Efficient fabrication of SERS plasmonics pesticides sensors by pulsed laser etching

Abstract

High efficiency pesticides sensors are so attractive to consumers in food safety. In the current study, the implantation of Au nanoparticles within the Si nano pillars layer of Surface Enhanced Raman Scattering - based sensor was inspected. Silicon nano-pillars layers of different topographical details were synthesized via pulsed laser induced etching using 50 and 100% laser pulse duty cycles. This was accomplished with the employment of (500 mW/cm2) intensity short wavelength (405 nm) laser. The dependence of sensors’ performances on topographical features of Si nano pillars was investigated. Two kinds of Si nano pillars / Plasmonics Au nanoparticles hot spots pesticides sensors were fabricated and studied to detect ultra-low concentration of Chlorpyrifos. The pesticides’ sensors were made by adopting a simple and low-cost ion reduction process through room temperature dipping of Si nano-pillars in diluted concentrations of HAuCl4 salt aqueous solution. The present findings indicated a Chlorpyrifos sensing dependence, at 25*10−8, 12*10−7, 6*10−6 and 3*10-5 M concentrations, on the topographical characteristics of Si nano-pillars (sizes, density of the Si nano pillars) and on the surface roughness of the substrate. Optimum performances with higher enhancement factor of 8.8*105 and 0.16 mg/kg limit of detection (LOD) were achieved for Si nano-pillars with 50% laser duty cycle; owing to the higher Au nanoparticles’ specific surface area and the high density of small dimensions hot spots regions.