Introduction: Picture this: clothing that changes color with temperature, anti-counterfeiting labels that display dynamic color shifts when pressed. These sci-fi scenarios are becoming reality. The integration of materials science and 3D printing has led to a revolutionary advancement - coaxial Direct Ink Writing (DIW) 3D printing of Cholesteric Liquid Crystal Elastomers (CLCEs). Published in Advanced Materials 2025, Vol. 37, Issue 10, this research was a joint effort by the University of Pennsylvania, Harvard University, and Lawrence Livermore National Laboratory, successfully overcoming the technical hurdles of 3D printing complex CLCE structures.

https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202416621

Recently, researchers from three prestigious US institutions - the University of Pennsylvania, Harvard University, and Lawrence Livermore National Laboratory - published a paper titled "Coaxial Direct Ink Writing of Cholesteric Liquid Crystal Elastomers in 3D Architectures" in the 2025 issue of Advanced Materials. The study successfully developed a smart material based on Cholesteric Liquid Crystal Elastomers (CLCEs) using coaxial 3D printing technology. Due to its unique internal helical structure, this material can dynamically respond to external stimuli such as temperature and pressure, for example, changing color with body temperature or displaying anti-counterfeiting information when pressed. The research team solved the structural instability issues in traditional manufacturing through a core-shell printing process, giving this material great potential in smart textiles, anti-counterfeiting technology, and soft robotics.

The paper mentioned that CF 756 (also known as LC756), a key component in Cholesteric Liquid Crystal Elastomers (CLCEs), is used to achieve the material's temperature and pressure responsiveness. This product is provided by our company, CHEMFISH TOKYO, and can be used as an additive or functional material to enhance the optical performance or mechanical stability of the material. It can be applied in coaxial 3D printing technology, used to optimize core-shell structures or improve printing accuracy.

Cholesteric Liquid Crystal Elastomers (CLCEs) are known as the "smart chameleons" of the materials world. Their internal helical molecular structure deforms under mechanical stress, causing dynamic changes in the reflected light wavelength and thus achieving reversible color changes. This material not only has the elasticity of a rubber band but can also convert physical deformation into an intuitive optical signal, showing great potential in smart textiles, pressure sensing, anti-counterfeiting labels, and soft robotics. For example, sportswear can monitor muscle stretching in real-time through color changes, and the "skin" of soft robots can provide color feedback on force conditions, offering a new visual interface for next-generation human-machine interaction.

The research team cleverly adopted coaxial printing technology, using low-viscosity CLCE ink as the core and wrapping it in high-viscosity silicone ink to form a protective layer. This "core-shell" design breaks through the traditional printing dilemma - the inner CLCE can freely align in a low-viscosity environment to form an ideal cholesteric phase, while the outer silicone provides structural support, enabling stable stacking of complex 3D architectures.

Experimental data shows that the mechanical color-changing sensitivity of the CLCE-silicone composite structure is nearly 20 times higher than that of pure CLCE (from 0.13 nm/kPa to 2.39 nm/kPa), allowing significant color changes to be triggered by minor pressure variations and greatly expanding its application scenarios as a sensor.

By precisely controlling printing paths and layer height parameters, the research team successfully constructed complex structures such as bistable thin-shell domes. These dome arrays with "physical memory" characteristics can maintain deformation and record maximum strain values when inverted, enabling strain history monitoring without electronic components.

Of particular note is that conformal printing technology ensures uniform dome thickness, creating a striking contrast between redshift (compression) and blueshift (tension) in different stress areas, paving the way for visual pressure sensing.

Although still in the laboratory stage, this technology has shown a clear path to commercialization:

High-security anti-counterfeiting: The complex dynamic color changes of CLCE structures offer physical encryption far superior to traditional anti-counterfeiting methods, suitable for luxury goods, pharmaceutical packaging, and IP protection.

Smart wearable devices: Battery-free self-sensing fabrics can monitor physical conditions in real-time, providing intuitive feedback for sports rehabilitation and potentially revolutionizing the sportswear market.

Soft robot visual feedback: CLCE "skin" enables robots to have visual pressure perception, enhancing the intuitiveness and safety of human-machine interaction.

As material performance continues to improve (such as enhanced elasticity and toughness) and printing processes are further refined (increasing speed and accuracy), CLCE technology is expected to give rise to more breakthrough applications. From temperature-controlled color-changing clothing to self-reporting flexible machines, this technology is building a smart ecosystem where materials can autonomously sense and communicate, quietly reshaping our interaction with the material world.

As color becomes the language of materials, a visual smart future is accelerating. CHEMFISH materials play a crucial role in the future presentation of smart technology, filling every evolution of future technology with the code of material intelligence.