Researchers from the University of São Paulo (USP) and the Federal University of Viçosa (UFV) in Brazil have developed a sustainable sensor, known as “plant-wearable,” that can detect the presence of pesticides directly on the surface of vegetables or fruits. Made from cellulose acetate, a material derived from wood pulp, this innovative device aims to help ensure food safety in a world facing food shortages and environmental and health issues caused by excessive agrochemical use.
The study’s findings are published in the journal Biomaterials Advances. Pesticides are commonly sprayed on crops to increase yield, but only 50% of the application reaches its target. The remaining pesticides can contaminate soil, groundwater, surface water, drinking water sources, wastewater, and food products. Monitoring pesticide levels in these environments is crucial to prevent public exposure through skin, lungs, or the digestive system.
“As an alternative, electrochemical sensors can combine affordability, rapid detection, miniaturization, large-scale production, convenience, ease of use, high selectivity and in situ pesticide detection. Our invention has all these features. The analysis is performed directly on the surface of fruit, vegetables or leaves. Hence the term plant-wearable,” said Paulo Augusto Raymundo-Pereira, last author of the article and a researcher at the São Carlos Physics Institute (IFSC-USP).
Current analytical tools, such as chromatographic techniques, are effective but have limitations, including the need for sample pretreatment, expensive equipment, specialized personnel, lengthy analysis times, and portability issues. Additionally, the use of organic solvents can lead to unsafe residues. The new plant-wearable sensor overcomes some of these challenges by using a biodegradable cellulose acetate substrate produced through a casting method and screen-printed electrodes.
“However, instead of the usual materials, which are environmentally unsustainable and take a long time to degrade, such as ceramics or plastic polymers derived from petroleum, we used cellulose acetate, a material derived from plants that has little impact on the environment and disintegrates completely in 340 days or less depending on local conditions. Of course, it has to have appropriate characteristics for any sensor, including low cost, portability and flexibility.”
In laboratory tests, the researchers simulated real-world use by spraying a solution containing carbendazim, a fungicide, and paraquat, a herbicide, on lettuce and tomatoes. Although paraquat was banned by the European Union in 2003 due to its hazardous effects on humans, it is still used in Brazil. The plant-wearable sensor was then attached to the produce, and measurements showed comparable detection levels to those obtained using polyethylene terephthalate, the most commonly used sensor material for this purpose.
