Biomechanical modeling of novel high expansion auxetic skin grafts

Abstract

Over 20 million burn injuries are reported every year, with severe cases requiring skin grafting. Traditionally, split thickness skin grafts are prepared by excising a small portion of healthy skin and its incision patterning using a suitable meshing device, which allows the graft to be expanded beyond its capacity. To date, the maximum expansion achieved through skin grafting has been reported to be less than three times, which is not sufficient for covering large burn sites with limited donor site skin. In this work, we have attempted to study skin graft expansion potential with novel auxetic patterns, which are known to exhibit negative Poisson's effect. Two‐layer skin graft models were developed using eight different auxetic incision patterns, and subjected to uniaxial and biaxial tensile strains. The Poisson's ratio, meshing ratio, and induced stresses were characterized for all graft models. The numerical results indicated expansion potentials greater than that of traditional skin grafts across all loads. Extremely high expansions (i.e., >30 times) were estimated for the I‐Shaped Re‐entrant and Rotating Triangles shaped auxetic models without rupture. Such pioneering findings are anticipated to initiate ground‐breaking advances towards skin graft research and improved outcomes in burn surgeries.

Traction performance modeling of worn footwear with perpendicular treads

“…Beyond this, hyperelastic modelling was invoked to simulate polymeric nonlinear stiffening effects. All the outsoles were meshed with 10-node SOLID 187 tetrahedral elements to facilitate ease in mesh convergence and enhance the models' accuracy [41][42][43]. The outsoles were computationally warped at an angle of 17°and a force of 275 N was evenly applied over the upper surface of the outsole model.…”

Auxetic incisions with alternating slit shapes: a promising technique for enhancing synthetic skin grafts expansion

“…It is commonly used to treat burns, wounds, and other injuries that have damaged the skin. While skin grafting has been successful in many cases, this procedure faces some global issues (i.e., limited donor skin, cost, lack of suitable donors, donor site morbidity) [22,23].…”

“…This study revealed that the randomly oriented cut auxetic structure exhibited a maximum negative Poisson's ratio value of −0.8 under maximum deformation. In literature, several studies were performed to understand the effect of structural parameters such as unit cell length, spacing and orientation in Poisson's ratio [22,[47][48][49]. Based upon the previous studies, on increasing the axial length of the slits, the effective Poisson's ratio decreased [23,50,51].…”

“…The study demonstrated noticeable changes in effective Poisson's ratio when both the strain rates and auxetic designs were varied within the experimental framework. In another study, Gupta et al [22] conducted computational study on different auxetic skin graft patterns and observed the different effective Poisson's ratios changing with the auxetic designs. Cabras et al [53] performed the experiments on thermoplastic lattice structures and tested uniaxially.…”

Development of an ultra-low-cost planar biaxial tester for soft tissue characterization

“…In universal testing machine (UTM), one end is fixed, and the other end is moving with specific strain rates, while the force-displacement data is collected. The most common way to characterize isotropic materials is through uniaxial tests [19][20][21][22]. However, soft tissues are viscoelastic, and exhibit anisotropic material properties [2,23,24].…”