Flexible Thermoelectric Ag Film/PEDOT:PSS/AgNPs Composites: Toward Universal and Ultrasensitive Sensing

Flexible surface enhancing Raman scattering (SERS) substrates have garnered significant research interest for in situ and on-site detection. However, conventional flexible materials often lack additional functionalities for SERS enhancement and introduce strong background fluorescence. This study integrates thermoelectric PEDOT:PSS with Ag nanoparticles (AgNPs) and Ag films to develop a multifunctional flexible SERS platform. Experimental results demonstrate that the thermoelectric field generated by PEDOT:PSS effectively modulates the carrier concentration of AgNPs, enhancing SERS sensitivity via chemical/electromagnetic mechanisms. The optimized substrate achieved detection limits as low as 0.005% for microplastics and 10^-8 M for SARS-CoV-2 spike protein. Furthermore, the thermoelectric effect enables the active regulation of SERS performance while suppressing substrate-derived fluorescence interference. This work provides fundamental insights into the thermoelectric modulation mechanism of SERS activity and advances the development of intelligent, flexible sensors for practical analytical applications.