Micromechanics and tribology of skin tissues and equivalents

Background:

Skin, the largest organ in the human body, is constantly in mechanical contact with agents from the outside world. This urges the need for a thorough investigation and optimization of the tribological properties of any material aimed at mimicking skin. In this regard, we studied adhesion, friction, and damage characteristics of three commercially available products, Dragon skin, Lorica leather, and cell-derived human skin tissue, in a set of linear reciprocation experiments. 

Research Overview:

We characterized four human skin substitutes, Dragon Skin 10, Lorica leather, porcine skin, and cell-derived human skin, for their tribological and mechanical properties through linear sliding and micro indentation experiments. In this context we measured viscoelastic energy dissipation, normal contact stiffness, elastic modulus, friction coefficient, and scratch resistance. Lorica was found to be closest to to the stratum corneum layer of human skin in terms of its elastic modulus, whereas porcine skin behaves similar to full thickness human skin and demonstrates the same softening effect of the underlying subcutaneous tissue. The friction behavior of Dragon Skin 10 was found to comply with wet fingertip contact and the adhesive theory of friction by exhibiting friction coefficients above 0.5 and an inverse relationship with normal force. The other materials are representative of dry skin friction with friction coefficient values clustered around or slightly below 0.5. Dragon Skin 10 and Lorica leather were found to be moire wear resistant than actual human skin whereas porcine skin and cell-derived human skin had wear resistance more similar to human skin, making it more eligible for mimicking wear of human skin. 

Funding:

• Kleenex

• UW-Madison Mechanical Engineering Department

Selected Publications:

Usta, A., Hess, C., Eriten, M., "Tribological and Mechanical Characterization of Human Skin Substitutes and Comparison with Human Skin," Journal of Biotribology (Submitted) 

People:

Ahmet Usta

Melih Eriten

Cole Hess