Development of an instrumented laparoscopic grasper determine safe grasping thresholds by measuring pinching and pulling forces
Ali Ramezani (ET-BDDP), Izadyar Tamadon (ET-BDDP), Nico Verdonschot (ET-BDDP), Gabrielle Tuijthof (ET-BDDP)
Abstract
Several minimally invasive surgical procedures require a combination of pull and pinch forces to soft tissues by a laparoscopic tool. Depending upon the relative magnitude of these applied forces and the tissue's physical properties, the tissue might slip or damage. Safe grasping or damage prevention shows high importance while manipulating delicate tissues such as nerves or colon. However, our knowledge is limited in how human tissue properties influence the combination of safe pinching and pulling forces.
An instrumented laparoscopic grasper is developed capable of measuring pinching and pulling forces in real-time. The combination of these force measurements and the interchangeability of jaws and handles irrespective of their connecting design offers a distinctive instrument for quantifying safe grasping.
This instrument is equipped with a linear encoder and a miniature force sensor. These sensors are integrated inside a dedicated box in the middle of the tool shaft. This integration helps us to have real-time data on jaws angle and force on jaw’s shaft leading to estimate pinch force with a maximum error of 4 % and pulling force with a maximum error of 2 %.
The instrumented grasper's design allows for connection to a variety of hinge-mechanism jaws to evaluate the interaction between various jaws and tissues. We will use this instrument to compile a database of safe combinations of pinching and pulling forces to grasp various delicate human tissues such as nerves, and the colon. Grasper-tissue interaction data acquired with this setup can help to develop enhanced (robotic) graspers.