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레이저 유도 그래핀 교차 전극 및 폴리이미드 전하저장층을 활용한 고체-액체 마찰전기 소형발전기
김도영(Do Young Kim),김백규(Baek Gyu Kim),김형우(Hyung Woo Kim),서경덕(Kyoung Duck Seo),박상민(Sang Min Park) 한국기계가공학회 2023 한국기계가공학회지 Vol.22 No.3
The triboelectric nanogenerator (TENG) is a prospective sustainable energy generator among energy sources such a solid-solid contact and solid-liquid contact electrification. In this study, we reported a facile fabrication of a solid-liquid TENG based on a laser-induced graphene (LIG) patterning process, which could fabricate complicated electrode shapes. In general, the solid-liquid TENG is comprised of the interdigitated electrode and contact layers. Thus, to enhance the output performance of the TENG, a charge-storage layer was frequently utilized between the electrode and contact layers. The LIG patterning process enables the fabrication of not only the interdigitated LIG electrode layer but also a polyimide charge-storage layer for LIG-TENG with stable electrical performance. Furthermore, by optimizing the LIG electrode design, the LIG-TENG demonstrated remarkable energy harvesting ability, sufficient to charge capacitors for the operation of an electronic device. Considering the simple fabrication process and energy harvesting sustainability, the LIG-TENG could be applied to self-powered sensors, wearable devices, and smart-factory systems.
에어-젯스프레이를 이용한 PCL 나노섬유 멤브레인의 제작 및 응용
백현우(Hyeon Woo Baek),남윤한(Yoon Han Nam),서경덕(Kyoung Duck Seo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Nanofibers in the field of tissue engineering are suitable for similarly manufacture Extracellular matrix(ECM) structures. This has high porosity, surface area and suitable conditions for cell culture. Manufacturing method of nanofibers include phase separation, electrospinning, air-jet, etc. In particular, air-jet technique is economical and can fabrication nanofibers within a short time. In this study, the fabricated membrane was composed of PCL nanofibers having a diameter of 50 to 300 nm using air-jet spray. To confirm the surface morphology of the nanofiber membrane, scanning electron microscope(SEM) images were captured. In addition, a customized transwell was manufactured in order to analyze cell culture characteristics and NIH 3T3 cells were cultured to confirm the possibility that this nanofiber membrane could be utilized as a suitable tool for culturing cells.
하이드록시아파타이트 표면 나노 구조 성장에 의한 고분자 표면의 초소수성 개질
남윤한(Yoon Han Nam),조용상(Yong Sang Cho),서경덕(Kyoung Duck Seo) 대한기계학회 2020 大韓機械學會論文集B Vol.44 No.2
초소수성 표면은 자가 세정, 방빙 등의 특성을 가지며, 산업 여러 방면에 활용될 수 있어 많은 관심을 받고 있다. 그러나 초소수성 표면 구현을 위해 제안된 기존의 방법들은 복잡한 제작 공정 및 고가의 장비가 필요하다는 한계가 있다. 따라서 본 연구에서는 의사체액(SBF: Simulated Body Fluid)을 이용하여 하이드록시아파타이트 마이크로/나노 구조를 고분자 표면 위에 성장시키고 SAM(Self-Assembled Monolayer) 코팅을 함으로써 손쉽게 초소수성 표면을 제작하였다. 제작된 초소수성 표면의 접촉각은 163.3±2.7°로 측정되었다. 더 나아가 마스킹 테이프를 이용하여 초소수성 표면을 다양한 형상으로 선택적으로 패터닝 할 수 있음을 확인하였으며, 제작된 초소수성 표면의 자가 세정 특성을 보임을 검증하였다. Superhydrophobic surfaces have attracted research interest owing to their self-cleaning characteristics, antiicing properties, etc. However, conventional fabrication methods for these surfaces still require complex processes and special facilities. Therefore, in this study, we propose a facile and cost-effective fabrication method for superhydrophobic surfaces using simulated body fluid (SBF). A PMMA (poly (methyl methacrylate)) substrate with a hydroxyl group is initially immersed in the SBF. Hydroxyapatite with micro/nanostructure is then crystallized on the substrate. Finally, a self-assembled monolayer (SAM) coating is prepared to introduce superhydrophobicity. After the coating process, the contact angle of the fabricated substrate is measured as 163.3 ± 2.7°. We also demonstrate that hydroxyapatite with a micro/nanostructure can be patterned with various shapes by using masking tape. In addition, the self-cleaning effect of the fabricated surface is observed.
비교적 큰 나노구조 표면에서 박테리아 부착 및 살균 메커니즘
김희경(Hee Kyeong kim),박준기(Jun Gi Park),Suvd Erdene Ganbaatar,서경덕(Kyoung Duck Seo),조영삼(Young-Sam Cho),박현하(Hyun-Ha Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Biofilms formed due to the attachment of bacteria to the surface are causing various problems in medical design and fabrication of a generation of bactericidal materials. Recently, mechano-bactericidal using a contact killing mechanism by mimicking the wings of cicada or dragonfly is being studied. Mechano-bactericidal has a mechanism in which the bacterial membrane is destroyed as the bacteria attached to the surface are stretched by the nanostructure. The bactericidal ability of the nanostructure is determined by the spacing, height, geometric structure of the nanostructure. The nanostructures reported so far mimic the wings of cicadas and dragonflies, and have high density and pointed nanostructures. Tear of the bacterial membrane by the nanopillars can induce bacteria to kill. The pointed nanostructures can pierce the bacterial membrane and kill the attached bacteria. However, this mechanism is predicted to kill due to the tearing by stretching of the bacterial membrane by relatively large nanopillars.
Jae-Seok Kim(김재석),Hun-Jin Jeong(정훈진),Kyoung-Duck Seo(서경덕),Young-Sam Cho(조영삼),Seung-Jae Lee(이승재) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Many tissues and organs of the human body such as the esophagus, blood vessels, and intestines are hierarchical structure with multi-cellular components. Although autologous tissue transplantation has been considered an ideal approach to repair tissue, there is still existence an imbalance between supply and demand. To overcome these limitations, various tissue-engineered approaches have been studied to create artificial tubular architecture which can replace the donor tissue. The artificial tubular construct has essentially required the flexible feature to avoid closing lumen when may occur by an external force in the body. Therefore, we designed and fabricated the tubular scaffold with patterning of the negative Poisson’s ratio to improve the bending performance via 3D-Dragging printing technique. The 2D negative Poisson's ratio sheet was fabricated via an extrusion-based 3D-printing technique using the polycaprolactone. And then, a 3D tubular construct fabricated rolling it up of the 2D patterning sheet. We demonstrated the flexible property of the negative Poisson’s ratio patterned tubular scaffold by bare hands and will investigate the capability as the tubular tissue-engineered constructs.