2024.10.30 14:20

AMSM 2024, Incheon, Korea

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AMSM 2024, Incheon, Korea

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


KakaoTalk_20241030_132639216.jpg


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.

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2020.02.12 15:05

AMSM 2019, Incheon, Korea

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AMSM 2019, Incheon, Korea

October 16 - 19, 2019 (Tue. - Fri.), Sheraton Grand Incheon Hotel


Wireless Powered VOC Sensor Based on Wi Fi Energy Harvesting Metamaterial with i-TPU

Wonwoo Lee, Heejoo Park, Hyunseung Jung, So Young, Kim, Do Hwan Kim, and Hojin Lee



원우_AMSM.jpg




Abstract


  In this paper, we propose a novel wireless powered VOC sensor system based on energy harvesting metamaterial combined with ionic thermoplastic polyurethane (i TPU) gas sensing channel at microwave frequency . The sensor consists of the SRR, rectifier circuit t o harvest the RF energy by converting electromagnetic energy into DC voltage, and i TPU gas sensing channel to detect VOC with the variation of resistance. For the practical wireless sensing system, we utilized widespread and easily accessible commercial 2 .4 GHz Wi Fi source as external electromagnetic wave energy, and the energy harvesting metamaterial was designed and optimized to resonate at 2.4 GHz. When i TPU was exposed to VOC , the diffusivity of ionic liquid (IL) increases leading to decrease of the resistance of i TPU that can be identified with the differential harvested energy induced from variation of resonance property for the energy harvest ng metamaterial sensor . As a result, by analyzing the differential harvested energy , the proposed sensor c ould provide the highly sensitive wireless VOC sensor system without bulky and complicated measurement system offering great accessibility and simplicity for the practical sensor applications Also, the wireless powered VOC sensor showed high stability and repeatability representing the rapid restoring to the initial resistance value of the i TPU gas sensing channel. Finally , it is expected that the proposed system can be applied to not only for VOC sensors but also for dynamic environmental sensing systems

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IDW '23, Niigata, Japan

December 6 - December 8, 2023 (Wen. - Fri.), TOKI MESSE Niigata Convention Center


KakaoTalk_20240317_133905249_01.jpg


Adaptive Frequency Driving Scan Driver for Low Power Display based on a-InGaZnO TFTs

Jinho Moon, Hyunwoo Kim, Yongchan Kim, and Hojin Lee


Abstract

 In this paper, a scan driver combined with logic circuit using amorphous indium-gallium-zinc-oxide (a-InGaZnO) thin-film transistors (TFTs) is proposed. Logic circuit masks the output signal from the scan driver in order to control the driving frequency. Proposed frequency adaptive scan driver is expected to reduce power consumption depending on the display contents.

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IDW '23, Niigata, Japan

December 6 - December 8, 2023 (Wen. - Fri.), TOKI MESSE Niigata Convention Center


KakaoTalk_20240317_133905249.jpg


Depletion-Mode a-IGZO TFT Pixel Circuit Compensating for Capacitance Deviation and Threshold Voltage Shift

Hyunwoo Kim, Jinho Moon, Yongchan Kim, and Hojin Lee


Abstract

 In this paper, we propose a novel pixel circuit using source follower scheme method compensating for threshold voltage (VTH) shifts of driving TFT (DR TFT) and storage capacitance deviations based on amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The proposed pixel circuit is composed of six TFTs and two capacitors. Simulation results confirmed that, when the VTH of the driving TFT and storage capacitance varies up to ±2 V and ±20%, the OLED current error could be suppressed to 5.1%, and 8.0%, respectively.

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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



용찬_SPIE.jpg





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.

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