Mechanical and Civil Engineering Seminar

Soft machines are transforming the fields of robotics and biomedical devices in that they are capable of sustaining large deformation and interacting safely with human beings. Soft active materials can be actuated in response to external stimuli, such as light, heat and electric fields, and are important building blocks of soft machines. The recent advance of 3D printing techniques allows the manufacturing of soft materials into complex structures. Predicting the spatiotemporal behavior of soft materials, and designing and fabricating soft structures with programmable functionalities are the major efforts in the field. In this seminar, I will talk about our recent progress in investigating soft materials for soft machines. Coupling the diffusion and reaction kinetics, we have developed a theoretical framework to predict the spatiotemporal responses of photo-responsive hydrogels, which can change their volume in response to light irradiation. Further accounting the inertia effect, we have predicted and developed self-excited photo-responsive hydrogel oscillators that can autonomously vibrate with an increasing amplitude under constant light irradiation. Tuning the properties of soft materials through sophisticated chemical synthesis is often challenging. To overcome this limitation, I will further demonstrate how we are able to vary the responses of soft materials by designing and fabricating them into mechanical metamaterials, which are materials with microarchitectures. A new mode of mechanical instability in metamaterials will also be discussed.