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191 results on '"Ko, Heung Cho"'

14. Three‐Dimensional Transformation of Membrane‐Type Electronics Using Transient Microfluidic Channels for the Sequential Selective Plasticization of Supportive Plastic Substrates.

Author

Cha, Jihun, Kim, Gi‐Gwan, Kim, Seung Hyun, Park, Dukkyu, Yoo, Jung Il, Jang, Hun Soo, Yoon, Jongwon, and Ko, Heung Cho

Subjects
INDIUM gallium zinc oxide, PLASTICS, THREE-dimensional printing, LIGHT emitting diodes
Abstract

This study demonstrates a technique for the development of 3D electronics based on planar membrane‐type devices and a supportive plastic (e.g., acrylonitrile butadiene styrene [ABS] used in this study) substrate containing internal microfluidic channels (µ‐FCs) that allow selective plasticization and transformation after the insertion of a liquid plasticizer (e.g., N,N‐dimethylformamide). The internal µ‐FC has a strong advantage of transiency and does not require an additional removal process because the channels are self‐closed by the swelling and dissolution of the plasticized regions. Furthermore, the 3D printing process to create internal µ‐FCs provides a considerable amount of freedom in channel design for sequential plasticization and transformation into complex structures. Using this method, extreme scenarios that involve complete bending of the metal electrodes and indium gallium zinc oxide thin‐film transistors laminated to the ABS substrates without electrical failure are possible, regardless of the bending direction and the vertical position of the electrode of the plastic substrate. Finally, a truncated octahedral light‐emitting diode display is successfully developed by multiple cycles of sequential plasticization and transformation processes to demonstrate the feasibility of this method. [ABSTRACT FROM AUTHOR]

Published
2023
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19. Omnidirectional stretchable inorganic-material-based electronics with enhanced performance

Author

Kumaresan, Yogeenth, Kim, Hyeonghun, Pak, Yusin, Poola, Praveen Kumar, Lee, Ryeri, Lim, Namsoo, Ko, Heung Cho, Jung, Gun Young, and Dahiya, Ravinder

Abstract

Inorganic material‐based devices are well known for their high performance, excellent stability, and hence suitability for fast computation and communication. But their nonflexibility and nonstretchability often hinder their application in several emerging areas where conformability with irregular 3D surfaces is required in addition to the high performance. Herein, with honeycomb like patterns, the omnidirectional stretchability and conformability of inorganic material‐based device are demonstrated without sacrificing the performance. The simple method presented here facilitates the transfer of patterned inorganic material‐based devices from rigid poly(methyl methacrylate) (PMMA)/glass substrate onto flexible/stretchable substrate such as polydimethylsiloxane simply by placing a water droplet at the PMMA/glass interface. As a proof of concept, the intrinsically brittle indium–gallium–zinc oxide (IGZO)‐based stretchable photodetector devices are fabricated. These devices can be stretched up to 10% without performance degradation, which is a significant improvement considering the less than ≈1% fracture limit of IGZO. With Au decoration, these devices show 127‐fold higher responsivity (295.3 mA W−1) than planar IGZO devices. The higher fracture strain together with the omnidirectional stretchability underpinned by the honeycomb pattern could allow presented devices to conform to complex hemispherical surfaces such as the human eyes, thus showing significant potential for future high‐performance stretchable electronics.

Published
2020

35. Enhancement of Interfacial Adhesion Using Micro/Nanoscale Hierarchical Cilia for Randomly Accessible Membrane-Type Electronic Devices

Author

Hwang, Youngkyu, Yoo, Seonggwang, Lim, Namsoo, Kang, Sang Myeong, Yoo, Hyeryun, Kim, Jongwoo, Hyun, Yujun, Jung, Gun Young, and Ko, Heung Cho

