POSTECH solves core challenge in stretchable displays with uniform multi-pixel strain control

A research team at POSTECH (Pohang University of Science and Technology), led by Professor Su Seok Choi from the Department of Electrical Engineering and Ph.D. candidate Jun Hyuk Shin, has successfully developed the world’s first technology that enables uniform and even stretching across multiple pixels in a stretchable display. This breakthrough overcomes a critical challenge in the field and has been selected as a Back Cover article in the prestigious international journal Advanced Functional Materials.

 

Global Race Toward Shape-Deformable Displays

Display technology is currently undergoing a global transformation, with intense competition surrounding shape-deformable devices. Innovations such as foldable, bendable, and slidable displays have already emerged, and now attention is rapidly shifting—especially in South Korea—toward stretchable displays, which go beyond simple curvature and can physically expand.

Stretchable displays are expected to evolve into next-generation devices that integrate with sensors to form electronic skin-like systems, capable of mimicking the flexibility and softness of human skin. For this direction, ideally fully and intrinsically stretchable technolgy with uniform control is highly desired.

 

The Limitations of Existing Stretchable Display Technologies

Most existing stretchable technologies rely on an extrinsic approach, using rigid electronic components connected by wavy or serpentine interconnects. While this allows some degree of mechanical deformation, it comes with significant trade-offs—limited stretching range, reduced pixel density, and degradation in display uniformity and image quality under strain.

In contrast, the intrinsic approach, which uses materials like silicone or rubber that are inherently stretchable, is considered the ideal path forward. However, such systems have struggled with non-uniform strain distribution, particularly in multi-pixel arrays. As each pixel experiences a different degree of deformation depending on its location, this leads to inconsistencies in color, brightness, and signal transmission.

This issue is fundamentally rooted in geometry and physics: when a stretchable material is pulled, areas farther from the point of tension receive less strain—similar to how the center of a rubber band or melted cheese stretches more than its edges. So far, achieving uniform stretching across all pixels in an intrinsically stretchable system has remained a critical and unsolved problem.

 

Uniform & Even Stretching with Multi-Pixel Operations

: Kirigami-Inspired Mechanical Design with Strain Stopper Integration

To overcome this challenge, the POSTECH team drew inspiration from kirigami, the traditional Japanese art of paper cutting. By introducing finely patterned incisions on the surface of the stretchable substrate, they were able to evenly distribute mechanical stress during stretching.

As a result, they successfully achieved uniform stretching up to 200% (twice the original length) in all areas of a 7×7 pixel array. Additionally, the researchers implemented a “strain stopper”—a rigid structure embedded in specific areas of the material—to suppress undesired deformation in certain directions. This marks the first successful demonstration of fully controlled, uniform, multi-directional stretching across a multi-pixel stretchable display system.

 

Expansion to Optical Encryption Using CLCE Materials, which are intrinsically stretchable & color-changeable

The team further integrated a chiral liquid crystal elastomer (CLCE)—an intrinsically stretchable and also mechanochromic material that changes color in response to mechanical stress. By combining CLCEs with their kirigami-structured platform, they developed a stretchable display capable of revealing hidden patterns only when stretched, a feature with strong potential in encryption and anti-counterfeiting applications.

The CLCEs also exhibit circular polarization selectivity, enabling high-level optical security. When paired with a polarization filter, the display shows different colors or patterns depending on the viewing angle, allowing for dynamic, angle-dependent, secure information display. This technology could enable encrypted displays that are invisible to the naked eye but detectable using special optical equipment.

 

Toward Real-World Applications

This research not only solves a long-standing mechanical issue in stretchable displays but also opens doors to new applications in wearable electronics, flexible displays, and data security. By demonstrating a working system that combines uniform mechanical performance and advanced optical functionality, the team provides a foundation for future commercial stretchable devices.

Professor Su Seok Choi commented, “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.”

 

National R&D Support

The study was supported by the Samsung Science and Technology Foundation and the Korea Evaluation Institute of Industrial Technology (KEIT) through the Stretchable Display Development and Demonstration Program.

 

 

Key Highlights:

• POSTECH developed the world’s first intrinsically stretchable display with uniform multi-pixel deformation across a 7×7 array. (Overcome current inhomogeneity problem in stretchable technologies)
• Introduced a kirigami-inspired mechanical design and integrated strain stoppers for fully controlled, direction-independent even stretching up to 200%.
• Integrated chiral liquid crystal elastomers (CLCEs) for mechanochromic color changes and polarization-dependent optical encryption.
• Enables encrypted displays that reveal hidden patterns only under mechanical strain and specific polarization views.
• Demonstrated on a functional platform, paving the way for wearable electronics, electronic skin, secure flexible displays, and anti-counterfeiting technologies.
• Featured as a Back Cover Article in Advanced Functional Materialsfor its scientific and technological significance.

 

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