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Extremely Thin and Highly Flexible Graphene-Based Thermoacoustic Speakers
A joint research team led by Professors Jung-Woo Choi and Byung Jin Cho of the School of Electrical Engineering and Professor Sang Ouk Kim of the Material Science and Engineering Department, all on the faculty of the Korea Advanced Institute of Science and Technology (KAIST), has developed a simpler way to mass-produce ultra-thin graphene thermosacoustic speakers.
Their research results were published online on August 17, 2016 in a journal called Applied Materials & Interfaces. The IEEE Spectrum, a monthly magazine published by the Institute of Electrical and Electronics Engineers, reported on the research on September 9, 2016, in an article titled, “Graphene Enables Flat Speakers for Mobile Audio Systems.” The American Chemical Society also drew attention to the team’s work in its article dated September 7, 2016, “Bringing Graphene Speakers to the Mobile Market.”
Thermoacoustic speakers generate sound waves from temperature fluctuations by rapidly heating and cooling conducting materials. Unlike conventional voice-coil speakers, thermoacoustic speakers do not rely on vibrations to produce sound, and thus do not need bulky acoustic boxes to keep complicated mechanical parts for sound production. They also generate good quality sound in all directions, enabling them to be placed on any surface including curved ones without canceling out sounds generated from opposite sides.
Based on a two-step, template-free fabrication method that involved freeze-drying a solution of graphene oxide flakes and the reduction/doping of oxidized graphene to improve electrical properties, the research team produced a N-doped, three-dimensional (3D), reduced graphene oxide aerogel (N-rGOA) with a porous macroscopic structure that permitted easy modulation for many potential applications.
Using 3D graphene aerogels, the team succeeded in fabricating an array of loudspeakers that were able to withstand over 40 W input power and that showed excellent sound pressure level (SPL), comparable to those of previously reported 2D and 3D graphene loudspeakers.
Choong Sun Kim, the lead author of the research paper and a doctoral student in the School of Electrical Engineering at KAIST, said:
“Thermoacoustic speakers have a higher efficiency when conducting materials have a smaller heat capacity. Nanomaterials such as graphene are an ideal candidate for conductors, but they require a substrate to support their extremely thinness. The substrate’s tendency to lose heat lowers the speakers’ efficiency. Here, we developed 3D graphene aerogels without a substrate by using a simple two-step process. With graphene aerogels, we have fabricated an array of loudspeakers that demonstrated stable performance. This is a practical technology that will enable mass-production of thermosacoustic speakers including on mobile platforms.”
The research paper is entitled “Application of N-Doped Three-Dimensional Reduced Graphene Oxide Aerogel to Thin Film Loudspeaker.” (DOI: 10.1021/acsami.6b03618)
Figure 1: A Thermoacoustic Loudspeaker Consisted of an Array of 16 3D Graphene Aerogels
Figure 2: Two-step Fabrication Process of 3D Reduced Graphene Oxide Aerogel Using Freeze-Drying and Reduction/Doping
Figure 3: X-ray Photoelectron Spectroscopy Graph of the 3D Reduced Graphene Oxide Aerogel and Its Scanning Electron Microscope Image
2016.10.05 View 16388 -
KAIST Ranked the World's Sixth Most Innovative University
KAIST took sixth place in the list of “The World’s Top 100 Most Innovative Universities.” Thomson Reuters released the list on September 28, 2016, which was based on the data compiled by its division of Intellectual Property & Science such as patent filings, number of research papers and their citations, and industry collaboration. American universities took ranks from first to fifth; KAIST was the only non-American university that ranked highest in the list. Stressing the importance of linking basic research with commercializing efforts, Thomson Reuters said, the listed universities were “doing the most to advance science, invent new technologies and help drive the global economy.”
