A microfluidic element for thoroughly mixing a liquid with a reagent used for the analysis of the liquid for an analyte contained therein and a method thereof are disclosed. The microfluidic element has a substrate and a channel structure. The channel structure includes an elongate mixing channel and an output channel. The mixing channel has an inlet opening and an outlet opening, and is implemented to mix the reagent contained therein with the liquid flowing through the inlet opening into the mixing channel. The outlet opening of the mixing channel is in fluid communication to the output channel. The outlet opening is positioned closer to the middle of the length of the mixing channel than the inlet opening.