Development of a testing machine for biaxial testing of soft tissue and biomaterials

Knowledge of the mechanical properties of soft tissues and biomaterials is the keystone for predictive modeling in cardio- and endovascular surgery, traumatology and orthopedics, neurosurgery, and the development of tissue-engineering constructs. Needed mechanical properties can be only explored via experimental tests. Therefore, mechanical experiments are forming the foundation of medical decision support systems, which are impossible without adequate mathematical models of the processes involved. Sirius University of Science and Technology has launched the project "Experimental research and mathematical modeling of the mechanical behavior of biomaterials". The goal of the project is to create an infrastructure for experimental study of the mechanics of soft tissues and biomaterials. At this stage, a machine for biaxial testing of soft tissues and biomaterials has been developed and put into trial operation. The developed machine takes into account the features of working with soft tissues: small sample size, maintaining certain environmental conditions to preserve the sample, various types of sample gripping to minimize edge effects and no slippage, non-contact methods for assessing displacement and deformation fields, variability in sample loading protocols. The result of the test is a data set that includes a test report and synchronized output readings of strain gauge, temperature, optoelectronic sensors with high-resolution images. Uniaxial verification tests of acrylic tapes VHB4910 were carried out by the developed machine. The results were compared with data obtained on a commercial dynamic mechanical analyzer RSA-G2 (TA Instruments) for similar materials under the same test conditions. A series of biaxial cyclic experiments were carried out for the pericardium of cattle, the cardiovascular patch Ecofolon PS04/PS01 (JSC NPK Ecoflon, St. Petersburg, Russia), and the GoreTex vascular graft (W.L. Gore and Associates, USA).