Design And Manufacturing Of Point-of-Care Testing Chip Based On The Microfluidics

Point-of-care testing (POCT) is one of the rapid testing technologies in the clinical medicine. Nowadays, it has been applied many aspects of detection, such as blood sugar, tumor, etc. The POCT chip based on the microfluidic is the combined application of the microfluidic technology, biomedical engineering, advanced manufacturing technology, etc. In this paper, about the development of the chip, the following several aspects of research have done:The POCT chip scheme was determined based on the microfluidic technology and the fluorescence immunoassay detection technology. The material of the chip is thermoplastics. The injection molding process and the ultrasonic welding technology were combined to achieve the purpose of the mass production of the chip. The structure of the chip mainly includes the sample loading area, the reaction chamber, the flow rate controlling structure, test chamber, waste reservoir, etc. To verify the feasibility of the structure scheme of the chip, the micromachining process was applied to fabricate the SU-8 mold and the PDMS microfluidic chips. Then the functional tests were carried out for each function areas of the chip, especially for the flow rate controlling structure. Finally, the design scheme of the chip was confirmed. The ultrasonic welding was used as the chip bonding method. And one kind of the cooperated bonding line was designed. Reasonable design of the overall structure of the chip is not only beneficial to the quality of the injection molding, but also meets the chip positioning and clamping requirements in the process of the bonding.Based on the Taguchi orthogonal experimental design method, the injection molding process tests were performed. The influence sequence and optimal level combination of the process parameters were obtained. And the influencing rules of the injection molding process parameters for the filling of the chip’s microstructures and the bonding surface flatness were also gained. The ultrasonic welding experiment platform was set up through customized special welding head and the home-made fixture. The optimal working parameters of the ultrasonic welding were obtained by multiple welding experiments.Using the sheep whole blood as experimental samples, the chips showed a good flowing stability. Calculating the standard deviation of the time of the blood flow frontier through the each area of the chip, the stability was sufficient. Through the multiple experiments, the standard deviation of the time of the time control unit is 8.3s, and the standard deviation of the time of the total chip is 19.4s.