Thermal Enhanced Electrokinetic Bacterial Transport in Porous Media

Soil bacterial communities are crucial to various ecosystem services, with significant implications for environmental processes and human health. Delivering functional bacterial strains to target locations enhances the preferred ecological features. However, the delivery process is often constrained by limited bacterial transport through low-permeability soil. Although electrokinetics breaks the bottleneck of bacterial transport in thin porous media, its efficiency remains limited. Here, we tested the hypothesis that thermal effects enhance electrokinetic transport by shifting the net force acting on the bacterium. We found that heating significantly increased electrokinetic transport by 2.75-fold at 1 V cm^-1 through porous media. Thermal enhancement mechanisms were interpreted by the heating shift of net force integrating matrix attractive and electrokinetic forces and verified by the Quartz Crystal Microbalance with Dissipation Monitoring (QCMD) observed adhesion rigidity shift. Thermal-dependent parameters liquid viscosity and dielectric constant were the primary contributors to the net force shift. Their variations reduce the attractive force and augment the electrokinetic forces, resulting in lower adhesion rigidity and enhanced bacterial transport. A mechanism-based approach interlinking electric field strength, thermal effect, and collision efficiency was established to facilitate the application of thermally enhanced electrokinetic bacterial transport. These findings provide new prospects for improving bacterial transport, hence optimizing soil ecosystem functions.