Microfluidic study of motion of the droplets in the salinity gradients
Abstract
Movement of colloid particles in micro confined space occurs in different natural and industrial processes, e.g. the transport of vesicles through biological membranes pores, transport of vesicles along fibrils in biological cells, drug delivery systems, oil recovery and membrane filtration.
We study the motion of micro oil droplets in thin capillaries by coupling a microfluidic droplet generator and a thin glass capillary.
The forces that mobilize the droplets were analyzed. We demonstrate, for the first time, that the droplets can move in confined space against pressure in the presence of non-uniform electrolyte concentrations.
The gradient-driven movement can be strong enough to drive a droplet through a narrow constriction in the middle of the capillary channel.
The movement of oil droplets may be manipulated by adjusting the composition of the saline solutions and the injection pressure.
The results may be applied in many areas, e.g. understanding the physical mechanisms for enhanced oil recovery and membrane filtration, design of drug delivery system and particle trapping in microfluidic devices.