A simple viscoelastic model for soft tissues in the frequency range 6-20 MHz

Area of Science:

• Biophysics
• Materials Science
• Biomedical Engineering

Background:

• Understanding the mechanical properties of biological tissues is crucial for medical applications.
• Traditional linear viscoelastic models sometimes yield non-physical results like negative storage moduli.
• Porcine tissues are often used as models for human tissues in biomechanical studies.

Purpose of the Study:

• To measure the shear properties of porcine skeletal muscle, liver, and kidney.
• To develop a novel viscoelastic model that can accurately describe these properties, especially under conditions yielding negative moduli.
• To validate the proposed model against experimental data.

Main Methods:

• Shear mechanical impedance measurements were performed on porcine tissues.
• Complex shear moduli were calculated in the frequency range of 6-20 MHz.
• A modified Voigt model incorporating mass was developed and fitted to the data.

Main Results:

• Experimental data revealed negative storage moduli under certain conditions.
• The proposed extended Voigt model successfully predicted these negative moduli.
• The model accounts for the observed phenomena by relating shear stress to material inertia at high frequencies and long relaxation times.

Conclusions:

• The developed extended Voigt model provides a more accurate description of porcine tissue viscoelasticity compared to traditional models.
• This model resolves the issue of negative storage moduli by incorporating inertial effects.
• The findings have implications for biomechanical modeling and understanding tissue mechanics.