Shifty Manipulation Of Microdroplets

Taking inspiration from similarly named electronic devices, Michele Zagnoni and Jonathan M. Cooper of the University of Glasgow, in Scotland, have developed a microdroplet-based “shift register,” a microfluidic device that allows easy formation, storage, and retrieval of water droplets in oil (Lab Chip, DOI: 10.1039/c0lc00219d). Such devices could be used in biological and drug-screening applications. Electronic shift registers are information storage devices in which the components are arranged in a line or in an array of lines and serially move through the device to be read. The microdroplet-based analog of the electronic devices consists of a main channel connected to either end of a wider channel containing rectangular pillars that create alternative paths for fluid flow. Water droplets flow through oil and are trapped by the pillars until they fill the register’s entire length. Droplets can be stored or moved by controlling the pressure applied to the oil and water phases. In addition, the interfaces between the droplets can be manipulated by varying the pressure. The researchers tested the system using hexadecane and biologically relevant phospholipids to generate artificial lipid bilayers.