A Mechanics-Based Model for 3-D Steering of Programmable Bevel-Tip Needles

Abstract

We present a model for the steering of programmable bevel-tip needles, along with a set of experiments demonstrating the three-dimensional steering performance of a new, clinically viable, 4-segment, preproduction prototype. A multibeam approach based on Euler–Bernoulli beam theory is used to model the novel multisegment design of these needles. Finite element (FE) simulations for known loads are used to validate the multibeam deflection model. A clinically sized (2.5 mm outer diameter), 4-segment programmable bevel-tip needle, manufactured by extrusion of a medical-grade polymer, is used to conduct an extensive set of experimental trials to evaluate the steering model. For the first time, we demonstrate the ability of the 4-segment needle design to steer in any direction with a maximum achievable curvature of $({\text{0.0192}} \pm {\text{0.0014 mm}}^{-1})$ . FE simulations confirm that the multibeam approach produces a good model fit for tip deflections, with a root-mean-square deviation (RMSD) in modeled tip deflection of 0.2636 mm. We perform a parameter optimization to produce a best-fit steering model for experimental trials with a RMSD in curvature prediction of ${\text{1.12}} \times {\text{10}}^{-3} {\text{mm}}^{-1}$ .