Pareto-optimization of hypodermic needles with respect to flow, buckling and piercing

Abstract Hypodermic needles for the injection of fluids generally have annular cross-sections. The preference for round shapes is, besides manufacturing reasons, due to the ideal ratio between the cross-section circumference and area, which leads to optimal flow properties. However, when additional parameters are considered in the design, other forms can prove to be better: the healing of the wound induced by the needle is highly individual and effects such as skin tension can make non-round shapes more suitable. When reimagining the shape of hypodermic needles, relevant factors such as the buckling of the needle during piercing/injection, and the fluid flow through the needle must be considered. The current work demonstrates an approach for the identification of different geometries within the framework of multi-objective optimization. Conflicting aspects of microfluidic flow, buckling under piercing/injection conditions, as well as (simplified) tissue damage suggest the notion of Pareto-optimal solutions. Equipped with more advanced models, the proposed take on hypodermic needles can lead to a better standard geometry and even concepts of ad-hoc manufacturing of individually optimal geometries through additive methods in the context of personalized medicine.