Micro-nano 3D Printing Of Functional Hydrogel And Application

Hydrogels are hydrophilic networks consisting of numerous crosslinked polymer chains,which are widely applied in the fields of tissue engineering,soft robotics by adding conductive materials(such as salts)to enhance its conductivity.However,the tedious fabrication process severely limits its further applications.Recently,3D printed hydrogels have become a hot topic in polymer fields with the fast development of additive manufacturing technology.The unique electric,mechanical and optical properties enabled by 3D printing technique will definitely broaden the potential applications in the field of sensors,flexible electronics,etc.In this work,hydrogels with super stretchability,strong adhesion,conductivity and anti-freezing properties were prepared by Projection micro stereolithography(PμSL)3D printing.The interaction energy within hydrogel was calculated using molecular dynamics theory.In addition,we further demonstrated as-printed hydrogel could be used as ionic conductor,sensors and human-machine interfaces.(1)A series of parameters including adjusting exposure time and grayscale by level set method were optimized with Projection micro stereolithography(PμSL)3D printing.The complex structures of hydrogel fabricated by 3D printing were well prepared.(2)The properties of hydrogel including super stretchability,strong adhesion,conductivity,and anti-freezing were optimized by changing contents of monomers and solvents.The stretchability of hydrogel could be adjusted by monomers and crosslinkers.The hydrogel could adhere to various surfaces of materials,indicating strong adhesive properties.The hydrogel exhibited anti-freezing and conductive properties,which could be used as ionic conductor to light LED at the temperature of-80℃.(3)The interaction energy of hydrogel including hydrogen bonds,van der Waals forces was calculated using molecular dynamics theory to reveal its underlying mechanisms.(4)The hydrogel working as ionic conductor could transmit network data.The hydrogel acting as flexible strain sensor with high sensitivity could detect human motion including bending,knee motion,swallowing and speaking even at the temperature of-80℃.The hydrogel could also be used as pressure sensor based on the changes of capacitance.(5)The hydrogel acting as flexible man-machine interface could collect physiological electrical signals including electrooculogram(EOG),electrocardiogram(ECG)and electromyography(EMG).The EMG signal collected by our 3D printed hydrogel flexible electrode could accurately control the movement of robots including playing the piano,even at a temperature of-80℃.