Multifunctional Cellulose-Based Hydrogels for Wearable Sensing and Osmotic Energy Harvesting
- Alternative Title
- 웨어러블 센싱 및 염도차 에너지 하베스팅을 위한 다기능성 셀룰로오스 기반 하이드로젤
- Abstract
- This dissertation focuses on the development of advanced hydrogels and ionogels for multifunctional applications in wearable electronics and sustainable energy systems. First, a highly stretchable and conductive hydrogel composed of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and PEDOT:PSS was developed. The hydrogel exhibited excellent mechanical properties, with a tensile strength of 0.391 MPa and an elongation of 303.8%. It also showed low electrical hysteresis (0.101% at 50% strain), a conductivity of 2.04 S/m, and a gauge factor of 1.034. It enabled accurate motion detection with 100% classification accuracy using machine learning, and 16 films in series generated 2.01 V to power an LED, highlighting its dual role in sensing and energy generation. In the second study, a recyclable biohybrid hydrogel was synthesized using CMC, gelatin, PEDOT:PSS, and an ionic conductor. This material achieved high conductivity (8.67 S/m), stretchability (378%), and environmental sustainability. Demonstrations included an ACEL device with a luminance of 115.54 cd/m² under 200% strain and a body movement detector sensitive to various motions, confirming its potential for wearable and green electronics. Lastly, an advanced ionic conductive hydrogel based on a CMC-Borax/CaCl₂ system exhibited ultra-high conductivity (67.303 S/m), extreme stretchability (526.4%), and optical transparency. These results underline its suitability for flexible sensors and optoelectronic applications. The materials developed in this research were systematically characterized using various analytical techniques to evaluate their structural, electrical, mechanical, and optical properties. Emphasis was placed on balancing conductivity and mechanical robustness, enabling reliable long-term performance in practical environments. The integration of sustainable components and recyclable formulations further addresses growing concerns regarding the environmental impact of electronic materials. Overall, this work provides innovative material platforms with excellent mechanical, electrical, and multifunctional properties, advancing the field of soft electronics and eco-friendly technologies.
Keywords: Hydrogel, Wearable Sensor, Sustainable Energy, Conductivity, CMC, ACEL Device, Motion Sensing.|이 논문은 웨어러블 전자기기 및 지속 가능한 에너지 시스템에 적용 가능한 다기능성 고급 하이드로겔 및 아이오노겔의 개발에 중점을 두고 있습니다. 첫 번째로, 카르복시메틸셀룰로오스(CMC), 폴리비닐알코올(PVA), 그리고 PEDOT:PSS로 구성된 고신율성과 전도성을 갖춘 하이드로겔이 개발되었습니다. 이 하이드로겔은 인장강도 0.391 MPa, 신율 303.8%, 50% 스트레인에서 전기 히스테리시스 0.101% 및 전도도 2.04 S/m, 게이지 팩터 1.034의 우수한 기계적 및 전기적 특성을 보였습니다. 머신러닝 기반 동작 감지에서 100% 분류 정확도를 달성하였으며, 16장의 필름을 직렬로 연결하여 2.01 V를 생성하여 LED를 구동하는 등 감지와 에너지 생성의 이중 역할을 입증하였습니다. 두 번째 연구에서는 CMC, 젤라틴, PEDOT:PSS 및 이온 전도체로 구성된 재활용 가능한 바이오하이브리드 하이드로겔이 합성되었습니다. 이 소재는 전도도 8.67 S/m, 신율 378% 및 환경 지속 가능성을 달성하였습니다. 200% 스트레인 하에서도 115.54 cd/m²의 휘도를 발하는 ACEL 장치 및 다양한 동작에 민감하게 반응하는 움직임 감지기를 통해 웨어러블 및 친환경 전자기기 응용 가능성을 확인하였습니다. 마지막으로, CMC-Borax/CaCl₂ 시스템 기반의 고급 이온전도성 하이드로겔은 매우 높은 전도도(67.303 S/m), 극도의 신율(526.4%) 및 광학적 투명성을 보여주며 유연 센서 및 광전자 응용 분야에 적합함을 입증하였습니다. 본 연구에서 개발된 소재들은 구조적, 전기적, 기계적, 광학적 특성을 평가하기 위해 다양한 분석 기법을 통해 체계적으로 특성화되었습니다. 전도성과 기계적 강인성의 균형을 중시하여 실제 환경에서도 안정적인 장기 사용이 가능하도록 하였습니다. 또한, 지속 가능한 구성 요소와 재활용 가능한 제형을 통합함으로써 전자소재의 환경적 영향을 줄이기 위한 사회적 요구에 부응하고자 하였습니다. 전반적으로 본 연구는 우수한 기계적, 전기적, 다기능성 특성을 갖춘 혁신적인 소재 플랫폼을 제시하며, 소프트 일렉트로닉스 및 친환경 기술 분야의 발전에 기여하고자 합니다.
키워드: 하이드로겔, 웨어러블 센서, 지속 가능한 에너지, 전도도, CMC, ACEL 소자, 동작 감지.
