For over 50 years, a silent form of pollution has been detected throughout the planet, infiltrating the highest ocean depths to the highest mountains: microplastics. In addition to the environment, these fragments smaller than five millimeters are also present within our bodies.
Although theoretically scientists knew that microplastics would continue to fragment, it was not yet spoken in simply because there were no technologies that can detect them. Traditional methods of optical microscopy and visual analysis did not “see them”.
The scientific community has dedicated decades of research to understand how macro and microplastics behave. On the other hand, information on nanoplastics with diameters below a micrometer remains limited, although we know that these particles can cross important biological barriers.
A thousand times smaller than micro versions, nanoplastics cross even the hematoencephalic barrier, the selective natural defense that the body uses to protect the brain from potentially dangerous substances. This means that these pollutants have unrestricted access to virtually any part of the human organism.
To address the impact potential of these plastic fragments in nanoscale, it is proposing “a cheap, easy and reliable way to detect nanoplastics”: the optical sieve, a device that uses light to “filter” and identify tiny particles.
How does the optical sieve work?
Technologically revolutionary, the optical sieve consists of simply and cheaply. In practice, it is a device two in one: it works as a physical sieve with holes of different sizes, and detects particles with color changes.
Simple to use and provide the diagnosis – as a pregnancy test – the optical sieve is a nail size chip, thin as a credit card, but with invisible microscopic holes. When you put a water sample on it, a color pattern appears through a microscope.
This is because when nanoplastics pass through the holes of the chip, they interact with special microscopic structures that change color depending on the size of the present particles. Each size produces a different color, not only allowing them to detect them, but also determine their sizes and count them.
The great differential of this technology is in its simplicity: while nanoplastics detection today requires hundreds of thousands of dollars as electronic microscopes, the optical sieve It works only with a common microscope and a basic camera.
First author of the article, Dominik Ludish, a doctoral student at the University of Stuttgart, Germany, explains in a statement that particles, ranging from 0.2 to 1 µm, “are filtered from the liquid using the sieve where the size and depth of the holes can be adapted to nanoplastic particles.”
Tests and potential uses of the new technology
In practice, the optical sieve acts as a selective filter of high precision. The system rejects particles too large for microscopic holes, while the very small ones cannot adhere to the structures properly. Only nanoplastics of the exact size are retained in the corresponding cavities.
Like a microscopic chess board, the chip is divided into different areas: one has holes of 200 nanometers, another from 300, another 500, and so on. When the water is placed on the chip, it goes through a washing process: 200 nm nanoplastics fit, but those of 300 nm and 150 nm are washed.
To validate technology, researchers added known amounts of spherical nanoplastics to controlled samples using real lake water, containing sand and organic components. In order to reproduce what probably occurs in naturethey adjusted the concentration to 150 µg/ml.
The result was a success: the optical sieve accurately determined the exact number and the distribution of nanoplastic sizes in the synthetic sample. This has found that technology can work not only in sterilized laboratory environments, but also with complex environmental samples.
Already planning future experiments with non -spherical nanoplastic particles, the head of the 4th Institute of Physics of the University of Stuttgart, Mario Hentschel, explains that “in the long run, optical sieves will be used as a simple tool for analysis in environmental and health research.”
