Figure 3.
Schematic. (i) The wall of the reactor tube (or capillary tube) is coated with labeled capture antibodies. The analyte solution is pumped into the tube. (ii) Upon entry, there is a two-way transport that takes effect: dominant advection in the streamwise (indicated by yellow horizontal arrow) and diffusion in the cross-stream (indicated by vertical purple arrow) directions. (iii) The analyte molecules displace the fluorescent labels from the sites of the antibodies. (iv) Due to consumption of the analyte at the wall and reduced transport from the middle of the tube, there is a point of exhaustion along the tube length beyond which the concentration of analyte is too low, fixed at 1 aM (10–18 M or 23.8 fg/L cTnI) in this study.