Effect of liquid droplet impact velocity on liquid wicking kinetics in surface V-grooves

Abstract

The liquid droplet inertia effect on liquid wicking in V-groove has direct implications to the liquid sample flow in microfluidic devices using V-groove channels and to the ink wicking along the inter-fibre gaps on uncoated paper surfaces, which is critical to the ink jet print quality. In this study liquid droplet inertia and the V-groove geometry is systematically varied to understand the effect of droplet impact, V-groove apex angle and groove width on the liquid wicking rate in the groove. Our results show that both the apex angle and the groove width influence the rate of liquid wicking in V-grooves forced by liquid droplet inertia. The inertia effect lasts for only a short time and its influence to the sample delivery accuracy in V-groove microfluidic devices can be minimised or eliminated by improving microfluidic channel design. On improving ink jet printing quality of uncoated papers, this work shows that applying surface sizing to uncoated ink jet papers is likely to be an effective way to change the geometry of the inter-fibre gaps and therefore can reduce the feathering effect in ink jet printing.