Engineering
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2015 QS World University Rankings by Subject: KAIST's Chemical Engineering ranks 17th and 19th for Materials Science in the World
Chemical Engineering (1st in Korea)
1
MIT (US)
2
UC Berkeley (US)
3
Stanford University (US)
4
University of Cambridge (UK)
5
National University of Singapore (Singapore)
17
KAIST (Korea)
Materials Science and Engineering (1st in Korea)
1
MIT (US)
2
Stanford University (US)
3
UC Berkeley (US)
4
University of Cambridge (UK)
5
North Western University (US)
19
KAIST (Korea)
Electrical and Electronic Engineering (1st in Korea)
1
MIT (US)
2
Stanford University (US)
3
UC Berkeley (US)
4
Harvard University (US)
5
ETH Zurich – Swiss Federal Institute of Technology (Switzerland)
22
KAIST (Korea)
Civil and Structural Engineering (1st in Korea)
1
MIT (US)
2
Delft University of Technology (The Netherlands)
3
National University of Singapore (Singapore)
4
Imperial College London (UK)
5
University of Cambridge (UK)
22
KAIST (Korea)
Mechanical, Aeronautical and Manufacturing Engineering (1st in Korea)
1
MIT (US)
2
Stanford University (US)
3
University of Cambridge (UK)
4
UC Berkeley (US)
5
Michigan University (US)
26
KAIST (Korea)
Chemistry (2nd in Korea)
1
MIT (US)
2
UC Berkeley (US)
3
University of Cambridge (UK)
4
Harvard University (US)
5
University of Oxford (UK)
26
KAIST (Korea)
Computer Science and Information Systems (1st in Korea)
1
MIT (US)
2
Stanford University (US)
3
University of Oxford (UK)
4
Carnegie Mellon University (US)
Harvard University (US)
39
KAIST (Korea)
The QS World University Rankings released its 2015 rankings by subject on April 29, 2015.
According to the rankings, KAIST’s Chemical and Biomolecular Engineering and Materials Science Engineering were listed in the top 20 global universities, 17th and 19th, respectively.
KAIST took first place in six subjects among Korean universities, including electrical and electronic engineering; civil and structural engineering; mechanical, aeronautical and manufacturing engineering; and computer science and information systems.
The QS World University Rankings by Subject highlights the world’s top universities in a range of popular subject areas, covering 36 subjects as of this year. Published annually since 2011, the rankings are based on academic reputation, employer reputation, citation count, and research impact.
For a full list of the rankings: http://www.topuniversities.com/subject-rankings/2015
2015.04.29 View 5316 -
Professor Sang Ouk Kim Receives the POSCO Academic Award
Professor Sang Ouk Kim of KAIST’s Department of Materials Science and Engineering received the 2015 POSCO Academic Award. The award ceremony took place at the annual conference of the Korean Institute of Metals and Materials on April 23, 2015.
The POSCO Academic Award has been presented to the Institute's researchers and academics in recognition of their contributions to the advancement of metals and materials engineering in Korea.
Professor Kim is known for his pioneering work in manipulating the properties (work function, conductivity, surface energy, chemo-responsiveness, etc.) of carbon-based materials using double-element doping. Through his research, Professor Kim showed that carbon materials could be extremely useful in various areas including solar batteries and flexible devices. His work has been recognized and published in such journals as Advanced Materials, which invited him to write a review paper on his research in its 25th anniversary issue in 2014, along with world-renowned scholars including the Nobel laureate Alan Heeger.
Professor Kim has published a total of 143 Science Citation Index papers in journals like Nature, Science, Nature Materials, Nature Communications, Advanced Materials, Nano Letters, and Physical Review Letters. According to Scopus, a bibliographic database containing abstracts and citations for academic journal articles, he has been cited 6,456 times and has the h-index of 44, an index describing the scientific productivity and impact of a researcher.
2015.04.22 View 9483 -
KAIST Researchers Develops Hyper-Stretchable Elastic-Composite Energy Harvester
A research team led by Professor Keon Jae Lee (http://fand.kaist.ac.kr) of the Department of Materials Science and Engineering at KAIST has developed a hyper-stretchable elastic-composite energy harvesting device called a nanogenerator.
