The Development Of Ionic Skin Based On Printable Double-network Hydrogel

Inspired by human skin,ionic skin,which can simulate the perception and physiological characteristics of human skin,has developed rapidly in recent years.Ionic skin has broad application prospects in the fields of biological signal monitoring,biological surface signal monitoring,tissue repair process monitoring,wearable devices,bionic devices,and flexible robots.Ionic skin generally consists of two parts: base material and sensing material.The base material uses a hydrogel material similar to the human tissue structure,and the sensing material uses salt that is easy to ionize.Salt can provide a large number of movable ionic in the hydrogel network.When the ionic skin receives an external force,the distribution of ionic in the hydrogel will change,resulting in a corresponding change in the capacitance or resistance of the ionic skin.Compared with bionic skins made of traditional materials,ionic skin has better biocompatibility.Compared with human skin,the developed ionic skin still cannot achieve similar high sensitivity and high spatial resolution perception.The main purpose of this paper is to construct an ionic skin array with high sensitivity and high spatial resolution.The main work of this article is divided into the following three parts:(1)From the material point of view,double-network hydrogels with different elastic moduli were designed,in which nanoparticles forms the first network through physical crosslinking,and polyacrylamide forms the second network through chemical cross-linking.The first physical network formed by nanoparticles has excellent shear-thinning properties and can be used to 3D printing of ionic skin.Shear-thinning properties and self-healing properties of different concentrations of nanoparticles were explored through rheological experiments.The cross-linking of the polyacrylamide network and nanoparticles by UV light form a doublenetwork hydrogel.The mechanical properties of the double-network hydrogel were explored.Adding Na Cl with a concentration of 1 mol/L to the material of the double-network hydrogel makes the hydrogel contain a large amount of ionic liquid.These ionic liquids can provide signal pathways for the perception and transmission of external force.(2)From the perspective of manufacturing methods,a 3D extrusion bioprinting platform for ionic skin array printing is built.The screw is used as the execution part,and the STM32F407 chip is used as the main control chip.The computer software is finished by QT development platform which can control 3D extrusion bioprinting platform.To design the printing path of the ionic skin array,a printing path design software is developed using the QT platform.By optimizing the printing path,the number of pins of the ionic skin array is greatly reduced.The 3D extrusion bioprinting platform can not only be applied to the printing of ionic skin,but also has broad application prospects in tissue engineering,artificial organs and other fields.(3)The double-network hydrogel is used to print the ionic skin array using the 3D extrusion bioprinting platform.By optimizing and debugging different printing parameters,a ionic skin array with high sensitivity and high spatial resolution is printed.The ionic skin array can imitate the characteristics of the skin and make corresponding response of external force.In the ionic skin array,each unit can independently sense external force,so as to imitate the real response of human skin to external force.The personalized setting of the printing path of the ionic skin array can make the application range of the ionic skin array more extensive.In summary,the main work of this paper is to construct a high-sensitivity,high-spatial resolution ionic skin array through the 3D extrusion bioprinting platform and double-network hydrogel.This ionic skin array has great responsiveness and a wide range of application prospects in signal monitoring,personal medical treatment,flexible robots and other fields.