It takes about 10 minutes for the spinach to take up the water into the leaves. To read the signal, the researchers shine a laser onto the leaf, prompting the embedded nanotubes to emit near-infrared fluorescent light. This can be detected with a small infrared camera connected to a small, cheap Raspberry Pi computer.
The signal can also be detected with a smartphone by removing the infrared filter most have. A plant/human communication was created. Plants like this can detect virtually anything.The lab has previously developed carbon nanotubes that can be used as sensors to detect hydrogen peroxide, TNT, and the nerve gas sarin. “The plants could be use for defence applications, but also to monitor public spaces for terrorism related activities, since we show both water and airborne detection,” said Co-author Prof Michael Strano, from MIT.