Researchers at the São Carlos Institute of Physics at the University of São Paulo (IFSC-USP) in Brazil have developed biodegradable wearable sensors that detect pesticides on plants and food surfaces in just over three minutes. The flexible devices use cellulose acetate bioplastic and carbon ink instead of conventional petroleum-based plastics.

The sensors attach directly to leaves, stems and fruit surfaces. They monitor plant health in real time and can identify pesticides, dehydration, humidity, nutrient levels and plant diseases. The technology supports faster and more localised agricultural monitoring without damaging crops.

Flexible Bioplastic Replaces Conventional Plastics

The research team produced the transparent sensor substrate from cellulose acetate, a plant-based material that can come from agricultural waste streams. Cellulose is abundant, lightweight and biodegradable. It also offers flexibility and thermal stability, making it suitable for wearable electronics.

Unlike many existing wearable sensors, the cellulose-based material adapts easily to curved and uneven plant surfaces. This allows the sensors to conform closely to leaves, stems and fruits during testing.

The researchers designed the sensors as low-cost disposable devices. Each sensor reportedly costs less than one US cent to produce. The team also states that the carbon ink may be recovered after use and reused in new sensors under controlled conditions, supporting circular production methods.

Rapid Analysis on Fruit and Plant Surfaces

Each biodegradable platform contains two sensor units that identify three pesticide classes simultaneously: diquat, carbendazim and diphenylamine. The system performs the analysis directly on the plant surface using a small drop of water to create conductivity.

The device connects wirelessly to a portable potentiostat and sends results to a smartphone through Bluetooth. The complete testing process takes approximately three minutes and twenty-eight seconds.

Researchers tested the sensors on apples and bell peppers treated with agrochemical solutions. The trials simulated real agricultural conditions and demonstrated rapid on-site analysis without laboratory equipment.

Potential Applications Beyond Agriculture

The research team believes the technology could also support healthcare and environmental monitoring. According to the researchers, the sensors could analyse pesticide residues in saliva, sweat, urine and tap water.

The team describes the devices as some of the first biodegradable wearable sensors made from natural sources that could potentially adapt for human use. Existing wearable sensors for healthcare applications often rely on petrochemical plastics.

Patent applications for both the wearable sensor and an earlier glove-based sensing system have already been filed in Brazil.

Source: Agência FAPESP
Photo: Paulo A. Raymundo-Pereira