A method to print text or pictures onto flexible surfaces using ultraviolet light is reported in Nature Communications this week. The system allows repeated printing without the need for additional inks.

Yadong Yin and colleagues show that by incorporating photoactive dyes into a surface, the colour can be changed by exposing parts of the surface to UV light. Using a pre-printed mask to cover specific parts of the film allows control over what is printed, from regular text to micrometre sized patterns. The patterns were retained for several days and could be erased by warming if needed. The authors hope that these reusable displays could reduce the need for both paper and inks; however, further development is needed.