Mechanical characterization of functionally graded soft materials with ultrasound elastography

Area of Science:

• Continuum Mechanics
• Materials Science
• Biomedical Engineering

Background:

• Functionally graded soft materials (FGSMs) offer tailored properties but pose characterization challenges.
• Non-destructive in vivo/in situ mechanical property assessment of FGSMs remains a significant hurdle.

Purpose of the Study:

• To investigate ultrasound elastography for mechanical characterization of FGSMs.
• To develop methods for identifying mechanical parameters in FGSMs with varying elastic gradients.

Main Methods:

• Developed an efficient finite-element model to compute surface wave dispersion relations in FGSMs.
• Analyzed transient wave motion to correlate group velocities with local mechanical properties.
• Validated the method using polyvinyl alcohol (PVA) cryogel experiments.

Main Results:

• The dispersion relation effectively identifies mechanical parameters for FGSMs with large elastic gradients.
• Group velocities at different depths infer local mechanical properties when elastic gradients are below a critical value.
• Experimental results demonstrate the method's practical utility.

Conclusions:

• Ultrasound elastography provides a viable approach for non-destructive mechanical characterization of FGSMs.
• The findings have implications for FGSM applications and clinical shear wave elastography in diagnosing diseases affecting tissue elasticity.