A research team at POSTECH (Pohang University of Science and Technology), headed by PhD candidate Jun Hyuk Shin and Professor Su Seok Choi from the Department of Electrical Engineering, has created the first technology in the world that allows for consistent and even stretching across multiple pixels in a stretchable display, according to a study published in Advanced Science. This innovation solves a significant problem in this field.
Visualization of encrypted numeric patterns enabled by uniform strain distribution and polarization filtering. Image Credit: Pohang University of Science and Technology
Global Race Toward Shape-Deformable Displays
The world of display technology is changing, and shape-deformable gadgets are the focus of fierce rivalry. Stretchable displays, which go beyond mere curvature and can physically extend, are gaining interest, particularly in South Korea, despite innovations like folding, flexible, and slidable displays.
It is anticipated that stretchable screens will develop into next-generation gadgets that combine sensors to create electronic skin-like structures that replicate human skin's suppleness and elasticity. It would be excellent for this path to have uniformly controllable, totally and innately stretchy technology.
The Limitations of Existing Stretchable Display Technologies
Most existing stretchable technologies use an extrinsic method, which involves hard electronic components coupled by wavy or serpentine interconnects. While this allows for some mechanical deformation, there are substantial trade-offs, including a limited stretching range, lower pixel density, and a loss of display uniformity and picture quality under strain.
In contrast, the intrinsic method, which employs naturally stretchy materials such as silicone or rubber, is the best way forward. However, these systems have suffered with non-uniform strain distribution, especially in multi-pixel arrays. Color, brightness, and signal transmission are inconsistent because each pixel encounters various distortions based on its position.
Similar to how the center of a rubber band or melted cheese extends more than its edges, regions farther from the point of tension suffer less strain when a flexible material is stretched. This problem has its roots in geometry and physics. A crucial and unresolved issue to far has been the achievement of consistent stretching over every pixel in an inherently stretchy system.
Uniform & Even Stretching with Multi-Pixel Operations: Kirigami-Inspired Mechanical Design with Strain Stopper Integration
The POSTECH team used the ancient Japanese paper-cutting technique known as kirigami as inspiration to solve this obstacle. They could disperse mechanical stress during stretching by making precisely designed incisions on the flexible substrate’s surface.
Consequently, they were able to accomplish consistent stretching in every region of a 7×7 pixel array up to 200% (twice the initial length). To prevent undesirable deformation in particular directions, the researchers also used a “strain stopper,” a hard structure inserted in particular regions of the material.
This is the first time a multi-pixel stretchable display system has successfully demonstrated completely controlled, uniform, multi-directional stretching.
Expansion to Optical Encryption Using CLCE Materials, Which are Intrinsically Stretchable and Color-Changeable
The group also included chiral liquid crystal elastomer (CLCE), which is a naturally stretchy and mechanochromic substance that undergoes color changes in reaction to mechanical stress. They created a stretchy display that can only disclose concealed patterns when stretched by fusing CLCEs with their kirigami-structured platform. This feature has significant potential for use in encryption and anti-counterfeiting applications.
The CLCEs' preference for circular polarization makes high-level optical security possible. When combined with a polarization filter, the display may display information in a dynamic, angle-dependent, and secure manner by changing colors or patterns based on the viewing angle. With the use of specialized optical equipment, it may be possible to identify encrypted displays that are undetectable to the human eye.
Toward Real-World Applications
This study addresses a long-standing mechanical difficulty in stretchy displays and opens the door to new applications in wearable electronics, flexible displays, and data security. By showing a workable system that combines consistent mechanical performance and superior optical capabilities, the team lays the groundwork for future commercial stretchable gadgets.
By addressing the challenge of non-uniform deformation, this work greatly enhances the practical potential of intrinsically stretchable materials such as silicone, rubber, and artificial skin. It will also contribute significantly to the development of stretchable optical components and secure display technologies.
Su Seok Choi, Professor, Pohang University of Science and Technology
National R&D Support
The Samsung Science and Technology Foundation and the Korea Evaluation Institute of Industrial Technology (KEIT) funded the study as part of the Stretchable Display Development and Demonstration Program.
Journal Reference:
Hong, I. and Choi, S.S. (2025) Localized Sound‐Integrated Display Speaker Using Crosstalk‐Free Piezoelectric Vibration Array. Advanced Science. doi.org/10.1002/advs.202414691.