A Novel Compression Tester for Detecting Anisotropy in Very Soft Biological Tissues

Quantifying the mechanical behavior of very soft tissues (VST) is important when studying responses to injury or designing therapeutic devices; fat, brain, or liver being examples of such tissues. VST can have poor suture retention or clamp holding strength, making tensile tests difficult. As a result, uniaxial compression tests are typically the preferred choice to quantify the mechanical behavior. In these tests, isotropy is generally assumed and measuring the deformation in only one direction is needed if the material is considered incompressible [13]. In this study we present a novel testing apparatus for use on VST under uniaxial compression that can detect anisotropic behavior of the tissue if present. We validate the tester using cardiac adipose tissue and isotropic rubber as the control. Understanding the directional behavior of the tissue is important since anisotropy would require testing in multiple directions to fully characterize the material properties.