Effect of increasing sample volume on assay signal and noise. The PfHRP2 antigen was magnetically enriched from 100 or 500 μL volumes down to 10 μL, representing 10 or 50-fold volumetric enrichment, respectively. For the 100 μL processed volume, the magnetic enrichment immunoassay resulted in a false negative test result (a, top right), while for the 500 μL of processed sample (a, top left) a strong true positive signal at the test line was obtained. The assay noise remained low at each volume processed (a, bottom left and right). (b) Line scans from the positive sample, offset along the y-axis for clarity. (c) The integrated green channel pixel intensity at the test line (mean ± standard deviation, n=3) for the positive (“signal”) and negative (“noise”) samples.