Development of droplet based microfluidic system for agglutination assays

Agglutination reactions have been carried out for several applications such as assessment of bacterial infection, blood typing or detecting non-infectious diseases. To observe agglutination reactions, several approaches have been developed. Although microfluidic methods are more costly compared to the common methods in clinical practice, microfluidic systems provide a reliable and more controlled environment. Due to the ability of droplet based systems to manipulate minute volumes of fluids, microfluidic systems allow screening of several agglutination reactions at a single run. In comparison to standard microfluidic devices, droplet based microfluidic systems provide efficient mixing which is a crucial parameter for agglutination reactions. This study reports detection of agglutination reactions of whole blood in microdroplets using impedimetric measurement method. As a proof of concept demonstration of agglutination reaction, blood typing method was implemented in microdroplets. Using label free impedimetric measurement approach, agglutination reaction in microdroplets was monitored. Impedance monitoring was achieved using microelectrodes in the microchannel to measure the impedance signal generated by droplets in the continuous phase. Besides monitoring the reaction, an empirical approach was applied to find the lumped element model of the system. This model can be used as a guidance to design a detection system and to test the sensitivity of the detection system that is used for other type of immuno-diagnostic assays in microdroplets.