Design and development of warp knitting structures for ECMO membrane fabrics

The clinical efficacy of extracorporeal membrane oxygenation (ECMO) is largely determined by the mechanical properties and gas permeance of membrane materials. Current warp knitting methods can harm poly(4-methyl-1-pentene) (PMP) hollow fiber membranes because the tension from the yarns affects their ability to provide oxygen. This study systematically investigates the influence of three representative warp knitting structures—pillar stitch, tricot stitch, and cord stitch—on PMP membrane integrity using a design-based approach. A novel multiparameter model, the Membrane Damage Index (MDI), is proposed to quantify membrane damage across structural variants. Experimental results reveal that the pillar stitch configuration significantly reduces fracture strength loss (7.8%), CO₂ flux reduction (12.7%), and outer diameter compression (7.56%) by optimizing stress distribution and minimizing the underlap length (0.97 mm). Nonlinear regression analysis of the data led to the development of an MDI model (R² = 0.992), highlighting the importance of the number of needle back traversal stitches (n) in minimizing membrane damage. This study offers a theoretical framework and optimization strategy for developing low-damage ECMO membranes, ultimately enhancing clinical efficacy and the long-term durability of ECMO technology.