| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 104 === In this study, a droplet-based immunoassay chip having passive droplet positioning features was developed for performing immunoassays. Using MEMS fabrication techniques, the mold of the microfluidic channels was manufactured on the printed circuit board (PCB). Then, the microfluidic layer was formed by casting SYLGARD polydimethylsiloxane (PDMS) in the mold. In addition, a layer of Ni–Co film was coated on the PCB substrate by electrodeposition in order to immobilize the multiplex histidine-tagged proteins. Finally, the droplet-based immunoassay chip was produced by bonding the microchannel layer on the PCB substrate. To test this proposed droplet-based immunoassay chip, the tumor suppressor protein p53 and the extracellular-signal-related kinase 1 (ERK1) were used, and the silicon oil was chosen as the carrier fluid. When the reagents were injected, they passed through the zigzag mixing channel for rapid and thorough mixing. The mixture then arrived the double-T junction structured by a suspended diaphragm and sheared by the carrier flow, two different kinds of droplets were generated. These droplets were not fused with each other. The monodispersed droplets can be generated under a lower flow rate, since silicon oil has a higher viscosity. Each droplet was transported and positioned in a hole of detection area due to the flow of carrier oil flowing to the oil-drain channel. Thus, the histidine-tagged proteins were immobilized by the Ni–Co layer in microarray format for consequent immunoassay and fluorescence detection. The detected fluorescence intensity is proportioned to the concentration of the encapsulated content in a small droplet. This proposed droplet-based immunoassay chip allows the operation sequence of immunoassay being conducted automatically through the manipulation of droplets.
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