Daegu Gyeongbuk Institute of Science and Technology
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Flexible multi-electrode neural probe using active-matrix design of transistor array
No full textTo realize a brain-machine interface, a neural probe is one of key hardware. For the neural probe, a high spatial resolution of an electrode array, high electrical sensitivity, and mechanical flexibility remain challenging and essential issues. In regard to these, implantable multi-electrode neural probe employing active-matrix design with field effect transistors (FETs) can attract attention due to their advantages of a suitable integration density and good signal-amplifying abilities. Therefore, we developed a flexible multi-electrode neural probe employing an active-matrix design based on a two-transistor (2T) scheme for application to a flexible neural signal recording probe. As a proof of concept, 4 × 8 electrode array (32 channels) with TFTs was demonstrated. For the flexible active-matrix design, back-gate indium-gallium-zinc-oxide (IGZO) thin film transistors (TFTs) were fabricated on a polyimide (PI). The TFTs used here can amplify signals and achieve a switching function to drive the active matrix. The probe structure was encapsulated by the same PI material again to achieve flexibility with good reliability, as the sandwich-like structure can induce a neutral plane on the TFT and electrodes. To ensure a high signal-to-noise ratio, the structural and process parameters of the TFT were studied. Among different annealing times and temperatures of the IGZO TFT, the optimized annealing condition of the TFT was found to be 250 °C a 1 hour on a flexible substrate. The width over length of the transistors was optimized to 50 μm/10 μm, and the field-effect mobility was 8.33 cm2/V·s. The on current was 2.28 × 10−6 A at a low driving voltage of 5 V. The transconductance was 2.16 μS and the threshold voltage (Vth) was 1.6 V. By applying 5 V, the switching TFT was turned on, and a doubly amplified signal (> 2.4 times) could be measured on the drain line. The electrode array probe with the active-matrix design can use for accurate neural recording and herald a new generation of flexible neural probes with high spatial resolutions. © 2024 Elsevier B.V.FALSEsciescopu
에너지소자용 고성능 및 고안정성 전극 설계
No full textLithium-ion batteries; Solid-state batteries; Electrode design; Composite electrode; Pre-lithiationⅠ. Introduction 1
1.1. Introduction to solid-state batteries (SSBs) 1
1.2. Electrode design for high-energy density SSBs 3
1.2.1. Anode 3
1.2.2. Cathode 4
1.3. Reference 6
Ⅱ. Dry Pre-Lithiation for Graphite-Silicon Diffusion-Dependent Electrode for All-Solid-State Battery 11
2.1. Introduction 11
2.2. Experimental 15
2.3. Results and discussion 18
2.4. Conclusion 44
2.5. Reference 52
Ⅲ. Digital-Twin-Driven Structural and Electrochemical Analysis of Li+ Single-Ion Conducting Polymer Electrolyte for Solid-State Batteries 53
3.1. Introduction 53
3.2. Experimental 56
3.3. Results and discussion 60
3.4. Conclusion 72
3.5. Reference 73
Ⅳ. Facile Sulfide Solid Electrolyte Coating via PTFE binder for Composite Electrodes with High Active Surface Area 77
4.1. Introduction 77
4.2. Experimental 79
4.3. Results and discussion 81
4.4. Conclusion 90
