ELECTROEXTRACTION ACROSS DROPLET-DROPLET INTERFACE

Abstract

Extraction of analytes from solvents is a crucial part of many medical, clinical, industrial and refinery processes. It is required for preconcentration of analytes into other solvents, purification of solvents and detection of harmful or toxic molecules. One of the very important methods of extraction in microfluidics is liquid-liquid extraction (LLE). LLE involves the use of two immiscible liquids for diffusion of analytes across the interface. Recently there has been a growing interest in the coupling of external electric field with LLE to enhance the extraction of charged analytes. This has led to the birth of a new extraction method known as electroextraction. Although electroextraction has been mostly studied in continuous microfluidics, no significant effort has been made to integrate it with digital microfluidics for the development of lab-on-chip devices using electrowetting-on-dielectric (EWOD). As an initiation towards such integration, this thesis addresses the dependence of electroextraction across two stationary immiscible droplets on voltage, time and presence of surfactant. In this pursuit, an appropriate experimental set-up was designed with a coloured analyte. Then, a visual concentration measurement technique was developed using CIELAB color space and MATLAB code.