Fluid–solid interaction in porous materials is of tremendous importance to earth, space, energy, environment, biological, and medical applications. High-resolution 3D printing enables efficient fabrication of porous microfluidic devices with complicated pore-throat morphology, but lacking desired surface functionality. In this work, we propose a novel approach to additively fabricate functional porous devices by integrating micro-3D printing and solution-based internal coating. This approach is successfully applied to create energy/environment-orientated porous micromodels that replicate the μCT-captured porous geometry and natural mineralogy of carbonate rock. The functional mineral coating in a 3D-printed porous scaffold is achieved by seeding calcite nanoparticles along the inner surface and enabling in situ growth of calcite crystals. For conformal and stable coating in confined pore spaces, we manage to control the wetting and capillarity effects during fabrication: (i) capillarity-enhanced nanoparticle immobilization for forming an adhered seeding layer; (ii) capillary pore-throat blockage mitigation for uniform crystal growth. These transparent micromodels are then used to directly image and characterize microscopic fluid dynamics including wettability-dependent fluid propagation and capillarity-held phase transition processes. The proposed approach can be readily tailored with on-demand-designed scaffold geometry and appropriate coating recipe to fit in many other emerging applications.

中文翻译：

---

通过微3D打印和基于溶液的矿物涂层增强微流控能力。

多孔材料中的流固耦合对地球，空间，能源，环境，生物和医学应用至关重要。高分辨率3D打印可有效制造具有复杂的孔喉形态但缺乏所需表面功能的多孔微流体装置。在这项工作中，我们提出了一种通过集成微型3D打印和基于溶液的内部涂层来添加性制造功能性多孔器件的新颖方法。该方法已成功应用于创建以能量/环境为导向的多孔微模型，该模型可复制由μCT捕获的碳酸盐岩的多孔几何形状和天然矿物学。3D打印多孔支架中的功能性矿物涂层是通过沿内表面接种方解石纳米粒子并就地实现而实现的方解石晶体的生长。为了在有限的孔隙空间中形成保形和稳定的涂层，我们设法在制造过程中控制润湿和毛细作用：（i）增强毛细作用的纳米粒子固定化，以形成附着的种子层；（ii）缓解毛细孔喉的阻塞，使晶体均匀生长。然后将这些透明的微模型用于直接成像和表征微观流体动力学，包括取决于润湿性的流体传播和毛细作用保持的相变过程。可以轻松地根据需求设计支架几何形状和合适的涂层配方来调整提议的方法，以适合许多其他新兴应用。