A device for the filtration of a complex fluid composition such as blood, includes a base (12) with a bottom (18), a top (14) with a bottom (30), and a membrane (16) that is arranged between the base and the top so as to define a low chamber C1 and a high chamber C2, with an input tap (26) of the complex composition that is to be filtered emptying into the low chamber C1, an output tap (28) of the retentate with elements for adjusting the flow rate emptying into this same low chamber C1, and an output tap (36, 36-1) of the high chamber C2, whereby this output tap (36, 36-1) of the permeate is subjected to negative pressure.
