Sensor for measuring blood pressure

PCT No. PCT/CH93/00273 Sec. 371 Date Aug. 1, 1994 Sec. 102(e) Date Aug. 1, 1994 PCT Filed Dec. 6, 1993 PCT Pub. No. WO94/13207 PCT Pub. Date Jun. 23, 1994A sensor with a first, second and third force pick-up includes a piece of foil made of piezoelectric material which serves all three pick-ups and carries a number of electrodes. The second and third pick-up are located one on either side of the first pick-up and are characterized by a smaller pick-up surface than the first one. For measuring blood pressure the sensor is pressed against a part of a patient's body such that the first force pick-up, i.e., the one in the middle, is at the shortest possible distance from a large artery. During measurement the absolute values of the changes in the measurement values of the three force pick-ups, which are due to the pulsating blood stream, are added. On the other hand the changes in the measurement values caused by interfering forces will cancel each other out.