Development of an automatic procedure to mechanically characterize soft tissue materials

In literature a standard protocol to develop an automatic procedure to mechanically characterize soft tissue material does not exist yet. in this paper we propose a procedure that permits to automatically calculate the Young's modulus and the Poisson ratio for a soft material characterized during a uniaxial tensile test. The experimental setup requires the use of several markers and a camera for automatically obtaining the true stress strain curve of the soft material under test. in fact, in post processing the image analysis permits to automatically measure the real displacement of the material tracking the movement of the markers and the mean width variation of the specimen using a black and white threshold technique. Moreover, the algorithm through an automatic routine is able to linearize the true stress strain curve: the user can decide the number of linear segments desired and the regions of the stress strain curve in which to perform the linearization process. The procedure was initially tested and validated using a known silicon material and, after that, applied on a biologic material. The procedure was accurate, independent by eventual slipping of the specimen with respect to the tensile machine, and suitable not only for synthetic soft materials, but also for biological ones.