Selecting a blood dialysis membrane spinneret for NIPS-based production demands uncompromising control over precision, biocompatibility, and stability. In hemodialysis applications, the spinneret governs lumen formation, wall-thickness uniformity, and early-phase demixing, which together determine uremic-toxin clearance, ultrafiltration behavior, and hemocompatibility. The right choice aligns orifice geometry, wetted materials, and flow-channel design with the polymer/solvent/nonsolvent system and the plant’s multi-hole uniformity requirements.