Way to go, Gitanjali. Tethys is awesome! From NPR:
When the drinking water in Flint, Mich., became contaminated with lead, causing a major public health crisis, 11-year-old Gitanjali Rao took notice.
“I had been following the Flint, Michigan, issue for about two years,” the seventh-grader told ABC News. “I was appalled by the number of people affected by lead contamination in water.”
She saw her parents testing the water in their own home in Lone Tree, Colo., and was unimpressed by the options, which can be slow, unreliable or both.
“I went, ‘Well, this is not a reliable process and I’ve got to do something to change this,’ ” Rao told Business Insider…
…Here is how it works.
The carbon nanotubes in the cartridge are sensitive to changes in the flow of electrons. Those tubes are lined with atoms that have an affinity to lead, which adds a measurable resistance to the electron flow.
When the cartridge is dipped in water that is clean, the electron flow doesn’t change and the smartphone app shows that water is safe to drink. But when the cartridge is dipped in contaminated water, the lead in the water reacts to the atoms, causing resistance in the electron flow that is measured by the Arduino processor. The app then shows that the water isn’t safe to drink.
Read more and see more from The Discovery Education 3M Young Scientist Challenge on YouTube