Piezoelectric sensor in a living organism for fluid pressure measurement

A fluid pressure sensor for a lead or catheter adapted to be placed in a living organism, said sensor comprising a rigid, annular supporting structure and a piezoelectric element delivering an electric signal when subjected to a pressure variation, said piezoelectric element exhibiting circumferential sensitivity and being disposed on at least a portion of an outer surface of said rigid annular supporting structure, said sensor having a rigidity such that

• a) the charge generated by said sensor when said sensor is covered by a 1 mm thick layer of a silicon elastomer having a modulus of elasticity of at least 1.49 MPa (as measured with 6% deformation of the material) and is immersed in distilled water at 20° C. to a depth of 50 mm in a pressure chamber and is subjected to an increase of pressure amounting to 2 kPa, is at least 90% of the charge generated by said sensor when immersed into distilled water at 20° C. to a depth of 50 mm in a pressure chamber and subjected to an increase of pressure of 2 kPa but not covered with said silicon elastomer layer, and
• b) the amplitude of the signal from said sensor when said sensor is covered by a 1 mm thick layer of said silicon elastomer and is immersed in distilled water at 20° C. to a depth of 50 mm in a pressure chamber and is subjected to a pressure increase varying sinusoidally between 0 and 2 kPa at a frequency increasing from 1 to 30 Hz over an entire frequency range between 1 and 30 Hz does not deviate more than 3 dB from the amplitude of the signal obtained from said sensor when said sensor is immersed in distilled water at 20° C. to a depth of 50 mm in a pressure chamber and subjected to a pressure increase varying sinusoidally between 0 and 2 kPa at a frequency increasing from 1 to 30 Hz but not covered by said silicon elastomer.