Design and Modeling of Motorized Tapping Mechanism for Effective Needle Penetration

Abstract

Robot-assisted needle insertion is widely employed in minimally invasive percutaneous interventions such as biopsy, brachytherapy, or ablation; however, most existing systems predominantly emphasize needle dexterity and manipulation within the soft tissue, neglecting the significant challenge of percutaneous access. In practice, conventional needle insertions often require excessive force that causes significant deformation of both tissue and needle, particularly when penetrating stiff skin or fibrotic tumors. To address this, we develop a novel tapping mechanism that generates instantaneous momentum at the needle tip to achieve efficient tissue penetration. Theoretical models are formulated to describe the force–deformation behavior and fracture mechanics induced by the tapping motion. Experiments on porcine tissue demonstrated that the tapping motion reduced the mean rupture force and tissue deformation from 9.75 N and 34.44 mm obtained via the conventional continuous insertion to 2.79 N and 19.85 mm, respectively. Furthermore, the tapping mechanism enabled successful insertion into the two-barrier porcine tissue using compliant needles that would otherwise buckle under continuous insertion, increasing the second-barrier successful penetration rate from 0/15 to 13/15.