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Professor Ho Won Jang’s Research Team Successfully Implements Micropatterned Graphene on Flexible Substrates
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2021.03.02
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Professor Ho Won Jang’s Research Team Successfully Implements Micropatterned Graphene on Flexible Substrates
- Applied to next-generation functional electronic devices such as wearable devices, self-activated sensor arrays
- Research published as the cover paper for the world-renowned journal 'Advanced Materials'
▲(From left ) Graphene micropatterns transcribed to flexible substrates, graphene micropattern-based 2x2 gas sensor arrays, Research paper cover page
Researchers at Seoul National University's College of Engineering have developed a technology that will greatly advance research related to next-generation functional electronic devices that can be worn or folded by humans.
On January 28, Dr. Yeon Hoo Kim, Ph.D. Candidate student Tae Hoon Kim and Professor Ho Won Jang of the Department of Materials Science and Engineering announced to have developed a technology to transfer micrometer-sized graphene patterns onto flexible, 4-inch polymeric substrates using the "Polymer Direct Hardening Transcription Method."
With the recent increase in interest in new technologies such as flexible, foldable and transparent wearable devices, graphene is receiving the spotlight as an alternative to solving the problem of opacity and brittleness of metals and metal oxides that are used as major materials for conventional electronic devices. In order to utilize the unique characteristics of graphene, micro-patterning technology used in semiconductor processes must be incorporated on flexible substrates.
However, the most representative method of graphene transcription, in other words, the process of manufacturing under wet‐transfer conditions using poly(methyl methacrylate) or PMMA, had the graphene micro-patterns to find difficulties to withstand and was easily damaged with PMMA, that was used as a transcription material, to leave residues on the graphene surface.
To overcome this problem, Professor Ho Won Jang's team developed a process to directly cure macromolecules that will be used as final substrates on top of graphene micropatterns. When macromolecules in the solution state are cured after coating them on a graphene pattern, the macromolecules act as flexible substrates while maintaining a graphene micro pattern. This method enabled graphene micropatterning very reliably on a flexible polyimide substrate with a 4-inch wafer area up to a minimum of 5 micrometers of line width.
Although existing methods leave residues as the contaminated graphene during the manufacturing process becomes the surface of the final stage, the new transcription method has the additional advantage of being clean without residue as unexposed graphene is vertically inverted during the process and faces the surface at the final stage.
Micrometer-sized graphene, which is micropatterned onto polymer substrates exhibits self-heating phenomena caused by Joule heat reaction under applied voltage. Professor Myoung-Gyu Lee's team of the Department of Materials Science and Engineering at Seoul National University, who co-participated in the study, analyzed graphene self-heating phenomena according to substrate materials and graphene pattern conditions through finite element simulations. Simulation results indicated that heating phenomena can be efficiently controlled depending on the shape or substrate material of graphene patterns.
Using the polymer direct curing transcription method developed by the research team, flexible and transparent graphene-based gas sensor arrays can be produced. Graphene fine pattern-based gas sensors can be activated on their own without additional heat energy through self-heating phenomena. In the experiments that used this, a sensor array of four types of single sensors decorated with different precious metals successfully classified several types of gases at room temperature.
"It is a simple and reliable way to transcribe fine patterns of not only graphene but also various two-dimensional materials onto transparent and flexible substrates in a large area. We expect this technology to contribute greatly to the development of next-generation functional electronic devices that can be worn or folded on an individual's body based on two-dimensional materials," said Professor Ho Won Jang.
The results of the study were published online on January 14 in "Advanced Materials," a world-renowned journal in the field of materials, and will be published as a cover paper for the official issue in recognition of its excellence.
The study was jointly conducted by the research teams of Professor Ho Won Jang, Professor Myoung-Gyu Lee, and Professor Byung Hee Hong of the College of Natural Sciences, Department of Chemistry, and was supported by the Korea Research Foundation's mid-sized research project and nano-material technology development project.
[Published Research Paper]
<Tailored Graphene Micropatterns by Wafer-Scale Direct Transfer for Flexible Chemical Sensor Platform>
[Participating Researchers]
Dr. Yeon Hoo Kim (Seoul National University, Currently at the Los Alamos National Laboratory, first author), Tae Hoon Kim (first author), Dr. Seo Yun Park, Dr. Tae Hyung Lee, Dr. Hoon Kee Park, Sol A Lee, Professor Min Sang Kwon (Seoul National Uinversity), Dr. Jinwoo Lee (Materials Deformation Department, Korea Institute of Materials Science), Yong Seok Choi (Seoul National University, Currently at the Advanced Institute of Convergence Technology), Dr. Joonhee Moon (Research Center for Materials AnalysiResearch Center for Materials Analysis), Professor Hyung‐Gi Byun (Kangwon National University), Professor Jong‐Heun Lee (Korea University), Professor Myoung‐Gyu Lee (Seoul National University, corresponding author), Byung Hee Hong (Seoul National University, corresponding author), Ho Won Jang (Seoul National University, corresponding author)