MagSculptor: A High-Resolution Microfluidic Magnetic Separator for Subtype Isolation of Low-Expression Cells

Subtype isolation of cells with low surface protein expression remains a longstanding bottleneck in various biological and biomedical investigations. Herein, we present MagSculptor, a novel bio-magnetic separator that leverages passive magnetic field shaping through engineered soft magnetic strip arrays embedded within a microfluidic platform. By integrating high-permeability amorphous soft magnetic materials with a tunable background magnetic field, the system creates a series of localized high-flux density zones with magnetic field gradients exceeding 2,000 T/m at a distance of 50 μm. Both numerical simulations and experimental results demonstrate that MagSculptor enables dynamic and highly resolute separation of magnetically labeled cells by precisely modulating the external magnetic field intensity and the spatial arrangement of soft magnetic elements. Consequently, cells can be classified into four distinct subtypes: High (H), Medium (M), Low (L), and Negative (N), based on magnetic labeling, which correlates linearly with the target protein expression level. The system exhibited superior resolution in sorting cancer cell lines such as MDA-MB-231 and A549 based on EpCAM expression, with cell viability exceeding 95%, making it a powerful and versatile tool for downstream applications in single-cell transcriptomics, genomics, and mechanistic biological investigations.