Abstract: The present invention relates to a transducer (11) comprising—a membrane (31) configured to change shape in response to a force, the membrane (31) having a first major surface (16) and a second major surface (17),—a piezoelectric layer (18) formed over the first major surface (16) of the membrane (31), the piezoelectric layer (18) having an active portion,—first and second electrodes (19) in contact with the piezoelectric layer (18), wherein an electric field between the first and second electrodes (19) determines the mechanical movement of the piezoelectric layer (18),—support structures (40) at the second major surface (17) of the membrane (15) on adjacent sides of the active portion of the piezoelectric layer (18), at least part of the support structures (40) forming walls perpendicular, or at least not parallel, to the second major surface (17) of the membrane (31), so as to form a trench (41) of any shape underlying the active portion, so that an ultrasound transducer is obtained with a high output press

Abstract: The invention proposes to equip the tip of a surgical instrument such as a needle or catheter or any other instrument with an ultrasound transducer array to measure flow just in front of the tip by means of time and frequency differences between the sent and received pulses. Since no image is required, only a few transducer elements are required. The transducer elements generate a pressure pulses in specific directions and receives its echo's without the use of imaging techniques and complex driving electronics. Using the frequency shift and time delay of the received signals the proximity and lateral direction of the blood flow may be detected, thus identifying blood vessels.