Research on low-tension weft insertion method for manufacturing ECMO membrane fabrics based on warp knitting technology

This study addresses the technical challenges in fabricating oxygenated membrane fabrics for extracorporeal membrane pulmonary oxygenation (ECMO) systems, specifically focusing on the development of a low-tension weft insertion technique for polymethylpentene (PMP) membrane knitting. In the research, we utilized a weft insertion warp knitting machine for fabric preparation and conducted a comprehensive analysis of weft yarn tension dynamics. Initially, tension variations during yarn consumption were investigated using a conventional negative weft insertion method. Subsequently, considering the unique properties of PMP membranes—characterized by low strength and high elongation—an innovative positive weft insertion method was developed and evaluated against the traditional negative approach. Experimental findings demonstrated that the proposed positive lay-up method significantly enhanced the weft insertion process by substantially reducing tension during PMP membrane unwinding and insertion. Specifically, in this novel approach, a minimum 90% reduction in tension amplitude and a 92.5% decrease in mean tension values was achieved, compared with the negative method. Furthermore, the positive insertion technique maintained stable tension control during PMP membrane unwinding and weft-laying at operational speeds up to 600 r/min, meeting ECMO membrane fabric manufacturing standards. In this research, we present an optimized technical solution for ECMO membrane fabric production, making a significant contribution to tension reduction in weft insertion warp knitting machinery.