Design and Manufacturing Principles of Smart Fibers

The long-standing role of fibers as basic structural components has given way to a new paradigm of smart fibers that integrate environmental sensing with programmable responses. Despite recent progress in materials chemistry and device engineering, fabrication choices are often guided by cost and convenience at the expense of advanced capabilities. This review reframes manufacturing as a central design axis that governs not only morphological properties but also molecular orientation, hierarchical organization, and interfacial properties, all of which determine performance. In this review, we first discuss the design principles of activation triggers and response mechanisms, highlighting how they interplay with the unique geometry of fibers. We then provide a detailed comparison of manufacturing strategies, including continuous single fiber spinning, non-woven deposition, and direct synthesis, emphasizing their distinct trade-offs in scalability, resolution, and material compatibility. We further examine post-processing and multiscale integration as steps that preserve, refine, and extend fiber-level properties into system-level functions. Finally, we discuss emerging directions toward fiber electronics and intelligent systems that merge physical in-fiber processing with data-driven interpretation. Together, these principles establish a task-dependent framework that aligns design, manufacturing, and function, advancing smart fibers from isolated demonstrations to integrated next-generation devices.