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Abstract

A sensor that utilizes strips of piezoelectric material to noninvasively measure the surface force/displacement resulting from a blood pressure wave traveling through an artery and transmitted through the arterial wall and overlying tissue, while canceling noise artifact signals is disclosed. Piezoelectric elements create an electrical signal when pressure is applied to their surface. In the preferred embodiment, the sensor is constructed so that there are three sensing elements--a signal sensing element in the center and one noise sensing element on each side of the center element. The center element is placed over an individuals artery, e.g., the radial artery in a persons wrist. When positioned this way, the two noise sensing elements are positioned on each side of the artery. The center element generates a signal that is a function of the pressure wave in the artery, whereas this signal is highly attenuated in the noise sensing elements. However, all three elements detect the noise artifact signals in the general area of the sensor. The area of the noise elements, when combined, is equal to that of the center element. This provides an average of the noise detected by the center element. The signals from the two noise sensing elements are subtracted from the center element signal, thereby canceling the noise in the center element. Also disclosed is a unique method that allows repositioning of the sensor after it has been attached to the patient, a mechanism for maintaining the appropriate hold down pressure, a wrist stabilization device for stabilizing the wrist during monitoring of the blood pressure. The present invention also allows blood pressure calibrations to be obtained using the wrist and arm stabilizer assembly.

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First Claim