A Hyperelastic Finite-Element Model of Human Skin for Interactive Real-Time Surgical Simulation

Abstract

A finite-element (FE) model of human skin is proposed for future use in an interactive real-time surgical simulation to teach surgeons procedures, such as facial reconstruction using skin-flap repair. For this procedure, skin is cut into flaps that are stretched to cover openings in the face. Thus, the model must recreate the visual, haptic, and force feedback expected by the surgeon. To develop the FE model, a series of in vitro experiments were conducted on samples of human skin, subjected to uniaxial and planar tensile straining. Reduced polynomial hyperelastic (HE) materials were found to fit many of the samples' stress-strain data well. Finally, an explicit dynamic FE mesh was developed based on the fitted HE material models. A total Lagrangian formulation with the half-step central difference method was employed to integrate the dynamic equation of motion of the mesh. The mesh was integrated into two versions of a real-time skin simulator: a single-threaded version running on a computer's main central processing unit and a multithreaded version running on the computer's graphics card. The latter was achieved by exploiting recent advances in programmable graphics technology.

Tribology of Skin: Review and Analysis of Experimental Results for the Friction Coefficient of Human Skin

“…A detailed overview on the different test methods and mechanical properties is beyond the scope of this review. Relevant papers are available in the literature [120,122,125,126]. In brief, there is experimental evidence that the SC exhibits stiffness values and elastic moduli (10 kPa-1 GPa) of at least two orders of magnitude higher than the dermis (0.5 kPa-45 MPa) [127][128][129][130] and subcutaneous fat tissue (0.12 kPa-30 kPa) [125,127,131] (Fig.…”

Development of a lower extremity model for high strain rate impact loading

“…Future work will aim to study this strain-rate dependency. However, there is precedent for using hyperelastic material models (Lapeer et al, 2011;Cox et al, 2007), indicating that we may still be confident in the validity of our model. (Untaroiu et al, 2005) .3 (Untaroiu et al, 2005) 50 (Krone and Schuster, 2006) 5.3 (Untaroiu et al, 2005) 13.4 (Untaroiu et al, 2005) …”

“…The soft tissue should also allow for flexion of the joints. The soft tissue was modelled as a Mooney-Rivlin hyperelastic material following examples found in literature supporting the use of this material model (Majumder et al, 2007;Lee et al, 2009;Hendriks et al, 2003;Lapeer et al, 2011). The Mooney-Rivlin material formulation is represented as follows (LSTC, 2015a):…”

“…A study of in vivo soft tissue of amputees tested lower leg soft tissue at 7-11 locations at three rates on seven subjects and found a range of hyperelastic coefficients from .01 kPa-700 kPa (Tönük and Silver-Thorn, 2003). Furthermore, while some models use hyperelastic material models (Lapeer et al, 2011;Cox et al, 2007), others models incorporate viscoelasticity (Gabler et al, 2014;Untaroiu et al, 2005). Due to the variation of human material properties found in literature, parametric studies regarding flesh material properties may offer insight into the effects of this variability on results.…”

Review on Finite Element Material Modelling Of Brain Tissue for Surgical Simulation

“…Hyperelastic materials can be considered to be isotropic, incompressible and strain rate independent. Due to the large deformations seen on tissues during surgeries, these models are used extensively for all kinds of tissues such as brain [13,18], liver tissue [14], skin [15], soft tissues [16] and for general laparoscopic simulation [17]. The relevant equations of the strain energy function can be explained as follows [18]:…”