US Patent 7331236 Pressure sensor

A sensor and insertion assembly 2 is used for intravascular measurement of pressure in a living body. The assembly includes, a sensor chip 6 having a substrate body 8 with a recess covered by a pressure sensitive film 10 thereby forming a cavity 12. A piezoelectric element, preferably in the form of a piezoelectric film 14, is arranged in connection with the pressure sensitive film, and energy is applied to the piezoelectric element such that acoustic waves are generated in the element. The piezoelectric element is arranged to generate an output signal, representing the pressure at the film, in dependence on the measured properties of the acoustic waves related to the deflection of the pressure sensitive film.