A Study Of The Puborectalis-like Artificial Anal Sphincter

Fecal Incontinence(FI)is a common clinical condition,which causes many problems for patients due to the loss of self-control ability to the intestines.At present,there are various treatment options for FI,conservative treatment consists of dietary adjustment,drug treatment and enema,surgical treatment consists of sphincter angioplasty,muscle transplantation,sacral nerve stimulation,and enterostomy.However,due to the complicated operation,high incidence of complications and easy recurrence,artificial anal sphincter(AAS)is proposed,it mainly includes magnetic beads,water pump and memory alloy.After long-term clinical experiments,the current AAS does not have a sense function,and patients cannot control themselves according to the weight information of excreta in the intestine.Moreover,since the control is performed by clamping the rectum,it is easy to cause excessive local pressure in the intestine,thereby causing ischemia and necrosis.Therefore,the existing AAS is still immature and needs further improvement.This paper is supportted by the National Natural Science Foundation of China(No.61673271,No.81601631),Shanghai Research Project(No.15441903100)and China Postdoctoral Fund(No.2016M601587).Aiming at anal incontinence,a new treatment plan is proposed.It is a pseudo-pubic artificial anal sphincter system which establishes a system of constipation,so that patients can control defecation like normal people.It provides a new idea for solving FI.The main work of this paper includes the following aspects:1.Design a pseudo-pubic artificial anal sphincter system.This paper designs a new artificial anal sphincter system,which simulates the normal body control mechanism.The system drives the swing arm to move the rectum,so that the intestine forms a certain anorectal angle,and the patient completes the control.2.Complete the design of wireless power supply module.The system needs to be implanted in the body for a long time,so the energy supply method of wireless energy transmission is designed basing on human body safety.Under the condition of power demand of the receiving part,the transmission efficiency is optimized by changing the transmission angular frequency and the number of turns of the coil.It has been verified by experiments that the wireless energy transmission efficiency can reach 60% when the transmission distance is 10 mm.3.Completing the design and test of the wireless charging circuit.For the voltage regulator module,changing the original linear voltage regulation mode to DC/DC voltage regulation mode according to the actual situation of the system.4.Completed the design of the independent transmission system.In view of the problem of water seepage at the joint between the ring and the sleeve of the mechanism,the mechanism changes the original transmission mode,and separates the swing arm of the middle ring from the sleeve to form a self-contained independent transmission system.For the problem of water seepage at the joint between the center ring and the sleeve of the mechanism,changing the transmission mode by separating the middle ring from the sleeve and completing underwater test.5.Complete the design of pressure sensor package.In order to collect the pressure of the intestinal contents against the three rings,the pressure sensor,silicone gel and silicone membrane are packaged together to form a flexible pressure sensor system embedded in the three rings of the mechanism.The package has good biocompatibility and sealing.The silicone membrane is placed between the outer wall of the intestine and the pressure sensor,and the pressure sensing area is enlarged by the silicone membrane.Therefore,the package changes the sensing mode of the pressure sensor system from point contact to area contact.6.Completing the design of software system.The software system mainly includes a communication module,a control and defecation module,an internal pressure information acquisition module and a battery voltage information acquisition module.In order to extend the system's working time in the body,a low-power mode is designed.When the patient does not need to defecate,the system goes to sleep,thereby the system power consumption is reduced.7.Complete system assembly and experiments.Vitro experiments mainly include wireless energy supply experiment,constipation experiment,defecation experiment and control experiment,which are designed to verify the stability and sealing of the system in vitro environment.Animal experiments are designed to verify biocompatibility and system reliability in complex internal environment.