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This Isn't Your Grandpa's Litmus Paper

Simple, paper color-change tests are being developed for environmental pollutants and a variety of health markers. Cynthia Graber reports

It’s similar to a pregnancy test: a drop of liquid on a strip of paper causes an easily seen color change. But imagine that kind of simple, cheap technology employed in testing for pollution or health issues, anywhere and on the cheap. Researchers at Colorado State University describe such a system in the journal Lab On A Chip. [David M. Cate et al., Simple, distance-based measurement for paper analytical devices]

Other paper tests may give only slight color differences, and some rely on expensive equipment to read the results.

For the new technology, the research team designed a system that creates a dramatic color change on the paper. The user drops liquid to be analyzed at the bottom of the paper. As capillary action pulls the liquid up, substances in the paper react, causing the color change.

So far, three tests exist for the system. One looks for nickel, which can be an environmental pollutant. The other two are for glutathione, a health marker, and glucose, for diabetics.

In trials, the paper tests competed with conventional methods at measuring concentrations.

The university is now spinning off a company to develop the technology. If successful, it could bring cheap, easy analysis to scientists—and citizens—around the world.

—Cynthia Graber

[The above text is a transcript of this podcast.]

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