Soft Magnetically Steerable Suction Device for Endoscopic Endonasal Brain Tumor Extraction

This paper introduces a soft, magnetically steerable suction (MSS) device for brain tumor extraction via the endoscopic endonasal approach. The device integrates a soft end-effector into a rigid, straight suction device, enhancing maneuverability and safety during minimally invasive neurosurgery. The soft tip’s design, made from Ecoflex 00-50 silicone with an embedded permanent magnet for magnetic actuation, was optimized through experimental testing of various geometries and materials and then fabricated using a four-part mold. Magnetic steering capabilities were tested using an electromagnet coil system with uniform magnetic fields ranging from -25 mT to 25 mT. A mechanical model was also developed based on constant curvature kinematics, which predicts the bending angle. The model’s accuracy was validated using image segmentation of the soft tip’s centerline against the experimental setup. Tensile tests were performed according to ISO-37 standards to determine the mechanical properties of Ecoflex 00-50, which were then used in non-linear FEA simulations. The FEA results are closely aligned with experimental data, validating the equivalent mechanical properties of the entire suction device and enabling future simulations of various loading conditions. The MSS device achieved over 90° of bending under applied magnetic fields of 25 mT, with an equivalent Young’s modulus of 0.273 MPa enabling controlled deformation. The device demonstrated suction capabilities of 80-90 kPa through its 1.8 mm diameter channel, providing approximately 0.23 N of suction force at the tip. The mechanical model predicted the bending behavior with a mean fit error of less than 1% (0.76 mm), validating its accuracy for surgical planning.