Effect of evaporation through nanoporous medium on diffusiophoresis

Abstract

Diffusiophoresis near a nanoporous medium is the phenomenon that particles were spontaneously moved from low concentration region to high concentration region. However, unidirectional particle motion impeded further application of this phenomenon and lack of studies about the external convective flow effect such as evaporation through a nanoporous medium were reported. In this work, we investigated the evaporation effect through a nanoporous medium on spontaneous particle exclusion zone induced by diffusiophoresis. Consequently, particles motion was divided into three regimes: diffusiophoresis regime, transition regime, and evaporation regime depending on the evaporation effect. The experiment in which the time of initiating evaporation effect was controlled by adjusting the region of PDMS on a nanoporous medium showed that evaporation plays a critical role in studying the spontaneous particle exclusion zone. This rigorous analysis would provide a useful strategy for optimizing a spontaneous particle preconcentration/detection platform.