Preparation And Application Of Conductive Hydrogel As Electronic Skin And Wearable Devices

Hydrogel has three-dimensional network structure and similar mechanical properties to human tissue,which can conduct electrical signals like human skin.It is an ideal material to fabricate electronic skins for robots or artificial limb.However,traditional hydrogels are easy to freeze in low temperature environments or lose water in high temperature environments due to their own large amounts of water,ultimately lose their excellent performance.Therefore,the environmental adaptability and stability of hydrogel wearable devices and electronic skins is a challenge which needs to be solved.In addition,it is undesirable that the hydrogel will fall off from the surface of human body or cause bacterial infections if the hydrogel is used as wearable device or a wound electronic skin.Therefore,the adhesion and antibacterial properties of the hydrogel also need to be considered.The main work is following:1.In this work,we designed an electronic conductive hydrogel that can maintain stable operation in low/high temperature environments.The hydrogel can be applied as wearable devices and robotic electronic skins.This hydrogel is composed of acrylamide(AAm)and acrylic acid(AAc)copolymer,little amount of N,N'-methylenebisacryloyl(MBAA)is used as cross-linkinger,polyaniline network is employed as conductive medium formed by in-situ polymerized aniline monomer.Adding glycerin into hydrogel could protect freezing due to decrease the freezing point of water effectively.Furthermore,it can absorb water from open environments or at high temperature to achieve the purpose of anti-freezing and anti-water loss,respectively.This hydrogel has excellent mechanical properties,fatigue resistance,electrical conductivity and stability in extreme temperature environments,and stable output signal can be obtained at the temperature of-18? or 60?.2.We designed a stretch sensor and a pressure sensor as wearable devices to monitor the joint motivation of index finger and to detect the pulse beats based on the excellent strain sensitivity(GF=4.37)and compress sensitivity(1 513.7 MPa-1)of this hydrogel.Putting the sensor on different parts of the mechanical hand could monitor the bending state and how much force suffered if grasping an object.Different temperature tests proved that the electronic skins can work stably under extreme temperature environments,which demonstrate this hydrogel has great potential application as electronic skin for robots.3.Zwitterionic polyelectrolyte hydrogel(ZPE)was prepared,and its adhesion property to skin and the antibacterial property were studied.The zwitterions make the hydrogel have strong adhesion strength to pig skin(90°peel test can reach 2.3 N/m).The antibacterial test results show that the zwitterionic polyelectrolyte hydrogel has an antibacterial effect over 99%against Gram-positive and Gram-negative bacteria.The results show that zwitterionic hydrogel as an artificial electronic skin can stably adhere to the human,and can effectively prevent bacterial infections during application.