Abstract
Minimally invasive robotic surgery often requires functional tools that can change their compliance to adapt to the environment and surgical needs. This paper proposes a submillimeter continuous variable stiffness catheter equipped with a phase‐change alloy that has a high stiffness variation in its different states, allowing for rapid compliance control. Variable stiffness is achieved through a variable phase boundary in the alloy due to a controlled radial temperature gradient. This catheter can be safely navigated in its soft state and rigidified to the required stiffness during operation to apply a desired force at the tip. The maximal contact force that the catheter applies to tissue can be continuously modified by a factor of 400 (≈20 mN–8 N). The catheter is equipped with a magnet and a micro‐gripper to perform a fully robotic ophthalmic minimally invasive surgery on an eye phantom by means of an electromagnetic navigation system.
Highlights
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The controller sends a signal to the power drives, which apply a voltage to the heating wires embedded in the continuous VS (CVS) catheter
In order to investigate the relationship between the electrical resistance, the temperature, and the phase of the Low-melting point alloys (LMPAs), the CVS catheter was placed in a controlled environment
Summary
The retina is susceptible to physical damage that could be induced by the surgeon’s hand tremor or unintended movements, as well as sudden patient movements.[34] A functionalized catheter with adjustable compliance could increase the safety and precision of the procedure.[35,36] To achieve this, the CVS tool, with an outer diameter of 1 mm, was equipped with an automated microgripper and tested on an eye phantom to perform robot-assisted epiretinal membrane peeling. When we reach the desired area, the stiffness of the tool is increased such that we can apply forces to the tissue and close the gripper
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