Rate dependency during needle insertions with a biologically inspired steering system: An experimental study

Percutaneous intervention is a common Minimally Invasive (MI) surgical procedure for the treatment of various disorders. It generally involves the insertion of slender needles deep within tissue, as lesions can be several centimetres below skin level. Consequently, deviations might occur which need to be accounted for and corrected by steering the needle tip during the insertion process. Needle steering systems, however, are necessarily disruptive to the substrate, with the potential to cause larger migrations of deep-seated targets, as well as potentially increasing the extent of tissue trauma at the needle interface, when compared to straight needles. This study aims to investigate different insertion modalities for a biologically inspired multi-segment needle, which is able to steer along three-dimensional trajectories by exploiting a quasi-linear relationship between the relative displacement of the needle segments and the curvature magnitude and direction plane at the tip. We demonstrate that different segment insertion speeds do not affect this relationship during experiments in gelatine, and thus a new steering approach is proposed to steer the needle into the substrate which substantially improves upon the manoeuvrability (i.e. the rate of change of steering angle) of the needle.