Micro- and nanoplastics are in the food we eat, the water we drink and the air we breathe. They show up in our bodies, from our testicles to our brain matter. Researchers at the University of British Columbia have now developed a low-cost, wearable device that can accurately measure plastic emissions from everyday sources such as disposable cups and water bottles. The device, coupled with an app, uses fluorescent markers to detect plastic particles ranging from 50 nanometers to 10 micrometers – too small to be seen with the naked eye – and delivers results within minutes. The method and results are described in detail in ACS sensors.
“The breakdown of larger plastics into microplastics and nanoplastics poses a significant threat to food systems, ecosystems and human health,” said Dr. Tianxi Yang, assistant professor in the School of Land and Food Systems, who developed the tool. “This new technique enables rapid and cost-effective detection of these plastics, which could help protect our health and ecosystems.”
Nano- and microplastics are byproducts of decomposing plastic materials such as lunch boxes, cups and cutlery. As very small particles with a large surface area, nanoplastic particles are particularly concerning for human health because they are better able to absorb toxins and penetrate biological barriers in the human body.
Detecting these plastics typically requires skilled personnel and expensive equipment. Dr. Yang’s team wanted to make detection faster, more accessible and more reliable.
They created a small, biodegradable, 3D-printed box that contained a wireless digital microscope, green LED light, and an excitation filter. To measure the plastics, they adapted MATLAB software with machine learning algorithms and combined it with image acquisition software.
The result is a portable tool that works with a smartphone or other mobile device and counts the number of plastic particles in a sample. The tool takes only a tiny sample of liquid – less than a drop of water – and shines the plastic particles under the green LED light in the microscope to make them visible and measured. The results are easy to understand, whether for a technician in a food processing lab or simply someone curious about their morning cup of coffee.
For the study, Dr. Yang’s team tested disposable polystyrene cups. They filled the cups with 50 ml of distilled boiling water and allowed it to cool for 30 minutes. The results showed that the cups released hundreds of millions of nano-sized plastic particles, about one-hundredth the width of a human hair and smaller.
“Once the microscope in the box captures the fluorescent image, the app matches the pixel area of the image with the number of plastics,” said co-author Haoming (Peter) Yang, a master’s student in the School of Land and Food Systems. “The display shows whether and how much plastic is present. Each test costs only 1.5 cents.”
The device is currently calibrated to measure polystyrene, but the machine learning algorithm could be optimized to measure different types of plastics, such as polyethylene or polypropylene. Next, the researchers want to commercialize the device to analyze plastic particles for other real-world applications.
The long-term effects of ingesting plastic through drinks, food and even plastic particles in the air are still being studied but are cause for concern.
“To reduce plastic intake, it is important to avoid petroleum-based plastic products and instead choose alternatives such as glass or stainless steel for food containers. The development of biodegradable packaging materials is also important to replace traditional plastic products and create a more sustainable world,” said Dr. Yang.
