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Wearable sensors are becoming essential tools for monitoring personal exposure to environmental hazards. A team of researchers from Khalifa University has developed a novel wearable material that senses temperature and ultraviolet radiation using color-changing hydrogels enhanced with artificial intelligence. The device, manufactured through advanced 4D printing, is built from a hydrogel composite that mimics the strength of plastic and shifts color in response to environmental conditions.Ìý

Mohamed Elnemr, Ragi Adham Elkaffas, Rami Elkaffas, Dr. Yarjan Abdul Samad, Muhammed Hisham, Prof. Baker Mohammad and Prof. Haider Butt comprised the team from Khalifa University, working with Yasmin Halawani from the University of Dubai. They published their results in .Ìý

The new material offers strength similar to nylon and its durability means it functions reliably in everyday settings as part of rings, wristbands, or glasses. The key innovation lies in embedding thermochromic and photochromic powders into hydrogels. Thermochromic dyes change color with temperature, while photochromic dyes respond to UV light. These changes are interpreted by an artificial intelligence model trained to classify temperature ranges based on the color spectrum. In testing, it reached 98.75 percent classification accuracy.Ìý

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“Our goal was to create a material that communicates environmental risks in real time, without needing electronics. By combining color-shifting chemistry with AI, we’re turning simple materials into smart sensors.”

— Haider Butt, Mechanical & Nuclear Engineering

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In practical use, the wearable changes color visibly as temperature rises or UV exposure intensifies, serving as a real-time alert for environmental risks. Under high midday UV exposure, for example, the material turns dark blue. Under weaker sunlight or artificial light, there’s barely any change in color. This specificity makes the system useful as a quick, low-tech check on UV levels, which is ideal for outdoor workers or anyone concerned about sun exposure.Ìý

The team’s wearable works without batteries, circuits, or screens. It’s entirely passive and self-contained, and a concentration of just 2.5 percent of the chromic powders was enough to deliver visible changes without weakening the material, so the sensors are robust and inexpensive too. There are limits, of course. Prolonged exposure to sunlight can degrade the dyes over time, much like how transition lenses slowly lose effectiveness. But in most practical scenarios, the material would only need to last for a day or two, making it perfect for semi-disposable applications.Ìý

The research team sees this as a first step. Future versions could link with smartphone apps, expanding functionality while keeping the hardware minimal. For now, it’s a promising proof of concept, paving the way for low-cost, battery-free environmental monitoring.