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Immunoassay detection is a technology that determines related diseases by measuring the concentration of specific biomarkers in samples. In today's clinical medicine, it provides a simple and highly sensitive method for disease screening and tracking treatment. The integration of immunoassay detection and microfluidic chip has now become a very forward-looking technology, which can not only smoothly improve the shortcomings of traditional immunoassays that require a large number of samples, but also greatly reduce the detection time, and has more advantages in more medical applications, however, immunoassays with small sample requirements are very rare.
Among them, the microsphere-type microfluidic chip achieves the performance of smaller sample requirements, high sensitivity, and faster detection speed by virtue of the larger surface area of the microsphere per unit volume. At present, the mechanical buoyant microsphere digital microfluidic immunochip developed in our laboratory uses a mechanically movable chip to improve the high cost and biological adhesion of the immunochip. However, it is difficult to achieve active mixing due to the use of autonomous buoyancy aggregation of buoyant microsphere, the mixing and reaction efficiency still need to be improved, and the entire reaction process is still manually operated.
The objectives of this study are two-fold. The first is to develop an active mixing method suitable for this mechanical immunochip to improve mixing and reaction efficiency, and the second is to successfully automate the chip controlling platform.
In this paper, we successfully found that wind is the most appropriate auxiliary mixing method, and found the best mixing time. Using Human IL-1β as the assay antigen, the total reaction time can be reduced from 42 minutes to 18 minutes, and the detection variation (C.V. value) of each concentration are all less than 10%. The data at a concentration of 0.1 pg/mL was added and a calibration line was established with the Parameter Logistic (4PL) Curve, which reduced the limit of detection (L.O.D.) to 0.201 pg/mL. Finally, a PCL controller is used to control the stepper motor and the screw to achieve the result of automating the chip controlling platform.