Inkless But Colourful Thanks to Organized Microfibrillation
Humankind’s use of ink colouration to communicate images and writing has a long history. This time could be over now: Researchers from Japan developed a new printing method, which requires exactly zero drops of ink.
It’s smaller than most ants, fruit flies or a pixel – and that´s not even the most fascinating feature of the work from researchers from Kyoto University, Japan. They developed a method to create colourful high-resolution images without using ink: By the use of Organized Microfibrillation they were able to replicate Katsushika Hokusais “The Great Wave” and Jan Vermeers “Girl with a Pearl Earring”.
Crazing is the Key
If you´ve ever repeatedly twisted a transparent plastic piece like a ruler, you may have noticed that the stretched plastic begins to turn into an opaque white, rather than staying transparent. These networks of fine cracks, microcavities and hairlike structures called microfibrils tend to form around stress “hot spots” within the polymer structure. This process is known as “crazing” and may be the answer to pigment-less printing.
To fully understand this process, the Kyoto researchers analyzed it by scanning electron microscope snapshots at different times. Thus, they were able to document the microstructural changes of the polymer structure. The key, they found, is a periodic structure of porous layers and alternating density to emerge within the plastic. The optical result were standing waves that interfere to create several colours.
By controlling the way microfibrils were formed, the researchers were able to control the scattering of light to create colours from the entire visible spectra. This novel printing method, that is able to create images at resolutions of 14,000 dpi without ink, is called Organized Microfibrillation (OM).
Inkless Printing: What’s Next?
“OM allows us to print porous networks for gases and liquids, making it both breathable and wearable. So, for example in the area of health and well-being, it is possible to incorporate it into a kind of flexible ‘fluid circuit board’ that could sit on your skin, or your contact lenses, to transmit essential biomedical information to the Cloud or directly to your health care professional,” explains Professor Easan Sivaniah, head of the Pureosity Group at iCeMS, Kyoto University, where the research was developed.