Flexible Surface-Enhanced Raman Scattering Substrates for on-Site Detection in Real Application Scenarios: Development, Advantages, Classification, and Application Perspectives

Surface-enhanced Raman scattering (SERS) technology is widely used in various fields due to its extremely high detection sensitivity, yet its performance is highly dependent on the substrate material. Traditional rigid SERS substrates exhibit notable limitations for in situ detection on complex surfaces and rapid on-site analysis. This review provides a comprehensive review of emerging flexible SERS substrates. First, the evolution of SERS substrates from colloidal solutions and rigid solids to flexible platforms is traced, highlighting the need for this flexible design shift. Next, the key advantages of flexible SERS substrates over rigid ones are systematically outlined. On this basis, the main material systems used for flexible SERS substrates are elaborated in detail, and the important manufacturing strategies are summarized. Furthermore, the broad application prospects of flexible SERS substrates in cutting-edge areas are explored, including food safety, environmental monitoring and health monitoring. Finally, current challenges in interfacial stability, signal uniformity, and quantitative analysis of complex samples are summarized, and future directions are outlined. Through the deep integration of materials science and nanotechnology, flexible SERS substrates have successfully transformed SERS from a laboratory-confined precision instrument into a portable detection tool suitable for complex real-world scenarios, demonstrating significant application potential and societal value.