A scalable microfluidic dialyzer enabling low-flow hemodialysis with clinically relevant clearance

Miniaturization of dialyzers is critical for advancing home-based and wearable dialysis systems, yet conventional hollow-fiber architectures are constrained by high hydraulic resistance and limited form factors. Here, we present a scalable microfluidic dialyzer (MD) based on stacked flat-sheet membranes with integrated microchannel networks and evaluate its hydraulic and clearance performance. A three-dimensional coupled fluid-flow and porous-membrane transport model was developed and validated through bench-scale experiments using urea and vitamin B₁₂ as representative small- and middle-molecular-weight solutes, with water and milk employed as surrogate blood-side fluids for hydraulic and clearance characterizations. The results show that solute clearance and pressure drop are strongly coupled through microchannel geometry. The MD achieves clinically relevant clearance (>40 mL min^-1) while exhibiting an order-of-magnitude lower blood-side pressure drop than conventional hollow-fiber dialyzers. Analysis further reveals that transport is governed by coupled hydraulic and membrane resistances, with viscosity-dependent transmembrane pressure influencing clearance under constant ultrafiltration, and membrane permeability playing a dominant role in larger-solute removal. Despite substantial reductions in membrane area and extracorporeal volume, the MD maintains comparable dialysis functionality. These findings establish mechanistic design principles for microfluidic dialyzers and support their potential as compact, low-pressure platforms for low-flow and wearable dialysis applications.