Design And Optimization Of The Puborectails Muscle-like Artificial Anal Sphincter And Experimental Studies

Although fecal incontinence(FI)is not a fatal disease,it seriously affects the patient's quality of life.In recent years,the implantation of artificial anal sphincter(AAS)has become a popular research topic in the treatment of FI.Although the existing AAS system can meet the basic requirements of daily defecation control for FI patients,but the method of defecation control does not follow the physiological rules,and the lack of defecation awareness function seriously limits the effect of AAS in the treatment of FI.In addition,the lack of research on highperformance energy supply methods that meet the requirements of biosafety leads to the low level of intelligence,inconvenient operation and potential safety risks of AAS system.In view of the above defects,an intelligent AAS system that follows the characteristics of physiological defecation,can reconstruct the defecation perception of FI patients,and has a safe and stable energy supply will become the research direction in the field of FI treatment.Sponsored by NSFC(81971767,61673271)and Shanghai Science and technology research projects(19441910600,19441913800,19142203800),this paper studies a new intelligent puborectails like artificial anal sphincter(PAAS)system based on the bionic holding prosthesis,high performance transcutaneous wireless energy transmission(TET)and the function of rectal perception reconstruction with pressure sensor sampling.The specific work is divided into the following six aspects:a)Based on the characteristics of human defecation,defecation control and the physiological structure of excretion system,combined with the principles of bionics,mechanical strength design,transmission design and seal design,the mechanical clamping "three ring" prosthesis of PAAS system is studied.Through theoretical design optimization and experimental research,the maximum output of pubic like "three ring" prosthesis is 6.31 N ? m torque,and the maximum defecation control volume is more than 600 g.it can meet the daily defecation control needs of FI patients within 6 k Pa of blood supply safety pressure and the defecation control time is only 6-8 s.In addition,the sealing performance of the prosthesis can ensure that it can complete the clamping in 80 cm water depth without leakage.b)In order to improve the ability of anti accretion of PAAS prosthesis and extend the working time after implantation,the process of accretion and growth of prosthesis surface was deeply studied and the reasons of accretion affecting prosthesis working were analyzed.Three methods were used to optimize the prosthesis,namely,improving the torque output of prosthesis transmission structure,replacing the prosthesis manufacturing materials and increasing the isolation shell.Finally,the working time of the prosthesis in vivo was extended to 220 days,which was longer than that before optimization Increase by 214%.c)Based on the defects of the existing TET wireless charging module in the in vivo experiment,through the electromagnetic theory analysis and the circuit link model calculation,combined with the finite element method(FEM)simulation,the parameters affecting the wireless energy transmission performance of Tet are studied and optimized to improve the wireless charging power and efficiency under the weak coupling condition after implantation.After theoretical analysis,simulation and experimental verification,the energy emission of the optimized TET wireless charging module is improved to a series resonant circuit.The parameters of the transmitting coil and the receiving coil are Litz wire diameter 0.05 mm,number of strands 250,outer diameter 45.2 mm,inner diameter 12.3 mm,number of turns 17,and thickness of magnetic separator 0.8 mm.When the transmission distance is 15 mm,6 w power can be provided for the load end,and the energy receiving efficiency of the load end is up to 4 5.5% and can provide 2.5 w power for the system load to meet the system charging and working power requirements under the extreme condition of 30 mm transmission distance.d)In order to ensure the biosafety of the optimized tet wireless charging module,on the one hand,the electromagnetic radiation in the process of Tet wireless charging is analyzed by finite element simulation,and it is determined that the radiation meets the biosafety requirements.On the other hand,through indepth study of the causes of the heating of the charging circuit in the charging process,the charging circuit is optimized to reduce its heating capacity by42.6%.In addition,the thermal resistance model is used to analyze the heat transfer process of the charging circuit,and the upper limit of the wireless charging duration of Tet is reasonably planned to be 32 minutes,so as to avoid the burning of living organs and skin caused by long-term charging.e)This paper analyzes the characteristics of pressure sensor in PAAS system for pressure sampling of intestinal contents,establishes a pressure calculation model,combines the relationship between the quality of intestinal contents and the pressure generated,expands the pressure calculation model to a quality calculation model,and realizes the convenience reconstruction function.In vivo experiments show that the highest accuracy of mass calculation model is92%,and the accuracy of convenient reconstruction is 83%.f)Three generations PAAS systems were produced and the biocompatibility and biosafety of in vivo subsystem were verified by in vivo experiment.By analyzing the blood routine indexes and weight growth of the experimental subjects,the biological safety of the prosthesis of the internal subsystem was verified to be good;the biological safety of the energy supply module of the internal subsystem was verified to be good according to the changes of the struggling times and the skin burns of the experimental subjects during the charging process before and after the optimization of the energy supply module;the biological safety of the internal subsystem was analyzed by the staining test of the internal tissue section The biocompatibility of the prosthesis and the energy supply module was verified.In view of the deficiency of the existing AAS system,from the research background and design proposal to the solution and implementation of key technologies,combined with theory,simulation and experiment,the paper finally completed the physical construction of PAAS system,providing complete theoretical basis and design experience for the research of the intelligent AAS system,improving the convenience,reliability and safety of the AAS system,and further improving the treatment of FI disease by the AAS system The clinical application value of the disease enriches the treatment means of FI disease.