Experimental diffusiophoresis of porous and non-porous silica particles in dead-end pore microchannel geometry

The movement of colloids in response to a concentration gradient of solutes, known as diffusiophoresis (DP), plays a crucial role in various applications, including separations, sorting and reactant transport. In this study, we experimentally investigate DP of porous and non-porous silica particles in different electrolyte solutions using a microfluidic system with a dead-end pore geometry. Experimental results are linked to a theoretical analysis, which reveals that the direction of particle motion is governed by the interplay between electrophoresis (EP) and chemiphoresis (CP), influenced by effects such as double layer polarization (DLP) and electroosmotic flow (EOF). The type of electrolyte has a significant impact on the overall behavior, as different ions have significantly different interactions with the particles and each other. The findings provide valuable insights into the DP behavior of porous particles, which can be leveraged to optimize particle transport in biomedical and environmental applications.