Automatic characterization of soft tissues material properties during mechanical tests

The estimation of the non-linear viscoelastic characteristics of human soft tissues, such as ligaments and tendon, is often affected by the implemented procedure. This study aims at developing and validating a protocol, associated with a contactless and automatic procedure, enabling the determination of the material behavior and properties of any soft tissues.

Several markers were drawn onto the soft tissue specimen analyzed under uniaxial tensile test. An automatic contactless procedure, that uses a camera for recording the position of the markers during the test, was developed to compute the displacement, and the force applied, enabling the calculation of the true-stress/strain curve of the material. Young's modulus and Poisson's ratio can be calculated, on demand, for selected regions of interest of the soft tissues. The repeatability and reproducibility of the procedure were analyzed. The procedure was initially tested and verified on an artificial silicone material and later applied for investigating the mechanical behavior of a pig Achilles tendon and of a human patellar tendon.

The procedure show a high repeatability, independent by the operator, reliability and accuracy for the tested synthetic material (with a maximum error of 3.7% for Young's modulus). Additionally, the developed protocol was also suitable for the analysis of animal and human soft tissues.

A protocol to automatically and accurately determine material properties in soft tissues was developed, tested and validated. Such approach could successfully be implemented for the mechanical characterization of any biological soft-tissue.

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