Mechanism and solutions of appearance defects on microfluidic chips manufactured by UV-curing assisted injection molding

Abstract

A novel method for the chemical manufacturing UV-curing assisted injection molding was proposed in this paper. A prototype of UV-curing injection molding apparatus has been manufactured. By using the prototype, we have successfully fabricated microfluidic chips, which can be practically applied in micro mixing experiments. Similar to the thermoplastic parts molded by traditional injection molding, the appearance defects such as bubbles also occurred on products fabricated by UV-curing injection molding. The generation process of bubble defect has been observed and captured through the visualization device. Because there is no gas produced in the polymerization chemical reaction, the shrinkage was considered to be the essential reason of bubble defect. In this paper, the solution of bubble defect was studied by employing single factor control variable method from the aspects of process parameters, materials, and mode of irradiation. It was noted that the bubble defect could be improved by increasing holding pressure, reducing irradiation intensity, and improving viscosity. Nevertheless, the achievement of process parameters was limited. On equal experimental conditions of process, equipment, and material, results revealed that the dynamic irradiation pattern can improve the feeding capacity significantly in UV-curing injection molding. It is further demonstrated that the bubble defect is caused by the polymerization shrinkage. Eventually, we obtained the microfluidic chips with good surface quality, high dimensional accuracy, and high transparency by UVcuring injection molding. Moreover, it provides a feasible high efficiency and low cost manufacture technology for microfluidic chips in the future.