Ultra‐Thin Wearable and Flexible Electronics for Intelligent Healthcare: Materials Design, Devices, and Applications

ABSTRACT The rising burden of chronic diseases and aging populations has raised an urgent demand for real‐time, personalized, and continuous health monitoring. However, the rigidity and bulkiness of traditional medical devices often impair wearability and hinder practical deployment. In contrast, ultra‐thin wearable flexible electronic devices have emerged as promising alternatives, due to excellent inherent flexibility, minimal thickness, superior tissue conformability, and long‐term reliability. This Review presents a comprehensive overview of recent advances in this field by critically analyzing three core pillars: material engineering, device–tissue interface engineering, and application‐specific system integration. First, we summarize various functional materials from elastomers and textiles to hydrogels and metal nanomeshes, with emphasis on their chemical modification, structural design, and functional integration. Second, we examine strategies for constructing adhesive, seamless, and low‐impedance device–tissue interfaces via optimized molecular interactions, interfacial architectures, and mechanical conformality. Finally, we highlight representative applications in electrocardiogram (ECG) monitoring, stomatology, and ophthalmotology. By bridging materials, interfaces, and systems, this Review summarizes progress and challenges in wearable thin‐film electronics and proposes key future directions: automated patterning, standardized interface testing, and improved in vivo validation, which will help inspire future research across materials science and biomedical engineering.