A two-step strategy for delivering particles to targets hidden within microfabricated porous media

The delivery of small particles into porous environments remains highly challenging because of the low permeability to the fluids that carry these colloids. Even more challenging is that the specific location of targets in the porous environment usually is not known and cannot be determined from the outside. Here, we demonstrate a two-step strategy to deliver suspended colloids to targets that are hidden within closed porous media. The first step serves to automatically convert any hidden targets into soluto-inertial beacons, capable of sustaining long-lived solute outfluxes. The second step introduces the deliverable objects, which are designed to autonomously migrate against the solute fluxes emitted by the targets, thereby following chemical trails that lead to the target. Experimental and theoretical demonstrations of the strategy lay out the design elements required for the solute and the deliverable objects, suggesting routes to delivering colloidal objects to hidden targets in various environments and technologies.

Automated summary

The study proposes a two-step strategy to deliver suspended colloids to hidden targets in closed porous media by converting hidden targets into soluto-inertial beacons and introducing deliverable objects designed to autonomously migrate against solute fluxes emitted by the targets. Experimental and theoretical demonstrations show the design elements required for delivering colloidal objects to hidden targets in various environments and technologies.