Inho Ha

Samsung (South Korea)

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i-10 index

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Co-Authors

Seung Hwan Ko

Seoul National University

Jinhyeong Kwon

Korea Institute of Industrial Technology

Phillip Won

Carnegie Mellon University

Sukjoon Hong

Hanyang University

Hyunmin Cho

Stanford University

Habeom Lee

Pusan National University

Jinwook Jung

Kumoh National Institute of Technology

Kyun Kyu Kim

Stanford University

Yeosang Yoon

Seoul National University

Seonggeun Han

Chungnam National University Hospital

Cooperative Institutions

Seoul National University

Government of the Republic of Korea

Samsung (South Korea)

Hanyang University

Korea Advanced Institute of Science and Technology

Korea Institute of Science and Technology

Sungkyunkwan University

Yonsei University

University of California, Berkeley

Korea University

Author Statistics

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Research Field

Highly Stretchable and Transparent Electromagnetic Interference Shielding Film Based on Silver Nanowire Percolation Network for Wearable Electronics Applications

ACS Applied Materials & Interfaces (2017)

Jinwook Jung Habeom Lee Inho Ha Hyunmin Cho Kyun Kyu Kim

Future electronics are expected to develop into wearable forms, and an adequate stretchability is required for the forthcoming wearable electronics considering various motions occurring in human body. Along with stretchability, transparency can increase both the functionality and esthetic features in future wearable electronics. In this study, we demonstrate, for the first time, a highly stretchable and transparent electromagnetic interference shielding layer for wearable electronic applications with silver nanowire percolation network on elastic poly(dimethylsiloxane) substrate. The proposed stretchable and transparent electromagnetic interference shielding layer shows a high electromagnetic wave shielding effectiveness even under a high tensile strain condition. It is expected for the silver nanowire percolation network-based electromagnetic interference shielding layer to be beyond the conventional electromagnetic interference shielding materials and to broaden its application range to various fields that require optical transparency or nonplanar surface environment, such as biological system, human skin, and wearable electronics.

Wearable Technology

Stretchable electronics

Flexible Electronics

Percolation (cognitive psychology)

10.1021/acsami.7b14626

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Citations (293)

Cu Electrode Fabrication by Acid-assisted Laser Processing of Cu Nanoparticles and Application with Transparent·Flexible Electrode

Proceedings of the Korean Institute of Surface Engineering Conference (2018)

Hyeon-Min Jo Jin-Hyeong Gwon Inho Ha Seung-Hwan Go

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Effects of Pulping Conditions in the Reconstituted Tobacco Sheet Making Process on the Properties of the Pulp Slurry

Yong Joo Sung Young-Lim Han Kun-Soo Kim Moon-Soo Rhee Inho Ha

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Directional Shape Morphing Transparent Walking Soft Robot

Soft Robotics (2019)

Habeom Lee Hyeonseok Kim Inho Ha Jinwook Jung Phillip Won

Transparency in electronics can provide extra functionality and esthetic impression. Transparency plays an important role in accurate soft robot control because one can directly observe target surface condition that is usually blocked by a robot's body. Nowadays, demand for soft actuators has been rapidly increasing because soft robots have attracted much attention recently. However, conventional soft actuators are usually nontransparent with simple isotropic bending, limited performance, and limited functionality. To overcome such limitations of current soft robots, we developed a novel soft shape morphing thin film actuator with new functionalities such as high transparency and unique directional responses to allow complex behavior by integrating a transparent metal nanowire heater. A figure of merit was developed to evaluate the performance and derive an optimum design configuration for the transparent actuator with enhanced performance. As a proof of concept, various transparent soft robots such as transparent gripper, Venus flytrap, and transparent walking robot were demonstrated. Such transparent directional shape morphing actuator is expected to open new application fields and functionalities overcoming limitations of current soft robots.

Morphing

Soft Robotics

10.1089/soro.2018.0164

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Citations (65)

Stretchable Skin‐Like Cooling/Heating Device for Reconstruction of Artificial Thermal Sensation in Virtual Reality

Advanced Functional Materials (2020)

Jinwoo Lee Heayoun Sul Wonha Lee Kyung Rok Pyun Inho Ha

Abstract Along with visual and tactile sensations, thermal sensation by temperature feeling on the skin can provide rich physical information on the environment and objects. With a simple touch of objects, relative temperature can be sensed and even objects can be differentiated with different thermal properties without any visual cue. Thus, artificially reproducing accurate/controllable thermal sensation haptic signals on human epidermis will certainly be a major research area to reconstruct a more realistic virtual reality (VR) environment. In this study, for the first time, a skin‐like, highly soft and stretchable and bi‐functional (both cold and hot sensation) thermo‐haptic device is reported for wearable VR applications with a single device structure (not separate heater and cooler). The skin‐like thermo‐haptic (STH) device can actively cool down and heat up deformable skin surfaces with instantaneous and accurate adjustment of temperature based upon a feedback control algorithm to mimic desirable thermal sensation with 230% stretchability. As a proof‐of‐concept, the STH device is integrated with a finger‐motion tracking glove to provide artificial thermal sensation information to the skin in various situations such as touching cold beer bottles and hot coffee cups in virtual space. This new type of STH device can offer potential implications for next‐generation haptic devices to provide unique thermal information for a more realistic virtual‐world field and medical thermal treatment.

