Automatic Analytical System For Photonic Crystal Microbead Based Microfluidic Chip

Point of Care Testing (POCT) devices are commonly highly integrated, miniaturized, cost-effective and intelligentized, which are appropriate for testing specimens in community hospital, ward, family and the battlefield. However, there are limited reports on humoral detections using POCT devices due to the limitations of the principle, material, manufacturing technology and detection method. While the multiplex assays based on the photonic crystal beads (PCBs) could analyze multiple components of the specimen simultaneously. It meets the demand of application and development of POCT. And the combination of PCBs and the microfluidic chips will provide a more simple and convenient approach for POCT.Herein, we proposed an automatic reaction and detection system for PCBs in the microfluidic chip and utilized it to accomplish the multiplex assay. The detailed work is as follows.(1) The design of microfluidic chip and the liquid reaction system. The microfluidic chip based on the capillary was proposed and the principle, the model design and the manufacture steps are studied. Then an automatic liquid reaction system was designed according to the immune response process. The system consists of the micropump, microvalves and the integrated circuit board. It’s controlled to select and deliver the appropriate reagent/buffer to accomplish the reaction. And the parameters were optimized.(2) The design of the optical imaging system. Based on the detection principle of PCBs, we designed a miniaturized imaging system and studied the controlling process and the software. The system could automatically capture the epi-white light and the epi-fluorescence images by switching the filtering cubes and controlling the cameras.(3) The image processing and the multiplex protein assay. The designed system was utilized to realize the detection of different concentrations of protein antigens. A series of image processing algorithms were proposed to analyze the captured images. In the algorithm, the epi-white light image was firstly registered and then the epi-fluorescence image was denosied, enhanced, segmented and every intact bead in the image was accurately extracted and decoded by photonic crystal colors, which stand for the target species. Finally we demonstrated the system for multiplex protein assay. The detection limit of the system is 62.6 ng/mL and the accuracy reaches 85%. The system is automatically controlled by the software and algorithms, which provides adequate supports for the general automated analysis of POCT based on PCBs.