New approach to noninvasive manometry based on pressure dependent resonant shift of elastic microcapsules in ultrasonic frequency characteristics

Abstract

To measure physiological pressure in situ, we have developed a new technique based on the principle that an elastic microcapsule in liquid changes its resonant frequency depending on the surrounding pressure. The following results were ohtained: 1) The frequency characteristics of transmission wave through microcapsules showed marked attenuation with a specific spectral peak, indicating the resonance of the microcapsules. 2) Pressure dependent change in amplitude of the attenuation peak increased linearly with the increment of pressure. 3) Pressure dependent resonant shifts were also observed in proportion to the pressure increment. © 1988 The Japan Society of Applied Physics.