Department of Biological Engineering, School of Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Zurich, Switzerland.
Adv Sci (Weinh). 2024 May;11(20):e2310121. doi: 10.1002/advs.202310121. Epub 2024 Mar 6.
Microfluidic models are proving to be powerful systems to study fundamental processes in porous media, due to their ability to replicate topologically complex environments while allowing detailed, quantitative observations at the pore scale. Yet, while porous media such as living tissues, geological substrates, or industrial systems typically display a porosity that spans multiple scales, most microfluidic models to date are limited to a single porosity or a small range of pore sizes. Here, a novel microfluidic system with multiscale porosity is presented. By embedding polyacrylamide (PAAm) hydrogel structures through in-situ photopolymerization in a landscape of microfabricated polydimethylsiloxane (PDMS) pillars with varying spacing, micromodels with porosity spanning several orders of magnitude, from nanometers to millimeters are created. Experiments conducted at different porosity patterns demonstrate the potential of this approach to characterize fundamental and ubiquitous biological and geochemical transport processes in porous media. Accounting for multiscale porosity allows studies of the resulting heterogeneous fluid flow and concentration fields of transported chemicals, as well as the biological behaviors associated with this heterogeneity, such as bacterial chemotaxis. This approach brings laboratory studies of transport in porous media a step closer to their natural counterparts in the environment, industry, and medicine.
微流控模型被证明是研究多孔介质中基本过程的强大系统，因为它们能够复制拓扑复杂的环境，同时允许在孔尺度上进行详细的定量观察。然而，尽管像活组织、地质基质或工业系统等多孔介质通常具有跨越多个尺度的孔隙率，但迄今为止大多数微流控模型都限于单一孔隙率或小范围的孔径。在这里，提出了一种具有多尺度孔隙率的新型微流控系统。通过在具有不同间距的微制造聚二甲基硅氧烷（PDMS）柱景观中通过原位光聚合嵌入聚丙烯酰胺（PAAm）水凝胶结构，创建了具有跨越几个数量级的孔隙率的微模型，从纳米到毫米。在不同孔隙率模式下进行的实验证明了这种方法的潜力，可以在多孔介质中表征普遍存在的基本生物和地球化学输运过程。考虑多尺度孔隙率可以研究由此产生的非均相流体流动和被输运化学物质的浓度场，以及与这种非均质性相关的生物行为，如细菌趋化性。这种方法使多孔介质中的输运实验室研究更接近其在环境、工业和医学中的天然对应物。
