Even though technological advances have increased the application area of minimally invasive surgery (MIS), there are still hurdles to allow for widespread adoption for more complex procedures. The development of steerable instruments, in which the surgeon can alter the tip orientation, has increased the application area of MIS, but they are bulky, which limits their ability to navigate through narrow environments, and complex, which complicates miniaturization. Furthermore, they do not allow for navigating through complex anatomies. In an effort to improve the dexterity of the MIS instruments, while minimizing the outer dimensions, the previously developed cable-ring mechanism was redesigned, resulting in the thinnest, Ø2mm (Ø 1mm lumen), eight degrees-of-freedom (DOF) multisteerable tip for MIS to date. The multisteerable tip consists of four steerable segments of 2DOF stackable elements allowing for ±90 deg articulation, as well the construction of complex shapes, actuated by 16 Ø0.2mm stainless steel cables. In a proof-of-principle experiment, an ultrasound transducer and optical shape sensing (OSS) fiber were inserted in the lumen, and the multisteerable tip was used to perform scanning motions in order to reconstruct a wire frame in three-dimensional (3D). This configuration could in future be used to safely navigate through delicate environments and allow for tissue characterization. Therefore, the multisteerable tip has the potential to increase the application area of MIS in future, as it allows for improved dexterity, the ability to guide several tip tools toward the operation area, and the ability to navigate through tight anatomies.

In current bipolar electrosurgical instruments, a high frequency electrical sinusoidal wave is passed through the patient's body from an active electrode to the return electrode to cut, coagulate, or desiccate tissues. Even though current bipolar electrosurgical instruments have proven effective in minimizing blood loss, advancement is needed to allow for improved dexterity and adaptability. With current advances in threedimensional (3D)-print processes and its integration in the medical field, it has become possible to manufacture patient-and operation-specific instruments. In this study, we introduce the first 3D-printed steerable bipolar grasper (□ 5 mm) for use in minimal invasive surgery. The grasper significantly improves dexterity by the addition of two planar joints allowing for ±65 deg for sideways and ±85 deg for up- and downward movement. The joints enable a significantly higher bending stiffness, 4.0 N/mm for joint 1 and 4.4 N/mm for joint 2, than that of currently available steerable instruments. The tip consists of two metallic movable jaws that can be opened and closed with angles up to 170 deg and allows for grasping and coagulating of tissues; reaching tissue temperatures of over 75 °C for an activation time of ~5 s, respectively. In order to actuate the joint, tip, and electrosurgical system, as well as to tension the steering cables, a ring handle was designed. In summary, the 3D-printed steerable bipolar grasper provides the surgeon with electrosurgical capabilities, improved dexterity, improved stiffness, and the versatility that is needed to provide patient- and operation-specific care.

A typical mechanical failure mode observed in slender percutaneous instruments, such as needles and guidewires, is buckling. Buckling is observed when the axial compressive force that is required to penetrate certain tissue types exceeds the critical load of the instrument and manifests itself by sudden lateral deflection of the instrument. In nature, several organisms are able to penetrate substrates without buckling while using apparatuses with diameters smaller than those of off-the-shelf available percutaneous needles and guidewires. In this study we reviewed the apparatuses and buckling prevention strategies employed by biological organisms to penetrate substrates such as wood and skin. A subdivision is made between buckling prevention strategies that focus on increasing the critical load of the penetration tool and strategies that focus on decreasing the penetration load of the substrate. In total, 28 buckling prevention strategies were identified and categorized. Most organisms appear to be using a combination of buckling prevention strategies simultaneously. Integration and combination of these biological buckling prevention strategies in percutaneous instruments may contribute to increasing the success rate of percutaneous interventions.

In the field of vascular interventions, forward-looking intravascular ultrasound transducers (FL-IVUS) are needed for better visualization of complex lesions, such as chronic total occlusions. In this work, we propose a strategy for 3D imaging using a single-element transducer and an optical shape sensing fiber (OSS) in a steerable catheter tip. We evaluate the performance of the integrated device by imaging a six-wire phantom submerged in water. While steering the catheter tip across the wires, ultrasound and OSS data are acquired continuously. We combine the distance information obtained from the ultrasound data with the tip position and direction obtained from the OSS data to reconstruct the wires in 3D space. We quantify the accuracy of the imaging technique by the distance between the wires, and find a mean relative error of 36%. We discuss how this estimate can be further improved by modifications of the probe. This proof-of-principle test demonstrates the feasibility of FL-IVUS imaging using a single-element transducer integrated in a steerable catheter together with an OSS fiber.