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Biodegradable sensor developed by USP scientists uses cellulose acetate, carbon ink, and Bluetooth reading to identify pesticides directly on the surface of plants, with analysis in a few minutes, low cost per unit, and potential use also in water and saliva.
Biodegradable sensor created by USP scientists detects pesticides directly on leaves, bark, and stems, shows real-time results on the cell phone, and costs US$ 0.077 per unit, bringing low-cost plant health monitoring closer to Brazilian fields.
Pesticides can be measured directly on the plant
The technology was developed at the University of São Paulo and published in February in the journal Biosensors and Bioelectronics: X. The device is screen-printed on transparent and flexible bioplastics, using carbon ink.
Being miniaturized and malleable, the sensor can be attached to leaves, bark, and stems. It allows monitoring of temperature, humidity, dehydration, biomarkers, diseases, nutrients, and pesticides without destroying the analyzed sample.
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Cellulose acetate replaces fossil plastic
The wearable sensor was made of cellulose acetate, a flexible plant-based material that can be produced from agricultural waste. Cellulose is described as the most abundant natural polysaccharide on Earth.
The cited characteristics include biocompatibility, thermal stability, flexibility, low toxicity, affordable cost, lightness, biodegradability, and easy handling.
The difference matters because many current wearable sensors use petroleum-derived plastic polymers and may have low adherence to complex plant surfaces.
Each device combines two sensory units, with different techniques. In the same evaluation, they detect three classes of pesticides: diquat, carbendazim, and diphenylamine.
Water drop, sensor, and Bluetooth
The identification occurs on the plant surface but in an aqueous medium. A drop of water is placed on points like leaves, the peduncle of tomatoes or apples, and grooves of bell peppers.
The drop allows the necessary conductivity for electrical and chemical reading. Then, the sensor is positioned over this point and measures the interface between the electrode and the aqueous solution.
The platform is integrated with a portable wireless potentiostat, a device that controls voltage and measures electric current. The result appears on the cellphone via Bluetooth.
Each device costs US$ 0.077. Since the sensors are single-use, they need to be cheap and biodegradable. Considering the two units in sequence, the complete analysis takes three minutes and twenty-eight seconds.
Tests simulated use in food
In the tests, a pesticide solution was sprayed on the skin of apples and peppers, at a concentration of 1,000 micrometers. The food dried for five hours before on-site analyses.
Next, the sensor was attached to the skin. To allow reading, researchers added a drop of 500 microliters of phosphate buffer solution, used to stabilize the environment.
The team had already created, in 2022, a glove with sensors on the fingertips for the same purposes. The new sensor, however, can be applied directly to the sample and follows the surface shape.
Raymundo-Pereira highlights that the glove is not biodegradable. The wearable sensor is biodegradable and the carbon ink can be reused, through burning under specific conditions, to produce new devices.
Water, saliva, and patent application
Besides agricultural use, the sensors were tested in human saliva and tap water added with pesticides. The technology can also measure components present in urine and sweat.
The patent applications for the glove and the wearable sensor are already at the National Institute of Industrial Property. The study was supported by FAPESP and included researchers from USP and the Federal University of Viçosa.
Have you ever imagined producers, researchers, and consumers monitoring pesticide residues and plant health signals directly in the field, without relying solely on analyses far from the production site? Comment on what this technology could change in food monitoring, sensor use, and agricultural routine.
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