Active SERS Platform Based on 2D Materials-Flexible Nanotip Array

Two-dimensional materials with nanostructure have been introduced as promising candidates for SERS platform for sensing application. However, dynamic control and tuning SERS remains a long-standing problem. Here, we demonstrated active tuning of enhancement factor of the first and second-order Raman mode of monolayer(1L) MoS2 transferred onto flexible metallic nanotip array. Using mechanical strain, the enhancement factor of 1L MoS2/nanotip is modulated from 1.23 to 8.72 for 2LA mode. For the same mode, the SERS intensity is enhanced by ~31 times when silver nanoparticles of ~10 nm diameter are deposited on 1L MoS2/nanotip, which is tuned up to ~ 34 times by compressive strain. The change in SERS enhancement factor is due to the decrease (increase) in gap-width as the sample is bent inwardly (outwardly). This is corroborated by FEM structural and electromagnetic simulation. We also observed significant control over mode peak and linewidth, which may find application in biosensing, chemical detetction, optoelectronics.