Flexible electronics have come into the market and are enabling new technologies like flexible displays in mobile phone, wearable electronics, and the Internet of Things (IoTs). However, is the degree of flexibility enough for most applications? For many flexible devices, elasticity is a very important issue. For example, wearable/biomedical devices and electronic skins (e-skins) should stretch to conform to arbitrarily curved surfaces and moving body parts such as joints, diaphragms, and tendons. They must be able to withstand the repeated and prolonged mechanical stresses of stretching. In particular, the development of elastic energy devices is regarded as critical to establish power supplies in stretchable applications. Although several researchers have explored diverse stretchable electronics, due to the absence of the appropriate device structures and correspondingly electrodes, researchers have not developed ultra-stretchable and fully-reversible energy conversion devices properly.
Recently, researchers from KAIST and Seoul National University (SNU) have collaborated and demonstrated a facile methodology to obtain a high-performance and hyper-stretchable elastic-composite generator (SEG) using very long silver nanowire-based stretchable electrodes. Their stretchable piezoelectric generator can harvest mechanical energy to produce high power output (~4 V) with large elasticity (~250%) and excellent durability (over 104 cycles). These noteworthy results were achieved by the non-destructive stress- relaxation ability of the unique electrodes as well as the good piezoelectricity of the device components. The new SEG can be applied to a wide-variety of wearable energy-harvesters to transduce biomechanical-stretching energy from the body (or machines) to electrical energy.
Professor Lee said, “This exciting approach introduces an ultra-stretchable piezoelectric generator. It can open avenues for power supplies in universal wearable and biomedical applications as well as self-powered ultra-stretchable electronics.”
This result was published online in the March issue of Advanced Materials, which is entitled “A Hyper-Stretchable Elastic-Composite Energy Harvester.”
YouTube Link: “A hyper-stretchable energy harvester”
https://www.youtube.com/watch?v=EBByFvPVRiU&feature=youtu.be
Figure: Top row: Schematics of hyper-stretchable elastic-composite generator enabled by very long silver nanowire-based stretchable electrodes.
Bottom row: The SEG energy harvester stretched by human hands over 200% strain.
2015.04.14 View 12837 -
Wall Climbing Quadcopter by KAIST Urban Robotics Lab
Popular Science, an American monthly magazine devoted to general readers of science and technology, published “Watch This Creepy Drone Climb A Wall” online describing a drone that can fly and climb walls on March 19, 2015. The drone is the product of research conducted by Professor Hyun Myung of the Department of Civil and Environmental Engineering at KAIST. The flying quadcopters can turn into wall-crawling robots, or vice versa, when carrying out such assignments as cleaning windows or inspecting a building’s infrastructure. Professor Myung leads the KAIST Urban Robotics Lab (http://urobot.kaist.ac.kr/). For a link to the article, see http://www.popsci.com/watch-drone-climb-wall-video.
Another Popular Science article (posted on April 3, 2015), entitled “South Korea Gets Ready for Drone-on-Drone Warfare with North Korea,” describes a combat system of drones against hostile drones. Professor Hyunchul Shim of the Aerospace Engineering Department at KAIST developed the anti-drone system. He currently heads the Unmanned System Research Group, FDCL, http://unmanned.kaist.ac.kr/) and the Center of Field Robotics for Innovation, Exploration, aNd Defense (C-FRIEND).
2015.04.07 View 11402 -
Anti-Cancer Therapy Delivering Drug to an Entire Tumor Developed
KAIST’s Department of Bio and Brain Engineering Professor Ji-Ho Park and his team successfully developed a new highly efficacious anti-cancer nanotechnology by delivering anti-cancer drugs uniformly to an entire tumor. Their research results were published in Nano Letters online on March 31, 2015.
To treat inoperable tumors, anti-cancer medicine is commonly used. However, efficient drug delivery to tumor cells is often difficult, treating an entire tumor with drugs even more so.
Using the existing drug delivery systems, including nanotechnology, a drug can be delivered only to tumor cells near blood vessels, leaving cells at the heart of a tumor intact. Since most drugs are injected into the bloodstream, tumor recurrence post medication is frequent.
