%61%75%78%65%74%69%63%20%73%74%72%75%63%74%75%72%65
-
KAIST Develops Core Display Technology That Prevents Image Distortion Even When Stretched
Beyond bendable and foldable displays, the era of stretchable displays, whose screens can expand freely like rubber, is now emerging. KAIST researchers have developed a core technology that allows text, images, and other on-screen information to retain their original shape even when the screen is stretched by up to 15%. The achievement is expected to help solve the problem of image distortion and accelerate the commercialization of next-generation high-quality stretchable displays.
KAIST (President Choongsik Bae) announced on the July 8 that a research team led by Professor Seunghyup Yoo of the School of Electrical Engineering, in collaboration with Professor Hanul Moon’s team at Dong-A University (President Hae Woo Lee), has successfully implemented an auxetic-based stretchable display platform. Auxetic structures expand in both width and length when pulled, allowing the display to stretch uniformly at the same ratio in all directions without distorting the image on the screen.
Conventional stretchable displays are generally made by forming light-emitting devices on a stretchable substrate, which serves as the base layer of the display. However, when such a substrate is stretched in one direction, it tends to shrink in the opposite direction, causing letters and images on the screen to become flattened or distorted. Auxetic structures have been used to address this problem, but most previous approaches were limited to maintaining the overall horizontal-to-vertical ratio of the screen, while the letters and images within the screen still remained vulnerable to distortion.
Instead of bonding the auxetic structure and the stretchable substrate across the entire surface, as in conventional methods, the research team proposed a new design approach that uses computational analysis to selectively connect only the necessary points that ensure isotropic expansion throughout the substrate.
In the conventional approach, the twisting deformation that occurs as the auxetic structure stretches is directly transferred to the substrate, distorting the image inside the screen. In contrast, the platform developed by the research team was designed so that each region moves evenly outward from its original position. This allows not only the entire screen but also small areas such as letters and images to expand together while maintaining their original shapes.
The research team verified the platform’s performance by repeatedly stretching a substrate patterned with letters and images in both the horizontal and vertical directions. In the conventional method, the patterns underwent local deformation, whereas in the new platform, the shapes of the letters and images remained intact. This demonstrates that not only the whole screen but also fine images on-screen can expand uniformly without distortion.
The team also integrated an LED array, a structure in which multiple LEDs are arranged at regular intervals, onto the platform to verify its performance as an working stretchable display. Even when stretched by up to 15% in both the horizontal and vertical directions, stable electrical operation and the screen brightness were maintained. After repeated stretching to 15%, the decrease in brightness remained below 2%, confirming the platform’s potential for practical display applications.
This technology is expected to serve as a core platform for next-generation electronics with freely changeable shapes, including wearable electronic devices, electronic skin, or e-skin, which refers to electronic devices that stretch like skin while sensing and displaying information, medical biosensors, soft robots, and curved displays for automobiles and aircraft.
Professor Seunghyup Yoo of KAIST said, “For stretchable displays to be used as actual information display devices, they must not only stretch well, but also preserve on-screen information accurately during stretching,” adding, “This platform enables uniform expansion from small areas of the screen to the entire display, and will serve as a key foundational technology for accelerating the commercialization of high-quality stretchable displays.”
This study was led by KAIST Dr. Su-Bon Kim and Dr. Junho Kim as co-first authors, with Professor Hanul Moon of Dong-A University and Professor Seunghyup Yoo of KAIST as co-corresponding authors. The research was published in the international journal Nature Communications on June 10.
※ Paper title: Hybrid auxetic metamaterial platforms enabling multiscale isotropic expansion for distortion-free stretchable displays, DOI: 10.1038/s41467-026-74141-6
This research was supported by the National Research Foundation of Korea (NRF) Mid-Career Researcher Program, the Future Display Strategic Research Laboratory Program, the Korea Planning & Evaluation Institute of Industrial Technology (KEIT), and the Korea Institute for Advancement of Technology (KIAT) HRD Program.
