MIT researchers create new sensors that warn you when plants are running out of water using carbon-based ink. These sensors are placed on leaves and let researchers examine the stomata (Photo from Betsy Skrip)
Plants can be a wonderful addition to any home. They make the room look nicer, can give off good smells, and just be a pleasant experience. But, what inevitably happens is you forget to water it, and there goes your plant in the trash. What if your plants could alert you when they’re running out of water? Engineers at MIT may have found a way to do just that.
The team at MIT created sensors that are printed on plant leaves that tell you when it's running out of water. The sensors rely on the plants’ stoma, small pores on the surface of a leaf that lets the water evaporate. When this happens, water pressure in the plant drops allowing it to suck up water from the soil in a process known as transpiration. When exposed to light, the stomata open ─ and it closes in the dark, which scientists are now able to study in real time.
So how does printing on a leaf work? The team used an ink made of carbon nanotubes, which are tiny hollow tubes of carbon that conduct electricity. The ink is dissolved in an organic compound called sodium dodecyl sulfate that doesn’t cause damage to the stomata. The ink can be printed across a pore to make an electronic circuit. Once the pore is closed, the circuit is active and the current can be measured by connecting the circuit to a device called a multimeter. The circuit breaks and the current stops flowing when the pore opens, which lets researchers measure when a pore is opened or closed.
Scientists study the opening and closing of the stomata over a few days and found that they can tell when a plant is running out of water. Results show that stomata take seven minutes to open after it’s exposed to light, while it takes 53 minutes to close when it gets dark. But during dry conditions, these responses change. If the plant doesn’t have enough water, the stomata take roughly 25 minutes to open and 45 minutes to close.
Not only could this save your house plants, but it could alert farmers when their crops are in danger. While there are devices that warn farmers of an upcoming drought, like soil sensors and satellite imaging, they don’t detail which specific plant is drying out.
Right now, MIT researchers are working on a new way to place electronic circuits by placing a sticker on a leaf instead of using the carbon-based ink. They believe this new research could have big implications for farming and could save more corps and plants in the face of drought or water shortages. And maybe now your houseplants can survive longer than a week.
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