Over several years, Rao designed a device to cheaply test water. The device is called Tethys (TEH-thuhs). It contains small tubes made of carbon, a chemical element. The tubes are fitted with atoms, tiny particles of matter, that react if lead is present. The results are sent to a smartphone.
Rao has won several awards for her work. She’s now hoping to sell Tethys so that people can check whether their drinking water is safe. “The purpose of science is to make a difference,” Rao says.