The fFN  (vaginal secretion) has been designed to detect fFN thrisough visual interpretation of color development in the internal device. The membrane was immobilized with anti-fFN antibodies on the test region. During the test, the specimen is allowed to react with colored anti-fFN antibodies colloidal gold conjugates, which were precoated on the sample pad of the test. The mixture then moves on the membrane by a capillary action,  and interact with reagents on the membrane. If there were enough fFN in specimens, a colored band will form at the T region of the membrane. Presence of colored band indicates a positive result, while its absence indicates a negative result. Appearance of a colored band at the control region serves as a procedural control. This indicates that proper volume of specimen has been added and membrane wicking has occurred.