High Expansion Auxetic Skin Graft Simulants for Severe Burn Injury Mitigation

Burn injuries are commonly treated with split-thickness skin grafting. However, low expansions offered by spilt-thickness skin grafting inhibit the treatment of large and severe burn injuries when limited donor skin is available. To overcome this gap, in this work, it was attempted to study the expansion potential of skin grafts with novel auxetic incisions with rotating rectangle (RR), honeycomb (HC), alternating slit (AS), H-shaped (HS), Y-shaped (YS), and I-shaped (IS) unit cells, through development of skin graft simulants. Clinically relevant biaxial load testing was conducted to estimate the stress-strain response, void area, and meshing ratio. Moreover, hyperelastic constitutive models were employed to characterize the non-linear biomechanical behavior of the skin graft simulants. The maximum void area increase was observed in the HS skin graft simulant, indicating low skin cover. Overall, the IS auxetic skin graft design exhibited meshing ratio higher than traditional grafts (>3:1), low void area and stresses, which can be beneficial for large skin cover and burn wound healing. With further optimization and clinical tests, the auxetic skin graft designs may find a place with the graft manufacturers for fabrication of grafts with better surgical outcomes for severe burn injuries.