Simple Empirical Model for Identifying Rheological Properties of Soft Biological Tissues

TL;DR

This paper introduces a simple empirical model based on Fractional Dynamics and Exponential Nonlinearity (FDEN) to identify the rheological properties of soft biological tissues, validated through experiments on porcine liver samples.

Contribution

The paper presents a novel, minimal-parameter empirical model (FDEN) that accurately captures the rheological behavior of soft biological tissues from experimental data.

Findings

Biological tissue exhibits power law increases in elastic moduli with frequency.

The tissue shows constant phase delay over a frequency range.

The model uses only three parameters to describe tissue properties.

Abstract

Understanding the rheological properties of soft biological tissue is a key issue for mechanical systems used in the healthcare field. We propose a simple empirical model using Fractional Dynamics and Exponential Nonlinearity (FDEN) to identify the rheological properties of soft biological tissue. The model is derived from detailed material measurements using samples isolated from porcine liver. We conducted dynamic viscoelastic and creep tests on liver samples using a rheometer. The experimental results indicated that biological tissue has specific properties: i) power law increases in storage elastic modulus and loss elastic modulus with the same slope; ii) power law gain decrease and constant phase delay in the frequency domain over two decades; iii) log-log scale linearity between time and strain relationships under constant force; and iv) linear and log scale linearity between strain and stress relationships. Our simple FDEN model uses only three dependent parameters and represents the specific properties of soft biological tissue.