OK, sometimes you just have to work with Nature, not against it.
Scientists in California have put specially treated carbon nanotubes, small “threads” of carbon atoms, into spinach plants ! Why would they want to do this?. Well, scientists have “highjacked” the plant and turned it into a self-powered sensor for EXPLOSIVES. As the plants take up ground water, they also take up any contaminants in the water. The specially treated nanotubes have been treated with a chemical that is sensitive to certain chemicals found in explosives! When the contaminated water and the special nanotubes interact, the plant GLOWS !!! Well, it emits a form of light that is invisible to your eye but can be “seen” by a special camera, like in a smart phone. And they don’t even have to touch the plant, they just have to look at it !!
These particular plants have been engineered to detect explosive residue, but the same technique could be used to make them sense other contaminants, or to sense nutrients or water.