New security print innovation inspired by beetles

Researchers at China’s Southeast University have developed a new colour changing ink inspired by a beetle. This new print innovation is designed to be longer lasting and harder to copy than existing security inks.

The ink is inspired by a type of longhorn beetle (called Tmesisternus isabellae) which changes colour from gold to red depending on humidity levels. The reason for the colour change is that the beetle’s scales refract light differently when exposed to water vapour, and this is the same process that the new ink is based on.

Made from colloidal photonic crystal particles, the new ink changes colour when exposed to vapours. The idea is that blowing on the ink would cause a big enough change in humidity to change the colour of the ink.

Colour changing inks already exist (like the one used on US banknotes) however they do not always prove effective in preventing forgery. The ink used on US notes fades over time, and in the past has been replicated by scammers using homemade technology. As the new ink uses inkjet printers, it would also be cheaper to implement than current technology.

According to the researchers, the new ink is resistant to bleach and light and supposedly difficult to copy, “the complicated and reversible multicolour shifts of mesoporous CPC patterns are favourable for immediate recognition by naked eyes but hard to copy” reads the research paper. The inks can be printed onto a number of rigid and flexible surfaces, so could potentially be used for a variety of other applications including colour-changing displays.

Although new inks and techniques are a welcome addition to the fight against counterfeit notes and other security documents, in order to be effective, this new print innovation would need to be used in association with other security print solutions. As one of the foremost security printers in the world, we can combine high security features such as holograms, watermarks and complex numbering to create highly secure documents.