Multi-Modal Mechanism for Enhancing Haptics and Safety in Handheld Surgical Grasping

Haptic feedback, which provides surgeons with interaction force information between instrument and tissue, is limited in handheld laparoscopic tissue graspers. Surgeons report difficulties to maintain precise control of the applied tissue forces when using state-of-the-art instrumentation, which is linked to accidental tissue trauma. Research describes the mechanical limitations of the conventional rigid-body mechanism tooltip design as culprit. This work replaces the conventional tooltip with a monolithic compliant mechanism that exhibits multi-modal stiffness properties to enhance haptic feedback and safety. Using experimental methods, the force transmission and input displacements are measured for the compliant tooltip and conventional tooltip. The authors compare representative metrics of grasping performance to demonstrate the transformation of the prior force-based control task into a position-based control task with amplified kinesthetic and cutaneous cues. As a prelude to user testing, the authors hypothesize several user benefits including the prevention of overloading and the enhancement of force sensitivity during tissue manipulation tasks.