Design, Fabrication and Testing of a Thin-Film Soft Robot with Multiple Degrees of Freedom to Expand the Reach of Open and Endonasal Skull Base Approaches

Introduction: Current robotic developments in neurosurgery primarily involve rigid robotic devices, aiding surgeons in placing spinal hardware and guiding electrodes toward brain targets. These robots lack the flexibility to navigate narrow anatomical spaces, are costly, cannot turn corners, and would exert excessive force when dissecting and retracting brain tissue. Consequently, the use of robots for complex procedures involving the manipulation of delicate structures, such as those found in skull base, remains limited. Soft pouch manipulator devices can overcome some of these challenges, as their materials and mechanisms confer great flexibility and biocompatibility. Here, we present a novel soft robot prototype, manufactured with technology developed by the authors, aiming to introduce soft robotics to the skull base armamentarium.

Methods: A soft pouch manipulator was created using a novel rapid and scalable system called IMPRINT (Integrated Multi-layer Pouch Robots with INkjetpatterned Thin-films). Made from four layers of thin LDPE films, the manipulator has a thin deflated profile (152 μm), allowing it to fit into tight spaces which would be difficult for other soft robots ([Fig. 1]). The manipulator also contains five joints capable of bending up to 50 degrees in either direction, with each joint operating independently. The robot carries a camera and channels for working tools. Four cadaveric models were used to evaluate the efficacy of our robotic prototype in navigating anatomical structures during simulated endonasal and posterior fossa approaches.

Fig. 1

Results: The proposed robotic prototype is a soft continuum manipulator with 12 control inputs and 6 independently controllable degrees of freedom ([Fig. 2]). This design enables in-plane obstacle avoidance and orientation control. The robot is trapezoidal-shaped, with a total weight of 0.4 g, a 10-mm-wide distal end, a 42mm-wide proximal end, and a length of 138mm. The total production cost of the manipulator is $2. The manipulator demonstrated its potential use for anterior skull base approaches by entering the maxillary sinus and navigating the endonasal corridor ([Fig. 3]). It also successfully navigated around the pons in a simulated retrosigmoid approach ([Fig. 4]).

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Conclusion: The robot described here offers a promising solution for safely navigating the narrow corridors encountered during skull base approaches. The multiple bending points of the robot also allow it to turn around immovable structures, expanding the reach of current skull base surgery. The cost-effectiveness and rapid production of the soft pouch robotic arm are significant advantages for its use in neurosurgery; in addition, considering the robot is capable of passive deformation and elicits negligible tangential forces, it could be used to perform painless outpatient paranasal sinus biopsies that currently need general anesthesia, further amplifying the cost-effectiveness reach of this technology.