2026.07.08 View 1438 -
KAIST Develops Stretchable Displays Featuring 25% Expansion Without Image Distortion
Stretchable displays, praised for their spatial efficiency, design flexibility, and human-like flexibility, are seen as the next generation of display technology. A team of Korean researchers has developed a stretchable display that can expand by 25% while maintaining clear image quality without distortion. It can also stretch and contract up to 5,000 times at 15% expansion without any performance degradation, making it the first deformation-free stretchable display with a negative Poisson's ratio* developed in Korea.
*Poisson’s ratio of -1: A ratio where both width and length stretch equally, expressed as a negative value. A positive Poisson's ratio represents the ratio where horizontal stretching leads to vertical contraction, which is the case for most materials.
KAIST (represented by President Kwang-Hyung Lee) announced on the 20th of August that a research team led by Professor Byeong-Soo Bae of the Department of Materials Science and Engineering (Director of the Wearable Platform Materials Technology Center) , in collaboration with the Korea Institute of Machinery & Materials (President Seoghyeon Ryu), successfully developed a stretchable display substrate that suppresses image distortion through omnidirectional stretchability.
Currently, most stretchable displays are made with highly elastic elastomer* materials, but these materials possess a positive Poisson's ratio, causing unavoidable image distortion when the display is stretched.
*Elastomer: A polymer with elasticity similar to rubber.
To address this, the introduction of auxetic* meta-structures has been gaining attention. Unlike conventional materials, auxetic structures have a unique 'negative Poisson's ratio,' expanding in all directions when stretched in just one direction. However, traditional auxetic structures contain many empty spaces, limiting their stability and usability in display substrates.
*Auxetic structure: A special geometric structure that exhibits a negative Poisson's ratio.
To tackle the issue of image distortion, Professor Bae's research team developed a method to create a seamless surface for the auxetic meta-structure, achieving the ideal negative Poisson's ratio of -1 and overcoming the biggest challenge in auxetic meta-structures.
To overcome the second issue of elastic modulus*, the team inserted a textile made of glass fiber bundles with a diameter of just 25 micrometers (a quarter of the thickness of human hair) into the elastomer material. They then filled the empty spaces with the same elastomer, creating a flat and stable integrated film without gaps.
*Elastic Modulus: The ratio that indicates the extent of deformation when force is applied to a material. A higher elastic modulus means that the material is less likely to deform under force.
The research team theoretically identified that the difference in elasticity between the auxetic structure and the elastomer material directly influences the negative Poisson's ratio and successfully achieved an elasticity difference of over 230,000 times, producing a film with a Poisson's ratio of -1, the theoretical limit.
< Figure 2. Deformation of S-AUX film. a) Configurations and visualized principal strain distribution of the optimized S-AUX film at various strain rates. b) Biaxial stretching image. While pristine elastomer shrinks in the directions that were not stretched, S-AUX film developed in this study expands in all directions simultaneously while maintaining its original shape. >
Professor Byeong-Soo Bae, who led the study, explained, "Preventing image distortion using auxetic structures in stretchable displays is a core technology, but it has faced challenges due to the many empty spaces in the surface, making it difficult to use as a substrate. This research outcome is expected to significantly accelerate commercialization through high-resolution, distortion-free stretchable display applications that utilize the entire surface."
This study, co-authored by Dr. Yung Lee from KAIST’s Department of Materials Science and Engineering and Dr. Bongkyun Jang from the Korea Institute of Machinery & Materials, was published on August 20th in the international journal Nature Communications under the title "A seamless auxetic substrate with a negative Poisson's ratio of –1".
The research was supported by the Wearable Platform Materials Technology Center at KAIST, the Korea Institute of Machinery & Materials, and LG Display.
< Figure 3. Structural configuration of the distortion-free display components on the S-AUX film and a contour image of a micro-LED chip transferred onto the S-AUX film. >
< Figure 4. Schematic illustrations and photographic images of the S-AUX film-based image: distortion-free display in its stretched state and released state. >
2024.09.20 View 13004