Immunochromatography, a combination of chromatography and immunoassay has been widely used in diagnostics over the past few decades. More recently, microfluidic immunoassays have emerged as a cutting-edge application of microfluidics immunodiagnostics. Both immunochromatography and microfluidic immunoassay based reagent kits and analyzers realize rapid detection used in point-of-care testing. However, these two technologies still differ in terms of detection performance and application scenarios. 

1. Principle

• Microfluidic immunoassay kits are designed to precisely control fluid flow within channels or chambers at micrometer (µm) to nanometer (nm) scales. Thanks to this innovative technology, the multiple steps, from whole blood separation to detection, can be fully integrated into one single microfluidic immunoassay kit.With the antibodies pre-coated, the kits can detect antigens in microliter of analyte through antigen-antibody binding, with the signal readout via optical sensor in the analyzers. 
• Traditional immunochromatography kits are based on lateral flow immunochromatography, where solid phase carriers (e.g., nitrocellulose membranes) serve as reaction platform. Samples migrate along solid phase carriers, such as membranes, under capillary action. The antigens react with the antibodies immobilized in the membranes to form antigen-antibody complex.Thus, a visible test line is formed. The signals will be read out based on the intensity of test line.

2. Sensitivity and Specificity

• Microfluidic immunoassay kits integrate multiple microfluidic structures to complete the immune reaction process. JIEZLAB’s kits feature a unique cleaning mechanism designed to effectively enhance both sensitivity and specificity, which enables the kits to detect antigens as low as pg/mL. For instance, hs-cTnT can be reliably (CV≤8%) detected to fulfill the needs of clinical diagnosis.
• Traditional immunochromatography kits have a relatively higher detection limit, which limits their ability to detect target antigens at low concentrations eg., hs-cTnT. Therefore, the immunochromatography kits are commonly applied in qualitative analysis. Compared with microfluidic immunoassays, immunochromatography is more susceptible to interfering factors, especially non-specific binding, which compromises its specificity.

3. Quantitative Analysis

• The microfluidic immunoassay kits design enables whole blood separation through a centrifugation module within the analyzer. The separated plasma is then measured precisely in a quantitative chamber, ensuring that only accurately quantitated plasma is used for analyte detection. Therefore, microfluidic immunoassay kits offer accurate quantitative results compared to traditional qualitative or semi-quantitative immunochromatography kits, which are especially important for clinical applications requiring precise quantitative diagnostics. 
• Most immunochromatography kits provide qualitative or semi-quantitative results. One reason is that these kits can’t eliminate the bias introduced by individual different HCT.The hematocrit (HCT) is the volume percentage (vol%) of the red blood cells. HCT can vary based on factors such as gender, race, etc. Males have a higher HCT than females. When whole blood sample is applied to immunochromatography kits, the red blood cells are removed through filtration. The plasma is not accurately quantitated. Therefore, the readout will be impacted by individual variations in HCT. 

4. Environmental influence

• Microfluidic immunoassay kits provide an enclosed environment. The microfluidic immunoassay analyzer also ensures the reaction temperature is constant at 37±0.2°C. Therefore, microfluidic immunoassay kits are less affected by environmental conditions, eg., temperature and humidity.
• Immunochromatography kits are mostly susceptible to environmental conditions. Incubation time, along with environmental temperature, humidity, and other conditions have an impact on results. 

In summary, microfluidic immunoassay kits and analyzers are rapid, reliable and easy to use.  Because of the high sensitivity, microfluidic immunoassay kits and analyzers are capable of detecting antigens at the Pico level in the analyte with repeatability CV≤6% for most of the products. The kits and analyzers are easy-to-use, “whole blood sample in, reliable results out”. As there is no liquid circuit within the analyzer, only simple maintenance is needed for end users.

JIEZLAB’s Microfluidic Immunoassay Analyzer supports the detection of cardiovascular biomarkers and infectious biomarkers. All results are available within 12 minutes. JIEZLAB’s comparison with immunochromatography products is as follows: