Sensing of hazardous metals is urgent
in many areas (e.g., water
pollution and meat products) as heavy metals threaten people’s
health. Laser-induced breakdown spectroscopy (LIBS), as a rapid, in
situ, and multielemental analytical technique, has been widely utilized
in rapid hazardous heavy metal sensing. However, loose and water-containing
samples (e.g., meat, plant, and soil) are hard to analyze by LIBS
directly, and heavy metal depth profiling for bulk samples remains
suspenseful. Here, inspired by the Needle, the sword of Arya Stark
in Game of Thrones, we propose an insertable, scabbarded, and nanoetched
silver (NE-Ag) needle sensor for rapid hazardous element sensing and
depth profiling. The NE-Ag needle sensor features a micro–nanostructure
surface for inserting into the bulk sample and absorbing hazardous
analytes. For accurate elemental depth profiling, we design a stainless-steel
scabbard to wrap and protect the NE-Ag needle from pollution (unexpected
contaminant absorption) during the needle insertion and extraction
process. The results for cadmium (Cd) show that the relative standard
deviation equals to 6.7% and the limit of detection reaches 0.8 mg/L
(ppm). Furthermore, the correlations (Pearson correlation coefficient)
for Cd and chromium (Cr) depth profiling results are no less than
0.96. Furthermore, the total testing time could be less than 1 h.
All in all, the insertable and scabbarded NE-Ag needle senor has high
potential in rapid hazardous heavy metal depth profiling in different
industries.