Multifunctional displays, which have various functions in single-device systems without external circuits, are actively investigated as future human–machine interfaces owing to performability of unprecedented functions in compact design. However, their application is limited to visualize the mechanical/electrical signals in light. Herein, stretchable high-resolution multicolor synesthesia display, which can generate synchronized sound and light as input/output sources, is presented by transfer-printing. Transfer-printed emissive composite leads to display with enhanced optical performance and fine sound pressure level. Owing to inherent stretchability of the device, the synesthesia display can stably operate under static and dynamic deformation without distortion in sound relative to the input waveform. User-interactive synesthesia displays are demonstrated for visual−acoustic encryption, which facilitate advanced encryption, as well as multiplex quick response code that bridges multiple domains with a single device. This approach provides new directions for multifunctional displays, with potential applications in reinforced authentication.
The future of human-machine interfaces is on the cusp of a revolution with the unveiling of a groundbreaking technology – a stretchable high-resolution multicolor synesthesia display that generates synchronized sound and light as input/output sources. A research team, led by Professor Moon Kee Choi in the Department of Materials Science and Engineering at UNIST, has succeeded in developing this cutting-edge display using transfer-printing techniques, propelling the field of multifunctional displays into new realms of possibility.
Traditionally, multifunctional displays have been confined to visualizing mechanical and electrical signals in light. However, this pioneering stretchable synesthesia display shatters preconceived boundaries by offering unparalleled optical performance and precise sound pressure levels. Its inherent stretchability ensures seamless operation under both static and dynamic deformation, preserving the integrity of the sound relative to the input waveform.
A key advantage of this groundbreaking technology is its potential to revolutionize wearable devices, mobile devices, and the Internet of Things (IoT) as the next generation of display. By seamlessly generating sound and light simultaneously, the stretchable display delivers a distinctive user experience and unlocks untapped potential for advanced encryption and authentication.
Figure 1. (Left) Images of the device at strains ranging from 0% to 120%. (Right) Effect of tensile strain on luminance (blue dot) and SPL (red dot) generated by the device.
To demonstrate the capabilities of this synesthesia display, the research team presented two innovative applications. Firstly, they showcased visual-acoustic encryption, an advanced encryption method that combines visual and auditory cues. This breakthrough sets the stage for reinforced authentication systems that leverage the power of both sight and sound, elevating security to new heights.
Secondly, the team introduced a multiplex quick response code that bridges multiple domains with a single device. This remarkable technology empowers users to interact with the display, ushering in a new era of seamless integration and user-friendly experiences.
Professor Choi enthused, “The demand for next-generation displays is skyrocketing, and this stretchable high-resolution display that generates sound and light simultaneously overcomes the limitations of previous light-emitting devices. Our novel light-emission layer transfer technology, achieved through surface energy control, enables us to achieve remarkable patterns and maintain stability even under deformation.”
Figure 2. EML patterning characteristics. (Left) SEM image revealing the minimum pattern dimension. (Center) Photoluminescence image of a high-resolution mosaic pattern. Painting adapted and reproduced with permission from the Louvre. (Right) Multicolor device images on a curved object.
The manufactured device boasts exceptional brightness and sound characteristics, with a circular shape maintained at a remarkable rate of over 95% in more than 5,000 deformation experiments. This unparalleled durability and versatility render the stretchable display ideal for a wide range of applications, including wearable speakers, double encryption devices, and multi-quick response code implementations.
According to the research team, this remarkable advancement in display technology propels us one step closer to a future where multifunctional displays seamlessly integrate with our daily lives. As the demand for advanced human-machine interfaces continues to surge, the stretchable high-resolution multicolor synesthesia display offers a tantalizing glimpse into the limitless possibilities of tomorrow.
Figure 3. Applications of synesthesia display as an input device for user-interactive visual–acoustic encryption and multiplex QR.
The research findings have been published in the online version of the esteemed journal, Advanced Functional Materials, on August 14, 2023. This research was supported by the National Research Foundation of Korea (NRF) grant, funded by the Korean Ministry of Science and ICT (MSIT).
Jisu Yoo, Subin Ha, Gwang Heon Lee, et al., “Stretchable High-Resolution User-Interactive Synesthesia Displays for Visual–Acoustic Encryption,” Adv. Funct. Mater., (2023).