Self-powered microfluidic chip enables nucleic acid diagnostics

The ability of doctors to use nucleic acid-based diagnostic tests in their offices rather than sending out blood samples to contract clinical labs will require simple, easy-to-use devices. Luke P. Lee and coworkers at the University of California, Berkeley, have developed a prototype—a disposable, inexpensive microfluidic device about the size of a microscope slide that only needs a drop of blood and even carries its own power supply (Sci. Adv. 2017, DOI: 10.1126/sciadv.1501645). The researchers pattern the reagents needed for nucleic acid amplification directly into microwells on the chip. When in operation, blood flows through the microfluidic channels, the blood cells are removed, and the plasma is partitioned into the microwells where nucleic acid amplification occurs upon heating in an oven or by reusable heat packs. Sequences of interest are detected by fluorescence readings. The chip is powered by a precharged vacuum battery, which pumps samples by pulling air through gas-permeable silicone and has a 2.5-hour lifetime. Lee and coworkers used the device to quantify HIV-1 RNA and Staphylococcus aureus DNA spiked into human blood at levels ranging from 10 to 200,000 copies per microliter. “Because nucleic-acid testing requires a number of different steps, it is important that a point-of-care device integrates all these steps together,” says Samuel K. Sia of Columbia University, who was not involved in the research. This work represents “a practical approach” for getting all the needed microfluidic innovations into one package, Sia says.