Soft tissue resists indentation elastically before the blade tip exceeds its local fracture stress and begins to cut. Required force grows with depth and stiffness, but a sharper edge concentrates the same force into a smaller contact area, cutting cleanly with less collateral compression.
F_required(d) = k · d^1.4 / sharpness
stress = k · d / A_tip (Hookean approximation)
risk = stress / stress_damage_threshold
- Insertion depth — how far the tool tip advances into the tissue block.
- Applied force — the force the surgeon/robot applies; compared against the force required to cut at that depth.
- Tissue stiffness — soft / medium / firm tissue types (e.g. fat vs. muscle vs. fascia), raising the force needed for the same depth.
- Blade sharpness — sharper tools need less force for a clean cut and lower surrounding tissue stress.
- Auto cycle — sweeps the arm through a repeating insertion/retraction motion.
Real surgical robots (e.g. da Vinci-style systems) use force-feedback sensors at the instrument tip so surgeons can feel tissue resistance remotely and avoid excess force that tears rather than cuts.