Microfluidic chips have become a critical component in advanced applications such as biochemical analysis, medical diagnostics, drug development, and environmental monitoring because of their ability to precisely control fluid flow at the microscale. The functionality of these chips is highly dependent on the precision and dimensional stability of microchannel structures formed on them. While injection molding is an efficient method for a mass production of microfluidic chips, it is required to minimize undesirable deformation due to thermal and mechanical stresses, which can degrade the overall performance. This study investigated global (Macro-scale) and local (Micro-scale) deformation behaviors of injection-molded microfluidic chips. Effects of processing parameters, including mold temperature, melt temperature, filling time, and packing pressure, were investigated. The Taguchi-based design of experiments approach was employed to systematically analyze these effects and to determine optimal conditions to minimize deformation.

The Electrochemical Hydrogen Compressor is an optimal device for compressing low-pressure hydrogen to high-pressure hydrogen. It has a similar structure to the Proton Exchange Membrane Fuel Cell but operates at extremely high pressures, requiring multiple cells sealed with End Plates. The End Plate design must provide initial cell activation support, withstand maximum operating pressure within the stack, and prevent internal gas leakage. This study applies a multi-objective optimization method and grey relation analysis to determine the optimal design parameters for the End Plate based on the activation area of Dummy Cells. Finite Element Method (FEM) analysis is conducted to verify the effectiveness of the optimized End Plate design, considering the uniform pressure distribution with stacked Dummy Cells (1, 3, 6, 12). The analysis reveals that the parameters affecting the uniform pressure distribution include the End Plate design, stack sealing pressure, individual Cell design parameters, and the number of Cell stack layers.

Electro discharge machining (EDM) is one of the most frequently used processing methods for machining conductive materials. Taguchi method combined with Grey relational method has been used to accommodate requests for multiple object functions in the EDM process. In the present study, an attempt was made to determine optimum parameters for minimum size of hole and number of shots. The size of the hole is related to the quality of the hole while the number of shots affects machining time. Grey relational analysis was used to determine optimal machining parameters. Electrode length and unit discharge were found to be the most significant parameters. Optimal conditions were: pulley position of 39 ㎜, voltage of 120 V, a capacitance of 1500 pF, and a resistance of 500 Ω. In experiments, such electrical conditions (voltage, capacitance, and resistance) generated electrical energy of 10 μj. Under these conditions, a micro hole of 184.9 ㎛ in average diameter could be machined with 16 shots.