Triangular Au nanoparticle arrays based on flexible materials as temperature-sensitive SERS substrates

Abstract

In this study, PS microspheres were used as masks to obtain tip-connected triangular Au nanoparticle arrays on the surface of Cu films by thermal evaporation. Then transferred to flexible polydimethylsiloxane (PDMS), triangular Au nanoparticle arrays (Au NPAs/PDMS) were obtained by increasing the temperature using concentrated stress to cause fracture at the junction. The prepared Au NPAs/PDMS was used as an active substrate for surface-enhanced Raman spectroscopy (SERS), and the Raman signal of probe molecule rhodamine 6G (R6G) was collected while the substrate was heated. Due to the thermal expansion of PDMS, the gap of Au NPAs/PDMS changes with increasing temperature, enabling dynamic SERS detection. When the temperature reaches 64 °C, the substrate achieves the optimal Raman enhancement with a low RSD value of 5.8 % and a detection limit of 10−8 M for R6G. Furthermore, we modified the substrate hydrophobic, and finally obtained a low concentration of 10−10 M, with an enhancement factor of 3.5 × 108, to achieve highly sensitive SERS signal detection. In addition, due to the high optical transmittance and flexibility, the PDMS can be well-fitted to the surface of the object, indicating the potential of the fabricated substrates for in-situ detection.