Metal Nanowires for Flexible and Wearable Sensors: Synthesis, Processing, and Device Applications

Metal nanowires (MNWs), especially Ag and Cu nanowires, are promising building blocks for transparent and stretchable electrodes as well as active sensing platforms in wearable electronics. In this review, we comprehensively discuss the advancements of MNWs covering various aspects from materials design to device integration. First, we systematically clarify the structure-property relationships of MNWs, including optical-electrical trade-offs, junction resistance, mechanical durability, nanowire aspect-ratio, and surface-chemistry. Afterward, we discuss advanced NMW synthesis approaches, such as polyol process, soft-template growth, Cu(I)-mediated method, microwave, and flow syntheses, as well as stability improvement strategies, including core-shell passivation, encapsulation, and alloying. In addition, MNW processing and integration methods are thoroughly introduced, including solution coating, inkjet printing, NMW alignment, junction welding, and polymer embedding. For applications, we evaluate NMW strain/pressure sensors with novel designs, such as hydrogel and textile hybrids, microstructure integration, and anisotropic architectures, by comparing their gauge factor, working range, linearity, response speed, and cycling stability. Finally, conclusions and outlooks are given with future research directions. Overall, this review provides insights and design rules, paving the way for next-generation MNW-based flexible sensors.