At Brazil's São Carlos Institute of Physics, researcher Paulo Augusto Raymundo-Pereira has unveiled a solution to one of modern agriculture's persistent challenges: detecting pesticides on crops in minutes rather than days. The sensors are made from cellulose acetate, a plant-based bioplastic printed with carbon ink, and they can be placed directly on the skin of fruits and vegetables—or even on leaves and stems—to reveal the presence of harmful chemicals in just three minutes and twenty-eight seconds.
This matters because conventional pesticide detection requires sending samples to laboratories, a process that can take weeks. For farmers managing thousands of acres, or for produce handlers protecting consumers, that delay creates a costly window of uncertainty. The World Economic Forum recognized wearable sensor engineering as one of the top ten emerging technologies of 2023, specifically for its potential to improve plant health and increase agricultural productivity. Yet most existing wearable devices are made from petroleum-derived plastics that don't grip curved or uneven surfaces and won't break down in soil.
Raymundo-Pereira's sensors solve both problems. Each cellulose acetate platform contains two separate sensor units that work in tandem, using different analytical techniques to detect three classes of pesticides—diquat, carbendazim, and diphenylamine—simultaneously. One unit employs square-wave voltammetry to identify diquat; the other uses differential pulse voltammetry to analyze the other two. The sensors are tested by applying a single drop of water to the fruit's surface (where the measurement takes place at the electrode-water interface) and then positioning the sensor over that droplet. The results stream wirelessly to a smartphone via Bluetooth.
The elegance lies in the material itself. Cellulose acetate is flexible enough to conform to the wavy surface of an apple or the lateral grooves of a bell pepper, yet it's nontoxic, biodegradable, lightweight, and—crucially—inexpensive to produce. Each sensor costs 0.077 cents, making it economically viable as a single-use device. The team tested the platform by spraying a pesticide solution onto apples and bell peppers, letting them dry for five hours to simulate real-world contamination, then running the detection directly on the fruit's skin. The study, published in Biosensors and Bioelectronics: X, demonstrates that the system works reliably under practical conditions.
What sets this innovation apart from earlier approaches—Raymundo-Pereira's team created a gloved sensor device in 2022—is its true biodegradability and material efficiency. Used sensors can be burned under specific conditions to recover the carbon ink, which can then be used to manufacture new devices. This circular approach means waste becomes feedstock.
The technology opens doors beyond agriculture. Raymundo-Pereira notes that the same sensors can detect pesticide residues in human saliva or tap water, work the team has already validated in testing. For regions where agricultural runoff contaminates drinking water supplies, or where workers in the fields need rapid health screening, these tiny cellulose platforms offer a decentralized, portable, real-time monitoring tool. What began as a solution for one crop could reshape how we track contamination across food systems and beyond.