Therefore, the team used liposomes that can fuse to the cell membrane and enter the cell. Once inside liposomes the drug can travel into the bloodstream, enter tumor cells near blood vessels, where they are loaded to exosomes, which are naturally occurring nanoparticles in the body. Since exosomes can travel between cells, the drug can be delivered efficiently into inner cells of the tumor.
Exosomes, which are secreted by cells that exist in the tumor microenvironment, is known to have an important role in tumor progression and metastasis since they transfer biological materials between cells. The research team started the investigation recognizing the possibility of delivering the anti-cancer drug to the entire tumor using exosomes.
The team injected the light-sensitive anti-cancer drug using their new delivery technique into experimental mice. The researchers applied light to the tumor site to activate the anti-cancer treatment and analyzed a tissue sample. They observed the effects of the anti-cancer drug in the entire tumor tissue.
The team’s results establish a ground-breaking foothold in drug delivery technology development that can be tailored to specific diseases by understanding its microenvironment. The work paves the way to more effective drug delivery systems for many chronic diseases, including cancer tumors that were difficult to treat due to the inability to penetrate deep into the tissue.
The team is currently conducting experiments with other anti-cancer drugs, which are being developed by pharmaceutical companies, using their tumor-penetrating drug delivery nanotechnology, to identify its effects on malignant tumors.
Professor Park said, “This research is the first to apply biological nanoparticles, exosomes that are continuously secreted and can transfer materials to neighboring cells, to deliver drugs directly to the heart of tumor.”
Picture: Incorporation of hydrophilic and hydrophobic compounds into membrane vesicles by engineering the parental cells via synthetic liposomes.
2015.04.07 View 11106 -
Professor Rim Presents at IAEA Workshop in Vienna
Professor Chun-Taek Rim of the Department of Nuclear and Quantum Engineering at KAIST recently attended the International Atomic Energy Agency (IAEA)’s workshop on the Application of Wireless Technologies in Nuclear Power Plant Instrumentation and Control System. It took place on March 30-April 2, 2015, in Vienna, Austria.
Representing Korea, Professor Rim gave a talk entitled “Highly Reliable Wireless Power and Communications under Severe Accident of Nuclear Power Plants (NPPs).” About 20 industry experts from 12 countries such as AREVA (France), Westinghouse (US), Oak Ridge National Laboratory (US), Hitachi (Japan), and ENEA (Italy) joined the meeting.
The IAEA hosted the workshop to explore the application of wireless technology for the operation and management of NPPs. It formed a committee consisting of eminent professionals worldwide in NPP instrumentation and control systems, communications, and nuclear power to examine this issue in-depth and to conduct various research projects for the next three years.
In particular, the committee will concentrate its research on improving the reliability and safety of using wireless technology, not only in the normal operation of nuclear plants but also in extreme conditions such as the Fukushima Daiichi nuclear accident. The complementation, economic feasibility, and standardization of NPPs when applying wireless technology will be also discussed.
Professor Rim currently leads the Nuclear Power Electronics
and Robotics Lab at KAIST (http://tesla.kaist.ac.kr/index_eng.php?lag=eng).
Picture 1: Professors Rim presents his topic at the IAEA Workshop in Vienna.
Picture 2: The IAEA Workshop Participants
2015.04.07 View 11339 -
Novel Photolithographic Technology Enabling 3D Control over Functional Shapes of Microstructures
Professor Shin-Hyun Kim and his research team in the Department of Chemical and Biomolecular Engineering at KAIST have developed a novel photolithographic technology enabling control over the functional shapes of micropatterns using oxygen diffusion.
The research was published online in the March 13th issue of Nature Communications and was selected as a featured image for the journal.
Photolithography is a standard optical process for transferring micropatterns on to a substrate by exposing specific regions of the photoresist layer to ultraviolet (UV) light. It is used widely throughout industries that require micropatterns, especially in the semiconductor manufacturing industry.
