Laboratories and hospitals all over the world use similar, albeit cumbersome, hours-long processes in efforts to identify everything from DNA fragments to pathogens. King and Thomas Jones, professor of electrical and computer engineering, induce an electrical field around the droplet to be analyzed, and in one-tenth of a second the droplet elongates along an electrode into an electrified, liquid string. As the fluid is stretched, the electrical field separates the molecules laterally along the edges of the long droplet. Stretching the droplet along a specially prepared detector can lay down one set of molecules directly onto the detector, making their recognition highly efficient.
King and Jones found that a micro-liter of fluid or less is enough for the process to work with great efficiency. The most common method of separating proteins, called gel electrophoresis, requires more liquid and can take several hours.
The frequency of an electric field can be tuned to send one subset of particles in one direction, and another set of particles in the reverse direction based on the way they behave in an electric field. This is called the dielectrophoretic force.
The team is now looking into building electrodes with integrated particle detectors, and using fluorescence-marked proteins to see if they can increase the speed and accuracy of the process further yet.