- Issued Date
- 2025
- Awarded Date
- 2025-08
- Type
- Dissertation
- Keyword
- Hydrogel, Wearable Sensor, Sustainable Energy, Conductivity, CMC, ACEL Device, Motion Sensing
- Publisher
- 국립부경대학교 대학원
- Affiliation
- 국립부경대학교 대학원
- Department
- 대학원 스마트그린기술융합공학과
- Advisor
- Yong Hyun Kim
- Table Of Contents
- Chapter I. Introduction 1
Chapter II. Theoretical Background 3
II.1. Hydrogel 3
II.2. Natural and Synthetic Polymers for Gel Systems 4
II.2.1. Natural Polymers 4
II.2.2. Synthetic Polymers 6
II.2.3. Hybrid Polymer Systems 8
II.3. Crosslinking Mechanisms in Hydrogel Formation 9
II.4. Properties of Hydrogel 11
II.4.1. Swelling Behavior 11
II.4.2. Mechanical Integrity 12
II.4.3. Electrical/Ionic Conductivity 13
II.4.4. Antibacterial Properties. 14
II.5. Conductive Materials in Hydrogel Composites 15
II.5.1. Conductive Polymers 16
II.5.2. Carbon-Based Nanomaterials 17
II.5.3. Metal-Based Conductive Nanomaterials 18
II.5.4. Ionic Conductive Hydrogels 19
II.6. Application of Hydrogel 20
II.6.1. Wearable Sensing Technologies 20
II.6.2. Energy Harvesting Applications 21
II.6.3. Optoelectronic Devices 24
II.7. Machine Learning in Material Science 26
II.8. Hydrogel Characterization Techniques 28
II.8.1. Functional Evaluation 29
II.8.2. Mechanical and Thermal Properties 30
II.8.3. Structural Analysis 30
II.8.4. Morphology and Microstructure 31
Chapter III. Extremely-low electrical-hysteresis hydrogels for multifunctional wearable sensors and osmotic power generators. 32
III.1. Introduction 32
III.1.1. Conductive Hydrogel 32
III.1.2. Hydrogel Materials 33
III.1.3. Hydrogels for wearable sensors and hydrovoltaic electricity generation 34
III.1.4. Research Outcomes 36
III.2. Materials and methods 36
III.2.1. Materials 36
III.2.2. Preparation of conductive hydrogels 37
III.2.3. Fabrication of sensor 37
III.2.4. Fabrication of energy harvesting devices 38
III.2.5. Characterizations 38
III.2.6. Machine learning-assisted wearable sensor operation 38
III.3. Results and Discussion 40
III.3.1. Mechanical properties of conductive hydrogels 40
III.3.2. Antibacterial properties of hydrogel 45
III.3.3. Electromechanical properties of conductive hydrogels 47
III.3.4. Electrical response of conductive hydrogels 51
III.3.5. Wearable sensors based on conductive hydrogels 52
III.3.6. Machine-learning-assisted multimodal recognition by wearable sensors 54
III.3.7. Osmotic energy harvesters based on conductive hydrogels 57
III.4. Conclusion 58
Chapter IV. Innovative Biohybrid Hydrogels: Conductive and Recyclable Natural Polymer CMC-Gelatin Networks Loaded with PEDOT:PSS for Multi-Application 60
IV.1. Introduction 60
IV.1.1. Conductive hydrogel based on natural polymer 60
IV.1.2. Hydrogel for optoelectronic devices 61
IV.1.3. Hydrogel for sensor 63
IV.1.4. Recycle process of hydrogel 64
IV.1.5. Research Outcomes 65
IV.2. Experimental Section 66
IV.2.1. Material 66
IV.2.2. Preparation of CMC-Gel/PEDOT:PSS Hydrogels 66
IV.2.3. Solution preparation for post-treatment 66
IV.2.4. Fabrication of ACEL device 67
IV.2.5. Fabrication of Sensor 67
IV.2.6. Recycle Process 67
IV.2.7. Characterization 68
IV.3. Results and Discussion 68
IV.3.1. Fabrication and crosslinking mechanism of hydrogel 68
IV.3.2. Mechanical Properties of Pristine Hydrogel 69
IV.3.3. Electromechanical Properties of Conductive Hydrogel 71
IV.3.4. Enhancing Electrical Conductivity of Conductive Hydrogel by Post-treatment Process 75
IV.3.5. Alternative Current Electroluminescence Device (ACEL) 76
IV.3.6. Temperature Sensor 78
IV.3.7. Sensor Properties Characterization 79
IV.3.8. Hydrogel Motion Sensors for Real-Time Monitoring of Human Movements 80
IV.3.9. Machine learning-driven multimodal recognition via wearable sensors 81
IV.3.10. Recycle Process of Conductive Hydrogel 82
IV.4. Conclusion 87
Chapter V. Advanced Ionic Conductive Hydrogel with Ultra-High Conductivity, Transparency, and Multiple Functionalities based on CMC- Borax/CaCl2 88
V.1. Introduction 88
V.1.1. Ionic Conductive Hydrogel 88
V.1.2. Ionic Conductive Hydrogel for Optoelectronic Devices 89
V.1.3. Ionic Conductive Hydrogel for Wearable and Pressure Sensors (Morse Code Interface) 90
V.1.4. K-Nearest Neighbors (KNN) Machine Learning Method for Sensor Applications 91
V.1.5. Research Outcomes 92
V.2. Experimental Section 93
V.2.1. Material 93
V.2.2. Preparation of CMC-Borax/CaCl2 Hydrogels 93
V.2.3. Fabrication of ACEL device 94
V.2.4. Fabrication of Sensor 94
V.2.5. Motion Recognition Using Hydrogel Sensors 94
V.2.6. Characterization 95
V.3. Results and Discussion 95
V.3.1. Fabrication and crosslinking mechanism of hydrogel 95
V.3.2. Electrical and Optical Properties of Ionic Conductive Hydrogel 96
V.3.3. Mechanical Properties of Ionic Conductive Hydrogel 98
V.3.4. Electromechanical Properties of Conductive Hydrogel 100
V.3.5. Alternative Current Electroluminescence Device (ACEL) 103
V.3.6. Hydrogel Motion Sensors for Real-Time Monitoring of Human Movements 105
IV.3.7. Machine learning-driven multimodal recognition via wearable sensors 108
V.4. Conclusion 109
Reference 111
Acknowledgements 126
- Degree
- Doctor
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