'Lab on a phone' detects mercury in water

Researchers at UCLA are using a 3D printer to produce an inexpensive, lightweight smartphone attachment that could ultimately take the place of large, expensive lab equipment.

The whole testing process can take as little as 20 minutes. UCLA

Last month, a coal-processing compound spilled into West Virginia's drinking-water supply, leaving hundreds of thousands of people without safe tap water. The ability to test for harmful chemicals and elements in our water seems more crucial than ever before.

Unfortunately, testing for one of the most common harmful water contaminants, mercury, has traditionally been both expensive and time-consuming. The testing is done in labs using big, pricey instruments operated by trained professionals -- not exactly helpful on the fly.

But there's good news out of UCLA. A team of scientists and engineers have designed a $37 3D-printed smartphone attachment that, in just 20 minutes, can detect mercury in water at a concentration of 3 to 4 parts per billion -- an important level given the Environmental Protection Agency considers 2 parts per billion the maximum level to be safe to drink.

"Our new platform for mercury testing is essentially a lab on a phone," Aydogan Ozcan, head researcher on the project and a professor of electrical and bioengineering, said in a school news release. "It's portable, lightweight, and inexpensive to manufacture. And, because of the global proliferation of mobile devices, it could make testing for mercury widely available. Having this kind of test available in resource-limited areas and in the field was an important motivation for our work."

Because it's so portable, affordable, and easy to operate in conjunction with devices that more and more people already have (smartphones), the researchers report in the journal ACS Nano that their tech could be especially useful in remote and otherwise low-tech areas where mercury in the water is just as much of an issue.

The test, which takes all of 20 minutes, involves analyzing a water sample using a disposable test tube that could cost as little as 5 cents. The smartphone attachment's light-emitting diodes are set to two frequencies to detect tiny changes in light transmission picked up by the phone's built-in camera -- changes that are caused by mercury-induced nanoparticle clustering in the water.

From there, an Android app processes the resulting images to determine concentration levels, and it even organizes the test results and shares them to an online map to help track mercury pollution in the wider environment. Yep, we're talking crowdsourcing to track mercury contamination. In fact, the researchers did just that in this study, generating a mercury contamination map by measuring water samples at more than 50 locations across California that included city tap water, rivers, lakes, and beaches.

Researchers add that while the attachment costs $37 to make using a 3D printer, that number should go down as it is produced in larger quantities. It may also move beyond mercury detection as they continue to work on the design.

 

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