Rock-on-a-chip: a novel method for designing representative microfluidic platforms based on real rock structures and...

Area of Science:

• Geosciences
• Engineering
• Physics

Background:

• Microfluidics is crucial for studying pore-scale phenomena in porous media, vital for applications like oil recovery and carbon storage.
• Existing methods struggle to accurately replicate the complex morphology of natural rock pore structures in 2D microfluidic platforms.

Purpose of the Study:

• To develop a robust multi-step workflow for generating quasi-2D microfluidic chips that precisely preserve the pore morphology and size distributions of 3D rock samples.
• To improve the reliability of microfluidic studies by minimizing discrepancies between real pore space and microchip designs.

Main Methods:

• A multi-step workflow was developed to generate 2D pore throats from 3D network data derived from CT-scanned rock samples.
• Precise mask alignment was employed during fabrication to ensure accurate pore geometry, especially for narrow throats.
• Permeability was regulated by adjusting inlet areas while maintaining original pore and throat size distributions.

Main Results:

• The developed method demonstrated strong agreement between 2D and 3D pore and throat size distributions in both designed patterns and fabricated microchips.
• Accurate fabrication of microchips with narrow throats was achieved through precise mask alignment.
• Flow simulations revealed discrepancies between simulated and experimental permeability, particularly in low-permeability designs sensitive to etching.

Conclusions:

• The proposed workflow significantly minimizes common discrepancies between natural rock pore space morphologies and quasi-2D microchips.
• This advancement enhances the reliability of microfluidic studies requiring faithful representation of pore-scale structures.
• The method offers a valuable tool for research in subsurface energy and environmental applications.