Tech
Color-changing strip enables affordable nanoplastic analysis using ordinary microscope
A joint team from the University of Stuttgart in Germany and the University of Melbourne in Australia has developed a new method for the straightforward analysis of tiny nanoplastic particles in environmental samples. One needs only an ordinary optical microscope and a newly developed test strip—the optical sieve. The research results have now been published in Nature Photonics.
“The test strip can serve as a simple analysis tool in environmental and health research,” explains Prof. Harald Giessen, Head of the 4th Physics Institute of the University of Stuttgart. “In the near future, we will be working toward analyzing nanoplastic concentrations directly on site. But our new method could also be used to test blood or tissue for nanoplastic particles.”
Plastic waste is one of the central and acute global problems of the 21st century. It not only pollutes oceans, rivers, and beaches but has also been detected in living organisms in the form of microplastics. Until now, environmental scientists have focused their attention on larger plastic residues.
However, it has been known for some time that an even greater danger may be on the horizon: nanoplastic particles. These tiny particles are much smaller than a human hair and are created through the breakdown of larger plastic particles. They cannot be seen with the naked eye. These particles in the sub-micrometer range can also easily cross organic barriers such as the skin or the blood-brain barrier.
Because of the small particle size, their detection poses a particular challenge. As a result, there are not only gaps in our understanding of how particles affect organisms but also a lack of rapid and reliable detection methods.
In collaboration with a research group from Melbourne in Australia, researchers at the University of Stuttgart have now developed a novel method that can quickly and affordably detect such small particles. Color changes on a special test strip make nanoplastics visible in an optical microscope and allow researchers to count the number of particles and determine their size.
“Compared with conventional and widely used methods such as scanning electron microscopy, the new method is considerably less expensive, does not require trained personnel to operate, and reduces the time required for detailed analysis,” explains Dr. Mario Hentschel, Head of the Microstructure Laboratory at the 4th Physics Institute.
The “optical sieve” uses resonance effects in small holes to make the nanoplastic particles visible. A study on optical effects in such holes was first published by the research group at the University of Stuttgart in 2023. The process is based on tiny depressions, known as Mie voids, which are edged into a semiconductor substrate.
Depending on their diameter and depth, the holes interact characteristically with the incident light. This results in a bright color reflection that can be seen with an optical microscope. If a particle falls into one of the indentations, its color changes noticeably. One can therefore infer from the changing color whether a particle is present in the void.
“The test strip works like a classic sieve,” explains Dominik Ludescher, Ph.D. student and first author of the publication. Particles ranging from 0.2 to 1 µm can thus be examined without difficulty. The particles are filtered out of the liquid using the sieve in which the size and depth of the holes can be adapted to the nanoplastic particles, and subsequently by the resulting color change can be detected. This allows us to determine whether the voids are filled or empty.”
The novel detection method used can do even more. If the sieve is provided with voids of different sizes, only one particle of a suitable size will collect in each hole. “If a particle is too large, it won’t fit into the void and will simply be flushed away during the cleaning process,” says Ludescher.
“If a particle is too small, it will adhere poorly to the well and will be washed away during cleaning.” In this way, the test strips can be adapted so that the size and number of particles in each individual hole can be determined from the reflected color.
For their measurements, the researchers used spherical particles of various diameters. These are available in aqueous solutions with specific nanoparticle. Because real samples from bodies of water with known nanoparticle concentrations are not yet available, the team produced a suitable sample themselves.
The researchers used a water sample from a lake that contained a mixture of sand and other organic components and added spherical particles in known quantities. The concentration of plastic particles was 150 µg/ml. The number and size distribution of the nanoplastic particles could also be determined for this sample using the optical sieve.
“In the long term, the optical sieve will be used as a simple analysis tool in environmental and health research. The technology could serve as a mobile test strip that would provide information on the content of nanoplastics in water or soil directly on site,” explains Hentschel.
The team is now planning experiments with nanoplastic particles that are not spherical. The researchers also plan to investigate whether the process can be used to distinguish between particles of different plastics. They are also particularly interested in collaborating with research groups that have specific expertise in processing real samples from bodies of water.
More information:
D. Ludescher et al, Optical sieve for nanoplastic detection, sizing and counting. Nature Photonics (2025). DOI: 10.1038/s41566-025-01733-x. www.nature.com/articles/s41566-025-01733-x
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Color-changing strip enables affordable nanoplastic analysis using ordinary microscope (2025, September 13)
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The story of the park begins in 2014, when Enrique Peña Nieto, the president of Mexico at the time, announced plans for a new transport hub for Mexico City. It would be built on the largely dry bed of Lake Texcoco, the body of water that had once surrounded Mexico City’s ancient ancestor, Tenochtitlán, the center of the Aztec empire. The marketing promise was that NAICM would be one of the greenest airports in the world. The terminal, designed by Norman Foster—winner of the Pritzker Prize in 1999 and the Prince of Asturias Award for the Arts in 2009—was going to be the first to obtain LEED platinum certification, the highest international recognition for energy efficiency and sustainable design.
