Research On The Friction Behavior At Endoscope Tube-esophageal Mucosal Tissue Interface

In nature orifice transluminal endoscopic surgery(NOTES)or endoscopic examination procedure,because of the bending characteristics of the natural cavity,the actions such as retracting,reversing,or even rotating endoscope will led to extruding,stretching,and friction at the tube and esophageal tissue interface during insertion process,which will cause damage to the esophageal mucosal tissue.This article studied the friction characteristics between endoscopic tube and esophageal mucosa under different operating conditions by simulating the NOTES or endoscopic examination process.The main research methods and conclusions are summarized below.1.By simulating the esophageal environment,the effects of different lubricants on the surface of the esophageal mucosal tissue on the wettability of the endoscope tube and the adhesion work were studied.The results show that the smaller the surface free energy and contact angle of the lubricating medium is,the better the wettability and the smaller the adhesion work will be.2.Simulated endoscope compression and stretching of the esophagus surface,the axial and radial tensile properties of the esophageal mucosal tissue and the compressive properties of the esophageal tissue in the middle are tested.The results show that the axial tensile stress of the esophageal mucosal tissue is greater than that of the radial direction.Because the epithelial tissue of the mucosal surface is arranged in a pleated manner in the radial direction,this gives the esophageal mucosal tissue a large tensor in the radial direction.Both the tensile stress of the mucosal tissue and the compressive stress of the middle segment of the esophagus tissue increase with the increase of the velocity,and the stress increasing rate(Vstress)is greater than the strain increasing rate(Vstrain),which is determined by the viscoelasticity of the tissue.3.By simulating the endoscope operation,the frictional behaviors of the tube and esophageal mucosal tissue interface are studied under different normal loads,sliding speeds and lubricants(lidocaine hydrochloride,artificial saliva,artificial gastric juice,and physiological saline).The results are shown below.a.The friction coefficient at the interface between the tube and the esophageal mucosal tissue decreases with the increasing of the normal load.This is mainly due to the increasing of load,which resulting in an increase in the average contact stress(P);and this is the reason why the adhesion friction coefficient(?adh)diseases.And the deformation and hysteresis characteristics of the esophageal mucosal tissue is resulted in the decrease of its deformation coefficient of friction(?def)with increasing normal load.Therefore,the total friction coefficient(?)decreases with increasing normal load.b.The coefficient of friction at the interface of the esophageal-esophageal mucosa increases with the increase of the sliding speed.This is mainly due to the fact that the interface is fluid-lubricated,and the deformation coefficient of friction(?def)increases with the increasing of the sliding speed.The increase in speed results in an increase in the deformation of the mucosal tissue,which leads to an increase in the contact surface.The larger contact area will also lead to an increase in the coefficient of adhesion friction(?adh).Therefore,the total friction coefficient(?)increases as the sliding speed increases.c.In the four kinds of lubricating media,the relationship between the friction coefficient,friction force and energy consumption is:lidocaine<artificial saliva<saline<artificial gastric juice,which is mainly related to the wettability and adhesion work between the lubricant medium and the tube.Lubricating media with good wettability and low surface free energy have better lubrication characteristics and lower adhesion work,and can effectively reduce the interfacial adhesion friction coefficient(?adh)and deformation friction coefficient(?def),so it will effectively reduce the overall friction coefficient(?)between the low-column-esophageal mucosal tissue interfaces.