Wearable Plant Sensor for in Situ Monitoring of Volatile Organic Compound Emissions from Crops

Hussam Ibrahim, Satyanarayana Moru, Patrick Schnable, Liang Dong

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Methanol is a major volatile organic compound (VOC) emitted from plants. Methanol emission reflects indirect plant defense against insects, promotes cell-to-cell communication, and adapts plants to various environmental stresses. This paper reports a wearable plant sensor that can monitor methanol emission directly on the leaf of a plant under field conditions with low cost, high portability, and easy installation and use. The sensor technology eliminates the need for complex sampling, expensive instruments, and skilled operators for conventional gas chromatography-mass spectrometry. The sensor uses a composite of conducting polymer microcrystallites and platinum nanoparticles (PtNPs). The conducting poly(2-amino-1,3,4-thiadiazole) or poly(ATD) provides a high electrocatalytic activity with redox behavior. The modification of poly(ATD) with catalytic PtNPs enables efficient electrochemical oxidation of methanol at a specific potential. The advantages of poly(ATD) and PtNPs are synergized for high sensitivity and selectivity of the sensor for detecting methanol emissions with a sub-ppm limit of detection. Further, the infusion of a polymer electrolyte into the porous electrode of the sensor enables an all-solid-state VOC sensor. The sensor is integrated into a miniature gas collection chamber and capped with a hydrophobic gas diffusion membrane to minimize the influence of environmental humidity on the sensor performance. The sensor is installed on the leaf surface. In situ detection shows a difference in methanol emission between the lower and upper leaves of greenhouse maize plants. Further, under field conditions, the sensor reveals a noticeable difference in methanol emission concentration between two genotypes (Mo17 and B73 inbred lines) of maize plants. Therefore, the sensor will provide a promising new means of directly monitoring volatile emission of plants, which is a physiological phenotype as a function of genes and environment.

Original languageEnglish
Pages (from-to)2293-2302
Number of pages10
JournalACS Sensors
Issue number8
StatePublished - 26 Aug 2022
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported in part by the U.S. Department of Agriculture (USDA) under grant numbers 2018-67021-27845, 2020-67021-31528, and 2020-68013-30934; in part by the U.S. National Science Foundation (NSF) under grant numbers CNS-2125484 and IOS-1844563; in part by the AI Research Institutes program supported by NSF and USDA-NIFA under AI Institute for Resilient Agriculture under grant number 2021-67021-35329. The seed funding for this research was from the Plant Sciences Institute at Iowa State University. The authors claim that there is no conflict of interest and share equal contributions. The authors thank Lisa Coffey of the Schnable Lab for her assistance with plant care.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.


  • agricultural sensor
  • methanol
  • organic volatiles
  • wearable plant sensor


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