Watch out! Coming soon may be tests done on low-cost, paper-based “lab-on-a-chips.” Researchers at Harvard University are working to put assays on paper to improve diagnostics in developing countries. The paper-based test strips are similar to those used in at-home pregnancy tests, but may soon be able to offer inexpensive tests for liver, kidney, and metabolic diseases. The researchers aim to develop tests that are easy-to-use, cheap, portable, and disposable.
Although the goal is to make this testing and mass screening device affordable in developing countries, the technology easily could work its way into developed healthcare systems if it delivers high levels of sensitivity, specificity, and reliability.
The university’s Whitesides Research Group is working with Diagnostics-For-All (DFA), a non-profit venture in Cambridge, Massachusetts, to develop the low-cost, paper-based “lab-on-a-chip,” as DFA calls it. These simple diagnostic tests could be used in resource-poor areas of the globe. The technology was developed in the laboratory of George M. Whitesides, Ph.D., the Woodford L. and Ann A. Flowers University Professor, Department of Chemistry and Chemical Biology at Harvard University and a co-founder of DFA.
Here’s how it works. A paper-based microfluidic chip the size of a fingernail is pre-treated with reagents for color-based (or colorimetric) assays to test bodily fluids (such as blood, urine, or sweat) for proteins and other molecules that indicate the presence of disease. The paper is patterned with hydrophobic polymers, forming a series of channels that guide a fluid sample to pre-treated regions of the chip. The resulting color changes can then be read and translated into a diagnosis using a key based on the test being conducted.
The technology offers four distinct advantages over current diagnostic systems. First, the use of paper means the chips could be significantly cheaper-potentially as low as 1 cent per chip-than other microfluidic designs, which use on silicon, plastic, or glass.
Second, the technology is highly portable. No specialized equipment is required to process and read samples, and because it uses the inherent capillary action of paper, the device does not require pumps or power sources.
Third, the device is user-friendly allowing healthcare providers to read the color-based results in minutes with minimal training. DFA could train individual providers to conduct the tests using the chips, and then use cell phones to call doctors who would advise on diagnosis and treatment.
And, fourth, it can be disposed of easily and safety through incineration, which is significant in the developing countries that may lack the resources for biological waste disposal.
“What we have with this technology is the means to help address significant diagnostic disparities between the United States and the developing world,” Whitesides said. “For instance, over time about 5% of patients in the developing world receiving treatment for tuberculosis or AIDS-equivalent to approximately 1 million people-will succumb to drug-related liver complications because of a lack of proper health monitoring. In the United States, tests for these complications are conducted every two weeks, with results returned within hours. In the developing world, when these tests are done, which is rarely, it can take laboratories weeks to send back the findings.
“By developing a low-cost and broadly applicable test system designed to be deployed in regions with no or little access to complex laboratory diagnostic equipment, we hope to make a real impact on public health,” Whitesides added.