| The importantance of sound defecation function is self-evident forhuman metabolism and detoxification, and human beings have alwaysbeen exploring the mystery of anorectum and techniques of redemption ofanal incontinence in the development of medicine. In recent years,domestic and foreign researchers have developed artificial anal sphincter(AAS) systems, which provide a new method for the clinical treatment ofanal incontinence. However, there are many defects in the prosthesisstructure, defecation warning, blood supply safety, control mode, price&cost, thus to design an artificial anal sphincter system in accordance withhuman body physiological requirement has become an important subject ofbiomedical engineering.Supported by the National Natural Science Fund of China(NO.30800235), and Medical Cross Fund of Shanghai Jiao TongUniversity (YG2011MS05), this paper further studed artificial analsphincter system to meet the requirements human physiology and keytechniques; completed work of structure optimization, functionalupgrading, performance improvement for each function in the prophaseresearch, and investigate system integration and packaging; developed athird generation of the AAS system and explored defecation sensationreconstruction.1. Research on pillar-bag-style anal sphincter prosthesis with uniformclamp pressure. Designed actuators combined with medical micro pumpand a liquid storage bag; explored the driving and control parameters, environmental adaptability and safety of blood supply.2. Design and optimization of hardware and software function of invitro and in vivo control system. Designed key modules as①pressure/temperature detection②Amplifier&ADC③S i4431wireless communi-cation④m icro-pump river⑤wireless powering⑥power management⑦S D storage⑧LCD⑨a larm⑩battery power detection. Formulatedcommunication protocol and programmed with ten kinds of functionalmodes.3. Defecation sensation reconstruction. Developed integrated anddie-style precise biological pressure sensor, with work in package design,pressure calibration, stability testing (resistance of water, pressure,temperature), signal acquisition and processing, threshold alarm algorithm;inserted a pressure sensor inside the prosthesis to detect intestinal pressurechange; explored the method in detection of fecal mass in vivo flexible gut,and established the correspondence between the amount of manure anddetection parameters, through in vitro and in vivo experiments.4. Designed wireless energy supply system based coupled resonanceprinciple.Optimized the efficiency and stability of the received power asthe goal; mainly studied the coil selection, transmission level, transmissionpath, obstacle influence and implantation in vivo experiment. Finally,results indicates that under the coupling of two spiral coils with diametersof6cm and3.5cm respectively and the intrinsic frequency of230KHz, theproposed system has achieved a satisfied coupling, with emission power2W and maximum transfer efficiency82%. Moreover, it can still provide arobust transfer efficiency of63%~75%under a percutaneous distance of10~15mm, meeting the power requirement of AASS abundantly.5. Exploration in system integration and packaging. Applied medicalsilicone rubber to encapsulate medical micro pump, a liquid storage bagand internal control circuit as an integration A, with package size5.5×4.5×2.5cm, weight115g; connected A to the prosthesis by medicalsilica gel tube. Integrated the energy receiving coil with a ferrite core, rechargeable lithium polymer battery, a charging control circuit asintegration B, with package size45×35×6mm, weight20g; implanted Bunder subcutaneous fat layer, and connected it with micro pump unit viasubcutaneous glue sealing wire. Sprayed the integration of A, B and Cuffwith clustering xylene.6. Evaluation on system functionality, security, stability andbiocompatibility by vivo experiments. In the process of a15-day living pigexperiment and another7-week beagle experiment, the animalssuccessfully survived the rejection period, and sphincter continence,wireless power charging, internal and external communication, andbiocompatibility were effectively validated, with relevant animalexperiments and postoperative management experience accumulated.Moreover, the X-ray imaging, anorectal manometry analysis, serumchemistry and histopathological analysis were conducted in beagleexperiment. Results of medical experiments indicate that AASS systemprovides a very promising and effective method in the treatment of severeanal incontinence. |
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