Flexible electronics such as touch sensors have provided one of the most intuitive human-machine interface with the birth of touch electronics. This technology demonstrates a flexible, foldable and waterproof capacitive-touch-panel based on a transparent cellulose-based conductor. It can be mounted onto non-conformal surfaces and operated with human finger for writing, drawing or scribing. Its touch functions can be preserved even after subjected to extreme deformations and even after a coffee spill. Capacitive-touch-panel are electronic devices composed of transparent conductor and dielectric layer, which can recognise the exact locations of mechanical touch by detecting the capacitance changes. Existing products are mainly based on the rigid substrates (glass) with integration of ITO electrode, even though some flexible polymer substrates and ductile metal nanowires electrode have been developed for replacement of glass and ITO, respectively, but the limited optoelectronic performance and flexibility, especially the needs for extreme foldability and waterproof performance are not met for emerged flexible electronics. In this invention, innovative materials and fabrication approach have been developed to create touch panel that can accommodate extreme folding radius of 5 µm, showing superior optoelectronic performance and water resistance. The flexible and foldable touch panels can be adopted for touch-screen displays, smart windows, electronic paper devices, and transparent or flexible optoelectronic devices.
The technology is comprised of an innovative conductive mesh for the high transparency and conductivity, a dielectric substrate and a capping overcoat layer for device fabrication. The thickness of dielectric layer and the conductive layer can be readily controlled. The uniform conductivity ensures the precise recognition of touching locations. Compared with the conventional random metallic nanowires network, under the same conductivity, the transparency of this innovative conductive mesh can be improved by 2~10%, the relative haze can be decreased by 2~6%. The fabrication process delivers the remarkable mechanical durability and chemical stability, and the overcoating encapsulation renders the touch panel washable and highly stable even under the harsh environment. It maintains the touch functions after being subjected to extreme deformations and even after a coffee spill.
The flexible and foldable touch panel are compatible with transparent and flexible optoelectronic devices, such as (but not limited to) the following:
The transparent conductive paper can serve as the transparent electrode for electrochromic smart windows, photovoltaic devices, organic light emitting diodes (OLEDs), transparent heaters, and electromagnetic shields.
This technology carries the following advantages: