Characterization of auxetic polyurethanes foam for biomedical implants

Aging, accidents and diseases are the leading causes of disability in today's world. Therefore, implants and prostheses for hard and soft tissues are becoming increasingly common to restore daily activity and improve the quality of life of patients. Although implants have been extensively developed and are in the clinical use, deformation mechanism, inflexibility and mismatch of the elastic and mechanical behavior of the implants with native tissues are challenges for tissue engineering. The objective of this study was to characterize auxetic polyurethane foam as an auxetic soft tissue implant based on mathematical modeling using a nonlinear elasticity theory. The compressibility effects on auxetic soft tissue implants due to equibiaxial loading were studied. Numerical results were computed using experimentally obtained data and compared with the non-auxetic behavior of a soft tissue.