Scientists working at the University of São Paulo (USP) and the Federal University of Viçosa (UFV) have come up with a biodegradable "plant-wearable" sensor designed to offer decentralized detection of pesticides —with a view to improving food safety as a result.
"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," last author Paulo Augusto Raymundo-Pereira told Agência FAPESP's Julia Moióli of the work.
"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."
Dubbed "plant-wearable," as they're designed to be deployed directly on the surface of the fruit being monitored, the team's cellulose acetate sensor — built through screen-printing three electodes on to a cast substrate — proved its worth in laboratory testing: using differential pulse (DPV) and square wave voltammetry (SWV) the sensors were able to pick up carbendazim and paraquat, a fungicide and a herbicide respectively, on lettuce, tomato, and even within water samples.
The project also offers insight into how much of these pollutants remain on the fruit we consume, with at least 36 per cent of both — and up to 60 per cent of carbendazim on lettuce — remaining even after washing the fruit for two hours in water. "Washing an immersion," Raymundo-Pereira concludes. "were clearly insufficient to remove residues of the pesticides."
The team is hoping to bring the technology to agencies responsible for agriculture and food safety and to those looking to certify organic crops as being free from pesticides. For general farming, the team proposes, the same sensors could monitor pesticide levels within the fields — helping to reduce their overuse on crops that don't need additional doses.
The team's work has been published in the journal Biomaterials Advances under closed-access terms.