Abstract

The recent technology of transfer printing using various membrane-type flexible/stretchable electronic devices can provide electronic functions to desirable objects where direct device fabrication is difficult. However, if the target surfaces are rough and complex, the capability of accommodating surface mismatches for reliable interfacial adhesion remains a challenge. Here, we demonstrate that newly designed nanotubular cilia (NTCs), vertically aligned underneath a polyimide substrate, significantly enhance interfacial adhesion. The tubular structure easily undergoes flattening and wrapping motions to provide a large conformal contact area, and the synergetic effect of the assembled cilia strengthens the overall adhesion. Furthermore, the hierarchical structure consisting of radially spread film-type cilia combined with vertically aligned NTCs in specific regions enables successful transfer printing onto very challenging surfaces such as stone, bark, and textiles. Finally, we successfully transferred a temperature sensor onto an eggshell and indium gallium zinc oxide-based transistors onto a stone with no electrical failure.

Published
2020
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36. Robust and stretchable indium gallium zinc oxide-based electronic textiles formed by cilia-assisted transfer printing

Author

Yoon, Jongwon, primary, Jeong, Yunkyung, additional, Kim, Heeje, additional, Yoo, Seonggwang, additional, Jung, Hoon Sun, additional, Kim, Yonghun, additional, Hwang, Youngkyu, additional, Hyun, Yujun, additional, Hong, Woong-Ki, additional, Lee, Byoung Hun, additional, Choa, Sung-Hoon, additional, and Ko, Heung Cho, additional

Published
2016
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37. Chemical Sensing of 2D Graphene/MoS2 Heterostructure device

Author

Cho, Byungjin, primary, Yoon, Jongwon, additional, Lim, Sung Kwan, additional, Kim, Ah Ra, additional, Kim, Dong-Ho, additional, Park, Sung-Gyu, additional, Kwon, Jung-Dae, additional, Lee, Young-Joo, additional, Lee, Kyu-Hwan, additional, Lee, Byoung Hun, additional, Ko, Heung Cho, additional, and Hahm, Myung Gwan, additional

Published
2015
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39. Charge-transfer-based Gas Sensing Using Atomic-layer MoS2

Author

Cho, Byungjin, primary, Hahm, Myung Gwan, additional, Choi, Minseok, additional, Yoon, Jongwon, additional, Kim, Ah Ra, additional, Lee, Young-Joo, additional, Park, Sung-Gyu, additional, Kwon, Jung-Dae, additional, Kim, Chang Su, additional, Song, Myungkwan, additional, Jeong, Yongsoo, additional, Nam, Kee-Seok, additional, Lee, Sangchul, additional, Yoo, Tae Jin, additional, Kang, Chang Goo, additional, Lee, Byoung Hun, additional, Ko, Heung Cho, additional, Ajayan, Pulickel M., additional, and Kim, Dong-Ho, additional

Published
2015
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42. Graphene-based gas sensor: metal decoration effect and application to a flexible device

Author

Cho, Byungjin, primary, Yoon, Jongwon, additional, Hahm, Myung Gwan, additional, Kim, Dong-Ho, additional, Kim, Ah Ra, additional, Kahng, Yung Ho, additional, Park, Sang-Won, additional, Lee, Young-Joo, additional, Park, Sung-Gyu, additional, Kwon, Jung-Dae, additional, Kim, Chang Su, additional, Song, Myungkwan, additional, Jeong, Yongsoo, additional, Nam, Kee-Seok, additional, and Ko, Heung Cho, additional

Published
2014
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47. Thin Film Transistors: All-Solution-Processed Transparent Thin Film Transistor and Its Application to Liquid Crystals Driving (Adv. Mater. 23/2013)

Author

Lee, Kwang-Ho, primary, Kim, Sang-Mook, additional, Jeong, Huisu, additional, Pak, Yusin, additional, Song, Hui, additional, Park, Jeongpil, additional, Lim, Keon-Hee, additional, Kim, Jae-Hoon, additional, Kim, Youn Sang, additional, Ko, Heung Cho, additional, Kwon, Il Keun, additional, and Jung, Gun-Young, additional

Published
2013
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