In a microfluidic assembly, a microfluidic device is provided with a body in which at least a first inlet for loading a fluid for analysis, and a buried area in fluid communication with the first inlet are defined. An analysis chamber is in fluid communication with the buried area and an interface cover is coupled in a fluid-tight manner above the microfluidic device. The interface cover is provided with a sealing portion in correspondence to the analysis chamber, operable to assume a first configuration, in which it leaves the analysis chamber open, and a second configuration, in which it closes the analysis chamber in a fluid-tight manner.