Design of a Polymer-based Steerable Cannula for Neurosurgical Applications

Robotically steerable compliant surgical tools offer several advantages over rigid tools, including enhanced dexterity, reduced tissue damage, and the ability to generate non-linear trajectories in minimally invasive neurosurgical procedures. Many existing robotic neurosurgical tools are designed using stainless steel or nitinol materials. Using polymer-based materials instead can offer advantages such as reduced interference in magnetic resonance imaging, enhanced safety for guiding electrically powered instruments, and reduced tissue damage due to inherent compliance. Several polymer materials have been used in robotic surgical applications, such as polyimide, polycarbonate, and elastic resin. Various fabrication strategies have also been proposed, including standard microfabrication techniques, thermal drawing, and 3-D printing. In our previous work, a tendon-driven, notched-tube was designed for several neurosurgical robotic tools, utilizing laser micromachining to reduce the stiffness of the tube in certain directions. This fabrication method is desirable because it has a single-step process, has high precision, and does not require a cleanroom or harsh chemicals. Past studies have explored laser-micromachining of polymer material for surgical applications such as stent fabrication. In this work, we explore extending the use of the laser micromachining approach to the fabrication of polyimide (PI) robotically steerable cannulas for neurosurgical applications. Utilizing the method presented in this work, we fabricated joints as small as 1.5 mm outer diameter (OD). Multiple joints were fabricated using PI tubes of different ODs, and the loading behavior of the fabricated joints was experimentally characterized.

Evaluating the Navigation Capabilities of a Modified COAST Guidewire Robot in an Anatomical Phantom Model

To address the issues that arise due to the manual navigation of guidewires in endovascular interventions, research in medical robotics has taken a strong interest in developing robotically steerable guidewires, which offer the possibility of enhanced maneuverability and navigation, as the tip of the guidewire can be actively steered. The COaxially Aligned STeerable (COAST) guidewire robot has the ability to generate a wide variety of motions including bending motion with different bending lengths, follow-the-leader motion, and feedforward motion. In our past studies, we have explored different designs of the COAST guidewire robot and developed modeling, control, and sensing strategies for the COAST guidewire robot. In this study, the performance of a modified COAST guidewire robot is evaluated by conducting navigation experiments in an anatomical phantom model with pulsatile flow. The modified COAST guidewire robot is a simplified version of the COAST guidewire robot and consists of two tubes as opposed to three tubes. Through this study, we demonstrate the effectiveness of the modified COAST guidewire robot in navigating the tortuous phantom vasculature.