Sunlight is essential to life, but it is also an "invisible enemy" that threatens skin and eye health. A domestic research team has developed the world's first transparent wearable sensor that can accurately monitor ultraviolet exposure in real time.
A research team led by Professor Kang Sung-jun in the Department of Advanced Materials Engineering at Kyunghee University said on the 16th that, together with the optical sensor developer Uvision Lab, it developed a fully transparent ultraviolet A (UVA) detection sensor. The findings were published the same day in the international journal Science Advances.
Prolonged sun exposure can burn the skin, accelerate aging, and in severe cases cause ophthalmic diseases and even skin cancer. One of the causes is ultraviolet radiation. Ultraviolet light is divided into three types by wavelength—UVA, UVB, and UVC—and among them, UVA has the longest wavelength, penetrates the ozone layer, and reaches deep into the skin.
Most existing ultraviolet measuring devices are opaque, making it difficult to accurately determine the actual amount of transmitted ultraviolet light. Because only a small portion of light passes through the sensor to reach the internal semiconductor, measurement accuracy suffered.
The research team fabricated a high-performance yet fully transparent photodiode by stacking multiple layers of oxide semiconductors. A photodiode is a semiconductor device that converts light energy into electrical energy. Using the transparent photodiode, the team developed a transparent ultraviolet sensor that lets visible light pass through while selectively and precisely detecting only the UVA range.
The transparent ultraviolet sensor achieves an average light transmittance of 75%. Thanks to this, it is barely noticeable even when attached to the skin, while precisely measuring ultraviolet data. At the same time, it detects light with world-class sensitivity and converts it into electrical signals.
Together with Uvision Lab, the researchers also developed a real-time ultraviolet monitoring system that links a transparent sensor attached to the skin with a smartphone app. When exposure reaches 80% of the ultraviolet level likely to cause a burn, the smartphone sends a warning alert. Users can recognize exposure in advance and respond immediately by moving to shade or reapplying sunscreen.
The research team said, "This technology will serve as a real-time monitoring tool that complements the limits of sunscreen." Because sunscreen's effects diminish after a certain time, using it together with a device that shows actual exposure maximizes skin protection.
The sensor is transparent and lightweight, so it can be applied in various forms such as clothing, watches, and bracelets. The research team noted, "If it is applied to smartwatches or fitness bands in the future, ultraviolet management will be possible even during everyday outdoor activities," adding, "It will greatly help prevent skin cancer and support skin health management."
Kang Sung-jun said, "With the transparent ultraviolet sensor, we can accurately identify an individual's ultraviolet exposure, allowing advance warnings and prevention of diseases such as skin cancer, photoaging, and cataracts," adding, "In the future, this could strengthen Korea's technological competitiveness across the transparent electronics and optical sensor industries."
References
Science Advances (2025), DOI: https://doi.org/10.1126/sciadv.aea7218