Stimuli-responsive materials, so called smart materials, are a fascinating research field in terms of materials science as well as their applications. From the nature, we can find beautiful examples of stimuli-responsive properties; for example, color-changing chameleon and self-stiffing sea cucumber. Also, there are on-going approaches to investigate various stimuli-responsive functionality of materials, and apply them for various research fields. In my lab, we are especially interested in stimuli-responsive polymers and molecules. Based on the chemical structure design and synthesis, we work on researches to control intrinsic property as well as intermolecular interaction of polymers and molecules, to realize unique stimuli-responsive properties for various applications. In this talk, two research topics will be presented based on stimuli-responsive smart materials and their application. First, biomimetic soft robotics research to reproduce complete shapes and functionalities of body parts will be discussed. And second, diagnostic device research will be discussed which is designed for early diagnosis of cancer metastasis.