Plants send out distress signals when they are attacked by pests, drought or disease, but these signals are often invisible to the naked eye. Now, scientists have developed a tiny wearable sensor that attaches to plant leaves and detects stress before the plant suffers visible damage.
By measuring hydrogen peroxide levels, an early biochemical warning, the patch helps farmers and gardeners respond quickly to improve plant health and crop yields. Best of all, it provides real-time results within a minute at an affordable price.
Environmental factors such as pests, drought, temperature extremes and infections can put great stress on plants, creating challenges for home gardeners and farmers. Early detection of this stress (before leaves begin to fade, wilt, or wilt) is critical for effective intervention.
Now, researchers report today (March 19) in the journal ACSSensors that they have developed a wearable patch that can be attached directly to plant leaves, allowing growers to monitor plant health in real time. This electrochemical sensor detects hydrogen peroxide, a key distress signal sent by plants under stress.
When a plant is stressed, its normal biochemical processes are disrupted, triggering the production of hydrogen peroxide. This molecule not only sends a distress signal but also helps activate the plant's defense mechanisms. Identifying these chemical changes early allows growers to respond quickly to minimize damage and increase crop yields even in adverse conditions.
However, most existing methods for detecting hydrogen peroxide are complex, requiring leaf samples, multiple processing steps, or external detectors that rely on fluorescence—an approach that is often complicated by chlorophyll interference. Previous research on plant wearables has focused on monitoring leaf water content as a health indicator, but Liang Dong, a professor of electrical engineering at Iowa State University, and his team sought a more direct approach. They have developed a self-contained patch that can quickly and accurately detect hydrogen peroxide levels in living plants, providing a simpler and more effective way to monitor plant stress.
To create a patch that sticks to the underside of a leaf, the researchers created an array of tiny plastic needles on a flexible base. On this patterned surface, they coated a chitosan-based hydrogel mixture that can convert small changes in hydrogen peroxide into measurable differences in electrical current. The mixture contains an enzyme that reacts with hydrogen peroxide to produce electrons and reduces graphene oxide, conducting those electrons through the sensor.
The researchers tested their patches on live, healthy soybean and tobacco plants and compared them with bacterially infected plants. They found:
For two crops infected with the bacterial pathogen Pseudomonassyringaepv.tomato DC3000, the sensor generated more current on stressed leaves than on healthy leaves, and the current levels were directly related to the amount of hydrogen peroxide present.
The sensor's measurement of hydrogen peroxide is accurate and confirmed by routine laboratory analysis.
After about 1 minute, the levels of hydrogen peroxide in the leaves measured by the patch were significantly lower than levels previously measured in live plants using needle sensors.
The patch can be reused nine times before the microneedles lose their shape.
The new strategy provides information that can help growers make efficient decisions about their crops. "We can make direct measurements in less than a minute and cost less than a dollar per test," Dong said. "This breakthrough will greatly simplify analysis and enable farmers to monitor crop diseases in real time using our patch sensors."
The researchers are very excited to continue moving this research forward. "Our next step is to refine this technology and increase its reusability," Dong concluded.
Compiled from /ScitechDaily