体外膜肺氧合经编膜织物自适应张力的低损伤制备

Low-damage preparation of extracorporeal membrane oxygenationwarp knit membrane fabrics with adaptive tension

针对体外膜肺氧合(ECMO)系统中使用的氧合膜织物国产化制备技术难题,进行了ECMO系统用经编膜织物低损伤制备及其透气性能研究。采用特种特里克型经编机开展了不同送经量下的氧合膜织物制备实验,分析了聚甲基戊烯(PMP)中空纤维膜丝的编织损伤机制;提出一种自适应张力控制下的ECMO系统用氧合膜织物低损伤制备方法,对比分析了采用该方法制备的氧合膜织物性能指标。实验结果表明:基于氧合膜织物提出的自适应张力控制方法可有效调控经纱张力的“削峰补谷”缺陷,实现氧合膜织物的低损伤制备;用该法制备的ECMO系统用氧合膜织物纵密为20横列/cm,编织位置外径损失3%,强力损失5%;编织前后N 2通量衰减17%,CO_(2)通量衰减12%,O_(2)通量衰减14%;同时,氧合膜织物平整度、密度、气通量等均已达到国外同类产品水平。

Objective Extracorporeal membrane oxygenation(ECMO)is used to provide continuous extracorporeal blood oxygenation to patients with severe cardiopulmonary failure to maintain the patients′life.The ECMO device consists of an oxygenator,a centrifugal pump,and a control system,of which the oxygenator is the core component for accomplishing the blood oxygenation.This study addresses the problem of technological gaps in the preparation of separation membrane fabrics for oxygenators and presents a study on the low-damage preparation of ECMO membrane fabrics based on warp knitting technology.Method Through the stitch analysis of membrane fabrics made from polymethylpentene(PMP)hollow fibers membrane,the parameters such as knitting stitch,yarn type and other fabric specifications of membrane fabrics were determined.The knit fabrics were manufactured on the special Tricot warp knitting machine from PMP hollow fiber membrane.Based on the experimental results and the understanding of the knitting equipment,warp yarn tension was identified as one of the main influencing factors affecting the damage of the PMP hollow fiber knitting.An adaptive warp yarn tension control method was proposed with the Tricot warp knitting machine through the PID control strategy design and the fifth degree polynomial curve planning,aiming to achieve low-damage knitting of PMP hollow fiber.Results The results showed that the damage of prepared ECMO membrane fabrics was mainly caused by the mismatch of yarn demand between the warp feed and knitting action at constant speed.The knitting tension amplitudes at 900,1000,and 1100 mm/rack warp feed were 28,23,and 19 cN,respectively,which led to the attenuation of PMP hollow fiber strength,outer diameter,and air flux.The ECMO membrane fabrics were prepared using the adaptive tension control method.The warp tension amplitude in a single cycle was regulated from 2.4-23 cN to 3-10 cN at the warp feed of 1000 mm/rack,and the tension fluctuation amplitude was reduced by 56.5%.The results of ECMO film fabric preparation under adaptive tension control showed 3%loss of outer diameter and a 5%loss of strength at the weaving position.The N_(2) flux was decayed by 17%,CO_(2) flux by 12% and O2 flux by 14%before and after braiding.Compared with the experiment without adaptive tension control,each gas flux index showed 65%enhancement of N_(2) flux,63%enhancement of CO_(2) flux,and 62%enhancement of O_(2) flux,which further exemplified the effectiveness of the adaptive tension control scheme for the low-damage preparation of ECMO membrane fabrics.Conclusion In this paper,based on warp knitting technology,a self-adaptive warp tension regulation method was developed to realize the low damage preparation of ECMO warp-knitted membrane fabrics by using homemade PMP hollow fibers as the substrate.The main research conclusions are as follows.1)Through the membrane fabric preparation experiments,an adaptive tension control method is proposed,and through the PID control strategy and the fifth polynomial speed planning curve,the"peak shaving and valley filling"of the warp yarn tension curve in the preparation process of ECMO membrane fabrics is accomplished,realizing the low-damage preparation of ECMO membrane fabrics.2)The strength,outer diameter,and air flux of the PMP hollow fiber are significantly attenuated during the knitting process of the ECMO membrane fabric on a HKS Tricot warp knitting machine.This attenuation is primarily attributable to the material properties of the PMP membrane.A key contributing factor is the mismatch between the constant speed let-off rate and the actual amount of yarn required for the knitting process.3)By testing ECMO membrane fabrics preparation under adaptive tension control,it was found that the mechanical properties,outer diameter,and air permeability of the PMP hollow fibers were significantly improved.The N_(2) flux of the prepared ECMO membrane fabrics was attenuated by 17%,the CO_(2) flux was attenuated by 12%,and the O_(2) flux was attenuated by 14%.The flatness,density,and gas flux results of the fabric have reached the level of foreign products.