FIG. 2.

Predicted mean and standard deviation of concentration of labeled-antigen for the case when sample antigen and antibody are absent. (a) Mean concentration field of labeled-antigen for inlet labeled-antigen concentration of 19 nM. (b) Spatial variation of total standard deviation of labeled-antigen concentration. The uncertainty is minimum along the centerline and is highest at nearly half of the diffusion length from the centerline. The uncertainty “diffuses” further in the y-direction at downstream locations. (c) Lateral concentration variation with $\pm 3\sigma$ uncertainty bars at the T-sensor exit (x = 6.4 mm). The sigmoidal shape of concentration profile is characteristic of transient one-dimensional diffusion; here x-coordinate is the “time-like” variable. (d) Individual contributions of uncertainty in model parameters to the overall uncertainty in concentration at x = 6.4 mm. The diffusivity of labeled-antigen D_LA is the major contributor to uncertainty. The contributions of uncertainty in flow speed u and diffusivity of labeled-antigen D_LA dip near the centerline resulting in a minima in the overall standard deviation.