Team creates low-cost, 3D-printed water pollution sensor

The developers of a new low-cost 3D-printed sensor for water pollution say it could be a game changer in environmental monitoring.

The sensor was developed by a team of researchers from Universities in Scotland, Portugal, and Germany. It can detect pesticides at very low levels in water samples.

Their work is outlined in a paper published in today’s journal Macromolecular Engineering and MaterialsWater monitoring could be made easier, quicker and more affordable with.

Pesticides, which are widely used to stop the loss of crops in agriculture, are used all over the world. They must be handled carefully, as even a small spill into the soil, seawater, or groundwater can harm human, animal, and environmental health.

It is crucial to monitor the environment regularly in order to minimize water pollution. This will allow you take swift action if pesticides are detected. Currently, most pesticide testing is done in laboratories with techniques like chromatography and Mass Spectrometry.

Although these tests produce accurate and reliable results, they can be time-consuming and costly to conduct. A chemical analysis tool known as surface-enhanced Raman Scattering (SERS) is an alternative that offers promising results.

Light scattered by molecules has distinct frequencies that depend on their molecular structure. By analyzing the unique “fingerprint”, scientists can detect and identify vestiges of molecules that are adsorbed onto a metal surface.

It is possible to enhance the effect by improving the surface of the metal to allow it to adsorb molecules. This will increase the ability of sensors in detecting low concentrations of molecules.

The research team wanted to develop a portable and affordable way to test water samples using 3D printed materials that would adsorb the molecules. They also wanted to get accurate first results.

In order to do this, they investigated several types of cellular architectural designs made using mixtures polypropylene/multi-walled carbon nanotubes. The architectures were created using fused filament manufacturing, a type of 3D printer.

Surface-enhanced Raman Scattering was achieved by coating the surfaces of the cellular structures with gold and silver nanoparticles.

The team tested several different 3D-printed designs to see if they could adsorb and uptake molecules of a dye organic called methylene green, before analysing them using a Raman spectrometer.

The best-performing material from those initial tests—a lattice (periodic cellular architecture) design combined with silver nanoparticles—was then added to test strips. SERS tests were performed on samples of sea and freshwater containing low levels of pesticides thiram or paraquat.

The water was drawn from an estuary in Aveiro, Portugal and from taps in the same area—locations which are subject to regular real-life water pollution monitoring tests.

The researchers found that the test strips were capable of detecting molecules of both pesticides at concentrations as low as 1 micromolar—equivalent to one molecule of pesticide to a million molecules of water.

Professor Shanmugam Kumar of University of Glasgow’s James Watt School of Engineering was one of the authors of this paper. The work is based on his research using 3D printing to create nanoengineered lattices.

He stated that SERS is an invaluable diagnostic technique, with applications in various fields. The sensor substrate material we’ve developed benefits from a an optimal combination of the nanocarbon-engineered architected lattice’s large surface area and the remarkable optical properties of the metallic nanoparticles.

The interaction between the local electromagnetic field of the metallic nanoparticles with the chemical mechanisms in carbonaceous materials creates an extremely active surface for SERS.

“The results are very encouraging. These low-cost materials may be used for SERS sensors to detect pesticides at very low levels.”

Sara Fateixa of CICECO Aveiro Institute of Materials of University of Aveiro, designed the nanoparticles that allow the SERS method. She stated, “While the paper examines the system’s potential to detect specific types water pollutants, it could be easily adapted to monitor a variety of chemicals in sample.

“In agriculture, for instance, the milk of cattle that have been treated with antibiotics and are now recovering cannot be sold before the drugs have left their system. Our diagnostic materials can be adjusted to produce reliable results more affordably.

“We look forward to further developing this very promising material for SERS applications.”