Design of Layer Jamming Liver Retractor for Surgical Access, Deployment, and Removal

Abstract

Retractors for laparoscopic surgery face competing challenges: they must be sufficiently soft/small to be (1) deployed and removed through a small opening and (2) manipulated into a desired configuration, but also (3) sufficiently rigid/wide to affix tissue atraumatically. Existing rigid designs are functional, but present the need for additional incisions and external anchoring. We developed a jamming-based foldable retractor capable of deployment, atraumatic anchoring within the body, retraction, and removal without the need for any additional incisions or surgeon involvement. Through FEA and experiments, including mechanical testing and in-porcine testing, we assessed the effect of different device cross-sectional areas on their ability to retract a liver. A patterned high-friction surface on one side of the device provides atraumatic anchoring to the abdominal wall, we compared different patterns, surface conditions, and preloads experimentally. To facilitate easy (i.e., low-force) removal, the device has a tapered end. When removed via the trocar, the taper causes the device to self-fold, with different tapers resulting in different removal forces. Validated by experimental testing and a in-porcine case study, our device demonstrates the ability of layer-jamming-based approaches to fill a hole in the current surgical toolkit and presents applicability beyond liver retraction.