Monolithic Stretchable Functional Fibers With Structurally Tunable Percolation Networks for Seamlessly Integrated Wearable Electronics

Fiber‐shaped electronics are essential for unobtrusive wearable monitoring due to their seamless integration into textiles. However, achieving both high sensitivity and stable interconnectivity within a single, monolithic platform remains a significant challenge. Here, we present a facile and novel strategy to fabricate monolithic function‐tunable fibers (FTFs) with spatially controlled electromechanical properties via a vertical encapsulation‐induced densification mechanism. By engineering asymmetric AgNW percolation networks, we precisely tune the gauge factor (GF) within a single 1D architecture, creating highly sensitive strain sensors (SS, GF = 93.2 beyond 50% strain) and strain‐insensitive conductive threads (CT, GF = 6.46). The SS detects deformations as small as 1%, while the CT maintains robust pathways even under 90% strain with an 8.9‐fold reduction in sensitivity compared to the SS. The FTFs (SS‐CT) exhibit exceptional durability, maintaining structural integrity and electrical continuity over 10 000 stretching cycles and 45 washing cycles. The practical utility has been demonstrated through an underwater strain‐responsive light‐emitting diode switch and a waterproof near‐field communication antenna integrated into a junctionless, single‐fiber platform. This monolithic approach eliminates the need for heterogeneous bonding agents, providing a promising pathway for durable, high‐performance, and fiber‐based wearable electronics.