Transport of Materials Into-and-Out of Dead End Pores

Achieving transport inside dead end pores is not currently possible with pressure driven mechanisms, which limits our ability to obtain material from these pores, or to put material into them. Here we show that the phenomenon of diffusioosmosis can be used to drive flows in dead end pores, and the flows can be used to sweep otherwise-trapped materials from the pore into a sink, or vice versa. These flows arise along the walls of the channel due to an imposed or self-generated salt gradient. We observe that tracer particles have a finite axial speed of roughly 10 µm/s, as well as a finite crosswise transport due to mixing inside these pores caused from the transient nature of the diffusioosmotoc flows. Using electrokinetic modeling along with independently measured system parameters, we find solid agreement between predicted speeds and our experimental data. The temporal nature of the salt gradients may explain some of the other phenomena like the LoSal waterflooding process and DNA translocation in solid-state nanopores.