SPIE Photonics West 2020, San Francisco, USA

February 1 - 6, 2020 (Sun. - Thur.), Moscone Centor

High-Performance Ionic Polymer Mechanotransducer for Soft Tactile Feedback

Yongchan Kim, Changhyeon Cho, So Young Kim, Hanbin Choi, Do Hwan Kim, and Hojin Lee

Abstract

  In this talk, we propose an i-EAP actuator with wide bandwidth of over 200 Hz and high blocking force based on PEDOT:PSS electrode with additives and ionic-polymer with nanofibrillary network for effective haptic feedback. In particular, we developed an actuator that improves the interfacial properties between electrodes and an ionic-polymer as well as electrical conductivity of electrodes by simple and effective way through spray-coating of PEDOT:PSS solution with additives. As a result, the proposed i-EAP actuator was successfully operated with a large displacement up to 2.7 mm at an operating frequency of 20 mHz under an applied voltage of 2 V. These our actuator is capable of driving up to a high frequency of 200 Hz and shows an improved blocking force up to 0.4 mN. We believe our i-EAP actuator will provide a rational guide to future haptic feedback.

2013 iMiD, Daegu, Republic of Korea

August 26-29, 2013 (Monday - Thursday), EXCOAugust 26-29, 2013 (Monday - Thursday), EXCO

<Poster Session : P2-54>

A Novel P-type LTPS Pixel Circuit for AMOLEDs with Dual-Compensation Function

Yeonkyung Kim, Yongchan Kim, and Hojin Lee

Abstract

In this paper, we proposed a novel voltage-programmed pixel circuit with p-type low temperature polycrystalline-silicon thin film transistor (LTPS TFT) for active-matrix organic light-emitting display (AMOLED) with an enhanced electrical stability and uniformity. Through an extensive simulation work based on p-type LTPS TFT and OLED experimental data, we confirm that the proposed pixel circuit can compensate for both mobility variation and threshold voltage shift of the driving TFT.

AMSM 2024, Incheon, Korea

October 27 - October 30, 2024 (Sun. - Wen.), Songdo ConvensiA

Monolithic VOC Sensor Circuit Based on a-IGZO TFT

Kyungmin Choi, Keun-Yeong Choi, and Hojin Lee

Abstract

Volatile organic compounds (VOCs) generated in industrial production lines are harmful to human health, prompting significant research into detecting VOC gases. For detection of various VOCs, Amorphous oxide semiconductors (AOS) have been highly researched to achieve high-sensitivity chemo-resistive-type VOCs gas sensors. Especially, amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) are attracting high attention due to their high field-effect mobility, low leakage current, good uniformity, and superior electrical stability at low processing temperatures. In this paper, we propose a monolithic sensor circuit designed to amplify the sensing signal of solution-processed a-IGZO sensor TFTs, achieving high sensitivity. The fabricated a-IGZO sensor TFT showed significant changes in transfer characteristics upon exposure to acetone gas, with decreased resistance and a negative threshold voltage shift. The proposed circuit, comprising three a-IGZO TFTs and one capacitor, demonstrated successful gas sensing through simulation, confirming accurate operation. Through this study, we confirmed that the proposed a-IGZO TFT sensor circuit was successfully operated with accurate gas sensing operations. It is expected that the proposed monolithic sensor circuit can be applied to future VOCs systems with highly sensitive detection.

2016 iMiD, Jeju, Republic of Korea

August 24 - 26, 2016 (Wed - Fri), ICC Jeju

<Oral Session : 67. Physics of Metamaterials>

Self-Complementary Meta-Atom based Transmissive Terahertz Metasurface with High Transparency in Visible Range

Hyunseung Jung, Hojin Lee

Abstract

In the past few years, meta-surfaces for focusing and steering the incident terahertz light have been reported by using metamaterial super-cells, which consist of various metamaterial atoms to spatially change the phase of terahertz waves [1]. Particularly, the transmissive meta-surfaces, in which complementary meta-atoms are formed on the metal-plane, have been considered as meta-lenses or holograms with higher signal-to-noise ratio in comparison with reflective type metamaterials [2]. However, since they can only transmit the resonant terahertz light and are nearly opaque in other frequency ranges, there are limitations to utilize frequency resources outside their resonances. In this paper, we develop novel meta-surfaces that not only exhibit transmissive resonance but also can transparent in visible range.