Research On Specimen Extraction Methods And Instrument Design In Natural Orifice Transluminal Endoscopic Surgery Based On Braided Structure

As a new surgical approach,Natural Orifice Transluminal Endoscopic Surgery(NOTES)has the advantages of light pain,quick recovery and no scar on the body surface,demonstrating bright development prospect.Due to the type and size of the human natural orifice,there are many ethical obstacles and technical difficulties that hinder the development of NOTES.In view of the difficulty in extracting specimen tissues in NOTES,we have carried out some theoretical analysis and experimental research based on the braided fiber structure,and we propose several device design schemes with the function of autonomously capturing specimen in this paper.The specific contents of this paper are as follows:Firstly,a method using the braided fiber tube to extract specimen via a channel of the surgical platform is proposed based on the excellent telescopic characteristics of the braided structure.Based on the theory of spiral spring,the geometric model of braided fiber tube is established.According to the geometric model,we can select a braided fiber tube which has the suitable initial parameters to the diameter of the extracted specimen.The mechanical behaviors of the braided fiber tube that carries a large specimen through the narrow passage is analyzed and the corresponding mechanical model is also established.Then,according to the characteristics of NOTES and the method of wire-driven,several design schemes for specimen extraction instruments are proposed.In order to make the instrument have the function of autonomously capturing the specimen tissues,we propose the method for fabricating a special shape braided structure and other methods for using accessibility tools to assist in capturing the specimen.By contrast,a vacuum-driven suction cup is selected to assist in capturing the specimen tissues,and a prototype is made according to the corresponding device design.Finally,relevant experiments are carried out on the established theoretical models and the prototypes.The results of monofilament-driven braided fiber tube bending experiment show that the braided fiber tube suffers from obvious hysteresis and complete rebound errors during the bending rebound process.The theoretical model verification experiment proves that the model accuracy can reach 85 % when the slip force is not less than 1 N.The results of the specimen extraction from the narrow channel show that the diameter of the extractable specimen does not exceed 1.75 times the diameter of the channel,and the braided fiber tube with a wire diameter of 0.5 mm can withstand tension force above 24.43 N without any damage.The simulation experiment of the prototype proves that the method of actively capturing the specimen by the suction cup and carrying the specimen through the narrow channel by the braided fiber tube is completely feasible.