LOKI: Laparoscopic Operational Kinematic Instrument

Laparoscopic surgery is an accepted surgical technique that is capable of improving patient outcomes when compared to open-surgery. However, one standing challenge is obtaining and maintaining an adequate field of view of the operative area through retraction. This paper presents LOKI, a laparoscopic operational kinematic instrument for surgical retraction that uses phase changing material (PCM) to switch between high dexterity and high stiffness. In this paper, we identify the clinical requirements, define the corresponding geometrical parameters of the PCM, propose a design for the arm and thermal management system of the thermal fluid, and perform thermal analysis using computational fluid dynamics to evaluate the phase transition time of the PCM across multiple flow rates. We demonstrate that despite the arm's relatively large size and thermal mass compared to prior art, the proposed thermal conduit permits an adequate thermal response. Observed computationally is a minimum phase transition time of 27 s for liquefaction and 14.5 s for solidification using a flow rate of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$20\left[\frac{\mathrm{L}}{~\min}\right]$</tex>.