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2017 SPIE Optics + Photonics, San diego, USA

 06-10 August, 2017 (Sun - Thu), San Diego Convention Center

 

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<Oral Session : Organic Field-Effect Transistors XVII>

A Rational Design of Polymer Semiconductors for High-Resolution Solution Tandem Electronics

Han Wool Park, Keun-Yeong Choi, Haejung Hwang, Boseok Kang, Hee Jun Yoon, Kyung Ah Nam,Yun-Hi Kim, Kilwon Cho, Hojin Lee, and Do Hwan Kim

 

 Abstract

Organic electronics has recently attracted a great deal of interest because of its solution-processed potential applications in flexible, wearble and even stretchable devices. Dissolvability of semiconducting organic materials in typical solvents potentially provides these materials with unique opportunities to acheive the electronics with cheaper and simpler manufacturing processes. This opportunity, however, serves as a trade-off when one tries to implement these processes in assembling practical electronic devices, since the as-deposited tandem layers would be defenceless to following solution processes. As a result, this controversial issue remains valid not only while applying advanced printing processes, but also while applying photolithography for semiconducting polymers.

Herein, we describe a whole new type of polymer semiconductors based on sol-gel chemistry, which is capable of remarkably showing chemical and mechanical reliability during sequential photolithography processes. The critical step in a sol-gel reaction is the formation of a highly cross-linked network out of molecular precursors through hydrolysis and condensation reactions. By carefully manipulating this step, we could prepare an orthogonal polymer semiconductor gel thin film with heterogeneous inter-penetrated polymer network (HIPN). The resulting structures yielded films that are highly tolerant against harsh external stimuli. Consequently, formation of high resolution patterns of various semiconductor polymers as well as fabrication of tandem devices and circuits based on multiple semiconducting materials could be readily attained using conventional photolithography processes, and finally fabricate high-resolution CMOS circuits with micron n- and p-type organic channels.

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2017 SPIE Photonics West, San Francisco, USA

January 28 - February 2, 2017 (Sat - Thu), The Moscone Center

 

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<Oral Session : Session 1: THz Sources and Detectors I>

Polarization dependent resonance manipulation by terahertz meta-molecules 

Hyunseung Jung, Eunah Heo, Jaemok Koo, Chihun In, Hyunyong Choi, Moon Sung Kang, and Hojin Lee

 

 Abstract

In this study, we propose polarization dependent resonance manipulation by meta-molecules at terahertz frequencies. The proposed meta-molecules are combined with various numbers of H-shaped meta-atoms, which we refer as ‘moleculization’ of meta-atoms. We confirm that the laterally moleculized H-shaped meta-molecules successfully realize the unique properties that can modulate the resonance frequency for the specific polarization of an incident wave, while can keep one identical resonance frequency for their orthogonal polarization direction, simultaneously. Moreover, for the vertically moleculized H-shaped meta-molecules, we also find that the electromagnetically induced transparency (EIT) –like phenomenon can be achieved for the specific polarization direction, with their exceptional field enhancement properties.

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2017 SPIE Photonics West, San Francisco, USA

January 28 - February 2, 2017 (Sat - Thu), The Moscone Center

 

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<Oral Session : Session 7: RF-Submillimeter-Wave II>

Wireless chemical sensor system based on electromagnetically energy-harvesting metamaterials

Wonwoo Lee, Yonghee Jung, Hyunseung Jung, and Hojin Lee

 

 Abstract

We propose a novel wireless chemical sensor system by using energy-harvesting metamaterials at microwave frequencies. The proposed metamaterial sensor consists of a single split ring resonator and rectifier circuit for harvesting the energy at the specific frequency. We confirmed that the concentration of ethanol mixed with water can be detected by the proposed sensor by resonance property between the source antenna and the metamaterial which induces the variation in the energy-harvesting rate of our sensor system. Finally, we expect that our metamaterial-based wireless sensor can pave the way to the miniaturized wireless sensor systems including biochemical and dielectric environment sensors.

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2018 CLEO, San Jose, United States

May 13 - 17, 2018 (Mon - Fri), San Jose Convention Center

 

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<Oral Session>

Electrically Controllable Reconfiguration of Terahertz Meta-Atoms into Meta-Molecules

Hyunseung Jung, Jaemok Koo, Wonwoo Lee, Moon Sung Kangand Hojin Lee

 

 Abstract

We report structural methodology for electrically switchable terahertz metamaterials between atom- and molecule-states by using limited conductance variation of graphene bridges. Based on experimental verification, we confirmed 39% of wide resonance tuning of terahertz metamaterials.

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2018.09.04 14:03

2018 iMiD, Busan, Korea

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2018 iMiD, Busan, Korea

August 28 - 31, 2017 (Tue. - Fri.), Exhibition Center I, BEXCO 


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High-Speed Electroactive Polymer Actuator for Artificial Muscle

Yongchan Kim, So Young Kim, Dayoon Lee, Eunsong Ji, Do Hwan Kim, and Hojin Lee

 

 Abstract

With the development of bio-friendly soft electronic devices, artificial muscles that mimic the shapes and functions of natural muscles are attracting attention in various fields. Recently, the artificial muscles represent soft actuators. They have many advantages such as high flexibility, light density, and low power consumption. Due to these characteristics, many studies about artificial muscles are being carried out in various fields such as soft robot, prosthetics, and haptic applications. Especially, among various soft actuators, ionic polymer actuators have been attracted much interest as the advantage of low driving voltage and flexibility using volume changing due to the movement of ions in an ionic polymer layer. However, artificial muscles based on ionic polymer suffer from low displacement and force at high operating frequencies. In this manner, engineering of an optimal ion transport in the ionic films as well as mechanical properties of actuators is strongly required to allow fast actuation under electrical stimuli. In this talk, we propose a high-speed ionic polymer muscle using ionic polymer and conducting polymer (PEDOT:PSS) solution with ionic liquid and DMSO as additive by spray coating method. Also, through these methods our actuator could control an interface structure from nano to micro size between ionic polymer and electrodes. The actuator implemented by us was successfully operated with a large displacement up to 3mm (strain=0.4%) at an operating frequency of 1Hz under an applied voltage of 2V. Further, the actuator shows high-speed response under the bending strain of 0.1% and the displacement of 0.67mm even at frequency of 30Hz. This result indicates that controlling an interpenetration depth of PEDOT:PSS chains into the ionic elastomer not only decreases an internal resistance between two electrodes, but also forms more effective and nanostructured ion conducting channel, thereby leading to larger displacement and faster response of actuators even under low voltage bias. We believe that high-speed ionic polymer actuator demonstrated by us will be an effective way to implement a novel engineering design for artificial muscle capable of physiologically actuating under electrical stimuli. In this talk, we propose a high-speed ionic polymer muscle using ionic polymer and conducting polymer (PEDOT:PSS) solution with ionic liquid and DMSO as additive by spray coating method (Fig. 1). Also, 

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