A Novel Variable-Diameter-Stiffness Guiding Sheath for Endoscopic Surgery

In natural orifice transluminal endoscopic surgery, instruments such as endoscopes can be flexibly advanced into the human colon or stomach via tortuous natural orifices. However, the insertion of endoscope causes great discomfort to the patient, resulting in vomiting, bleeding and even perforation. In this letter, we propose a novel variable-diameter-stiffness guiding sheath that can be compatible with flexible endoscopes for stable and safe endoscopic procedures. The sheath uses a foldable hose in conjunction with airbag to allow variable diameter for smooth passage of endoscopic instruments. The sandpaper jamming mechanism enables a rapid transition of the guiding sheath from flexible state to rigid state, providing a stable and robust support for endoscopic instruments. Experimental results showed that the outer diameter of the guiding sheath can be expanded from 13.6 to 21 mm, providing an inner access up to 14.6 mm (achieves a radial folding ratio of 3.24) for endoscopic instruments. The sandpaper jamming mechanism achieved a stiffness gain of approximately 10.67. Phantom experiments validated the effectiveness and usability of the guiding sheath in assisting endoscope insertion, demonstrating the potential clinical value of the guiding sheath.