Enhanced colloidal particle trapping in microgrooved channels via diffusiophoresis*

The controlled transport of sub-micron colloidal particles within a confined environment, such as a porous medium or a dead-end channel, is a key feature in several technological applications (e.g., drug delivery, diagnostics) as well as in living systems (e.g., mass transport in tissues and capillaries).

Recently, we demonstrated how solute gradients in steady-state continuous flows past a microgrooved surface can be exploited to induce the controlled and reversible trapping of sub-micron particles within the dead-end grooves. The trapping mechanism is governed by diffusiophoresis, which drives particle motion along a solute gradient.

In this study, we investigate how the particle trapping is affected by the groove geometry, channel surface chemistry and solute gradient intensity, thereby determining the conditions for enhancing the particle trapping performance. The microfluidic devices, featuring a 3-inlet junction for generating the salt gradients, are made of an optical glue (NOA-81) layer, laid on a silicon microgrooved substrate. The proposed approach for particle transport in lab-on-a-chip devices has potential applications in point-of-care, drug delivery and biosensing industry.