Superhydrophobic 3D Forest-Like Ag Microball/Nanodendrite Hierarchical Structure as SERS Sensor for Rapid Droplets Detection

Real environment detection application by surface-enhanced Raman scattering (SERS) requires substrates with high sensitivity, rapid detection, and low cost. In this study, a rapid SERS detection of liquid droplets sample by a superhydrophobic 3D forest-like Ag microball/nanodendrite hierarchical structure is reported. Easy preparation is provided by electrochemical deposition method, developing a Ag forest-like hierarchical nanostructure. The vertically standing nanodendrites offer more amounts of SERS hot spots for enhancing the Raman signals. At the same time, the micro/nanostructures supply suitable condition for superhydrophobicity by low surface energy modification. Probe molecule droplets are directly detected by SERS on the substrate. Detection limit of crystal violet, methyl blue, and rhodamine 6G can be down to 10(-8), 10(-9), and 10(-9) m, with good sensitivity and reproducibility. Practical application is processed for proving the utility of the substrate in real environment by quantitatively detection of melamine in milk. 0.1 ppm melamine in aqueous solution and 0.5 ppm melamine in milk can be detected by droplet detection method, which are far lower than the standard of US Food and Drug Administration. In brief, the droplet detection method offers an extensive and promising application in real life rapid trace detection.