A newly developed display device using paper made of bacterial cellulose is attracting attention as an environmentally-friendly future technology with low production cost.
Cellulose is a polymer found in abundance in nature, and bacterial cellulose synthesized by bacteria has a very fine network structure made of ultra thin fibers that are about one thousandth the size of plant derived fibers. It has many unique properties, including strong water retention abilities, mechanical strength (difficult to tear) and biodegradability (easier to return to nature).
Fig. 1: Synthesizing bacterial cellulose
The display device is a fruit of Joint research undertaken by Ricoh Co.Ltd. and Associate Professor Kenji Tajima of Hokkaido University Graduate School of Engineering. We conducted research and development on a display device making full use of the characteristics of bacterial cellulose. And we have pinpointed the manufacturing method for bacterial paper with optimum porosity and uniform thickness to function as a display device, while still maintaining the fine network structure. By infusing the bacterial cellulose paper with an electrolyte solution containing dissolved electrochromic compounds that undertake a reversible transition from a blank state to a colored state when voltage is applied, and then forming electrodes on both sides of the paper, the paper display device has been created.
Fig. 2: Fabrication process of the display device
Fig. 3: Paper made from bacterial cellulose
Fig. 4: Display device
Fig. 5: Result of the Chromogenic testing
Unlike conventional displays, the paper itself displays colors or a blank surface without the need for supporting substrates made of glass or plastic. This reduces the use of materials and the production process as a whole, allowing production to be carried out at a lower cost. In addition, since it employs a low-energy manufacturing process using bacteria, it will not draw on forestry resources. The method is attracting attention as an environmentally-friendly future technology.
The practical application of this display device will still take a long time, but chromogenic testing has been successful at the laboratory level, and the possibility of a "paper" electronic paper has now been demonstrated.