The 3 cent microfluidics chip

Harvard chemists craft an inexpensive paper analytic device that could improve health care in developing nations

By | December 8, 2008

Chemists have created a device -- using little more than paper and sticky tape -- that can precisely separate liquids for further medical or environmental analysis. The scientists write in a __Proceedings of the National Academy of Sciences__ linkurl:paper; published today that they made their small, lightweight microfluidics chips for about $0.03 a piece. Similar "lab-on-a-chip" devices made of glass and polymers can cost hundreds of dollars a piece. "We are interested in providing technology for the third world," linkurl:George Whitesides,; Harvard chemist and senior author on the __PNAS__ paper, told __The Scientist__. His group hopes to get the devices into health clinics and environmental monitoring facilities in developing nations to improve health care, water analysis, and drug development. linkurl:Richard Zare,; the chair of Stanford University's chemistry department, told __The Scientist__ that while the chip made by Whitesides and his colleagues is significantly cheaper than similar microfluidics devices, it functions well, making it an ideal technology for the developing world. "As chemists, we always dream that we can benefit society in some way," said Zare, who was not involved with the study. "This [device] looks like it is a breakthrough."
__One of the paper and tape microfluidics chips made
by the Harvard group showing assays to
detect glucose and protein levels in urine__
__Photo: Andres W. Martinez__
Whitesides said that he and his coauthors sought to construct a microfluidic paper analytical device (µPAD) using the most basic and ubiquitous of materials. "The starting point with us was asking, 'What's the simplest, cheapest [material] we could think of?'" said "And that was paper," he said. The Harvard team laser-etched microscopic channels into squares of filter paper and sandwiched them between layers of perforated double-sided adhesive tape. Stacking several layers of paper and tape resulted in three-dimensional microfluidics chips capable of shuttling fluids such as serum into discrete compartments, or "detection zones." One chip that Whitesides and his colleagues made could take four different fluid samples and evenly distribute them into more than 1,000 separate detection zones. The key advantage to using paper, Whitesides said, is that it actively wicks fluids, moving them along separate channels, preventing mixing and distributing the liquid into analyzable quantities. Analyses on such fractionated liquid samples could include simultaneous tests for different pollutants in water samples and a suite of assays to detect disease antibodies in human blood or glucose levels in urine. Whitesides and his colleagues demonstrated ability of the device to keep fluids separate by injecting different colored dyes and tracking their movement through the layers. Other tests, using liquids containing glucose or proteins, further demonstrated the device's usefulness.
__Two µPADs demonstrating their ability to evenly distribute
different fluids into arrays of detection zones__
__Photo: Andres W. Martinez__
The wicking property also eliminates the need for electric pumps, which are required to move liquids through chips made of from glass or polymers, Whitesides explained. The cheapness of the construction materials and the low cost of operating the devices could represent significant savings in third world health clinics or environmental labs. Whitesides estimated that the paper-and-tape chips could be "a factor of ten or more" less expensive than existing microfluidics devices. Whitesides also said that mobile camera phones could be used to photograph assay results obtained in far-flung rural clinics so that distant colleagues could help with interpretation. Though the researchers used standard laboratory filter paper in their device, Whitesides said that they've constructed similar microfuidics chips using even more common paper products. "We've made this on paper towels, toilet paper, all kinds of stuff," he said. Whitesides added that Harvard's patent office has already filed patent applications for the devices, and that industry partners are showing interest in his design. "We've talked to a number of companies, and they seem interested in developing it," he said. Whitesides said that he envisions the devices eventually being produced on an industrial scale using large machinery resembling newspaper presses. The researcher said that his aim is to use any profits that might be gained from making and selling the devices in developed nations to fund manufacture and distribution of the devices in the developing world. "The objective is not for us to make money." But Zare said that the inexpensive devices such as Whitesides's could be just as useful in reforming healthcare here in the US. "I'd like to lower my healthcare costs," he said. Zare also predicted that the paper-and-tape microfluidics chip represented just the beginning of a push to develop and distribute low-cost diagnostic tools. "I think it's just the beginning in what will hopefully be a big push in this direction."
**__Related stories:__***linkurl:Let it flow;
[January 2008]*linkurl:Microfluidics;
[August 2005]

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