Wearable Sensors Measure Water Use in Crops
Iowa State University plant scientist Patrick Schnable quickly described how he measured the time it takes for two kinds of corn plants to move water from their roots to their lower leaves and then to their upper leaves.
This was no technical, precise, poster talk. This was a researcher interested in working with new, low-cost, easily produced, graphene-based sensors on tape that can be attached to plants to provide new 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,” he said. “That’s exciting. We couldn’t do this before. But, once we can measure something, we can begin to understand it.”
The tool making these water measurements possible is a tiny graphene sensor that can be taped to plants. Researchers have dubbed it a “plant tattoo sensor.”
Graphene is a wonder material. It’s a carbon honeycomb just an atom thick. It’s great at conducting electricity and heat, and it’s strong and stable.
The graphene-on-tape technology in this study has also been used to produce wearable strain and pressure sensors, including sensors built into a “smart glove” that measures hand movements.
Researchers describe the various sensors and the “simple and versatile method for patterning and transferring graphene-based nanomaterials” to create the flexible sensors in a paper featured in the journal Advanced Materials Technologies.
Liang Dong, an Iowa State associate professor of electrical and computer engineering, is the lead author of the paper and developer of the technology.
Seval Oren, a doctoral student in electrical and computer engineering, is a co-author who helped develop the sensor-fabrication technology.
“We’re trying to make sensors that are cheaper and still high performing,” Dong said.
To do that, the researchers have developed a process for fabricating intricate graphene patterns on tape. Dong said the first step is creating indented patterns on the surface of a polymer block, either with a molding process or with 3-D printing.
Engineers apply a liquid graphene solution to the block, filling the indented patterns. They use tape to remove the excess graphene. Then they take another strip of tape to pull away the graphene patterns, creating a sensor on the tape.
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