When IR Patterns Become Tunable

Until now, infrared-based security features have faced a drawback, in that once a pattern is printed or encoded, it cannot be changed. Most systems are static, meaning the same hidden pattern is locked in at the point of manufacture, limiting the complexity and adaptability of the protection.

A research team led by Xi Chen from the University of Science and Technology, Beijing, China, has now developed a solution to this problem: an electrically tunable infrared (IR) film that can show, hide or alter hidden IR patterns on demand ¹.

At the heart of the work is a material called polymer-stabilised cholesteric liquid crystal (PSCLC). Liquid crystals are already widely used in display screens, but in this case they are engineered to interact not with visible light, but with IR wavelengths. Their internal structure is highly sensitive to external signals, meaning they can switch between reflecting and transmitting IR light when voltage is applied.