A microfluidic chip and its use in characterising the particle-scale behaviour of Microbial-Induced Carbonate Precipitation (MICP)

TL;DR

This study introduces a microfluidic chip to observe particle-scale behaviors of bacteria and carbonate crystals during MICP, providing insights into the process that influence soil improvement techniques.

Contribution

A novel microfluidic device was designed to visualize and analyze particle-scale interactions during MICP, advancing understanding of the process mechanisms.

Findings

Bacteria distribute evenly after suspension injection.

Bacteria grow during settling and detach during cementation.

CaCO3 crystals form at pore constrictions during or after cementation.

Abstract

Microbial-Induced Carbonate Precipitation (MICP) is an innovative ground improvement technique which can enhance the strength and stiffness of soils, and can also control their hydraulic conductivity. These engineering properties of MICP-treated soils are affected by particle-scale behaviour of the precipitated carbonate, i.e. composition, amount and distribution, which are controlled by the MICP process occurring at the particle-scale. In this study, we designed and fabricated a microfluidic chip to improve our understanding of MICP at particle-scale by observing the behaviour of bacteria and CaCO3 crystals during this process. We found that bacteria became evenly distributed throughout the microfluidic chip after the injection of bacterial suspension, grew during bacterial settling, and detached during the injection of cementation solution. Bacteria aggregated during the cementation solution injection, and CaCO3 crystals formed at narrow pore throats or open pore bodies either during or after cementation solution injections.