FEA Modeling of Soft Tissue Interaction for Active Needles With a Rotational Tip Joint

A finite element analysis (FEA) model was developed for investigating the design and the tissue interaction of actively steerable needles with a rotational tip joint in soft tissue, based on the coupled Eulerian-Lagrangian (CEL) mesh. The new model is algorithmically simple in that the proposed CEL strategy allows needle insertion simulations along non-predetermined paths in soft tissue without the re-mesh at every direction change of the needle tip. For the features, various steering motions can be simulated and studied for different needle designs in a simpler approach by changing the needle geometry and boundary conditions. The developed FEA model, using the thoroughly measured material properties, was validated for predicting insertion path and estimating the tissue interaction forces inside two different gelatin tissue phantoms. Further, using the validated model, the effect of tip geometry on tissue was briefly investigated. Given bevel angles, it was found that the ratio of tip length to the diameter dominates the tissue damage gradient. The results demonstrate that the proposed model effectively examines the steering and tissue insertion of actively steerable needles and investigates the tip design to minimize the tissue damage by the needle steering.