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KIEEME 2020, Pyeongchang, Korea

July 8 - 10, 2020 (Wed. - Fri.), Phoenix Park

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Metamaterial based Wireless Power Transfer System for Neuro Stimulator

Semin Jo, Wonwoo Lee, and Hojin Lee


Abstract 


  

Bioelectronic devices require miniaturization, stability, and long-term operation characteristics for sustainable monitoring and stimulation within human body. In this regard, batteries have been widely used for the implantable device due to the long-term operation ability, but the battery working based implantable devices have some challenges in bulky size, limited lifetime, and need for replacement that essentially requires surgical method. Therefore, wireless power transfer (WPT) have been attracted significant attention as the alternative approach to enable the long-term operation of bioelectronic devices, and WPT based charging system for the implantable bioelectronic devices have been reported using near-field coil-pair coupling methods. Despite the satisfied charging capacity, however, the miniaturization of the WPT system is remained as a critical problem since the efficiency and power transfer depth strongly depends on the dimensions of coils. Recently, metasurface, that exhibit exotic electromagnetic (EM) characteristics with sub-wavelength thickness, based WPT system was introduced in Bioelectronics to enhance the efficiency and to reduce the geometrical dimension of WPT system. In this work, we propose a novel WPT method for biomedical implantable device using EM focusing metasurface at 5.8 GHz. The proposed metasurface has dimensions of length (l) = 49 mm, width (w) = 49 mm size, and thickness (t) = 4.69 mm which is much smaller than the operating wavelength (<l/10). The proposed metasurface consists of the 7 x 7 array unit cells with various shapes and sizes that shows gradient phase distribution to control the phase front of the transmit EM wave. Also, the proposed metasurface is designed to have 4 different layers to realize full 2p phase coverage for focusing the EM wave at specific depth in biological tissue. To confirm the EM wave focusing characteristics, the electric and magnetic field distribution of transmit field at the focal point was analyzed, and the proposed metasurface could successfully form a focal point at 4 mm depth of the biological tissue as desired. Furthermore, the proposed WPT enhanced the EM waves propagation efficiency from 16 % to 23 % into biological tissue by reducing the reflection loss at the air-tissue interface.

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2024.09.02 13:40

IMID 2024, Jeju, Korea

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IMID 2024, Jeju, Korea

August 20 - August 23, 2024 (Tue. - Fri.), ICC Jeju


KakaoTalk_20240902_105530006_08.jpg

Silicon-integrated Photolithography of Small-molecule Phosphorescent Emitter for Ultrahigh-resolution Micro-OLEDs 

Ryungyu Lee, Keun-Yeong Choi, Hyukmin Kweon, Borina Ha, Changhee Lee, Soyeon Lee, Do Hwan Kim, and Hojin Lee


Abstract

 In this paper, we propose an ultrahigh-resolution organic lightemitting diodes (OLEDs) pixels patterned by conventional photolithography through by incorporating silicone into phosphorescent small-molecule networks. This siliconeintegrated phosphorescent organic light-emitting diode (SIphOLED), in which silicone molecules are homogeneously crosslinked with small-molecule light-emitting materials, can effortlessly achieve to 3,000 PPI ultrahigh-resolution patterns using the photolithography process.

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2024.09.02 13:45

IMID 2024, Jeju, Korea

조회 수 76 추천 수 0 댓글 0
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IMID 2024, Jeju, Korea

August 20 - August 23, 2024 (Tue. - Fri.), ICC Jeju


KakaoTalk_20240902_105202000_03.jpg

Novel Pixel Circuit Compensating for Sub-threshold Swing Variations and Threshold Voltage Shifts of Depletion Mode a-IGZO TFT in AMOLED Displays 


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


Abstract

 We proposed a novel pixel circuit for AM-OLED displays with double gate structure based on a-IGZO TFTs. The proposed pixel circuit compensates for the operation in depletion mode and the variation in VTH and S∙S of the driving TFT.

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2024.09.02 13:56

IMID 2024, Jeju, Korea

조회 수 146 추천 수 0 댓글 0
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IMID 2024, Jeju, Korea

August 20 - August 23, 2024 (Tue. - Fri.), ICC Jeju


KakaoTalk_20240826_184724886_05.jpg

A Novel Scan Driver Based on a-IGZO TFTs with Extra Clock Modulation for Extremely Low Power Consumption


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


Abstract

 In this paper, we propose a scan driver with an extra clock signal using amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). By employing extra clock signal modulation-based frame masking driving and constant DC driving methods, the proposed scan driver achieves extremely low power consumption while simultaneously reducing the power consumption of the display panel. The proposed novel scan driver is suitable for operating ultra-low-power displays, such as always-on displays.

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2024.09.02 14:05

IMID 2024, Jeju, Korea

조회 수 489 추천 수 0 댓글 0
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IMID 2024, Jeju, Korea

August 20 - August 23, 2024 (Tue. - Fri.), ICC Jeju


KakaoTalk_20240902_105530006_04.jpg


Enhanced Optoelectrical Properties of Organic Light-Emitting Diodes by ZnO Nanoparticles Reacted with Organic Solvents 


Changhee Lee, Ryungyu Lee, Keun-Yeong Choi, and Hojin Lee 


Abstract

 In this study, we propose a novel post-processing method aimed at enhancing the Luminance of organic light-emitting diodes (OLEDs). This method leverages the reactivity between zinc oxide (ZnO) and organic solvents to improve device performance. Specifically, we aimed to increase the hole-to-electron matching ratio within the light-emitting layer by deliberately reducing the number of oxygen vacancies. These vacancies serve as pathways for carrier movement, and their reduction through the reaction of ZnO particles with organic solvents results in lowered electron injection. Consequently, this modification effectively increases the generation of excitons in the post-processed devices, leading to a significant improvement in luminance.

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