Conventional photolithography relied on photomasks which protected certain regions of the substrate from the input UV light. Areas covered by the photomasks remain intact with the base layer while the areas exposed to the UV light are washed away, thus creating a micropattern. This technology was limited to a two-dimensional, disc-shaped design as the boundaries between the exposed and roofed regions are always in a parallel arrangement with the direction of the light.
Professor Kim’s research team discovered that: 1) the areas exposed to UV light lowered the concentration of oxygen and thus resulted in oxygen diffusion; and 2) manipulation of the diffusion speed and direction allowed control of the growth, shape and size of the polymers. Based on these findings, the team developed a new photolithographic technology that enabled the production of micropatterns with three-dimensional structures in various shapes and sizes.
Oxygen was considered an inhibitor during photopolymerization. Photoresist under UV light creates radicals which initialize a chemical reaction. These radicals are eliminated with the presence of oxygen and thus prevents the reaction. This suggests that the photoresist must be exposed to UV light for an extended time to completely remove oxygen for a chemical reaction to begin.
The research team, however, exploited the presence of oxygen. While the region affected by the UV light lowered oxygen concentration, the concentration in the untouched region remained unchanged. This difference in the concentrations caused a diffusion of oxygen to the region under UV light.
When the speed of the oxygen flow is slow, the diffusion occurs in parallel with the direction of the UV light. When fast, the diffusion process develops horizontally, outward from the area affected by the UV light. Professor Kim and his team proved this phenomenon both empirically and theoretically. Furthermore, by injecting an external oxygen source, the team was able to manipulate diffusion strength and direction, and thus control the shape and size of the polymer. The use of the polymerization inhibitors enabled and facilitated the fabrication of complex, three-dimensional micropatterns.
Professor Kim said, “While 3D printing is considered an innovative manufacturing technology, it cannot be used for mass-production of microscopic products. The new photolithographic technology will have a broad impact on both the academia and industry especially because existing, conventional photolithographic equipment can be used for the development of more complex micropatterns.” His newest technology will enhance the manufacturing process of three-dimensional polymers which were considered difficult to be commercialized.
The research was also dedicated to the late Professor Seung-Man Yang of the Department of Chemical and Biomolecular Engineering at KAIST. He was considered one of the greatest scholars in Korea in the field of hydrodynamics and colloids.
Picture 1: Featured Image of Nature Communications, March 2015
Picture 2: Polymers with various shapes and sizes produced with the new photolithographic technology developed by Professor Kim
2015.04.06 View 9719 -
Polymers with Highly Improved Light-transformation Efficiency
A joint Korean research team, led by Professor Bum-Joon Kim of the Department of Chemical and Biomolecular Engineering at KAIST and Professor Young-Woo Han of the Department of Nanofusion Engineering at Pusan National University, has developed a new type of electrically-conductive polymer for solar batteries with an improved light-transformation efficiency of up to 5%. The team considers it a viable replacement for existing plastic batteries for solar power which is viewed as the energy source of the future.
Polymer solar cells have greater structural stability and heat resistance compared to fullerene organic solar cells. However, they have lower light-transformation efficiency—below 4%—compared to 10% of the latter. The low efficiency is due to the failure of blending among the polymers that compose the active layer of the cell. This phenomenon deters the formation and movement of electrons and thus lowers light-transformation efficiency.
By manipulating the structure and concentration of conductive polymers, the team was able to effectively increase the polymer blending and increase light-transformation efficiency. The team was able to maximize the efficiency up to 6% which is the highest reported ratio.
Professor Kim said, “This research demonstrates that conductive polymer plastics can be used widely for solar cells and batteries for mobile devices.”
The research findings were published in the February 18th issue of the Journal of the American Chemical Society (JACS).
Picture: Flexible Solar Cell Polymer Developed by the Research Team
2015.04.05 View 9931 -
Professor Shim Featured with His Drone System in IEEE Spectrum
The IEEE Spectrum, a technology and science magazine published by the Institute of Electrical and Electronics Engineers (IEEE), featured an article of KAIST’s autonomous unmanned aerial vehicles (UAVs) entitled “South Korea Prepares for Drone vs. Drone Combat,” posted on April 1, 2015.
