Developed by engineers from Glasgow University in collaboration with colleagues from the Łukasiewicz Institute of Microelectronics and Photonic (IMiF), the senors are made from electronic materials which degrade into plant nutrients, acting as fertiliser to help crops grow.
In a statement, project lead Professor Jeff Kettle of Glasgow’s James Watt School of Engineering, said: “We urgently need to find a way to make digital agriculture more sustainable in the years to come. Currently, around 80 per cent of the world’s electronics head straight to landfill once they’ve reached the end of their useful life, which creates massive environmental and public health challenges from the toxic materials which many of them contain.
“We’re keen to continue expanding our biodegradable sensor’s ability to detect other key indicators of plant growth and soil health. That could include adding sensitivity to ‘forever chemicals’ like PFAs, which have significant environmental impact.”
Improving sustainability
The biodegradable front-end sensors are paired with conventional electronics to monitor crop health. The team said their modular approach enhances the reusability of the overall existing electronic systems and significantly reduces electronic waste.
Their modular, hybrid electronics architecture has been applied to ‘digital agriculture’, an approach to farming using networked sensors directly applied to crops to monitor their environment and their growth. However, the current generation of sensors used in digital agriculture are made from non-recyclable materials.
In a paper published in ACS Applied Electronic Materials, the team described how they made a digital agriculture sensor from sustainable materials, combining a biodegradable patch with a matchbook-sized reusable electronic module.
The sensor patches are manufactured using a screen printing process, a low-cost, low-energy method of manufacturing that could help enable the large-scale deployment necessary for the wider adoption of digital agriculture globally.
In this work, conductive tracks are printed onto a biodegradable polymer substrate using graphene-carbon ink. Then, a sensing layer made from molybdenum disulfide is printed on top – so all materials used naturally break down into plant nutrients.
Data from the sensors, which are sensitive to the changes in pH and temperature which can be caused by infections in crops, are collected by the electronic module. The data can be sent wirelessly to computers, which could in the future help farmers build up a detailed picture of crop health.
Lab tests showed the sensors can reliably monitor soil pH levels, with consistent performance demonstrated in solutions ranging from pH 3 to pH 8 over the course of two weeks. The team also demonstrated that that the sensors can detect traces of ethephon, a widely used plant growth regulator that can be toxic to humans and wildlife if it contaminates groundwater. At the end of their useful lifecycle, the sensors degrade into key primary and secondary nutrients to support future plant growth.
The research is a development in the TESLA (Transient Electronics for Sustainable ICT in DigitaL Agriculture) project, a £1.8m effort funded by UKRI and CHIST-ERA, a consortium of research funding organisations.
This research was supported with funding from the Engineering and Physical Sciences Research Council (EPSRC), plus the São Paulo Research Foundation (FAPESP).
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