Development of a Novel DNA-Inspired Continuum Joint (DICJ) for a Robotic Flexible Endoscopic Instrument

This article introduces a DNA-inspired continuum joint (DICJ) for enhancing the performance of flexible endoscopic instruments. The proposed joint mimics the structural properties of DNA molecules, including an outer helical structure and four coaxially nested inner helical backbones, improving compressive and torsional stiffness. This biomimetic design leverages a stable multihelix configuration to enhance mechanical properties, such as minimal stress concentration, improved flexibility for large bending angles, constant curvature, and high payload capacity. FEA-based simulations and kinematic analysis were conducted to optimize the structure, demonstrating superior stiffness and reduced parasitic motion. Experimental investigations on the structural performance revealed excellent constant curvature characteristics, with a maximum bending angle of 242.7°, and significantly improved torsional and axial stiffness ( $1.324~\text {mN} \cdot \text {m}$ /° and 2.948 N/mm, respectively). The DICJ joint exhibited a maximum payload capacity of 10 N. Experiments on visual coverage and obstacle avoidance showed enhanced dexterity and expanded the surgical field of view, validating the potential of the DICJ joint for minimally invasive surgery, with notable improvements in workspace and loading capabilities.