A piezoelectric sensor for the detection and characterization of at least one biochemical element in a fluid, consisting of a piezoelectric substrate exhibiting at each of its opposite faces at least one conducting surface forming electrodes, said electrodes being linked to an electrical generator, at least one of said opposite faces being covered with a functionalized film, said electrodes forming transmission lines exhibiting a zone constituting an induction loop for an excitation of said piezoelectric substrate, and a link between said electrodes and said electrical generator being ensured by inductive coupling.