A bionic mimosa soft robot composed by PNIPAM-PEGDA copolymer

Deformation is very important for biological survival, more and more researchers are committed to 3D deformation of 2D materials. In this research, we make 3D deformation by applying different internal stresses to 2D materials. At the beginning, single layer PNIPAM hydrogel sheets with different combinations of microchannels were fabricated by UV curing technology. Because of the uneven distribution of internal stresses, they deformed into different 3D structures. In order to maintain these 3D structures though without continuous stimulation, PNIPAM-PEGDA bilayer structure was prepared. It was found that the bilayer structure could respond to both temperature and solvent composition due to the difference of solubility between PNIPAM and PEGDA. Based on the bilayer structure, we made the bionic Mimosa, which could not only realize the open-closing reversibly, but also maintained the normally closed state without continuous stimulation. This research provides a reference for the development of directionally programmable soft materials and has great potential in the fields of bionics and biomedicine.