Recent progress on three-dimensional substrates for surface-enhanced Raman spectroscopic analysis

Surface-enhanced Raman spectroscopy (SERS) has emerged as a promising spectroscopic technique due to its unique advantages of "spectroscopic fingerprint", fast response and nondestructive analysis. Recently, threedimensional (3D) SERS substrate with steric extension along z-axis dimension have attracted significant attention for their special construction. 3D SERS substrates possess larger overall surface area, more hotspots quantities, higher utilization efficiency of laser, and greater flexibility in all dimensions to enhance SERS performance and serve sample pretreatment. To better describe the recent progress on 3D SERS substrate, we briefly summarized the recent progress on 3D SERS substrate. The main categories of 3D SERS substrate and their features are summarized, including multilayer SERS substrates, microporous SERS substrates, array SERS substrates, and other 3D SERS substrates. The main applications in SERS analysis were also reviewed, including food safety, environmental analysis, and bio-medicine analysis. Finally, the existing challenges and future development on 3D SERS substrate are also discussed.