Harvard researchers have made the paper chips into a three-dimensional diagnostic device by layering them with punctured pieces of waterproof tape. A drop of liquid can move across channels and into wells on the first sheet, diffuse down through the holes in the tape, and react in test wells on the second paper layer. The ability to perform many more tests and even carry out two-step reactions with a single sample will enable the device to detect diseases (like malaria or HIV) that require more complicated assays, such as those that use antibodies. Results appear after five minutes to half an hour, depending on the test.
Whitesides cofounded the nonprofit Diagnostics for All in Brookline, MA, in 2007. It plans to deploy the liver function tests in an African country around the end of this year. The team hopes that eventually, people with little medical training can administer the tests and photograph the results with a cell phone. Whitesides envisions a center where technicians and doctors can evaluate the images and send back treatment recommendations.
The researchers hope the advanced version of the test can eventually be mass produced using the same printing technology that churns out newspapers. Cost for the materials should be three to five cents. At that price, says Folch, the tests "will have a big impact on health care in areas where transportation and energy access is difficult."