Cheap, paper-based test device can detect toxic compounds in water

A cheap, recyclable device that can detect toxic compounds in water has been developed by University of Bath researchers who believe it could help millions of people across the world access safe drinking water.

Access to safe drinking water is one of the UN’s Sustainable Development Goals, since it is a basic human right and is crucial to combating inequalities and reducing poverty.

This right is yet to be achieved in the world’s poorest countries, and one of the reasons for this is the lack of easily deployable and affordable water-testing tools.

The technology was inspired by the simplicity of litmus paper, which is commonly used for the rapid assessment of acidity in water.

It consists of a microbial fuel cell (MFC) obtained by screen printing biodegradable carbon electrodes on to a single piece of paper.

An MFC is a device that uses the natural biological processes of ‘electric’ bacteria – attached to the carbon electrodes - to generate an electric signal. When these bacteria are exposed to polluted water, a change in the electric signal occurs, which can be used as a warning message that the water is unsafe to drink.

The device, which researchers say is expected to cost no more than £1, is environmentally friendly as the paper sensor is made from biodegradable components.

It weighs less than 1g, so is easy to transport.

Dr Mirella Di Lorenzo, senior lecturer at the University of Bath’s Department of Chemical Engineering, said: “This work could lead to a revolutionary way of testing water at the point of use, which is not only green, easy to operate and rapid, but also affordable to all.

“This type of research will have a significant positive impact, especially benefiting those areas where access to even basic analytic tools is prohibitive.

“This device is a small step in helping the world realise the United Nations’ call to ensure access to safe drinking water and sanitation as a human right.”

The researchers are now investigating how to link up the sensor with an electric device such as a mobile phone, via a wireless transmitter.

This could create a user-friendly way of identifying if a water supply is safe to use.

Dr Janet Scott, reader in the University of Bath’s Department of Chemistry, said: “This is a great example of how scientists and engineers working closely together can develop useful technologies with the potential to impact positively on the lives of citizens globally - we were able to design the materials that facilitated the production of these devices and the engineering partners designed the devices.”

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