Wearable devices based on liquid crystal materials: Applications and challenges in visualisation

Liquid crystals (LCs) constitute a unique class of soft matter that combines the anisotropic properties of crystals with the fluidity of liquids, exhibiting optical anisotropy, self-assembled structures and stimulus responsiveness. LCs have revolutionised the display industry, and their well-established technologies provide a solid foundation for broader innovation. Recent research has expanded beyond traditional display applications, harnessing distinctive properties of LCs to develop advanced wearable visualisation devices. By programming molecular structures and orientation order, these devices can dynamically present visual information in response to external stimuli. Ranging from low-molar-mass LCs to LC polymers, these materials offer multimodal stimulus responsiveness, enabling applications in wearable visualisation sensors, camouflage and shielding, anti-counterfeiting and information encryption, cellular wearable devices, and integration with other wearable technologies. This review provides a comprehensive overview of LCs in wearable devices, emphasising recent advancements in visualisation wearable technology. Additionally, we discuss key challenges and future prospects for LC-based wearable visualisation devices. • Wearable devices utilizing stimulus responsiveness of LCs were summarized. • Distinct advantages in visual sensing are conferred by the ordered structure of LCs. • Camouflage and encryption are enabled by dynamic color modulation nature of LCs. • LCs can be integrated with other wearable devices and enrich their functionality.