Artificial Anal Sphincter System Based On Wireless Energy Transmission And Related Experimental Study

Fecal incontinence seriously affects the patient’s quality of life.Although the traditional surgical treatment has improved, the results areless than satisfactory. In recent years, artificial anal sphincter has beenproposed and implemented to provide the possibility to resolve theproblem of severe fecal incontinence. However, existing artificial analsphincter systems still have some defects like unable to detect the amountof feces nor control the defecation time independently, patients have tosqueezing the pump manually and most of them are very expensive. Todevelop the artificial anal sphincter to meet the physiological requirementshas become an important research direction of Biomedical Engineering.Supported by the National Natural Science Fund of China(NO.30800235), a third-generation of artificial anal sphincter system(AASS-III) has been studied, based on the results of second-generation ofartificial anal sphincter system (AASS-II) and previous research. AASS-IIIhas better user interface and more advantages. The research work is mainlyreflected in the following aspects.1. The external control and internal execution device both have beenupgrade.①Designed a new higher-speed wireless communication moduleto improve the stability and reliability of wireless communication.②Added a pressure storage module to record vivo rectal pressure data for along term. These data will help to summarize the motion law of rectum andchoose an appropriate close threshold for different patients.③Thesphincter prosthesis has became smaller and lighter and it is able to apply aforce on the rectum evenly, achieving continence within the safety pressure range of the human gut.④Studied the method for measuring the amountof feces in biological flexible bowel. Use a precise sensor to help patientsreconstruct rectal sensation.⑤With the rechargeable battery module,patients do not need to wear external transmitter module anywhere. Andthe power supply is able to keep stable when the wireless energy transferefficiency is influenced by some external factors.2. AASS-III has optimized the software architecture, developing acommunication agreement to achieve a better communication process. Inthis paper, both external and internal modules are integration and package.The internal module gathers circuit boards, micro-pumps and liquidstorage bags in one and seal with the silicone, improving thebiocompatibility of the system.3. Wireless energy transmission system based on electromagneticcoupling principle has been studied. Experiments are designed to find thebest transmission efficiency and maximum received power. Results showthat when two coupling coils have an axial displacement of9mm, no radialdisplacement nor rotation angle, the transfer efficiency reaches a maximumof84%.4. AASS-III has been implantable in a mini pig for15days. Thisexperiment verified the function of the sphincter prosthesis of AASS-III,the effect of wireless energy charging, system communication andbiocompatibility.AASS-III is able to simulate the normal sphincter, providing a newsolution for patients with severe fecal incontinence.