Scientists at MIT have made a bionic spinach plant that can warn of explosives without any wires.

The spinach can detect a bomb and warn nearby scientists, according to a new paper published in the journal Nature Materials. Researchers used tiny carbon cylinders to detect “nitroaromatics,” which are chemical compounds commonly found in explosives, to turn spinach into a bomb detector.

Spinach
IMAGE: FLICKR

Spinach plant becomes bomb detector

After the plant takes in air and groundwater from its surroundings, the carbon tubes detect any nitroaromatics present and give off a fluorescent signal. This signal is then registered by an infrared camera, sent to a computer or smartphone and emailed to the user.

“This is a novel demonstration of how we have overcome the plant/human communication barrier,” paper co-author Michael Strano, a chemical engineer at the Massachusetts Institute of Technology, said in a statement. While this particular paper concerns spinach plants, “you can apply these techniques with any living plant” to make all different types of sensors, he said.

The scientists found a way to make use of a set of skills that plants have developed over hundreds of millions of years. “Plants are very good analytical chemists,” said Strano, and these analysis skills can be put to use helping humans.

Plants have a lot to teach humans

Given that plants cannot move to look for food or escape from danger, they have to be capable in monitoring their surroundings and making full use of the resources nearby. Thanks to huge networks of roots and highly-developed internal transport systems, plants absorb water and any other substance in the soil around them on a constant basis, before sending it to their leaves.

As a result, plants are better at detecting substances in groundwater than almost any human-built machine. The MIT scientists harnessed these capabilities by embedding carbon nanotubes into the leaves of a spinach plant, turning them into sensors that detect explosives and send signals to a small device.

The only difficulty is that plants are not capable of telling us what they find in the soil. This is where the nanosensors come in. The carbon nanotubes are built to be sensitive to dangerous substances such as nitric oxide, hydrogen peroxide, TNT and sarin gas.

More research needed to unlock potential

If the selected compound is detected and reaches the carbon sensor, it changes the radiation emitted by the sensor under infrared light. The nanotubes were embedded into the leaves by painting them with a solution that contained the tiny sensors. From here they moved to the photosynthetic regions of the leaves and sent out a different kind of radiation when nitroaromatic substances were detected.

During the experiment, the scientists used a Raspberry Pi computer, but a smartphone camera with its infrared filter removed could serve the same purpose. As it stands the equipment can detect a change in radiation up to 1 meter from the plant, but the team is trying to increase that distance.

While most people have got used to the idea of bomb-detecting canine units, plants seem a bit more unlikely. However, the scientists behind this research claim that they could be very useful.

“Plants are very environmentally responsive,” he said in a statement. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signaling pathways, there is a wealth of information to access.”