Researchers develop sensors for continuous corn growth monitoring

Researchers develop sensors for continuous corn growth monitoring Robert Egan Senior Editor When is the best time to apply nitrogen? What plant response was there to fertilizer or any number of other treatments? There is a general answer to those questions now, but what if plant breeders and agronomists could download data from continuously monitored cornstalks and ears to develop specific answers for those questions? Research work at South Dakota State University has developed sensors that can do just that. Mazhar Sher, a biosensors engineer and an assistant professor in the Department of Agricultural and Biosystems Engineering, started developing sensors using laser-induced graphene in August 2022, when he arrived at SDSU. Graphene, which comes from graphite, was first successfully isolated as a single-layer sheet in 2004 by physicists Andre Geim and Konstantin Novoselov at the University of Manchester in the United Kingdom. Their pioneering experiments on graphene and its remarkable properties led to their receipt of the 2010 Nobel Prize in physics, Sher said. Laser-induced graphene was first reported in 2014 by researchers at Rice University, who demonstrated that a carbon dioxide laser could directly convert commercial polyimide into porous graphene, establishing a rapid and scalable method for fabricating graphene structures. Sensors created via lasers Sher explained that laser-induced graphene offers high electrical conductivity, large surface area, mechanical flexibility, porous structure and high sensitivity, making it well suited for sensor applications. He said current applications include fitness trackers. In fact, Sher worked on sensors for human diseases for his postdoctoral research at the University of Pennsylvania before coming to SDSU. The field of wearable plant sensors is just emerging, and no one has developed sensors to measure cornstalk or ear growth—until now. Sher and his master's student Chamika Kuruppuarachchi have completed initial testing. He hopes to be able to patent the technology. The next step is to conduct field trials in SDSU test plots and find funds for continued research. The sensors were developed in his biosensors lab in the Raven Precision Agriculture Center with the corn monitored in the SDSU greenhouse. The sensors measured cornstalk and ear diameter growth with data updated every 10 minutes. A key to the laser-induced graphene sensors is attaching them to a food-grade silicone band so that when the graphene bends to accommodate plant growth, contact is maintained. Sher also incorporates a spring mechanism that allows the silicone band to expand and not restrict plant growth. Grad students aid research To develop the best-quality graphene sensor, laser power and scanning speed must be at optimal levels, Sher said. Doing so increases graphene sensitivity and reduces defects, he said. The work of optimizing laser parameters was done by Sikander Ameer, a previous doctoral student who worked with Sher from August 2022 until his graduation in December 2025. Building on that foundation, Kuruppuarachchi has expanded the research by developing laser-induced graphene sensors for use as plant-wearable devices. He has also helped design and integrate the electronics needed to collect, process and report data from the sensors. Measurements are recorded on a microSD card, a tiny, removable flash memory card used to store data in a portable digital device. The electronics are designed for battery-powered operation during long-duration plant experiments. While the polyimide sheets used in creating laser-induced graphene cost less than a dollar, there is no vision for farmers to have sensors on their cornstalks. The intended audience is plant breeders and agronomists, who could then give more specific advice and recommendations to farmers. Provided by South Dakota State University