Ideally, a SERS substrate should possess super signal amplification, high uniformity and reproducibility. Up to now, an emphasis on reproducibility and uniformity has been crucial to ensure consistent chemical detection sensitivity across the surface of a SERS substrate. Here we demonstrate a simple and facile double sided tape-assisted transfer method to fabricate surface enhanced Raman scattering (SERS) substrates with prominent performance using hollow Au–Ag alloy nanourchins (HAAA-NUs). Such a large area, closely-packed flat film of the HAAA-NUs with a high density of “hot spots” exhibits a high SERS activity and reproducibility, simultaneously. The AFM-correlated nano-Raman and the point by point scanning of SERS signals verify the excellent spatial uniformity and reproducibility with a low relative standard deviation (RSD) less than 15% using crystal violet as probe molecule at the concentrations of 1 × 10⁻⁸ M and 1 × 10⁻¹⁰ M. The SERS signals of Sudan dye at a 1 × 10⁻⁸ M concentration also show high reproducibility with a low RSD of 13.8%. This facile protocol presented here could lead to a high quality SERS substrate and open tremendous potential for various applications.

Objectives: Terahertz (THz)‐based imaging techniques hold great potential for biological and biomedical applications, which nevertheless are hampered by the low spatial resolution of conventional THz imaging systems. In this work, we report a high‐performance photoconductive antenna microprobe‐based near‐field THz time‐domain spectroscopy scanning microscope.Materials and methods: A single watermelon pulp cell was prepared on a clean quartz slide and covered by a thin polyethylene film. The high performance near‐field THz microscope was developed based on a coherent THz time‐domain spectroscopy system coupled with a photoconductive antenna microprobe. The sample was imaged in transmission mode.Results: We demonstrate the direct imaging of the morphology of single watermelon pulp cells in the natural dehydration process with our near‐field THz microscope.Conclusions: Given the label‐free and non‐destructive nature of THz detection techniques, our near‐field microscopy‐based single‐cell imaging approach sheds new light on studying biological samples with THz.