Fig. 1. SpermCheck Fertility device and results. Device is shown before a sample has been added. Following a 20 minute semen liquefaction period, 100 µL of semen is sampled and mixed with a detergent that solubilizes the sperm's acrosomal membranes, releasing SP-10 protein. Four drops of the solution are applied to the sample well (1). Colloidal gold-conjugated monoclonal SP-10 antibodies present on the absorbent pad bind to the solubilized SP-10 antigen (2). The solution migrates along the nitrocellulose strips by capillary action. At test line (T), a second monoclonal antibody captures the gold-antibody-SP-10 complex, resulting in the appearance of a red line at this position (3). The appearance of lines at the control position indicates the device functioned properly. Diagnostic devices showing a concentration over 20 million (A–C), below 20 million (D), and a type of invalid test result (E). Presence of red control line must appear to ensure result is valid and test fluid has completely flowed over the test line, which must appear within the 7-minute assay period.