Preparation and application of invisible print based on patterned photonic crystals

How to establish a fast, remarkable, and different external stimulus response mechanism between similar "patterns" and "backgrounds" is a key issue in the design and preparation of invisible printed fabric based on photonic crystals. SiO₂ and P(St-MAA) were used to construct photonic crystals, which were used as "patterns" and "backgrounds" to prepare patterned invisible printed fabric. It also reveals the relationship between the size of the structural unit and the reflection wavelength of the photonic crystals and adjusts the structure of the two parts of the photonic crystals by controlling the particle size of the microspheres so that the "pattern" can achieve the effect of "invisible in the air, visible in the water." It has a simple external stimulus, fast response speed, and remarkable response, and it is easy to observe and difficult to copy. It is expected to be further expanded in combination with inkjet printing technology and to obtain promising applications in textile anticounterfeiting and identification marking.