Spinach is best known for its health benefits, but in the future the plant could play a very different role: detecting explosive material in soil.
Chemical engineers at MIT have integrated nanotechnology into spinach plants, transforming them into sensors that can detect explosives and then wirelessly relay that information to a handheld device.
By embedding spinach leaves with carbon nanotubes, MIT engineers have transformed spinach plants into sensors that can detect explosives and wirelessly relay that information to a handheld device similar to a smartphone.(Image source: Christine Daniloff/MIT)
Specifically, researchers embedded the leaves of spinach plants with carbon nanotubes in one of the earliest demonstrations of what’s called “plant nanobionics,” in which electronic systems are engineered into plants to allow them to interact in an intelligent way with their environment and transmit useful information to observers.
Plants are, quite literally, a natural fit for this type of task, as they already communicate extensively with the world around them, said Min Hao Wong, a graduate student at MIT and lead author on a paper about the work published in the journal Nature Materials .
“When we think of plants, we tend to think of them as being essentially static,” he told D esign News . “The fact is that plants are enormous sources of information. They interact constantly with the environment that we live in, absorbing and accumulating various particulates and compounds, and responding to changes in temperature or humidity. Our goal in this work is to show that humans can readily access this valuable information, and that actually plants can even signal this information to us.”
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Wong’s team—led by Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT—designed the plants to detect chemical compounds known as nitroaromatics, which are typically used in landmines and other explosives.
After engineering by the team, the plant, in its usual process of drawing water from the ground, can detect if one of these chemicals was present in the ground water. If that’s the case, the plant leaves emit a fluorescent signal that can be read with an infrared camera. The camera can be attached to a device similar to a smartphone, which then sends an email to the user to alert them that the chemical is present.
To give the plant its detection and information-transmission properties, the team used two types of single-walled carbon nanotubes, Wong said.
“For one type, we wrapped the carbon nanotube in a polymer that rendered it insensitive to any chemical near it, and used this as an infrared reference signal,” Winn explained. “The other was wrapped in a different polymer such that an explosive molecule changes the fluorescence if it binds.”
The two infrared signals can be