The article introduces the anti-drone defense system being developed by Professor “David” Hyunchul Shim of the Department of Aerospace Engineering at KAIST. With the goal of developing guard drones that can detect and capture unknown UAVs, the anti-drone defense system consists of reconnaissance drones, agile multi-rotor UAVs equipped with nets which are dropped to snare enemy drones, and transport UAVs to carry smaller drones.
Professor Shim currently leads KAIST’s Unmanned System Research Group (USRG, http://unmanned.kaist.ac.kr/) and Center of Field Robotics for Innovation, Exploration, aNd Defense (C-FRIEND).
For the article, please go to http://spectrum.ieee.org/automaton/robotics/aerial-robots/south-korea-drone-vs-drone.
2015.04.02 View 11485 -
Mutations Occurring Only in Brain Responsible for Intractable Epilepsy Identified
KAIST researchers have discovered that brain somatic mutations in MTOR gene induce intractable epilepsy and suggest a precision medicine to treat epileptic seizures.
Epilepsy is a brain disorder which afflicts more than 50 million people worldwide. Many epilepsy patients can control their symptoms through medication, but about 30% suffer from intractable epilepsy and are unable to manage the disease with drugs. Intractable epilepsy causes multiple seizures, permanent mental, physical, and developmental disabilities, and even death. Therefore, surgical removal of the affected area from the brain has been practiced as a treatment for patients with medically refractory seizures, but this too fails to provide a complete solution because only 60% of the patients who undergo surgery are rendered free of seizures.
A Korean research team led by Professor Jeong Ho Lee of the Graduate School of Medical Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) and Professor Dong-Seok Kim of Epilepsy Research Center at Yonsei University College of Medicine has recently identified brain somatic mutations in the gene of mechanistic target of rapamycin (MTOR) as the cause of focal cortical dysplasia type II (FCDII), one of the most important and common inducers to intractable epilepsy, particularly in children. They propose a targeted therapy to lessen epileptic seizures by suppressing the activation of mTOR kinase, a signaling protein in the brain. Their research results were published online in Nature Medicine on March 23, 2015.
FCDII contributes to the abnormal developments of the cerebral cortex, ranging from cortical disruption to severe forms of cortical dyslamination, balloon cells, and dysplastic neurons. The research team studied 77 FCDII patients with intractable epilepsy who had received a surgery to remove the affected regions from the brain. The researchers used various deep sequencing technologies to conduct comparative DNA analysis of the samples obtained from the patients’ brain and blood, or saliva. They reported that about 16% of the studied patients had somatic mutations in their brain. Such mutations, however, did not take place in their blood or saliva DNA.
Professor Jeong Ho Lee of KAIST said, “This is an important finding. Unlike our previous belief that genetic mutations causing intractable epilepsy exist anywhere in the human body including blood, specific gene mutations incurred only in the brain can lead to intractable epilepsy. From our animal models, we could see how a small fraction of mutations carrying neurons in the brain could affect its entire function.”
The research team recapitulated the pathogenesis of intractable epilepsy by inducing the focal cortical expression of mutated mTOR in the mouse brain via electroporation method and observed as the mouse develop epileptic symptoms. They then treated these mice with the drug called “rapamycin” to inhibit the activity of mTOR protein and observed that it suppressed the development of epileptic seizures with cytomegalic neurons.
“Our study offers the first evidence that brain-somatic activating mutations in MTOR cause FCDII and identifies mTOR as a treatment target for intractable epilepsy,” said co-author Dr. Dong-Seok Kim, a neurosurgeon at Yonsei Medical Center with the country’s largest surgical experiences in treating patients with this condition.
The research paper is titled “Brain somatic mutations in MTOR cause focal cortical dysplasia type II leading to intractable epilepsy.” (Digital Object Identifier #: 10.1038/nm.3824)
Picture 1: A schematic image to show how to detect brain specific mutation using next-generation sequencing technology with blood-brain paired sample. Simple comparison of non-overlapping mutations between affected and unaffected tissues is able to detect brain specific mutations.
Picture 2: A schematic image to show how to generate focal cortical dysplasia mouse model. This mouse model open the new window of drug screening for seizure patients.
