Deployable Manipulator with Tunable Stiffness for Natural Orifice Transluminal Endoscopic Surgery

Natural orifice transluminal endoscopic surgery(NOTES) has great potential in clinical applications due to its shorter and better recoveries, less trauma and postoperative pain compared with open surgery. In NOTES, a long manipulator is always placed through a tortuous human orifice to create a channel for surgical instruments and provide support when they are operated. Currently most manipulators have a large profile and low stiffness, and therefore are not able to meet the requirements of NOTES. A new deployable manipulator with tunable stiffness is proposed. The manipulator takes a braided structure to achieve radial deployment/folding, whereas hot melt adhesive is placed at the intersection points of the structure to adjust its stiffness. A mathematical model is built to calculate the stiffness in the rigid and flexible states, respectively. Experimental results demonstrate that by heating and cooling the adhesive, a flexible and a rigid states are achieved, and the ratio of bending stiffness in the rigid