SPH-based simulation of micro-impacts in human-tissue surrogate: A preliminary study on multilayered structure

Microparticle impact responses into soft tissue is of interest in various framework like transdermal durg delivery in pharmaceuticals. In order to investigate this phenomenon, experimental devices have been developed using human surrogate such as ballistic gelatin, rubber, or polymers, such as SEBS gel (styrene-ethylenebutylenestyrene), which is considered as an interesting simulant because of its properties (environmental stability, reproducibility, mechanical consistency, transparency), and its ability to represent correctly the mechanical behavior of soft tissues. Considering the perforation mechanical behavior of this surrogate, this paper investigates the multilayered SEBS gel structure of various concentration submitted to high velocity micro-penetrating impact at a numerical level using smoothed particle hydrodynamics formulation. Different concentrations of SEBS gels have been modeled, and the numerical results have been compared to analytical data and existing experimental results, which show a very good correlation, in terms of penetration time history for a single SEBS concentration, as well as a for superimposition of several layers of various concentration of SEBS gel. This paper is a first step in the understanding of penetration of microprojectiles into soft tissue surrogate at various concentrations, allowing further investigations of multilayered target, approaching the human epidermal with several different layers.