Title Page
ABSTRACT
국문 초록
Contents
CHAPTER 1. INTRODUCTION 13
CHAPTER 2. RESEARCH BACKGROUNDS 17
2.1. Wearable strain sensor 17
2.2. Flexible electrodes 19
2.3. Conductive hydrogel 22
CHAPTER 3. EXPERIMENT 23
3.1. Materials 23
3.2. Synthesis of ion gel conductor 23
3.3. Fabrication of CP and CPE sensors 25
3.4. Characterizations of the strain sensors 27
3.4.1. Method for Evaluating the Structure Analysis 27
3.4.2. Method for Evaluating the Mechanical and Electrical Properties 28
3.4.3. Method for Evaluating the Sensing Sensitivity 29
CHAPTER 4. RESULT AND DISCUSSION 30
4.1. Structure Analysis of strain sensor 30
4.2. Mechanical and Electrical properties of CP and CPE sensors 35
4.3. Human physiological motion signal detection of the CPE-3 sensor 49
CHAPTER 5. CONCLUSION 51
REFERENCES 52
Table 1. The component details of mixed ion gel conductors 24
Table 2. Physical properties of strain sensors 40
Table 3. Degree of hysteresis (DH) with loading-unloading cycles of strain sensors at 1500% strain 42
Table 4. The details of electrical conductivities of ion gel conductors 44
Figure 1. Schematic diagram of fabrication of the CP and CPE sensors. 26
Figure 2. FT-IR spectra of PEDOT:PSS and CP-0, CP-3, CPE-3 strain sensors. 32
Figure 3. (a) XPS spectra of CPE-3 strain sensor; C 1s XPS spectra of (b) CP-3 and (c) CPE- 3 sensors; O 1s spectra of (c) CP-3 and (f) CPE-3 sensors ; (d) S 2p XPS spectra of CP-3... 33
Figure 4. (a) Raman spectrum of CP-3 (blue solid line) and CPE-3 (red solid line) sensors. Curve-fitting analysis of (b) CP-3 and (c) CPE-3 sensors. 34
Figure 5. Tensile stress-strain curves of (a) CP and (b) CPE sensors; Tensile strength/Modulus of (c) CP and (d) CPE sensors. 39
Figure 6. Hysteretic resistance with different stretch-release cycles of (a) CP-3, (b) CPE-3 sensors at 1500% strain; (c) Gauge factors of the sensors. 41
Figure 7. Electrical conductivity depending on the PEDOT:PSS content of the CP and CPE sensors. 43
Figure 8. Responsive signals and response time of the sensors to stretching and releasing cycles at 150% strain and 4.33 Hz : (a, d) CP-0, (b, e) CP-3, and (c, f) CPE-3 sensors. 45
Figure 9. Responsive signals and response time of the sensors to stretching and releasing cycles at 150% strain and 1 Hz : (a, d) CP-0, (b, e) CP-3, and (c, f) CPE-3 sensors. 46
Figure 10. Long-term durability of (a) CP-3 and (b) CPE-3 strain sensors at different strains; (c) response time of CPE-3 sensor under 200% strain at 1 Hz before 100k cycles of stability... 47
Figure 11. The relative resistance variation of the CPE-3 sensor during 7,000 cycles under a strain of 300% and 1 Hz (top). The graph at the bottom shows the response signal of the... 48
Figure 12. Human motion detection signal of the CPE-3 strain sensor for monitoring various human physiological movements : (a) wrist, (b) ankle, (c) knee, (d) elbow, (e) neck... 50