Geomaterial-Functionalized Microfluidic Devices Using a Universal Surface Modification Approach

The layer-by-layer (LbL) self-assembly technique is used to coat the surface of flow channels in microfluidic chips with geomaterials. The surface modifications diminish the discrepancy between the surface chemistry of synthesized microfluidic devices and those of underground porous rocks. Hence, the use of visual models and, in particular, microfluidic devices is broadened to simulate the multiphase flows and fluid-solid interactions in actual rocks. Glass and quartz substrates are successfully coated with silicon dioxide (SiO2), bentonite, and montmorillonite. On-chip functionalization of polydimethylsiloxane (PDMS) and glass micromodels with SiO2 is also accomplished. The functionalized coatings using confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and contact angle measurements are characterized. The surface modification technique is shown to be material-independent, which generates a hydrophilic surface. The surface-coated chips, functionalized by clay particles, are utilized to illustrate the role of water salinity on oil displacement.