4.5. Reference 91
Summary in Korean 93DoctordCollectio
인간 미세아교세포에서 FGL2의 병리학적 역할 연구
No full textAlzheimer's disease;FGL2;microglia;ApoE4;SNP (rs73375428);thrombin;autophagyList of Contents
Abstract i
List of contents ii
List of tables and figures iv
Ⅰ. Introduction 1
1.1 Integrative analysis of eQTL and GWAS on Korean population 1
1.2 Fibrinogen-like protein 2 (FGL2) 2
1.2.1 The prothrombinase domain of FGL2 2
1.2.2 The immunosuppression domain of FGL2 3
ⅠI. Materials and Methods 5
2.1 Cell Culture 5
2.1.1 Human-induced pluripotent stem cell (hiPSC) 5
2.1.2 Immortalized Human microglia cell line (hMic) 5
2.2 Lentivirus packaging and purification 6
2.3 Antibodies 7
2.4 RNA extraction and cDNA synthesis 7
2.5 Quantitative real-time PCR 7
2.6 Aβ42 uptake 8
2.7 Immunocytochemistry 8
2.8 Immunoblotting 9
2.9 Thrombin activity assay 9
2.10 Statistical analysis 10
ⅠII. Results 11
3.1 Generation of isogenic hiPSCs using CRISPR-Cas9 system 11
3.2 Generation of isogenic hMic using CRISPR-Cas9 system 14
3.3 High expression of FGL2 protein in SNP (rs73375428) major homozygote hiPSC and ApoE4 hMic 17
3.4 Thrombin activity and Aβ42 uptake ability after drug treatment in ApoE3 and ApoE4 hMic 20
3.5 Autophagy in ApoE3 and ApoE4 hMic 25
3.6 Modulating FGL2 expression in ApoE3 and ApoE4 hMic using a viral-mediated inducible CRISPR activation/interference system 28
3.7 FGL2 overexpression and its impact on autophagy in ApoE3 hMic 33
3.8 Argatroban rescued impaired Aβ42 uptake in FGL2 Overexpressing ApoE3 hMic 37
IV. Discussion 41
V. References 44
Abstract in Korean 47
List of tables and figures
Table 1. Information of cell lines used in the research
Figure 1. Generation of isogenic SNP (rs73375428) homozygote hiPSCs
Figure 2. Generation of isogenic ApoE4 hMic
Figure 3. High expression of FGL2 in SNP (rs73375428) major homozygote hiPSC and ApoE4 hMic
Figure 4. Enhancement of Aβ42 uptake in ApoE4 hMic by Argatroban despite the similarity in thrombin activity between ApoE3 and ApoE4 hMic
Figure 5. No significant difference in autophagy between ApoE3 and ApoE4 hMic
Figure 6. Insignificant changes in FGL2 protein expression despite the mild modification of FGL2 transcripts using the CRISPRa/i system
Figure 7. FGL2 overexpression induced autophagy impairment in ApoE3 hMic
Figure 8. Restoration of FGL2 overexpression-induced impairment of Aβ42 uptake in hMic by ArgatrobanMasterdCollectio
Motion analysis using single particle tracking: Lipid phase separation and collective cell migration
No full textOptical microscopy;molecular diffusion;lipid phase separation;nanoparticles;collective cell migrationGeneral introduction · 1
Chapter Ⅰ. Analysis of phase heterogeneity in lipid membranes using single molecule tracking in live cells
1.1 Abstract 4
1.2 Introduction · 5
1.3 Result and Discussion 7
1.4 Conclusion 32
1.5 Material and Methods · 34
1.6 Reference 45
Chapter IⅠ. Deciphering the Physical Interactions during Collective Cell Migration via AI-based Single Cell tracking
2.1 Abstract 51
2.2 Introduction 52
2.3 Result and Discussion · 54
2.4 Conclusion 76
2.5 Material and Methods · 77
2.6 Reference 81
Chapter IIⅠ. Aging-associated alterations of cellular collectiveness and lipid phase separation
3.1 Abstract 84
3.2 Introduction 85
3.3 Result and Discussion · 87
