Plant patch can detect stress signals in real time

Environmental conditions can cause damaging stress to plants, posing challenges for home gardeners and farmers. Therefore, early detection — before leaves visibly discolor, wilt or wither — is crucial. Now, researchers reporting in ACS Sensors have created a wearable patch for plants that quickly senses stress and relays the information to a grower. The electrochemical sensor attaches directly to live plant leaves and monitors hydrogen peroxide, a key distress signal.

Pests, drought, extreme temperatures and infections all cause stress in plants. In response, plants’ normal biochemistry gets out of whack, and they produce hydrogen peroxide, which also acts as a signal between cells to activate their defense mechanisms. Early detection of this chemical clue could help people expertly tailor plant care and prevent further damage, thereby maximizing crop yields, even in difficult conditions. But most current methods for detecting hydrogen peroxide require removal of plant parts and multiple processing steps or external detectors that observe fluorescence changes, which can get muddled by chlorophyll. And researchers have previously investigated plant-wearable devices to monitor leaf water content as an indicator of plant health. So, Liang Dong and colleagues set out to design a stand-alone patch that quickly and accurately detects the hydrogen peroxide distress signals from living plants.

To build a patch that sticks to the underside of leaves, the researchers created an array of microscopic plastic needles across a flexible base. Onto this patterned surface they coated a chitosan-based hydrogel mixture that converted small changes in hydrogen peroxide into measurable differences in electrical current. The mixture contained an enzyme that reacted with hydrogen peroxide to produce electrons and reduced graphene oxide to conduct those electrons through the sensor. 

The researchers tested their patches on live, healthy soybean and tobacco plants and compared them to stressed bacteria-infected plants. They found:

• For both crops infected with the bacterial pathogen Pseudomonas syringae pv. tomato DC3000, the sensor produced more electrical current on stressed leaves than on healthy ones, and the current levels were directly related to the amount of hydrogen peroxide present.
• The sensor’s measurement of hydrogen peroxide was accurate and confirmed by conventional lab analyses.
• After about 1 minute, the patches measured hydrogen peroxide in the leaves at significantly lower levels than those previously reported from needle-like sensors for live plants.
• Patches could be reused nine times before the microscopic needles lost their form.

The new strategy provides information that could help growers efficiently make decisions about their crops. “We can achieve direct measurements in under a minute for less than a dollar per test,” says Dong. “This breakthrough will significantly streamline analysis, making it practical for farmers to use our patch sensor for real-time disease crop monitoring.”

And the researchers are excited to continue moving the research forward. “Our next step is to refine the technology and enhance its reusability,” concludes Dong.

The authors acknowledge funding from Iowa State University, the U.S. Department of Agriculture’s National Institute of Food and Agriculture, and the National Science Foundation.

The paper’s abstract will be available on March 19 at 8 a.m. Eastern time here: http://pubs.acs.org/doi/abs/10.1021/acssensors.4c02645

###

The American Chemical Society (ACS) is a nonprofit organization founded in 1876 and chartered by the U.S. Congress. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

Registered journalists can subscribe to the ACS journalist news portal on EurekAlert! to access embargoed and public science press releases. For media inquiries, contact newsroom@acs.org.

Note: ACS does not conduct research but publishes and publicizes peer-reviewed scientific studies.

Follow us: Facebook | LinkedIn | Instagram