A volumetric fluid flow sensor (100) includes a flow channel (120) for flowing a fluid therein; and a diaphragm (110) having an outer surface within the flow channel (120). The diaphragm (110) includes at least one flow disrupting feature mechanically coupled to or emerging from the outer surface of the diaphragm (110). A sensing structure (126) is coupled to the diaphragm (110) for generating a sensing signal responsive to a pressure signal on the diaphragm (110).