3.4 Conclusion 99
3.5 Material and Methods 101
3.6 Reference · 103
Overall conclusion · 106DoctordCollectio
Biodegradable conductive polymer fiber and manufacturing method thereof
No full text본 발명은 체내 삽입 후 일정시간이 경과하면 생분해되어 사라지는 생분해성 유연 섬유 추출기술과 생분해성 재료를 기반으로 전도성 전극을 제작하는 기술로 제조한 생분해성 전도성 섬유 및 이의 제조 방법에 관한 것이다. 구체적으로는 용융 추출(melt drawing) 공정을 통하여 생분해성 고분자 섬유를 제작하고, 입자 표면 삽입 기술을 통하여 상기 생분해성 고분자 섬유에 전도성을 부여하여 제조된 코어-쉘 타입의 생분해성 전도성 고분자 섬유 및 이의 제조방법에 관한 것이다
3D Structure Controlled Electrode and Electrolyte Membrane for Post Li-Ion Batteries
No full textlithium-ion batteries;lithium metal;patterning;all-solid-state batteries;solid electrolyte membraneLithium-ion batteries (LIBs) are widely utilized in various industries due to their high energy density and stable power generation. However, the quest for higher energy density LIBs have led to active research on higher energy density materials. Lithium metal batteries (LMBs) and all-solid-state batteries (ASSBs) with lithium metal anodes as their core aspect are among the options being explored to overcome the problems of conventional LIBs. With a high theoretical capacity of 3860 mAh g-1 and a low reduction potential of -3.04 vs. SHE, lithium metal is gaining popularity as a future anode material that can increase the energy density of LIBs. However, lithium metal encounter significant intrinsic limitations, including internal short circuits, continual side reactions, and volume expansion caused by dendritic growth on the lithium metal surface during the repetitive charging procedure. In addition, the ASSBs have numerous unresolved issues, including poor interfacial contact, side reactions, difficult manufacturing processes due to the nature of the solid state, and inferior ion transfer capability compared to liquid electrolytes. In this thesis, a 3D structure controlled electrode and electrolyte membrane are reported to outlines research directions for the practical application of post LIBs. The first part of the thesis identified the combined influence of two technologies, micropatterning and three-dimensional controlled micro-porous polyimide separators, on the control of dendrite growth on lithium metal surfaces. Second, surface-patterned graphite electrode with polymer/oxide hybrid electrolytes was proposed to improve the ion transfer property through the electrode layer while enhancing adhesion properties to the current collector. Finally, a simple but practical strategy for fabricating thin solid electrolyte membranes was proposed using perforated polyethylene frame as the supporting component which ensures mechanical robustness for commercial-level cell assembly. These results highlight the crucial role of structure design of electrodes and electrolyte membrane in the development of next-generation LIB technologies.|리튬 이온 전지는 높은 에너지 밀도와 고전압의 특성으로 고용량, 고효율의 안정적인 전력 공급이 가능하기에 전기차동차, 에너지저장장치 등의 동력원으로써 산업 전반에 사용되고 있다. 하지만 더 높은 에너지밀도의 리튬 이온 전지에 대한 추구하며 지속적으로 에너지 밀도가 높은 소재에 대한 연구는 활발하게 이루어지고 있으며, 다소 안정성이 떨어지는 인화성의 전해질을 포함하는 리튬 이온 전지의 특성상 과충전 시에 내부 단락이 일어나거나 충격을 주면 폭발할 수 있다는 문제점 또한 해결해야한다. 이러한 기존 리튬 이온 전지의 한계를 극복하기 위해 다양한 차세대 전지들이 개발되고 있으며, 그 중심에는 리튬 금속 음극을 기반으로 한 리튬 금속 전지와 전고체 전지가 있다. 리튬 금속 음극은 높은 이론적 용량 (3860mAh g‒1)과 낮은 환원 전위 (-3.04 vs. SHE)로 흑연과 실리콘 음극 기반의 현 리튬 이온 전지의 에너지 밀도를 한 단계 끌어올릴 수 있는 차세대 음극재로서 재조명 받고 있다. 