Research On Fabrication Of Polymeric Microfluidic Devices With A Bulk Metallic Glass Mold Insert And Its Demolding Process

Amorphous alloys,also known as metallic glasses,not only possess excellent properties in physical and mechanical,and can be molded accurately with hot embossing molding technology.Requirements for high quality mold were urgency due to the rapid development of micro-electro-mechanical systems?MEMS?,that is,a more reliable technology for mass production of micro-components with Micro-Nanostructures.Based on this,amorphous alloy as a candidate material for the fabrication of microstructured mold?tool inserts?is one of the tentative solutions.This paper is devoted to solving the problems faced by amorphous alloys as micro-mold in practical application.The feasibility of amorphous alloys as tool inserts in injection molding and the demolding characteristics of amorphous alloys in hot embossing technology are thoroughly studied.And the research contents are as follows:Bulk metallic glass(BMG,Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5)was prepared by copper mold suction casting method.The raw materials were cut into square flake samples by low-speed cutting machine.Then the tool inserts are fixed in the micro-injection mold,and polymeric microfluidic was molded by injection molding with appropriate injection process parameters.A series of characterization and test results show that the microfluidic can reproduce the characteristics of the mold insert,the sealing and functional test of the microfluidic chip are good.Compared with the traditional electroformed nickel material,the amorphous alloy has higher hardness.The research results show that it is feasible to use amorphous alloy as mold insert,and it has better performance than the commonly used materials of mold insert.Injection molding and hot embossing are two technologies for mass production of polymeric microfluidics.And they both requirement excellent quality of the tool inserts.Firstly,the surface adhesion force between PMMA and amorphous alloy were studied.Then,the technological parameters of each demolding process were optimized by orthogonal experiments.The results show that the minimum demolding work isobtained under the conditions of 60?,400 N,1 mm/min and peel mode,which means that the probability damage of microstructures is the smallest under these condition.Based on the mechanism background of the demolding process of polymer products,a theoretical model considering the effects of friction,adhesion and deformation is proposed.From this model,we can get the force magnitude of the side wall of microstructures at different temperatures,and the relationship between demolding work and demolding temperature.The theoretical predicted results are in good agreement with the experimental results,and the demolding temperature is also obtained at different demolding temperatures.According to the theoretical prediction results of each component?friction,adhesion and deformation?,according to the proportion of each component,we can purposefully optimize the process parameters.The demolding process was numerically simulated based on Abaqus software.The post-processing results were extracted by Python programmer,and the intuitive charts are helpful to analysis the results.The effects of process variables and structural variables on demolding performance at different time points were studied,and the optimal demolding conditions were explored according to the numerical simulation results.The results show that demolding temperature and demolding angle have the greatest influence on demolding process.And,relative higher demolding temperature?60-70??,demolding angle in 0 degree,lower density of microstructure and appropriate aspect ratio,which are conducive to complete demolding process successfully.