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Alumni Magazine

Plant patch enables continuous monitoring for crop diseases

Picture within a picture of enlarged portion of plant with patch sensor.

A new patch that plants can “wear” monitors continuously for diseases and other stresses, such as crop damage or extreme heat.

“We’ve created a wearable sensor that monitors plant stress and disease in a noninvasive way by measuring the volatile organic compounds (VOCs) emitted by plants,” said Qingshan Wei, co-corresponding author of a paper on the work. Wei is an assistant professor of chemical and biomolecular engineering at NC State.

Current methods of testing for plant stress or disease involve taking plant tissue samples and conducting an assay in a lab. However, this only gives growers one measurement, and there is a time lag.

Plants emit different combinations of VOCs under different circumstances. By targeting VOCs that are relevant to specific diseases or plant stress, the sensors can alert users to specific problems.

“Our technology monitors VOC emissions from the plant continuously, without harming the plant,” Wei said. “The prototype we’ve demonstrated stores this monitoring data, but future versions will transmit the data wirelessly. What we’ve developed allows growers to identify problems in the field — they wouldn’t have to wait to receive test results from a lab.”

The rectangular patches are 30 millimeters long and consist of a flexible material containing graphene-based sensors and flexible silver nanowires. The sensors are coated with various chemical ligands that respond to the presence of specific VOCs, allowing the system to detect and measure VOCs in gases emitted by the plant’s leaves.

The researchers tested a prototype of the device on tomato plants to monitor for two types of stress: physical damage to the plant and infection by P. infestans, the pathogen that causes late blight disease in tomatoes. The system detected VOC changes associated with the physical damage within one to three hours.

Detecting the presence of P. infestans took longer. The technology didn’t pick up changes in VOC emissions until three to four days after researchers inoculated the tomato plants.

“This is not markedly faster than the appearance of visual symptoms of late blight disease,” Wei said. “However, the monitoring system means growers don’t have to rely on detecting minute visual symptoms. Continuous monitoring would allow growers to identify plant diseases as quickly as possible.”

“Our prototypes can already detect 13 different plant VOCs with high accuracy, allowing users to develop a customized sensor array that focuses on the stresses and diseases that a grower thinks are most relevant,” said Yong Zhu, co-corresponding author of the paper and Andrew A. Adams Distinguished Professor of Mechanical and Aerospace Engineering.

Co-first authors of the paper are Zheng Li, a former postdoc at NC State, and Yuxuan Li, a Ph.D. student at NC State. The paper was co-authored by Jean Ristaino, William Neal Reynolds Distinguished Professor of Plant Pathology at NC State; Oindrila Hossain, Rajesh Paul and Shuang Wu, who are Ph.D. students at NC State; and Shanshan Yao, a former postdoc at NC State.