Count the joints everyone films, and you assume a robot arm is a stack of rigid links. US10912620B2, granted to Vanderbilt University in February 2021, describes the alternative: a continuum 'snare tool' manipulator that bends along its whole length like a tentacle rather than pivoting at discrete joints.
The mechanical philosophy is the story. A conventional manipulator gets its dexterity from stacking precise rotary joints; a continuum manipulator gets it from a flexible body that curves to reach around obstacles. Classified in the A61B surgical-robotics family with continuum-structure claims, the design trades the crisp repeatability of rigid joints for the ability to thread into spaces a rigid arm cannot enter.
Here is the trade, stated fairly. Rigid arms know exactly where their tip is because geometry is simple; continuum arms are harder to model and control precisely, because a flexible body's shape depends on loads and friction along its length. You buy reach and compliance with precision and modeling difficulty.
The honest limit is control. A continuum manipulator's strength — it conforms — is also its control headache, because the same flexibility that lets it snake around an obstacle makes its tip position uncertain. The patent's value is in the mechanism that makes such a flexible tool controllable enough to do useful work.
This sits in a lineage that runs from surgical robotics into the soft-robotics work that followed, where compliance is a feature, not a bug. It is a counterpoint to the rigid-actuator humanoid orthodoxy: not every manipulation problem is best solved by more, stiffer joints.
For readers auditing manipulation claims, the continuum approach widens the question. The right one is not just 'how many degrees of freedom,' but 'rigid or compliant, and why' — because the answer reveals what kind of task the designer actually expects the robot to face.