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microfluidic-3D printing technologies through mechanistic analysis of core principles

and developmental trajectories. Distinctively, this review adopts a deliberately clinical

lens—evaluating how these platforms directly address oncology practice gaps,
including generating patient-specific tumor models for therapy personalization and

liquid biopsy diagnostics at clinically actionable thresholds. Moreover, we uniquely

concentrate on 3D-printed microfluidic systems engineered explicitly for tumor

pathophysiology, dissecting cancer-tailored architectures like perfusable vascular

networks and metastasis models with tumor-derived bioinks. We specifically map

applications across physiologically relevant tumor modeling, therapeutic screening, and

high-sensitivity biomarker diagnostics using 3D-printed microfluidic platforms. Finally,

we provide a forward-looking perspective addressing current technical constraints and

emerging frontiers including transformative 4D/5D bioprinting paradigms.

2. Fundamental Principles of Microfluidic and 3D Bioprinting Technologies

2.1 Characteristics of Microfluidic Technology
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Microfluidics manipulates minute fluid volumes (10 to 10 liters) through
microscale channels (tens to hundreds of micrometers) 39 . Commercial devices

primarily utilize glass, PDMS, and thermoplastics for their mechanical stability,

chemical inertness, and biocompatibility 40,41 . Three principal fabrication techniques

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are summarized below and in Table 2 : (1) Micromolding: the most accessible method
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requiring minimal equipment, ideal for phase-transition biomaterials like hydrogels .
(2) Photolithography: employing photochemical processes (photo-

degradation/polymerization) to achieve geometrically complex quasi-planar networks

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with superior design flexibility . (3) 3D printing: offering unparalleled material
diversity and spatial freedom through unrestricted nozzle movement, enabling

biomimetic vascular networks and organ-on-a-chip architectures unattainable via
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conventional techniques .

As previously established, microfluidics involves studying and manipulating
fluids at submillimeter scales. Unlike macroscale systems where gravity dominates

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