A bead-based microfluidic system for joint detection in TORCH screening at point-of-care testing

A concise bead-based microfluidic system has been developed for joint detection in TORCH screening at point-of-care testing. Assisted by five functionalized polycarbonate single beads, totally five critical infections including TOX, RUB, CMV, HSV-1 and HSV-2 can be simultaneously detected with the microfluidic chip based on chemiluminescence. The microfluidic chip consists of multiple reaction chambers respectively for different reaction steps of the sandwiched chemiluminescence immunoassay, and each reaction chamber is divided into five interconnected independent cells to respectively hold five single beads in different position. With a guiding path, each single bead with a ferrous core can be easily transported between each two adjacent reaction chambers through magnetic control to consecutively react with the serum sample or other different reagents. Meanwhile, with magnetic control, each single bead within the reaction chamber can be moved back and forth to improve the detection sensitivity with enhanced mixing. In one time test, joint detection with five infections to one serum sample can be simultaneously implemented by introducing synchronous manipulation to five single beads. Chemiluminescence signal from five single beads is collected by a sensitive CCD camera in parallel. Qualitative detection is achieved by comparing the detection signal amplitude with the corresponding cutoff value for each infection. Experimental results show that accurate, simple, convenient and efficient TORCH screening can be achieved with the easy-to-operate and low-cost microfluidic system at resource-poor settings.