Technical Implementation And Parameter Study In Response To Additive Manufacturing Of Smart Hydrogel Structures

Responsive intelligent hydrogel structure is mainly a class of polymer hydrogel structure that can produce sensitive response to external environmental stimuli,and the responsive hydrogel structure with three-dimensional structure is widely used in the fields of biological drug delivery,actuator design,information sensing,etc.The regional three-dimensional structure position of intelligent hydrogel in space enables the hydrogel to adapt by accepting external environmental stimuli and achieving specific dynamic changes.dynamic environmental changes.The conventional processing methods currently used for smart hydrogels include masking,fixture fixation,etc.,which have the shortcomings of low processing efficiency and single processing structure.Compared with the conventional processing methods,additive manufacturing(3D printing)has the advantages of high efficiency and high processing accuracy,and3 D printing has become a research hotspot for processing responsive smart hydrogel structure processing methods.Based on this background.This thesis focuses on the research work of 3D printing preparation and molding of a new type of responsive intelligent hydrogel structure,and describes the relevant research work from four aspects: 3D printing platform construction,hydrogel preparation,hydrogel 3D printing performance research,and hydrogel flexible sensor application.For the demand of 3D printing of hydrogel,this thesis designs and develops two extrusion 3D printing platforms,cantilever type and frame type,to realize the motion control and temperature control of printing nozzle in 3D space.This paper analyzes the printing effect of the printing platform from two aspects: printability and printing accuracy.On the basis of ensuring the printing effect is guaranteed,this paper also tries the possibility of multi-material printing and coaxial printing,which proves the excellent 3D printing performance of the printing platform.Then,a gelatin/sodium alginate based composite hydrogel is proposed and prints a responsive smart hydrogel structure using a developed cantilever type extrusion 3D printing platform.By conducting rheological analysis tests and printing experiments of the smart hydrogel,we mastered the influence law of parameters such as air pressure,speed,and first layer height on the printing performance of the hydrogel,explored the interaction mechanism between ions and hydrogel structure strength and printing parameters and shape memory efficiency of the smart hydrogel,established a hydrogel shape memory model,realized the controlled deformation of the hydrogel mechanism,and verified that the smart hydrogel structure can respond to the function of gripper and material transport.Last,This paper concludes with a study of the application of smart hydrogel responsive structures in the field of soft strain sensors to verify the feasibility of printing hydrogel structures for flexible sensing.In this paper,we first verified the conductivity of the hydrogel structure,and conducted impedance-frequency monitoring of the 1D and 2D printed structures according to different printing parameters,analyzed the effect of printing parameters on the impedance of the printed structure,tested the relationship between hydrogel strain and impedance change,and realized real-time monitoring of knuckle flexion and throat swallowing action.In order to make the monitoring portable,we designed a circuit structure based on the principle of voltage divider circuit to monitor impedance and strain values and display them in real time,and verified the application of 3D printed structures as sensors for physiological signal monitoring.