developed by researchers at KAIST (Korea Advance Institute of Science & Technology).
The research, led by KAIST"s Professor Byoung-Soo Bae, was funded by the Engineering Research Center under the initiative of the Ministry of Education, Science and Technology and the National Research Foundation. The research result was printed as the cover paper of "Advanced Materials".
Professor Bae"s team developed a hybrid material with the same properties as fiber glass. With the material, they created a transparent, plastic film sheet resistant to heat. Transparent plastic film sheets were used by researchers all over the world to develop devices such as flexible displays or solar power cells that can be fit into various living spaces. However, plastic films are heat sensitive and tend to expand as temperature increases, thereby making it difficult to produce displays or solar power cells.
The new transparent, plastic film screen shows that heat expansion index (13ppm/oC) similar to that of glass fiber (9ppm/oC) due to the presence of glass fibers; its heat resistance allows to be used for displays and solar power cells over 250oC.
Professor Bae"s team succeeded in producing a flexible thin plastic film available for use in LCD or AMOLED screens and thin solar power cells.
Professor Bae commented, "Not only the newly developed plastic film has superior qualities, compared to the old models, but also it is cheap to produce, potentially bringing forward the day when flexible displays and solar panels become commonplace. With the cooperation of various industries, research institutes and universities, we will strive to improve the existing design and develop it further."
http://www.printedelectronicsworld.com/articles/kaist_paves_the_way_to_commercialize_flexible_display_screens_00003144.asp?sessionid=1
2011.03.01 View 14083