Diffusiophoretic separation of colloids in microfluidic flows

In this review, we cover recent advances in microfluidic colloid separation enabled by diffusiophoresis. Diffusiophoresis describes the motion of colloidal particles induced by local chemical gradients. Despite its long history, it is only recently that diffusiophoresis has gained a renewed interest in the scientific community. Such a resurgence is, in part, due to the recognition that diffusiophoresis may enable useful applications that are otherwise difficult to achieve or can be augmented by it. One example is continuous colloid separation, which requires the control of particle motion relative to the flow. This review aims to provide a fundamental understanding of diffusiophoretic separation along with a survey of the recent literature on diffusiophoretic colloid separation in microfluidic flows in both cross-gradient and counter-gradient settings.