A Validated Cohesive Finite Element Analysis of Needle Insertion into Human Skin

Abstract

Medical needles play important roles in many diagnostic and therapeutic applications. To design needles and procedures involving needles more efficiently, the investigation of the needle insertion process and the related parameters are key to developing related novel technologies. This paper provides a two-dimensional finite element model of needle insertion into the human skin, which is validated with available experimental results in the literature. The crack propagation in the tissue is modelled via the cohesive zone method. To this end, a curve-fitting approach based on the reaction force applied to the needle during the insertion is exploited to optimize cohesive parameters. Our simulations show that failure traction of 2 MPa, initial stiffness of 4000 MPa/mm, and separation length of 1.6 mm lead to a reliable model compared to the experimental results.  We also investigated the effect of needle diameter on the insertion force.