Quick reshuffle. different colored liquids stream from four entries on the top of a predetermined Micropad 64 tanks on the bottom.
Martinez et al . PNAS 105 (50) (16 December 08)
To help doctors and health workers in developing countries diagnose disease, researchers have developed simple detection devices made only of paper and adhesive tape that costs a fraction of conventional diagnostic equipment. The technology could also find applications in environmental monitoring and homeland security.
The laboratory work that hospitals and clinics regularly perform in developed countries is often unavailable in the Third World. Two main reasons are cost and lack of qualified personnel. The situation is unlikely to change anytime soon, so some researchers have been looking for simpler alternatives and cheaper chemical based analysis tools - such as beakers and test tubes - that workers' health use to detect diseases. That's what three Harvard University chemists have tried with a technology they call microPADs.
Their invention comprises pieces of double-sided carpet tape, pieces of paper, and a mixture of cellulose powder and the water used to fill between the sheets. The trio of chemists - Andres Martinez, Scott Phillips and George Whitesides - channel laser cut into the paper, punched holes in the tape, then stacked the two components in alternate layers. When the liquid droplets are deposited in the holes on the top of microPADs, capillary action draws through separate channels and down in small reservoirs in the lower layer. Scientists consider that the tanks contain chemical markers standards or tests, that change color when they detect the presence of bacteria, viruses or dangerous substances in the human body - or water supply. For example, if a volunteer lay person wanted to test a suspect water sample for lead levels in excess, all he or she needs to do is place a few drops in the upper holes, wait a few minutes and then how special chemicals react on the bottom.
As the researchers describe online this week in Proceedings of the National Academy of Sciences , the microPADs prototypes transported four separate liquid samples to 64 tanks designated within 5 minutes. In 27 tests on 30 devices moved the liquid without mixing. This means that theoretically microPADs can simultaneously test for thousands of potentially harmful chemicals - such as dioxin, lead, mercury or - for diseases such as diphtheria, malaria or typhoid. And the results can be transmitted from field agents to centralized laboratories taking a cell phone photo of the results on the colored dots (see picture). Researchers estimate that each Micropad could cost as little as 3 cents when produced in commercial quantities
The technique "has broad implications, and I would venture to suggest that it will also have an interest in developed countries. - as well as developing -. world "to produce inexpensive testing devices, said chemist Timothy Swager from the Massachusetts Institute of Technology in Cambridge He also said the microPADs are compatible with sufficient standard tests that they could even "inspire the creation of new tests." Whitesides said he and his colleagues are exploring uses for environmental monitoring devices, agricultural testing, and military operations.
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