2020.02.12 14:58

IMID 2019, Gyeongju, Korea

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IMID 2019, Gyeongju, Korea

August 27 - 30, 2019 (Tue. - Fri.), HICO



Active pixel sensor circuit using photo-patternable ionic PUA based coplanar a-InGaZnO TFTs

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



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Abstract


  Currently, the gate dielectric using the ionic polymer comprising ionic liquids in a polymer matrix to form the electric double layer (EDL) has been extensively studied thin-film transistors field thanks to its advantages of induced ultra-high density carrier attainability in the channel, improved capacitive coupling, low-voltage operation, and low-temperature fabrication process [1, 2]. For patterning the ionic polymer to be used as a gate dielectric for the complex circuits, there have been many different approaches reported such as ‘cut and stick’ method, aerosol printing process, or using additional mold to isolate the ionic liquids. However, most of methods reported so far have challenged on realizing micron-sized fine patterns. In this paper, we adopted photo-patternable ionic polymer as a gate dielectric in the coplanar TFT structure where the gate, source, and drain electrodes were deposited by one lift-off process.


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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



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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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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



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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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SPIE Photonics West 2020, San Francisco, USA

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


Active Capacitive Sensor Circuit Using Photo-Patternable Ionic Polymer Gate Dielectric Based Solution-Processed Coplanar a-InGaZnO TFTs

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



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Abstract


  In this paper, we propose solution-processed coplanar a-InGaZnO TFTs using photo-patternable ionic polyurethane acrylate (i-PUA) polymer as a gate dielectric. In our fabrication process, i-PUA is able to pattern micro-size (30μm) by using photocrosslinking property and maintain high capacitance through EDL. Based on developed TFTs, we fabricated an active pixel sensor (APS) circuit consisting of three coplanar a-InGaZnO TFTs for detecting capacitance changes through the difference of output voltages. Furthermore, we simultaneously fabricated a capacitive pressure sensor using an i-PUA on the same plane so as to integrated APS circuit and capacitive pressure sensor simply. Based on the experimental results, we confirmed that the proposed APS circuit could detect changes in the capacitance through various input pressure-levels in i-PUA based sensor. With these results, we believe that our proposed sensor system using the integration of APS circuit and sensor will be applicable to future wearable, human-interaction display with low-power consumption.

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SPIE Photonics West 2020, San Francisco, USA

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


Tandem structured 3-color micro-polymer light-emitting diodes (μ-PLEDs)

Keun-Yeong Choi, Han Wool Park, Do Hwan kim, and Hojin Lee




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Abstract


  In this study, we proposed a tandem structured 3-color micro-patterned polymer light-emitting diodes (μ-PLEDs) for super high-resolution organic light-emitting diode (OLED) micro displays. The proposed 3-color polymer light-emitting diodes consisted of red, green, and blue colored polymers patterned down to 20 μm. For the tandem structure, we adopted the recently developed sol-gel process to obtain the orthogonality of organic semiconductor against the solvents and chemicals so that we could apply the standard photolithography and dry-etch process to achieve micron-size patterns of light-emitting polymers. Experimental results showed that we could achieve the 3 distinct color emissions from our tandem PLEDs fabricated by the standard process, the which was confirmed by EL spectrum and CIE chromaticity diagram.

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