For details, go to the link below:
Reuters Top 100: The World’s Most Innovative Universities-2016
September 28, 2016
http://www.reuters.com/article/amers-reuters-ranking-innovative-univers-idUSL2N1C406D
2016.09.29 View 6560 -
Continuous Roll-Process Technology for Transferring and Packaging Flexible Large-Scale Integrated Circuits
A research team led by Professor Keon Jae Lee from KAIST and by Dr. Jae-Hyun Kim from the Korea Institute of Machinery and Materials (KIMM) has jointly developed a continuous roll-processing technology that transfers and packages flexible large-scale integrated circuits (LSI), the key element in constructing the computer’s brain such as CPU, on plastics to realize flexible electronics.
Professor Lee previously demonstrated the silicon-based flexible LSIs using 0.18 CMOS (complementary metal-oxide semiconductor) process in 2013 (ACS Nano, “In Vivo Silicon-based Flexible Radio Frequency Integrated Circuits Monolithically Encapsulated with Biocompatible Liquid Crystal Polymers”) and presented the work in an invited talk of 2015 International Electron Device Meeting (IEDM), the world’s premier semiconductor forum.
Highly productive roll-processing is considered a core technology for accelerating the commercialization of wearable computers using flexible LSI. However, realizing it has been a difficult challenge not only from the roll-based manufacturing perspective but also for creating roll-based packaging for the interconnection of flexible LSI with flexible displays, batteries, and other peripheral devices.
To overcome these challenges, the research team started fabricating NAND flash memories on a silicon wafer using conventional semiconductor processes, and then removed a sacrificial wafer leaving a top hundreds-nanometer-thick circuit layer. Next, they simultaneously transferred and interconnected the ultrathin device on a flexible substrate through the continuous roll-packaging technology using anisotropic conductive film (ACF). The final silicon-based flexible NAND memory successfully demonstrated stable memory operations and interconnections even under severe bending conditions. This roll-based flexible LSI technology can be potentially utilized to produce flexible application processors (AP), high-density memories, and high-speed communication devices for mass manufacture.
Professor Lee said, “Highly productive roll-process was successfully applied to flexible LSIs to continuously transfer and interconnect them onto plastics. For example, we have confirmed the reliable operation of our flexible NAND memory at the circuit level by programming and reading letters in ASCII codes. Out results may open up new opportunities to integrate silicon-based flexible LSIs on plastics with the ACF packing for roll-based manufacturing.”
Dr. Kim added, “We employed the roll-to-plate ACF packaging, which showed outstanding bonding capability for continuous roll-based transfer and excellent flexibility of interconnecting core and peripheral devices. This can be a key process to the new era of flexible computers combining the already developed flexible displays and batteries.”
The team’s results will be published on the front cover of Advanced Materials (August 31, 2016) in an article entitled “Simultaneous Roll Transfer and Interconnection of Silicon NAND Flash Memory.” (DOI: 10.1002/adma.201602339)
YouTube Link: https://www.youtube.com/watch?v=8OJjAEm27sw
Picture 1: This schematic image shows the flexible silicon NAND flash memory produced by the simultaneous roll-transfer and interconnection process.
Picture 2: The flexible silicon NAND flash memory is attached to a 7 mm diameter glass rod.
2016.09.01 View 13531 -
KAIST Named Asia's Most Innovative University by Thomson Reuters
Thomson Reuters ranked KAIST first among Asia’s top most innovative universities in a list that it released on August 30, 2016. Seventy-five Asian universities received this distinction.
Thomson Reuters created the list to identify those educational institutions that are “doing the most to advance science, invent new technologies, and help drive the global economy.”
The rankings were based on data drawn from each academic institution's research papers and patent filing information as evaluated by the Intellectual Property & Science division of Thomson Reuters.
Thomson Reuters described KAIST as producing "original and influential research" and noted that other organizations cited its patent portfolios as "significant prior art in their own patent applications, a strong indicator that the university has an outsized impact on global research and development."
For details, please go to the link below:
Asia’s Most Innovative Universities
Reuters
August 30, 2016
http://www.reuters.com/article/us-asiapac-reuters-ranking-innovative-un-idUSKCN1152B7#listing
2016.08.31 View 6113 -
'The 2016 Top 100 Research Projects in Korea'
The Ministry of Science, ICT and Future Planning (MSIP) of Korea recently released a list of the 2016 Top 100 Research Projects in Korea. The list included the work of KAIST Professors Dong-Ho Cho of the School of Electrical Engineering, Jeung Ku Kang of the Graduate School of Energy, Environment, Water and Sustainability (EEWS), and Sang Yup Lee of the Chemical and Biomolecular Engineering Department.
