Ⅰ. Introduction 1 1.1 Motivation of the research 1 1.1.1 Principle of thermal actuation 2 1.2 Aim of research 3 Ⅱ. Fabrication process of the AgNPs-based TCA 6 2.1 Non-conductive TCA 6 2.1.1 Optical images of fabrication process 8 2.2 Chemical reduction process 9 2.2.1 Image of the AgNPs-based TCA 9 2.2.2 In-situ chemical reduction cycle effect 10 Ⅲ. Electrothermal actuation of the AgNPs-based TCA 12 3.1 Characterization of electrothermal contraction and mechanical performance 12 3.1.1 Analytical model on the thermal response for the AgNPs-based TCA 18 3.1.2 Finite element analysis of the AgNPs-based TCA 24 Ⅳ. Self-resistance sensing of the AgNPs-based TCA 25 4.1 Resistive response of the AgNPs-based TCA in the stretchable sensor mode 25 4.2 Resistive response of the AgNPs-based TCA in the self-resistance sensing mode 28 Ⅴ. Self-sensing feedback control of the AgNPs-based TCA 29 5.1 Resistance feedback closed-loop of the AgNPs-based TCA 29 5.2 Demonstration of the resistance feedback closed-loop of the AgNPs-based TCA 31 Ⅵ. Wearable application of the AgNPs-based TCA 32 6.1 Structure of the wearable application 32 Ⅶ. Previous studies of the TCA 33 Ⅷ. Fabrication and measurement system of the AgNPs-based TCA 34 Ⅸ. Conclusion 35