High‐Performance Hydrogel SERS Chips with Tunable Localized Surface Plasmon Resonance for Coordinated Electromagnetic Enhancement with Chemical Enhancement

Abstract Hydrogel surface‐enhanced Raman scattering (SERS) chips with tunable localized surface plasmon resonance (LSPR) wavelength are prepared to coordinate the chemical enhancement (CM) and electromagnetic enhancement (EM) effects for molecules. When detecting different molecules, a laser with matched energy is selected according to energy intervals between the molecular energy levels and the Fermi level of Ag nanoparticles to obtain the strongest CM effect. Meanwhile, a hydrogel SERS chip with the LSPR wavelength matching with the laser is selected to gain the strongest EM effect. As a result, the constructed hydrogel SERS chips show outstanding activity to many molecules. Amoxicillin, pymetrozine, and chlorpyrifos are used as the model molecules to demonstrate the great importance of CM effect and the working principle of the obtained hydrogel SERS chips. Besides the ultrahigh activity, the obtained hydrogel SERS chips also show high uniformity, long‐term stability, and strong anti‐interference to the sample matrix, and thereby are highly practical. This work not only provides an efficient strategy for building high‐performance SERS substrates, but also sheds the light on the mechanism of wave selection of SERS.