Experts from academia, universities, and industries selected the 100 research projects, among 620 projects recommended by various government offices, in consideration of their contribution to the growth of science and technology in the nation.
Professor Cho conducts research on the development of 5G mobile communication systems based on the pattern polarization beam-division multiple access method.
Professor Kang works on the production of highly efficient energy materials and equipment by controlling them at the electron and atomic level.
Professor Lee focuses on the creation of strategies to produce important chemicals through a biological approach, i.e., microorganisms, which will help develop the means to mitigate climate change.
The MISP will publish a book that describes in detail each research project and will distribute copies of it to the National Assembly of Korea, libraries, and other public organizations.
For more information on the list, please go to www.ntis.go.kr.
Pictured from left to right are Professors Dong-Ho Cho, Jeung Ku Kang, and Sang Yup Lee.
2016.07.21 View 5928 -
ICISTS Hosts the International Interdisciplinary Conference
A KAIST student organization, The International Conference for the Integration of Science, Technology and Society (ICISTS), will host ICISTS 2016 at the Hotel ICC in Daejeon from 3 to 7 August with the participation of around 300 Korean and international students.
ICISTS was first established in 2005 to provide an annual platform for delegates and speakers to discuss the integration and the convergence of science, technology, and society regardless of their academic backgrounds.
This year’s conference, with the theme of “Beyond the Center,” emphasizes the ways in which technological advancements can change central organizations in areas such as financial technology, healthcare, and global governance.
The keynote speakers include Dennis Hong, a developer of the first automobile for the blind and a professor of the Mechanical and Aerospace Engineering Department at UCLA, Dor Konforty, a founder and a CEO of SNS platform Synereo, and Marzena Rostek, a professor of Economics at the University of Wisconsin-Madison.
Other notable speakers include: Gi-Jung Jung, Head of the National Fusion Research Institute; Janos Barberis, Founder of FinTech HK; Tae-Hoon Kim, CEO and Founder of Rainist; Gulrez Shah Azhar, Assistant Policy Analyst at RAND Corporation; Thomas Concannon, Senior Policy Researcher at RAND Corporation; Leah Vriesman, Professor at the School of Public Health, UCLA; and Bjorn Cumps, Professor of Management Practice at Vlerick Business School in Belgium.
The conference consists of keynote speeches, panel discussions, open talks, experience sessions, team project presentations, a culture night, and a beer party, at which all participants will be encouraged to interact with speakers and delegates and to discuss the topics of their interest.
Han-Kyul Jung, ICISTS’s Head of Public Relations, said, “This conference will not only allow the delegates to understand the trends of future technology, but also be an opportunity for KAIST students to form valuable contacts with students from around the world.”
For more information, please go to www.icists.org.
2016.07.20 View 10158 -
Top 10 Emerging Technologies by World Economic Forum
The World Economic Forum’s Meta-Council on Emerging Technologies announced its annual list of breakthrough technologies, the “Top 10 Emerging Technologies of 2016,” on June 23, 2016. The Meta-Council chose the top ten technologies based on the technologies’ potential to improve lives, transform industries, and safeguard the planet. The research field of systems metabolic engineering, founded by Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department at KAIST, was also citied. Systems metabolic engineering, which combines elements of synthetic biology, systems biology, and evolutionary engineering, offers a sustainable process for the production of useful chemicals in an environmentally friendly way from plants such as inedible biomass, reducing the need of using fossil fuels. Details about the list follow below:
https://www.weforum.org/press/2016/06/battery-powered-villages-sociable-robots-rank-among-top-10-emerging-technologies-of-2016
The picture below shows the “systems metabolic engineering of E. coli for the production of PLGA." PLGA is poly(lactate-co-glycolate), which is widely used for biomedical applications, and has been made by chemical synthesis. Now it is possible to produce PLGA eco-friendly by one-step fermentation of a gut bacterium which is developed through systems metabolic engineering.
