Figure 5.

Overall design of the QD barcode assay. Electrokinetics is used to transport QD-barcoded microbeads (Ø = 3.8 µm) into a microchannel. The flow is going from left to right: (i) magnetic barcodes are attracted by a first magnet to interact with the target ssDNA present in the upper stream, (ii) then they move toward the second magnet to interact with the reporter probe present in the lower stream, and (iii) they are pulled by the last magnet into a washing buffer and aligned for optical excitation and detection. They are individually detected by fluorescence as they pass through a focused laser spot. The figure shows the detection of one genetic target, but for multiplexed detection, the same process is done for the different ssDNA targets simultaneously [50].