다만, 리튬 금속 음극은 충전 과정동안 리튬 금속 표면의 수지상 성장으로 인해 내부 단락, 지속적인 산화 환원 반응, 부피 팽창 등의 치명적인 단점을 가진다. 또한, 리튬 이차 전지의 안전성을 향상시키기 위하여 난연성의 고체전해질을 사용하는 전고체 전지는 고체라는 상태가 가진 성질로 인해 이온 전달 능력이 액체전해질에 비해 떨어지며 계면 간 접촉 불량, 부반응, 어려운 제조 과정 등 해결해야 할 문제점이 많아 아직 상용화 단계에 도달하지 못하였다. 본 논문에서는 전극 및 전해질 막의 3D 구조적 설계를 기반으로 리튬 금속 전지와 전고체 전지를 제조함으로써 차세대 전지의 실상용화를 위한 다양한 연구 방향을 제시한다. 첫째, 리튬 금속 표면에서 리튬 이온의 흐름을 제어할 수 있는 두가지 기술인 리튬 표면 마이크로 패턴화와 3 차원 제어된 마이크로 다공성 폴리이미드 (3DOM PI) 분리막의 하이브리드 효과를 확인하였다. 둘째, 간단한 기계적 패턴화 공정을 통해 전고체 전지의 복합 전극 내 이온전달 능력 향상과 집전체와의 접착 특성의 향상을 동시에 꾀한 고분자/산화물 복합 고체전해질 포함 흑연 전극의 평가 및 분석을 진행하였다. 마지막으로 새로운 형태의 고분자 다공성 지지체를 도입한 고체전해질 막의 설계를 소개함으로써 전고체 전지의 상용화에 적합한 방식의 제조방식 제시와 에너지 밀도를 극대화를 동시에 할 수 있는 방안을 제시하였다.List of Contents
Abstract i
List of contents ii
List of figures iii
List of tables · vi
Ⅰ. Introduction 1
1.1 Introduction to post lithium-ion batteries 1
1.2 Challenges of the post lithium-ion batteries 2
1.3 Strategies to solve the challenging issues of the post lithium-ion batteries 4
Ⅱ. Hybrid effect of micropatterning and 3DOM PI separator on lithium metal batteries 7
2.1 Introduction 7
2.2 Experiment 10
2.2.1 Fabrication of micropatterned lithium metal 10
2.2.2 Separators 10
2.2.3 Cathode preparation and cell assembly 11
2.2.4 Electrochemical analysis 11
2.2.5 Morphological analysis 12
2.3 Results and discussion 13
2.4 Conclusion 19
Ⅲ. Effect of surface-patterning on graphite electrode for all-solid-state batteries 20
3.1 Introduction 20
3.2 Experiment 22
3.2.1 Material 22
3.2.2 Fabrication of hybrid solid electrolyte 22
3.2.3 Fabrication of surface-patterned graphite electrode 23
3.2.4 All-solid-state cell assembly 24
3.2.5 Electrochemical analysis 25
3.2.6 Adhesion analysis 25
3.3 Results and discussion 27
3.4 Conclusion 36
Ⅳ. Frame-based solid electrolyte membrane for all-solid-state batteries 37
4.1 Introduction 37
4.2 Experiment 39
4.2.1 Preparation of perforated polyethylene frame 39
4.2.2 Fabrication of frame-based solid electrolyte membrane 39
4.2.3 Characterization of solid electrolyte membranes 40
4.2.4 All-solid-state cell assembly 40
4.2.5 Electrochemical analysis 40
4.2.6 Electrochemical modeling workflow 41
4.3 Results and discussion 43
4.4 Conclusion 54
References 55
Summary in Korean 69DoctordCollectio
차세대 리튬 전지의 호스트 물질로써의 Cobalt Hexacyanoferrate의 합성과 전기화학적 특성 연구
No full text"Prussian-Blue Analogues"; "Sodium-ion batteries"; "Multivalent-ion batteries"List of Contents
Abstract i
List of contents ii
List of tables · iii
List of figures vi
Ⅰ. Introduction 1
1.1 The necessities of Post-Lithium ion batteries 1
1.2 Sodium-ion batteries (SIBs) 2
1.3 Multivalent-ion batteries : Magnesium and Calcium (MIB, CIB) 3
1.4 Prussian blue analogues (PBAs) 4
Ⅱ. Experimental section 5
2.1 Synthesis 5
2.2 Material Characterization 6
2.3 Electrochemical Characterization 7
2.4 Quantitative Examination of Na+ Insertion Characetristics 8
Ⅲ. Results and Discussion 9
3.1 Synthesis of Cobalt hexacyanoferrate 9
3.2 Electrochemical characterization 14
3.2.1 Na-cell system 14
3.2.2 Multivalent-cell system 19MasterdCollectio
Highly Reduced Phase Transition Hysteresis of Vanadium Dioxide Thin Films in Multilayer Structure with Titanium Dioxide
