Chip uses oil to move droplets

Researchers from North Carolina State University have devised a way to manipulate tiny droplets and particles on a chip. Key to the system is suspending what needs to be moved in a heavier liquid.

The researchers liquid-liquid chip uses an electric field to move, mix and manipulate droplets and objects including pure water, hydrocarbons, solid particles and capsules. The droplets and objects float freely in fluorinated oil. The oil contains the droplets and keeps materials from mixing until they are brought together.

The system could eventually be used in handheld labs-on-a-chip that handle biological cells and molecules. The method can also be used to precipitate materials out of droplets and even solidify them to make new materials, according to the researchers.

The system is relatively inexpensive, easy to implement, and takes two orders of magnitude less energy than systems that use electricity to move droplets that are sandwiched between plates or reside on a solid surface, according to the researchers. Biochips that move droplets on surfaces are faster, however.

The system could be used in practical applications in a few years, according to the researchers. The work appeared in the December 4, 2003 issue of Nature.