Digital liquid-liquid microextraction

In this paper, we demonstrated the method to control the concentration after liquid-liquid extraction by generating an encapsulated droplet with precisely controlled water to oil volume ratio by merging individually created aqueous and organic droplets through EWOD (electrowetting-on-dielectric) actuation. In addition, the core and shell droplets were separated after the extraction process by applying EWOD and DEP (dielectrophoresis) forces to manipulating aqueous and organic droplets, respectively. Herein, the minimum concentration in the aqueous droplet was 0.001 mM and the minimum organic droplet volume was 2.5 nl.