Rapid Fabrication of Biomimetic Perfusable Structures via Lift-Up Viscous Fingering.

Controllable yet accessible fabrication of biomimetic perfusable network structures remains a key bottleneck for translational tissue engineering and regenerative medicine. Although additive manufacturing can achieve micrometer-scale resolution, its reliance on expensive equipment, limited material compatibility, multi-step post-processing, and low throughput restricts widespread adoption in conventional laboratories. Viscous fingering (VF) is a highly advantageous fabrication technique with low-shear and self-organizing characteristics. However, conventional VF is highly sensitive to fluid parameters, readily generating stochastic geometric morphologies and thus hindering controllable fabrication. Here, we introduce a lift-up viscous fingering (LVF) strategy that employs a yield-stress (Bingham) fluid as a reversible template to generate controllable VF patterns within a confined Hele-Shaw cavity. Through a closed-loop five-step process ("lifting-demolding-crosslinking-bonding-perfusion"), using our self-built system, perfusable channel networks with characteristic dimensions of 200-2000 µm can be rapidly fabricated at extremely low material cost, without cleanroom facilities, lithographic processes, or additive manufacturing equipment. The resulting networks support immediate gravity-driven perfusion, demonstrated with anticoagulated rabbit blood, with preserved blood cell morphology and no observable flow blockage. By lowering technical, cost, and infrastructure barriers while enabling controllable and reproducible fabrication of branched perfusion networks, LVF provides a scalable and laboratory-friendly manufacturing route for microfluidic and vascular-mimetic applications.