Picture 3: Targeted medicine can rescue the focal cortical dysplasia symptoms including cytomegalic neuron & intractable epilepsy.
2015.03.25 View 13290 -
KAIST Introduces New UI for K-Glass 2
A newly developed user interface, the “i-Mouse,” in the K-Glass 2 tracks the user’s gaze and connects the device to the Internet through blinking eyes such as winks. This low-power interface provides smart glasses with an excellent user experience, with a long-lasting battery and augmented reality.
Smart glasses are wearable computers that will likely lead to the growth of the Internet of Things. Currently available smart glasses, however, reveal a set of problems for commercialization, such as short battery life and low energy efficiency. In addition, glasses that use voice commands have raised the issue of privacy concerns.
A research team led by Professor Hoi-Jun Yoo of the Electrical Engineering Department at the Korea Advanced Institute of Science and Technology (KAIST) has recently developed an upgraded model of the K-Glass (http://www.eurekalert.org/pub_releases/2014-02/tkai-kdl021714.php) called “K-Glass 2.”
K-Glass 2 detects users’ eye movements to point the cursor to recognize computer icons or objects in the Internet, and uses winks for commands. The researchers call this interface the “i-Mouse,” which removes the need to use hands or voice to control a mouse or touchpad. Like its predecessor, K-Glass 2 also employs augmented reality, displaying in real time the relevant, complementary information in the form of text, 3D graphics, images, and audio over the target objects selected by users.
The research results were presented, and K-Glass 2’s successful operation was demonstrated on-site to the 2015 Institute of Electrical and Electronics Engineers (IEEE) International Solid-State Circuits Conference (ISSCC) held on February 23-25, 2015 in San Francisco. The title of the paper was “A 2.71nJ/Pixel 3D-Stacked Gaze-Activated Object Recognition System for Low-power Mobile HMD Applications” (http://ieeexplore.ieee.org/Xplore/home.jsp).
The i-Mouse is a new user interface for smart glasses in which the gaze-image sensor (GIS) and object recognition processor (ORP) are stacked vertically to form a small chip. When three infrared LEDs (light-emitting diodes) built into the K-Glass 2 are projected into the user’s eyes, GIS recognizes their focal point and estimates the possible locations of the gaze as the user glances over the display screen. Then the electro-oculography sensor embedded on the nose pads reads the user’s eyelid movements, for example, winks, to click the selection. It is worth noting that the ORP is wired to perform only within the selected region of interest (ROI) by users. This results in a significant saving of battery life. Compared to the previous ORP chips, this chip uses 3.4 times less power, consuming on average 75 milliwatts (mW), thereby helping K-Glass 2 to run for almost 24 hours on a single charge.
Professor Yoo said, “The smart glass industry will surely grow as we see the Internet of Things becomes commonplace in the future. In order to expedite the commercial use of smart glasses, improving the user interface (UI) and the user experience (UX) are just as important as the development of compact-size, low-power wearable platforms with high energy efficiency. We have demonstrated such advancement through our K-Glass 2. Using the i-Mouse, K-Glass 2 can provide complicated augmented reality with low power through eye clicking.”
Professor Yoo and his doctoral student, Injoon Hong, conducted this research under the sponsorship of the Brain-mimicking Artificial Intelligence Many-core Processor project by the Ministry of Science, ICT and Future Planning in the Republic of Korea.
Youtube Link:
https://www.youtube.com/watchv=JaYtYK9E7p0&list=PLXmuftxI6pTW2jdIf69teY7QDXdI3Ougr
Picture 1: K-Glass 2
K-Glass 2 can detect eye movements and click computer icons via users’ winking.
Picture 2: Object Recognition Processor Chip
This picture shows a gaze-activated object-recognition system.
Picture 3: Augmented Reality Integrated into K-Glass 2
Users receive additional visual information overlaid on the objects they select.
2015.03.13 View 15490 -
KAIST Develops Ultrathin Polymer Insulators Key to Low-Power Soft Electronics
Using an initiated chemical vapor deposition technique, the research team created an ultrathin polymeric insulating layer essential in realizing transistors with flexibility and low power consumption. This advance is expected to accelerate the commercialization of wearable and soft electronics.
