In CAT, a reagent combines with an analyte in a sample (blood, urine, etc) and forms an agglutinate of larger molecules. The agglutinate acts to slow down the flow of the sample in micro-capillaries formed by precise injection moulding of a plastic “chip”. By comparing the flow rate in a test capillary to a comparator capillary, correction can be made for the effect of environmental factors and blood chemistry.
The change in flow rate in the test capillary is dependent on the concentration of analyte in the sample. A quantitative result can be generated which can be displayed digitally. The CAT principle is possibly the simplest and lowest cost signal measurement system used in IVD applications.