FIG. 4.

Effect of sample antigen concentration on uncertainty in T-sensor based diffusion immunoassay. Shown here are the contributions of various model parameters to the overall uncertainty for two cases: (a) when sample antigen is absent and (b) when inlet sample antigen concentration is 573 nM. (a) In the absence of sample antigen, the uncertainty variation is qualitatively similar to the case shown in Fig. 3(c) when antigen concentration is low. (b) At high concentration of sample antigen, the overall uncertainty decreases in most of the inter-diffusion region. Less binding sites are available for the labeled-antigen on the antibody, causing the labeled-antigen to diffuse without appreciable binding. Thus the spatial variation of uncertainty shown in (b) is qualitatively similar to the case shown in Fig. 2(d) where labeled-antigen diffuses in absence of antibody and sample antigen.