2016.06.27 View 13125 -
Next-Generation Holographic Microscope for 3D Live Cell Imaging
KAIST researchers have developed a revolutionary bio-medical imaging tool, the HT-1, to view and analyze cells, which is commercially available.
Professor YongKeun Park of the Physics Department at KAIST and his research team have developed a powerful method for 3D imaging of live cells without staining. The researchers announced the launch of their new microscopic tool, the holotomography (HT)-1, to the global marketplace through a Korean start-up that Professor Park co-founded, TomoCube (www.tomocube.com).
Professor Park is a leading researcher in the field of biophotonics and has dedicated much of his research career to working on digital holographic microscopy technology. He collaborated with TomoCube’s R&D team to develop a state-of-the-art, 2D/3D/4D holographic microscope that would allow a real-time label-free visualization of biological cells and tissues.
The HT is an optical analogy of X-ray computed tomography (CT). Both X-ray CT and HT share the same physical principle—the inverse of wave scattering. The difference is that HT uses laser illumination whereas X-ray CT uses X-ray beams. From the measurement of multiple 2D holograms of a cell, coupled with various angles of laser illuminations, the 3D refractive index (RI) distribution of the cell can be reconstructed. The reconstructed 3D RI map provides structural and chemical information of the cell including mass, morphology, protein concentration, and dynamics of the cellular membrane.
The HT enables users to quantitatively and non-invasively investigate the intrinsic properties of biological cells, for example, dry mass and protein concentration. Some of the research team’s breakthroughs that have leveraged HT’s unique and special capabilities can be found in several recent publications, including a lead article on the simultaneous 3D visualization and position tracking of optically trapped particles which was published in Optica on April 20, 2015.
Current fluorescence confocal microscopy techniques require the use of exogenous labeling agents to render high-contrast molecular information. Therefore, drawbacks include possible photo-bleaching, photo-toxicity, and interference with normal molecular activities. Immune or stem cells that need to be reinjected into the body are considered particularly difficult to employ with fluorescence microscopy.
“As one of the two currently available, high-resolution tomographic microscopes in the world, I believe that the HT-1 is the best in class regarding specifications and functionality. Users can see 3D/4D live images of cells, without fixing, coating or staining cells. Sample preparation times are reduced from a few days or hours to just a few minutes,” said Professor Park.
Two Korean hospitals, Seoul National University Hospital in Bundang and Boramae Hospital in Seoul, are using this microscope currently. The research team has also introduced the HT-1 at the Photonics West Exhibition 2016 that took place on February 16-18 in San Francisco, USA.
Professor Park added, “Our technology has set a new paradigm for cell observation under a microscope. I expect that this tomographic microscopy will be more widely used in future in various areas of pharmaceuticals, neuroscience, immunology, hematology, and cell biology.”
Figure 1: HT-1 and Its Specifications
Figure 2: 3D Images of Representative Biological Cells Taken with the HT-1
2016.03.29 View 14618 -
Efficient Methane C-H Bond Activated by KAIST and UPenn Teams
Professor Mu-Hyun Baik of the Chemistry Department at KAIST and his team collaborated with an international team to discover a novel chemical reaction, carbon-hydrogen borylation using methane, and their research results were published in the March 25th issue of Science.
For details, please refer to the following press release from the Institute for Basic Sciences (IBS) in Korea and the University of Pennsylvania in the United States.
Efficient Methane C-H Bond Activation Achieved for the First Time
The Institute for Basic Science, March 24, 2016
Penn Chemists Lay Groundwork for Countless New, Cleaner Uses of Methane
University of Pennsylvania, March 24, 2016
2016.03.25 View 11190 -
KAIST Ranks Third in the World's Top Universities for Attracting Industry Funding
The Times Higher Education released its World University Rankings online, naming the 20 best institutions that secured the largest amount of research funding from the private sector, on March 8, 2016.
The rankings were based on the 2013 record of industry-sector investments made per academic of an institution.
According to the list, KAIST ranked third with a figure of $254,700.
