A Representative Mechanistic Model of Multisolute Transport in Low-Flow Hollow-Fiber Dialyzers for Wearable Artificial Kidney-Oriented Design

To support the analysis of compact hollow-fiber dialyzers operated under low-flow conditions relevant to wearable artificial kidney development, a mechanistic model of multisolute transport was developed. Unlike conventional homogeneous-membrane descriptions, the dialysis membrane was represented as a three-layer asymmetric porous structure. Within a continuum framework, hindered diffusion, hindered convection, and transmembrane hydraulics were coupled to describe diffusion-convection-driven transport under low-flow conditions. Comparisons with manufacturer-style in vitro clearance data from commercial low-flow dialyzers showed that the model captured the main clearance trends of representative solutes under selected operating conditions. Apparent resistance decomposition further suggested that, under the baseline condition and the present resistance definition, the apparent blood-side boundary-layer fraction increased with solute size, whereas the apparent intramembrane fraction decreased. Parametric analyses were further conducted to examine the effects of selected operating and geometric factors in this model. The proposed framework may support the analysis and preliminary design evaluation of compact dialysis modules for WAK applications.