Lateral flow immunoassays utilize a porous membrane for performing the analysis, and the sample is permitted to flow laterally by capillary action from an application zone to a reaction zone on the membrane surface. The lateral-flow test kit usually has a sample slot for receiving biological fluids, such as whole blood, plasma, serum, urine, saliva and sweat. After the sample fluid is placed in the sample slot, the fluid flows from the sample pad through embedded reagents, in which specific chemical reactions occur. The reaction product continues to flow through the membrane until arriving at the capture reagents. The capture reagents are immobilized on the membrane as a band shape. The captured reaction product generates visually distinguishable color on the bands. Typically two bands are formed on the membrane, one is a test band (T band) for detecting the sample according to its concentration, and the other is the control band(C band) for confirming the success of the assay.