I just had a Zoom talk with Ethan Wilke, Jain Aabhas and Alejandro Chara, a research team from Vanderbilt university (https://www.medicalengineeringlab.com/), Nashville, Tennessee. They are working on a project in the frame of NIH sponsored research.
Their latest work focuses on what is known as needlescopic robots. Needlescopic surgery is generally defined as the use of surgical instruments measuring 3 mm or less in diameter. Although this idea has existed for decades, miniaturisation has always come at a price. As instruments become smaller, they usually lose dexterity, stiffness and, above all, grasping strength. For surgeons, this is a familiar compromise. A tiny instrument is attractive because it reduces tissue trauma and expands the possibilities for minimally invasive surgery in small surgical fields, but if it cannot reliably retract tissue, manipulate needles or perform blunt dissection, its clinical usefulness becomes limited. The Vanderbilt team decided to challenge that compromise.
The result is remarkable: a 3 mm wristed robotic grasper capable of generating grasping forces that exceed those of the much larger da Vinci instruments, while maintaining excellent torsional stiffness and active opening for blunt dissection.
What makes the project particularly elegant is that the performance does not come from simply increasing motor power. It comes from rethinking the mechanics of the instrument itself. Rather than relying on traditional tendon-driven actuation, the design uses a push-pull Nitinol tube combined with a novel cam mechanism that efficiently amplifies force at the jaws. Nitinol is a nickel-titanium alloy well known for its superelasticity and shape-memory properties, which has become one of the enabling materials of modern continuum robotics because it can undergo large elastic deformations while maintaining excellent fatigue resistance.
This grasper was conceived as the end-effector for concentric tube robots (CTRs), one of the most promising families of continuum robots currently being developed for surgery. Unlike conventional articulated robotic arms, concentric tube robots are constructed from nested pre-curved Nitinol tubes that rotate and translate relative to one another. By combining these simple motions, the robot can generate smooth, snake-like trajectories capable of navigating confined anatomical spaces with extraordinary dexterity.
Another feature is the instrument’s central working lumen. Because the actuation mechanism does not occupy the centre of the instrument, an open channel remains available throughout the device. This creates exciting possibilities. A laser fiber, for example, could be delivered directly through the instrument, but the same channel could also accommodate suction, irrigation, or other therapeutic tools.
Over the last twenty years, robotic surgery has largely been defined by increasingly sophisticated articulated robotic arms. Today, another direction is emerging. Around the world, researchers are investing in continuum robots, snake robots, flexible robotic arms and concentric tube systems capable of reaching anatomical targets that remain difficult (or impossible) for conventional robotic platforms. Rather than replacing existing systems, these technologies are likely to complement them, extending robotic surgery into increasingly narrow and complex anatomical corridors.
Perhaps the most inspiring part of the conversation was seeing how naturally surgeons and engineers worked together throughout the project. This is exactly how meaningful innovation happens. Surgeons identify the clinical problems that remain unsolved. Engineers rethink the underlying mechanics. Together, they create technologies that neither discipline could have developed alone, and that may ultimately find their way into the operating room.
J Granell. Jul 1, 2026
Reference
Wilke ER, Aabhas J, Chara AO, Herrell SD, Zamora IJ, Lovvorn HN, Webster RJ. The First Needlescopic Wristed Grasper to Surpass da Vinci Grasping Performance. 2026 International Symposium on Medical Robotics (ISMR) 2026: 179-184. DOI: 10.1109/ISMR69606.2026.11536216