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논문 기본 정보

자료유형
학위논문
저자정보

이소영 (경희대학교, 경희대학교 대학원)

지도교수
김갑진
발행연도
2014
저작권
경희대학교 논문은 저작권에 의해 보호받습니다.

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이 논문의 연구 히스토리 (4)

초록· 키워드

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Palladium nanoparticles (Pd-NPs) doped poly(vinylidene fluoride) (PVDF) exhibits higher β-crystalline phase content and superior piezoelectric property compared to neat PVDF. Piezoelectric sensors fabricated using Pd-NPs doped PVDF nanofiber web can generate current or voltage by external pressure due to induced orientation of C-F dipoles by high DC voltage through electrospinning. However, piezoelectric sensors can be used to measure only dynamic pressure and not static pressure, because piezoelectric signal is generated only by the change in preferential orientation of C-F dipoles in PVDF under external pressure. On the other hand, piezocapacitive sensors based on thermoplastic polyurethane (TPU) nanofiber web with low compression set show an increase in capacitance with decreasing film thickness under external pressure. Therefore, they are capable of measuring both static and dynamic pressure. Hence in this work, hybrid pressure sensor composed of PVDF with high β-phase content nanofiber web and TPU nanofiber web stacked on each other was prepared for measuring static and dynamic pressure, simultaneously. Furthermore, hybrid pressure sensor can be applied to smart insoles for observing piezoelectric and piezocapacitive signals from foot pressure and evaluating energy expenditure during walking or running.

목차

1. Introduction 1
1.1. Flexible polymer-based pressure sensors 1
1.2. Piezoelectric sensors based on PVDF nanofiber webs 1
1.2.1. Piezoelectric properties of PVDF 1
1.2.2. Electrospinning of PVDF 2
1.3. Piezocapacitive sensors based on thermoplastic polyurethane nanofiber webs 9
1.3.1. Piezocapacitive properties of TPU 9
1.3.2. Modeling of the stress relaxation and creep behaviors 9
1.4. Hybrid pressure sensors 10
1.5. Objectives 12
2. Experimental 13
2.1. Materials 13
2.2. Electrospinning of PVDF and TPUs 13
2.3. Fabrication of piezoelectric and piezocapacitive sensors 16
2.4. Characterization 20
2.4.1. Transmission electron microscope (TEM) 20
2.4.2. Fourier Transform Infrared (FTIR) 20
2.4.3. Field Emission Scanning Electron Microscope (FE-SEM) 20
2.4.4. Dielectric constants 20
2.4.5. Hysteresis measurement 21
2.4.6. Creep and stress relaxation behaviors 21
2.5. Fabrication and measurement of hybrid pressure sensors 21
2.5.1. Designing the smart shoes with sensors 21
3. Results Discussion 25
3.1. Pd-NPs doped PVDF nanofiber web based piezoelectric sensors 25
3.1.1. Transmission electron microscope (TEM) 25
3.1.2. Fourier Transform Infrared (FTIR) measurement 25
3.1.3. Field Emission Scanning Electron Microscope (FE-SEM) 27
3.1.4. Piezoelectricity from Pd-NPs doped PVDF nanofiber webs 27
3.2. TPU nanofiber web based piezocapacitive sensor 31
3.2.1. Field Emission Scanning Electron Microscope (FE-SEM) 31
3.2.2. Hysteresis and calibration 31
3.2.3. Creep and stress-relaxation 36
3.3. Hybrid pressure sensors 45
3.3.1. Evaluation of energy expenditure 49
4. Conclusions 53
References 54

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