Researchers from Iowa State University developed a low-cost, easily produced, graphene-based, sensors-on-tape that can be attached to plants to provide various kinds of data to researchers and farmers. "With a tool like this, we can begin to breed plants that are more efficient in using water," said plant scientist Patrick Schnable. "That's exciting. We couldn't do this before. But, once we can measure something, we can begin to understand it." The tool, which is now known as "plant tattoo sensor", is making these water measurements possible, as the tiny graphene sensor can be taped on to plants. According to the lead researcher Liang Dong, the sensors are made with graphene oxide, a material that is highly sensitive to water vapor. The presence of water vapor modifies the conductivity of the material, which is quantified to accurately measure the release of water vapor from a leaf. The plant sensors have been successfully tested in lab and pilot field experiments. (Source: Crop Biotech Update, International Service for Acquisition of Agri-Biotech Applications. www.isaaa.org) Iowa State University researchers have developed these "plant tattoo sensors" to take real-time, direct measurements of water use in crops.