A bio-inspired expandable soft suction gripper for Minimal Invasive Surgery - an explorative design study.

Gripping slippery and flexible tissues during Minimal Invasive Surgery is often challenging using a conventional tissue gripper. A force grip has to compensate for the low friction coefficient between the gripper's jaws and the tissue surface. This study focuses on the development of a suction gripper. This device applies a pressure difference to grip the target tissue without the need to enclose it. Inspiration is taken from biological suction discs, as these are able to attach to a wide variety of substrates, varying from soft and slimy surfaces to rigid and rough rocks. Our bio-inspired suction gripper is divided into two main parts: 1) the suction chamber inside the handle where vacuum pressure is generated, and 2) the suction tip that attaches to the target tissue. The suction gripper fits through a trocar with 10 mm diameter and unfolds in a larger suction surface when being extracted. The suction tip is structured in a layered manner. The tip integrates five functions in separate layers to allow for safe and effective tissue handling: 1) Foldability, 2) Air-tightness, 3) Slideability, 4) Friction magnification and 5) Seal generation. The contact surface of the tip creates an air-tight seal with the tissue and enhances frictional support. The suction tip's shape grip allows for the gripping of small tissue pieces and enhances its resistance against shear forces. The experiments illustrated that our suction gripper outperforms man-made suction discs, as well as currently described suction grippers in literature in terms of attachment force (5.95 ± 0.52 N on muscle tissue) and substrate versatility. Our bio-inspired suction gripper offers the opportunity for a safer alternative to the conventional tissue gripper in Minimal Invasive Surgery.