A Soft Laparoscopic Grasper for Retraction of the Small Intestine

Abstract

Laparoscopy can improve outcomes and patient re- covery times compared to open surgery. However, the minimally-invasive nature of these procedures deprives clinicians of tactile feedback which, when coupled with pinching graspers that deliver high-stress concentrations, increases the likelihood of inflicting iatrogenic trauma upon tissues, especially the small intestine [1]–[4]. Retraction of the small intestine is often necessary to vi- sualize and access nearby tissues [5], [6]. Commercially- available devices rely on passive structures to hold intestinal segments and do not embed compliance [7]. Prior research on surgical retractors has focused on granular jamming [5], pneumatic balloons [6], and either cable-driven [8] or vacuum [9] graspers. However, these devices are challenging to integrate into surgical work- flows, require auxiliary instruments, and do not provide feedback regarding tissue interaction forces. We introduce a laparoscopic grasper capable of passing through an 18 mm trocar, expanding to a controllable width once inside the abdominal cavity, and safely enveloping the small intestine to enable retraction. Upon entry into the abdominal cavity, the grasper estab- lishes an initial hold on a target intestinal segment by pulling vacuum through the suction unit on its distal tip (Fig. 1[a]); this functionality helps the surgeon isolate the target intestinal segment from surrounding bundles. Once a preliminary suction hold has been established, the grasper envelops the intestine by inflating a pair of pneumatic fiber-reinforced soft actuators (FRSAs) (Fig. 1[b]-[c]), whose separation can be modulated up to 40 mm using a miniaturized scissor lift mechanism (MSLM). This approach distributes the force necessary to grasp and hold the intestine over a large surface area (i.e., the whole surface of the FRSAs) rather than concentrating it in a small region, allowing safe, robust grasps even on dilated intestinal segments. Inflation of the FRSAs and suction are controlled using two buttons (Fig. 1 [d]). The horizontal position of the FRSAs and the separation between them are independently actuated via two linear motors, which the surgeon controls using a rocker switch and trigger, respectively (Fig. 1 [d]). Each actuator is equipped with two soft sensors to interpret 3D interaction forces via a machine learning algorithm.