Schematic diagram of the immunochromatographic strip test using the gRAD. The test line contains a biotin-binding protein that captures biotinylated capture mAb. The control line contains antibodies that bind the mouse antibody which is responsible for immobilizing the detection conjugate at the control line. When testing, samples were mixed with both the biotinylated capture mAb and the detection colloidal-gold mAb conjugate to form a complex in the running buffer. Then 100 μl of the mixture is applied to the sample well of the gRAD. The mixture migrates along the membrane of the gRAD to the test line which binds and immobilises the biotinylated capture antibody. After 10 minutes, results were determined by visualization. A positive result following the accumulation of complex (biotinylated capture mAb, FMDV and Colloid gold-mAb) is demonstrated by the appearance of reddish-purple bands at both the test line (T) and the control line (C). A negative result is demonstrated by a reddish-purple band at the control line only.