Lab-on-a-chip realizes potential

A portable instrument that replaces a full-size laboratory provides accurate multi-element analysis in less than a minute

Engineers from the A*STAR Institute of Materials Research and Engineering and colleagues at the University of Basel, Switzerland, have designed and developed a compact, portable analytical instrument that can detect multiple ions and molecules down to a level of 300 parts per billion (ppb) in less than a minute. The machine, based on lab-on-a-chip technology, needs only drop-sized liquid samples. The analysis is very quick, precise and sensitive, and can be performed remotely as no direct contact with the solution is necessary. As such, the device has widespread potential applications in the water, food and beverage, agriculture, environmental, pharmaceutical and medical industries.

“The instrument is now ready for commercialization,” says Kambiz Ansari, who led the research. “In this well-studied field, it is one of only a handful of actual lab-on-a-chip instruments reported so far.”

The easy-to-operate machine, which weighs only 1.2 kg, combines microchip electrophoresis (MCE) with a sensing technology known as a dual capacitively-coupled contactless conductivity detector (dC4D). The system first uses electrophoresis to separate ions and then detects the ions using dC4D. All analyses are performed in microfluidic channels consisting of capillaries inside polycarbonate plastic chips that are narrower than a human hair.

The beauty of the dC4D technology is its simplicity: it relies on remote conductivity measurements via a pair of electrodes. One electrode sends radio-frequency signals through a channel to the second electrode, and the signal received is read by a computer. Because the ions have charge, their resistance drops as they pass through the microfluidic channel, resulting in sudden peaks. Specially designed software then analyzes the data to provide both qualitative and quantitative information.

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