Germany’s Ludwig Maximilian University (Munich) took first place ($400,000), while the United State’s Duke University placed second ($290,000).
For a full list of the rankings, go to https://www.timeshighereducation.com/world-university-rankings/funding-for-innovation-ranking-2016.
2016.03.08 View 4268 -
ISCN and GULF Share Best Practices Report
The International Sustainable Campus Network (ISCN) and the Global University Leaders Forum (GULF) co-hosted a conference at the 2016 World Economic Forum held on January 20-23, 2016 in Davos, Switzerland, to present exemplary campus sustainability case studies provided by the world’s leading universities.
A total of 20 universities, including KAIST, Harvard University, University of Oxford, Yale University, the National University of Singapore, the Hong Kong University of Science and Technology, and the Swiss Federal Institute of Technology (Zurich), reported on their endeavors to demonstrate sustainable development in higher education in three different panels at the conference: Developing Skills and Building Capacities, Collaborating to Catalyze Change, and Innovating for Efficient Built Environments.
President Sung-Mo Kang of KAIST gave a presentation on the Saudi Aramco-KAIST CO2 Management Center as a sustainable development model for KAIST.
KAIST and Saudi Aramco, the world’s leading fossil-fuel provider, joined forces in 2013 to establish a joint research center on the reduction and management of carbon dioxide (CO2) emissions, a major driver of climate change.
The research center, located at the KAIST campus in Daejeon, South Korea, is currently sponsoring ten research projects involving more than 20 doctoral-level researchers and over 100 students.
The goal of the center is to develop materials for more energy-efficient CO2 capture, catalysts and processes for converting CO2 into valuable products, novel storage methods, and system-level analyses of major CO2 emitting industries to suggest industry-specific CO2 reduction strategies including energy efficiency improvement.
The center’s work also includes analyzing the impact of potential government or industry-wide policies in the face of uncertainties, some of which are technological and economic as well as political. Besides its research activities, the center has also sponsored seminars and workshops throughout the year to raise awareness of the importance of CO2 management in building a sustainable future.
President Kang said that, from the beginning, the center has prompted researchers and students with different academic backgrounds and skill sets to work together to find integrative and systematic solutions to address real problems of critical importance to the world’s sustainability.
ISCN is a global non-profit association of leading colleges and universities representing over 20 countries, working together to holistically integrate sustainability into campus operations, research, and teaching. As of now, more 75 universities worldwide are the members of ISCN.
The GULF is composed of the presidents of the top 25 universities in the world. The World Economic Forum created it in 2006 to offer a non-competitive platform for high-level dialogue in academia. KAIST is the only Korean GULF member.
For the full report of the 2016 ISCN and GULF conference, go to http://www.international-sustainable-campus-network.org/downloads/general/441-2016-iscn-gulf-best-practice-report/file.
2016.01.25 View 11661 -
Professor Naehyuck Chang Appointed a 2015 Fellow by the ACM
The Association for Computing Machinery (ACM), the world’s largest educational and scientific computing society, released a list of its new fellows on December 8, 2015, the 2015 ACM Fellows.
Professor Naehyuck Chang of the School of Electrical Engineering at KAIST was among the 42 new members who became ACM Fellows in recognition of their contributions to the development and application of computing in areas from data management and spoken-language processing to robotics and cryptography.
Professor Chang is known for his leading research in power and energy optimization from embedded systems applications to large-scale energy systems such as device- and system-level power and energy measurement and estimation, liquid crystal display power reduction, dynamic voltage scaling, hybrid electrical energy storage systems, and photovoltaic cell arrays. He is the fourth Korean to be nominated an ACM Fellow.
Professor Chang is also a Fellow of the Institute of Electrical and Electronics Engineers (IEEE) and the Editor-in-Chief of the journal, ACM Transactions on Design Automation of Electronic Systems (TODAES). He served as the President of the ACM Special Interest Group on Design Automation in 2012.
Additional information about the ACM 2015 Fellows, go to http://www.acm.org/press-room/news-releases/2015/fellows-2015:
2015.12.11 View 10954