Pioneering scientists in the UK have decoded a record-breaking two billion letters of DNA, it has been revealed.

Researchers who are developing biochips are taking two distinct approaches in devising ways to shunt tiny amounts of liquids around. One focuses on finding ways to form microscopic channels and tiny mechanical pumps. The other is aimed at using electricity to maneuver tiny droplets on surfaces.

Researchers from the University of Texas M.D. Anderson Cancer Center have advanced the second approach with a programmable biochip that uses an array of electrodes to place water droplets on a surface, insert substances into the droplets, and move and merge the droplets. The device contains no moving parts.

The droplets, which range from 20 to 500 microns in diameter and 0.5 to 65 nanoliters in volume, serve as carriers for samples, contaminants, chemical reagents, viral and genetic material, and cells. A nanoliter is one millionth of a milliliter, and there are about 5 milliliters to a teaspoon.

The device makes it possible to automate biochemical analysis and detection to, for instance, identify pathogens in the field.

The biochip and its computer controller could eventually be miniaturized and incorporated into portable medical, biological and chemical diagnostic devices, said Jon Schwartz, a research scientist at the University of Texas. “A long-term goal of this research is to provide a fluidic processor technology that can form the core of versatile, automated, microscale devices [for performing] chemical and biological assays at or near the point of care,” he said. This will “increase the availability of modern medicine to people who do not have ready access to modern medical institutions.”

The biochip contains a 32-by-32 array of electrodes. When energized, electrodes attract water droplets that are suspended in a thin film of liquid hydrocarbon.

The principle behind the droplet biochip is dielectrophoresis. Small electrically polarized particles or droplets that are suspended in a less polarized medium are attracted to nearby electric fields like those produced by electrodes. Water droplets are naturally polarized because water molecules are not electrically symmetrical; the arrangement of atoms leaves one end of the molecule positive and the other negative.

Droplets can be moved and merged simply by sending electrical current to the right sequence of electrodes. By programming electrodes in various sequences, multiple droplets can be moved around the chip and merged to mix their contents.

Source: Technology Research News