Moisture in the air changes how a tiny photonic structure reflects light, exposing concealed patterns for encryption, authentication and sensing.
(Nanowerk News) Engineers at the University of California San Diego have developed an optical device that reveals hidden images and changes colors in response to different levels of humidity. The technology, published in Light: Science & Applications (« Reversible optical data storage and encryption enabled by phase-change and hydrogel integration »), could lead to the development of new anti-counterfeiting labels, secure data storage, interactive displays and environmental sensors.
The device works by displaying different images depending on moisture levels in the air. Under normal conditions or low humidity levels, one image (UC San Diego Triton logo) is visible. When humidity increases, a second image (UC San Diego library logo) emerges and conceals the first. This transition can be triggered even when a person breathes on the device. It happens in a fraction of a second and can be repeated many times.
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