## 4 Discussion
This approach may offer an effective means of simultaneously enhancing the durability and practical functionality of the ENMH system [57]. Flexible and conductive heaters must satisfy a variety of functional and practical requirements. These include uniform heat distribution, mechanical flexibility, electrical and thermal stability under deformation, a low temperature coefficient of resistance, conformal contact to curved surfaces, and a cost-effective, scalable fabrication process. In addition, structural design tunability and reliable performance under repeated strain are also considered desirable features [1; 58; 59; 60]. The ENMH system developed in this study demonstrates performance characteristics that align well with these criteria. The conformal and continuous copper (Cu) layer penetrates deeply and uniformly into the nanofiber matrix, enabling stable thermal output and uniform heating even on curved surfaces. The use of a BSA-assisted surface modification significantly enhances interfacial adhesion, and the system maintains stable electrical conductivity and thermal responsiveness under repeated stretching and bending, ensuring strong mechanical durability and operational reliability. The fabrication process, based on solution-phase deposition under low-temperature conditions, is structurally simple and scalable, and enables efficient heating at low driving voltages (e.g., 0.4-1.0 V). Moreover, the heater retains stable thermal performance when applied to highly contoured regions such as finger joints and wrists, experimentally confirming its practical applicability as a flexible heater. Considering its structural design adaptability, electro-thermal stability, and overall functional robustness, the ENMH system may also be regarded as a promising thermal material candidate for future applications in smart textiles and next-generation wearable thermotherapy devices. Currently, the ENMH devices were fabricated in a compact format (2 \(\times\) 2 cm\({}^{2}\)) to standardize processing and characterization conditions. However, the solution-based low-temperature plating method and electrospun nanofiber matrix utilized in this study inherently offer structural scalability and processing flexibility, enabling their potential extension to larger-area substrates. These intrinsic features strongly suggest that the ENMH platform can be effectively expanded to various application scenarios requiring coverage of large or geometrically complex surfaces, such as smart textile-based thermal systems, automotive defogging layers, and architectural heating panels [1; 2; 3; 4]. Nevertheless, scaling up the device size may introduce technical challenges, including limited mass transport of the plating solution, geometric distortion, and current density nonuniformity, which can compromise the consistency of Cu deposition and thermal output over extended areas. To overcome these issues, future research will focus on optimizing electrode configurations and precisely controlling plating conditions. Moreover, dynamic heating and thermal stealth functionalities, achievable by modulating input current in response to changing environmental conditions, are also considered promising directions for expanding the capabilities of the ENMH platform. If Joule heating can be precisely controlled through programmable current input, adaptive thermal management may be realized across a wide range of practical applications [61]. Taken together, the flexible and conductive ENMH system offers substantial potential as a foundational technology capable of meeting diverse requirements in next-generation thermal applications.