Title Page
Abstract
Contents
Ⅰ. Introduction 11
1.1. Research backgrounds 11
1.1.1. Wearable sensor 11
1.1.2. Key points in wearable sensors - Adhesion and peeling resistance 12
1.2. Research concept & outline 14
Ⅱ. Fabrication Process for a Hybrid Adhesive Patch (HAP) 16
2.1. Fabrication process for bioinspired micropillar adhesive structures 16
2.2. Fabrication process for kirigami-inspired macrostructures 16
2.3. Fabrication process for a hybrid flexible adhesive patch 17
2.4. Fabrication process of a SWCNT selective coated hybrid adhesive patch 18
Ⅲ. Adhesion Behaviors of Bioinspired Micropillar Adhesive Structure 19
3.1. Effect of bioinspired micropillar structures on adhesion 19
3.2. Adhesion strength evaluation according to various parameters 20
3.3. Finite element analysis of peeling resistance according to the tip's morphology 25
Ⅳ. Peeling Behaviors of Kirigami-Inspired Macro Adhesive Structure 28
4.1. Peeling strength evaluation of non-kirigami adhesive patches 28
4.2. Peeling strength evaluation of various kirigami patterns on adhesive patches 29
4.3. Peeling strength evaluation of integrated hybrid crack trapping adhesive patch 32
Ⅴ. Application: Pressure Insensitive Strain Sensor Based on a Hybrid Adhesive Patch 34
5.1. Evaluation of the normal adhesion and peeling strength of the S-CNT HAP 34
5.2. Sensing behavior of the pressure-insensitive strain sensor 36
5.3. Monitoring physical human motion with the S-CNT HKA-based strain sensor 39
Ⅵ. Conclusion 41
References 43
Figure 1. Introduction of wearable sensors 11
Figure 2. Key points of wearable sensors and developments. 13
Figure 3. Concepts of a flexible hybrid adhesive patch (HAP). 15
Figure 4. Fabrication processes of hybrid adhesive patch 17
Figure 5. Fabrication process of selective CNT-coated hybrid adhesive patch 18
Figure 6. Fabricated hexagonal micropillar structure. 20
Figure 7. Normal adhesion results for fabricated hexagonal micropillar adhesive structures. 21
Figure 8. OM images for the additional contact after pre-load to the micropillar structure (D: 40 um, SR: 2 and 3) 21
Figure 9. OM images of hexagonal micropillar adhesive structure (D: 10 um) of the center (Left), and the corner (Right). 23
Figure 10. Normal adhesion test results of hexagonal micropillar adhesive structure regarding extruding tip widths (D: 40 um, 20 um, 10 um, SR=0.5) 24
Figure 11. FEM results of micropillar structure peeling motion (a-d). 27
Figure 12. Peeling force evaluation of 90° peel test against the displacement 29
Figure 13. 90° peel test results of kirigami hole (KH) patterned-adhesive patch 31
Figure 14. 90° peel test results of kirigami area (KA) patterned-adhesive patch 31
Figure 15. 90° peel test results of hybrid kirigami area (HKA) patterned-adhesive patch 33
Figure 16. Overall 90° peel test results of various adhesive patch 33
Figure 17. Normal adhesion results of bare PDMS (20:1), CNT coated PDMS (20:1), CNT coated hexagonal tip pillar (HTP, 20:1), and Selective-CNT coated hexagonal tip pillar (S-CNT HTP, 20:1). 34
Figure 18. Behaviors of 90° peeling for Bare PDMS (20:1), CNT PDMS (20:1), CNT HKA (20:1) and S-CNT HKA (20:1). 35
Figure 19. Photographs of adhesion and bending behaviors of CNT HKA (Left) and S-CNT HKA (Right). S-CNT HKA patch was in a fully attached state while the CNT HKA patch was in... 36
Figure 20. Strain sensing mechanism of HKA-based strain sensor in a being motion 37
Figure 21. Strain sensing results in various radius of curvature (R=15 mm, R=10 mm) 37
Figure 22. Pressure insensitivity and strain sensitivity test results in a bending (R=10 mm). 38
Figure 23. Repeatability test in the same strain (Bending motion due to 10 mm vertical displacement) over 230 times 39
Figure 24. Demonstration of monitoring the physical human motion on the wrist in the slow (yellow region) and fast (blue region) bending situations 40