An Ultralow‐Cost, Durable, Flexible Substrate for Ultrabroadband Surface‐Enhanced Raman Spectroscopy

Flexible devices have recently seen notable advancements for use in various areas. Surface‐enhanced Raman spectroscopy (SERS) has emerged as a transformative technology in this space. However, practical applications of flexible SERS substrates are often restricted to labs, hindered by challenges such as inconsistent reproducibility, limited scalability (<10 mm 2 ), short lifespan (<1 day), narrowband response (<100 nm), and especially high costs (>10 dollars mm −2 ). Addressing these barriers, an ultralow‐cost (≈10 cents mm −2 ), highly durable, flexible substrate that boasts exceptional SERS performance is studied. This highly scalable, adhesive, ultrathin nanomesh, crafted from a 3D network of silver‐deposited PVA nanofibers, ensures a high density of hotspots and consistent measurements (<20% CV). Its protective PVA layer keeps the silver unoxidized for sustained usage (>1 month). Remarkably versatile, this substrate works across a range of excitation laser wavelengths in both the visible and near‐infrared regions, including 488, 532, 633, and 785 nm. Furthermore, the substrate has shown its efficacy in analyzing residual pesticides on fruits for food safety testing and human biofluids (sweat and urine) for health monitoring. This innovation paves the way for transitioning SERS applications from labs to industrial settings.