No full textHerein, we present the electrical, structural, and optical characteristics of pristine VO2, VO2/TiO2, and TiO2/VO2/TiO2 thin films deposited on a conventional glass substrate via magnetron sputtering. To obtain a crystallized structure, the as-deposited films were annealed in a tube furnace at 450 and 550 °C in an oxygen atmosphere at 20-25 mTorr for 90 min. The prepared films were characterized by four-point probe resistivity, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible-near-infrared spectrophotometry, and field-emission transmission electron microscopy. The microstructural analyses revealed that using TiO2 as a buffer and the TiO2/VO2/TiO2 sandwich structure contributed to the improvement in VO2 crystallinity. In particular, the (011) diffraction peak parameters of VO2, such as crystallite size, increased when the d-spacing and microstrain of the films decreased. The atomic fraction of the VO2 phase in the TiO2/VO2/TiO2 sample increased from 11 to 19 at. % after annealing at 450 °C. In addition, the multilayer film exhibited relatively increased optical transmittance near the infrared region and showed a reduction in the hysteresis loop width (HLW) from 21 to 10 °C at a transition temperature of 65 °C in relation to those of pure VO2 and bilayer VO2/TiO2 films. Upon increasing the annealing temperature to 550 °C, the bilayer film showed the highest temperature-dependent infrared transmittance variation (ΔTIR) of ∼37% at a wavelength of 2000 nm. In addition, the TiO2/VO2/TiO2 sample showed the lowest HLW (3 °C) with a ΔTIR of ∼30%. The direct film fabrication on conventional glass substrates, relatively low HLW, and increase in optical transmittance in the near-infrared region can contribute to the production of cost-effective, fine-tuned, energy-saving smart windows and infrared switches. © 2024 American Chemical Society.FALSEsciescopu
Tailored Micromagnet Sorting Gate for Simultaneous Multiple Cell Screening in Portable Magnetophoretic Cell-On-Chip Platforms
Get PDFConventional magnetophoresis techniques for manipulating biocarriers and cells predominantly rely on large-scale electromagnetic systems, which is a major obstacle to the development of portable and miniaturized cell-on-chip platforms. Herein, a novel magnetic engineering approach by tailoring a nanoscale notch on a disk micromagnet using two-step optical and thermal lithography is developed. Versatile manipulations are demonstrated, such as separation and trapping, of carriers and cells by mediating changes in the magnetic domain structure and discontinuous movement of magnetic energy wells around the circumferential edge of the micromagnet caused by a locally fabricated nano-notch in a low magnetic field system. The motion of the magnetic energy well is regulated by the configuration of the nanoscale notch and the strength and frequency of the magnetic field, accompanying the jump motion of the carriers. The proposed concepts demonstrate that multiple carriers and cells can be manipulated and sorted using optimized nanoscale multi-notch gates for a portable magnetophoretic system. This highlights the potential for developing cost-effective point-of-care testing and lab-on-chip systems for various single-cell-level diagnoses and analyses. © 2024 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.TRUEsciescopu