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Minimally Invasive Surgery (MIS) has advanced in the last two decades due to its benefits, such as shorter hospitalization, reduced tissue trauma, and quicker re- covery times 1, 2. Neurosurgical MIS procedures such as biopsies, ablations, and fluid delivery/extraction often use straight catheters. The efficacy of these procedures depends on precise surgical area targeting and avoid- ing harm to surrounding tissues. Repeated instrument retraction and reinsertion can cause more tissue damage, making the procedure challenging 3. Robotic steerable needles have become increasingly pop- ular because they can overcome the limitations caused by operator error or catheter deflection 4 and can provide access to complex anatomical features that were previously difficult to target. Development of our robotic platform for precision neurosurgery, EDEN2020 (see Fig. 1), aimed to assess the potential of Convection Enhanced Delivery of chemotherapeutics along preferential path- ways that align with anisotropic brain structures 5. The system’s architecture and surgical workflow were tested in pre-clinical trials using the ovine model. The implan- tation was safe and demonstrated appropriate function 5. The robotic platform uses bio-inspired steerable Pro- grammable Bevel-tip Needles (PBN) with an outer di- ameter of 2.5mm. We have been working on reducing the size of PBNs using advanced thermal drawing tech- nology. This allows us to create significantly smaller catheters, with a 1 - 1.3mm diameter, compared to traditional ones. These smaller needles lead to more precise and effective catheters 6, but pose important challenges with actuation, owning to the tiny joining surfaces involved. In the current ecosystem, lead screw mechanisms are utilized to drive each needle segment. These mechanisms are attached to wing-like structures on the surface of the segments. In a surgical setting, the PBN must be positioned close to the patient skull. However, due to size and weight limitations, the large volume and high weight of the lead screw design require the actuator to be located at the base of the robot, with flexible transmission links used to transfer the motions to the needle segments. To overcome this challenge, an alternative solution based on friction and a gear-like assembly, used to maximise the transfer of contact forces, is proposed here, to achieve a lighter and more portable drive system, suitable for our new generation of small-sized PBNs. As slip is an important consideration when employing friction to create motion, a criterion for measuring and quantifying slip, which we then utilize to investigate different designs for the needle and gears.
Aktaş et al. (Tue,) studied this question.