Its site, Lake Texcoco, had already lost more than 95 percent of its original surface area, and in 2015 plans were made to drain it completely to build the airport. However, when Andrés Manuel López Obrador took office as Mexico’s president in 2018, he canceled the plan. It would end up costing more than $13 billion and would leave behind serious environmental damage: The incomplete project destroyed a key refuge for migratory birds; carved up mountains in the State of Mexico (the federal region that surrounds Mexico City); razed agricultural land; and altered the landscape of the cultural capital of the Nahua, an indigenous people that includes the Mexica (or Aztecs).
Echeverría, who says he has been obsessed with the area for nearly three decades, was appointed by the new government to restore the local ecosystem. “It felt like I was stepping onto Mars,” says the architect, reflecting on being placed at the helm of the project. The park covers an area equivalent to 21 times the area of Mexico City’s enormous Bosque de Chapultepec park. Echeverría offers his own comparisons: “This place is three times the size of the city of Oaxaca and, as a reference for those outside Mexico, it’s roughly three times the size of Manhattan.”
The restoration project wasn’t a mere whim of Mexico’s new president, but the culmination of a century of visions and plans. “We’ve been skating around this for 75 years,” Echeverría says, citing restoration projects that were proposed as early as 1913, including ones by Miguel Ángel de Quevedo (a celebrated early environmentalist) in the 1930s and agronomist Gonzalo Blanco Macías in the 1950s. What was missing, Echeverría says, “wasn’t a lack of ideas, but of political will.”
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Continuing a decades-long partnership, Ask Ralph was developed with Microsoft on its Azure OpenAI platform and uses advanced conversational AI technology and natural language processing to understand open-ended prompts, interpret context and provide tailored recommendations to closely mimic the experience of speaking with an in-store stylist.
Ralph Lauren has launched Ask Ralph, an AI-powered conversational shopping tool built with Microsoft on Azure OpenAI.
The feature offers personalised, shoppable Polo Ralph Lauren outfits in response to user prompts, simulating an in-store stylist experience.
Available first to US app users, it provides styling inspiration and tailored recommendations to enhance discovery and brand engagement.
“Twenty-five years ago, we partnered with Microsoft to launch one of the fashion industry’s first e-commerce platforms, and today, we are once again redefining the shopping experience for the next generation,” said David Lauren, Chief Branding and Innovation Officer, Ralph Lauren Corporation. “Whether getting ready for a first day of a new job, or creating the perfect look for a night out, Ask Ralph is about more than just discovery – it is about engaging consumers with what they love most about Ralph Lauren: our iconic, unique take on style, providing timeless head-to-toe looks that inspire them to step into our world.”
Shoppers can interact with Ask Ralph just as they would with a stylist in a Ralph Lauren store, through simple, conversational prompts. From “What should I wear to a concert?” to “Show me some women’s Polo Bear sweaters,” or styling queries like, “How can I style my navy-blue men’s blazer?” Ask Ralph responds, surfacing visually laid out, complete Polo Ralph Lauren looks with styling tips, integrating content from across Ralph Lauren’s digital channels. Users can ask clarifying questions and refine the recommendations to align with their own sense of style. Ask Ralph makes it easy to add individual elements of a look to shopping carts or purchase the head-to-toe recommendation.
“AI is transforming the way consumers get inspired, educated and purchase from fashion brands around the world,” said Shelley Bransten, Corporate Vice President of Global Industry Solutions, Microsoft. “We’re proud to bring the combination of our trusted generative AI capabilities through Azure OpenAI together with Ralph Lauren’s iconic brand to pave the way for an entirely new conversational commerce experience.”
Informed by how users initially use and engage with Ask Ralph, the tool will continue to develop, including releasing new features and increased personalized experiences, expanding to additional Ralph Lauren brands and launching across more platforms in markets around the world.
Ask Ralph is the latest milestone in Ralph Lauren’s rich history of innovation and in leading the industry in creating immersive and cinematic retail experiences that transport consumers into the World of Ralph Lauren. Twenty-five years ago, the Company was one of the first luxury brands to pioneer e-commerce, setting a new industry standard. Always pushing boundaries to surprise, delight and inspire consumers, the Company has long experimented with cutting-edge ideas that were years ahead of their time – from interactive and virtual shopping technology to holograms, 4D projections and CGI animations.
The Company also continues to invest in AI and other technologies to enhance the consumer experience, like more personalized marketing and engaging digital experiences, as well as to optimize its operations, including predictive inventory management and product demand forecasting.
Note: The headline, insights, and image of this press release may have been refined by the Fibre2Fashion staff; the rest of the content remains unchanged.
Fibre2Fashion News Desk (RM)
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