Low-frequency surface wave propagation and the viscoelastic behavior of porcine skin

摘要

A physical model describing the propagation of low frequency surface waves in relation to the viscoelastic behavior of porcine skin is presented along with a series of empirical studies testing the performance of the model. The model assumes that the skin behaves as a semi-infinite, locally isotropic, viscoelastic half-space. While the assumption of a semi-infinite body is violated, this violation does not appear to have a significant impact on the performance of the model based upon the empirical studies. One Hertz surface waves in the skin propagate primarily as Rayleigh waves with a wavelength and velocity of approximately 3 m and 3.0 m/s, respectively. The amplitude of the acoustic wave as measured by tracking the acoustic stress wave - induced shift in a backscattered laser speckle pattern, decreased exponentially with lateral distance from the acoustic source. Using this model of surface wave propagation, the mechanical loss factor or tan δ of the skin was measured to be on the order of 0.14?.07. The results presented herein are consistent with earlier works on the propagation of low frequency acoustic waves in biological tissues and should serve as a theoretical and empirical basis for using the wave characteristics of propagating surface waves in combination with the mechanical behavior of the tissue for biomechanical studies and for potential diagnostic applications.