When does too much of a good thing become a bad thing? That’s the
question Dr. Jonathan Claussen, assistant professor at Iowa State
University’s Department of Mechanical Engineering, and his team of
researchers aim to help farmers answer when it comes to pesticide use.
Underuse can harm farmers’ crops, while overuse can result in runoff
into the soil or waterways.
Claussen and his team created a flexible, low cost and disposable
biosensor that can detect pesticides in soil. This biosensor is made of
graphene, a strong and stable nanoparticle, and provides instantaneous
feedback, as opposed to the time and money it would otherwise take to
send a sample to a lab and await results.
USDA’s National Institute of Food and Agriculture (NIFA) supported
the project with an Agriculture and Food Research Initiative (AFRI)
grant as part of the Nanotechnology Program.
The biosensor is made by first printing graphene ink onto paper. A
laser then traces over the ink to improve its electrical conductivity by
welding together flakes of the graphene ink, making a nanostructured
surface that is three dimensional.
“The flakes almost look like rose petals coming up from the surface
of the paper,” said Claussen. “They form the base material to test soil
on.”
To do this, the biosensor is dipped into a slurry of soil and water.
It is then connected to an electrochemical reader in the field to test
for pesticide.
“It’s like a pH test strip,” said Claussen. Test results can help
farmers quickly understand how much pesticide is needed to maintain
healthy crops and minimize environmental damage. Also, results can help
farmers understand where environmental remediation may be needed if
pesticide overuse is evident.
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