A group of researchers at the Korea Advanced Institute of Science and Technology (KAIST) developed a high-performance ultrathin polymeric insulator for field-effect transistors (FETs). The researchers used vaporized monomers to form polymeric films grown conformally on various surfaces including plastics to produce a versatile insulator that meets a wide range of requirements for next-generation electronic devices. Their research results were published online in Nature Materials on March 9th, 2015.
FETs are an essential component for any modern electronic device used in our daily life from cell phones and computers, to flat-panel displays. Along with three electrodes (gate, source, and drain), FETs consist of an insulating layer and a semiconductor channel layer. The insulator in FETs plays an important role in controlling the conductance of the semiconductor channel and thus current flow within the translators. For reliable and low-power operation of FETs, electrically robust, ultrathin insulators are essential. Conventionally, such insulators are made of inorganic materials (e.g., oxides and nitrides) built on a hard surface such as silicon or glass due to their excellent insulating performance and reliability.
However, these insulators were difficult to implement into soft electronics due to their rigidity and high process temperature. In recent years, many researchers have studied polymers as promising insulating materials that are compatible with soft unconventional substrates and emerging semiconductor materials. The traditional technique employed in developing a polymer insulator, however, had the limitations of low surface coverage at ultra-low thickness, hindering FETs adopting polymeric insulators from operating at low voltage.
A KAIST research team led by Professor Sung Gap Im of the Chemical and Biomolecular Engineering Department and Professor Seunghyup Yoo and Professor Byung Jin Cho of the Electrical Engineering Department developed an insulating layer of organic polymers, “pV3D3,” that can be greatly scaled down, without losing its ideal insulating properties, to a thickness of less than 10 nanometers (nm) using the all-dry vapor-phase technique called the “initiated chemical vapor deposition (iCVD).”
The iCVD process allows gaseous monomers and initiators to react with each other in a low vacuum condition, and as a result, conformal polymeric films with excellent insulating properties are deposited on a substrate. Unlike the traditional technique, the surface-growing character of iCVD can overcome the problems associated with surface tension and produce highly uniform and pure ultrathin polymeric films over a large area with virtually no surface or substrate limitations. Furthermore, most iCVD polymers are created at room temperature, which lessens the strain exerted upon and damage done to the substrates.
With the pV3D3 insulator, the research team built low-power, high-performance FETs based on various semiconductor materials such as organics, graphene, and oxides, demonstrating the pV3D3 insulator’s wide range of material compatibility. They also manufactured a stick-on, removable electronic component using conventional packaging tape as a substrate. In collaboration with Professor Yong-Young Noh from Dongguk University in Korea, the team successfully developed a transistor array on a large-scale flexible substrate with the pV3D3 insulator.
Professor Im said, “The down-scalability and wide range of compatibility observed with iCVD-grown pV3D3 are unprecedented for polymeric insulators. Our iCVD pV3D3 polymeric films showed an insulating performance comparable to that of inorganic insulating layers, even when their thickness were scaled down to sub-10 nm. We expect our development will greatly benefit flexible or soft electronics, which will play a key role in the success of emerging electronic devices such as wearable computers.”
The title of the research paper is “Synthesis of ultrathin polymer insulating layers by initiated chemical vapor deposition for low-power soft electronics” (Digital Object Identifier (DOI) number is 10.1038/nmat4237).
Picture 1: A schematic image to show how the initiated chemical vapor deposition (iCVD) technique produces pV3D3 polymeric films: (i) introduction of vaporized monomers and initiators, (ii) activation of initiators to thermally dissociate into radicals, (iii) adsorption of monomers and initiator radicals onto a substrate, and (iv) transformation of free-radical polymerization into pV3D3 thin films.
Picture 2: This is a transistor array fabricated on a large scale, highly flexible substrate with pV3D3 polymeric films.
Picture 3: This photograph shows an electronic component fabricated on a conventional packaging tape, which is attachable or detachable, with pV3D3 polymeric films embedded.
2015.03.10 View 12467