人工肛门括约肌夹持机构的设计与优化

Design and optimization of an artificial anal sphincter clamping mechanism

针对现有人工肛门括约肌夹持机构存在生物相容性低、响应时间长的缺点,本文基于排便机制及力学特点,设计了一种新型封闭连杆式人工肛门括约肌(Novel Closed-link Artificial Anal Sphincter,NCAAS)的夹持机构。NCAAS夹持机构由基于沟槽凸轮摆杆的传动机构的三组交错叠放的夹持臂组成。为研究生物相容性与响应时间,本文根据虚功原理推导夹持臂的夹持力方程,并通过有限元分析夹持臂与肠道的力学特性。仿真所得机构控便时最大夹持力为1.6 N,肛肠角为62.2°~95.2°,满足人体日常控便需求。所制得NCAAS原型机质量55.19 g、高度42.7 mm、机构总长度不大于68.2 mm,平均响应时长为7.25 s。本文还通过猪大肠离体实验验证了NCAAS夹持肠道的生物相容性,最终控便量达700 g、肛肠角小于90°。NCAAS小型轻巧,生物相容性良好,响应时间较传统人工肛门括约肌大幅度缩短。

The existing artificial anal sphincter clamping mechanism has the disadvantages of low biocompatibility and long response time.Based on the defecation mechanism and physiological structure,this paper discusses the design of a Novel Closed-link Artificial Anal Sphincter(NCAAS)clamping mechanism.The NCAAS clamping mechanism consists of three sets of interlaced clamping arms and a transmission mechanism based on groove cam swing rods.To study its biocompatibility and response time,the clamping force equation of the clamping arm was derived from the principle of virtual work,and the processing of the finite element in instantaneous dynamic simulation.During simulated stool control,the maximum clamping force of the NCAAS is 1.6 N,and the anorectal angle is in the range of 62.2°~95.2°,which meets the demands of human daily stool control mass.The weight of the NCAAS prototype is 55.19 g,with a height of 42.7 mm and length of 68.2 mm.The response time of the improved system is 7.25 s.An in vitro experiment with a pig colon verified the biocompatibility of the NCAAS,which draws the result of a 700 g controlled stool mass at an anorectal angle of less than 90°.The NCAAS is small and light,with better biocompatibility and a response time that is significantly shorter than that of traditional artificial anal sphincters.