Fabrication And Application Of Hydrogel Microstructures Based On Micro-sterelithography Technology

In recent years,three-dimensional complex structure micro-devices have brought a technological impact on micro-electromechanical systems,and traditional microfabrication technology has been unable to meet the requirements.With the in-depth study of microstereolithography,it has been found that 3D printing technology can not only effectively solve the limitations existing in MEMS,but also has a great improvement in printing speed and accuracy.As a new type of material,the integration of hydrogel materials with 3D printing technology enables the fabrication of various dynamic hydrogel microstructures with specific shapes and sizes,and is therefore widely used in fields such as microfluidics,biomedicine and tissue engineering.This paper designs and builds a hydrogel microstructure fabrication system based on a digital micromirror array（DMD）.The process is as follows: firstly,through a comparative analysis of existing projection technologies,it is found that DLP projection display technology has superior performance,so it is decided to use DLP projection display as the exposure method of the system;secondly,the working principle and process flow of the whole system is studied;then,the core optical part of the system is studied,and the selection criteria of each component of the optical system are clarified Finally,a hydrogel microstructure fabrication system based on a digital micromirror array was built,which is capable of printing with an accuracy of 30 μm.The processing mechanism of hydrogel microstructures is described and a kinetic model of the UV curing reaction is developed.The main focus is on the simulation and investigation of the reaction mechanism of UV curing,with a focus on the mechanism of free-radical type light curing,leading to the establishment of a UV curing reaction kinetic model,and finite element solution in COMSOL Multiphysics 5.6 software.The results are analyzed to investigate the effect of the concentration of each component on the overall reaction.Based on this system,a micro-mixer has been successfully fabricated and related simulations have been carried out.Firstly,a PEGDA hydrogel solution with a concentration of 30% is prepared,and then the preparation of the micro-gear structure is completed using this concentration of hydrogel solution.The curing process is controlled by controlling the exposure time（12s）,and the final accuracy of the prepared micro-gear structure is measured to be 30 μm.Next,modelling and simulation are carried out in COMSOL Multiphysics 5.6software to analyze the velocity and pressure of the micro-gear structure in a laminar flow at a specific flow rate.Finally,the printed micro-gear structures are successfully applied as micro-mixers in the field of microfluidics.