Computational investigation of a 3D-printed skin substitute with orthotropy in mechanical property

As a promising treatment for third-degree burns, grafting with bioengineering skin substitutes shows a capability to overcome the deficiency of donor skin. Similar mechanical properties with human skin are required for employed skin substitutes to avoid secondary damage to patients. Given the representativeness of orthotropy in mechanical properties, there is a need for developing orthotropic skin substitutes. This paper presents computational investigation as well as structural design for the fabrication of orthotropic skin substitutes. A finite element method (FEM) based mechanics simulation model for analyzing the stress field in the skin substitute was developed, by which the stress distribution in mimetic structures of the epidermis and dermis can be acquired. Moreover, the equation of Young's modulus was deduced based on the simulation result, which expressed the mechanical property of designed skin substitutes. Furthermore, several structures of skin substitutes were proposed and their calculated Young's modulus ranged from 21.87 kPa to 213.32 kPa, which was similar to the human skin. Ultimately, uniaxial tensile tests were performed for three types of 3D-printed orthotropic skin substitutes, which validates the feasibility to regulate Young's modulus by regulating the structure of fabricated skin substitutes.