Thermal sensation

Sensation

Skin Temperature

10.1002/adfm.201909171

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Citations (125)

Artificial Thermal Sensation: Stretchable Skin‐Like Cooling/Heating Device for Reconstruction of Artificial Thermal Sensation in Virtual Reality (Adv. Funct. Mater. 29/2020)

Advanced Functional Materials (2020)

Jeong Yong Lee Heayoun Sul Wonha Lee Kyung Rok Pyun Inho Ha

In article number 1909171, Seung Hwan Ko and co-workers present the development of a skin-like, highly soft, and stretchable and bi-functional (both cold and hot sensation) thermo-haptic device for wearable cutaneous virtual reality applications to reproduce the more realistic and fast thermal sensations on the human epidermis in a virtual world.

Thermal sensation

Sensation

Skin Temperature

10.1002/adfm.202070196

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Citations (4)

Reconfigurable Multilevel Optical PUF by Spatiotemporally Programmed Crystallization of Supersaturated Solution

Advanced Materials (2023)

Youngchan Kim Jaemook Lim Ji Hwan Lim Eunseung Hwang Hyunkoo Lee

Physical unclonable functions (PUFs) are emerging as an alternative to information security by providing an advanced level of cryptographic keys with non-replicable characteristics, yet the cryptographic keys of conventional PUFs are not reconfigurable from the ones assigned at the manufacturing stage and the overall authentication process slows down as the number of entities in the dataset or the length of cryptographic key increases. Herein, a supersaturated solution-based PUF (S-PUF) is presented that utilizes stochastic crystallization of a supersaturated sodium acetate solution to allow a time-efficient, hierarchical authentication process together with on-demand rewritability of cryptographic keys. By controlling the orientation and the average grain size of the sodium acetate crystals via a spatiotemporally programmed temperature profile, the S-PUF now includes two global parameters, that is, angle of rotation and divergence of the diffracted beam, in addition to the speckle pattern to produce multilevel cryptographic keys, and these parameters function as prefixes for the classification of each entity for a fast authentication process. At the same time, the reversible phase change of sodium acetate enables repeated reconfiguration of the cryptographic key, which is expected to offer new possibilities for a next-generation, recyclable anti-counterfeiting platform.

Physical unclonable function

Control reconfiguration

10.1002/adma.202212294

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Citations (20)

A Gradient Stiffness‐Programmed Circuit Board by Spatially Controlled Phase‐Transition of Supercooled Hydrogel for Stretchable Electronics Integration

Advanced Materials (2024)

Minwoo Kim Sangwoo Hong Jung Jae Park Yeongju Jung Seok Hwan Choi

Due to emerging demands in soft electronics, there is an increasing need for material architectures that support robust interfacing between soft substrates, stretchable electrical interconnects, and embedded rigid microelectronics chips. Though researchers have adopted rigid-island structures to solve the issue, this approach merely shifts stress concentrations from chip-conductor interfaces to rigid-island-soft region interfaces in the substrate. Here, a gradient stiffness-programmed circuit board (GS-PCB) that possesses high stretchability and stability with surface mounted chips is introduced. The board comprises a stiffness-programmed hydrogel substrate and a laser-patterned liquid metal conductor. The hydrogel simultaneously obtains a large stiffness disparity and robust interfaces between rigid-islands and soft regions. These seemingly contradictory conditions are accomplished by adopting a gradient stiffness structure at the interfaces, enabled by combining polymers with different interaction energies and a supercooled sodium acetate solution. By integrating the gel with laser-patterned liquid metal with exceptional properties, GS-PCB exhibits higher electromechanical stability than other rigid-island research. To highlight the practicality of this approach, a finger-sensor device that successfully distinguishes objects by direct physical contact is fabricated, demonstrating its stability under various mechanical disturbances.

Supercooling

Flexible Electronics

Stretchable electronics

10.1002/adma.202313344

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Citations (8)

SiO2 thin film which apply to roll-to-roll mass product grown by Reactive DC pulse sputtering

한국진공학회 학술발표회초록집 (2015)

Dong-Hoon Lee Eunmi Park Kunhui Han Inho Ha Eunsun Jo

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Highly Controlled Nanoporous Ag Electrode by Vaporization Control of 2-Ethoxyethanol for a Flexible Supercapacitor Application

Langmuir (2017)

Jinwoo Lee Jaehak Lee Jinhyeong Kwon Habeom Lee H.J. Eom

Controlling the surface morphology of the electrode on the nanoscale has been studied extensively because the surface morphology of a material directly leads to the functionalization in various fields of studies. In this study, we designed a simple and cost-effective method to fine-tune the surface morphology and create controlled nanopores on the silver electrode by utilizing 2-ethoxyethanol and two successive heat treatments. High electrical conductivity and mechanical robustness of nanoporous silver corroborate its prospect to be employed in various applications requiring a certain degree of flexibility. As a proof-of-concept, a high-performance supercapacitor was fabricated by electrodepositing MnO2. This method is expected to be useful in various electronic applications as well as energy storage devices.

Nanoporous

Nanopore

Surface Modification

Vaporization

10.1021/acs.langmuir.6b04625

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Citations (10)