SEIRA low-cost sensor base detects extremely low concentrations of chemical residues.

Abstract

She proposed a low-cost surface-enhanced infrared spectrophotometric sensor (SEIRA) substrate composed of a randomly distributed high-geometry silver nanowire network on a porous filter paper substrate. The silver nanowires were synthesized using a controlled polyol method, where FeCl3 acts as a catalyst and the reduction time of FeCl3 determines the geometry ratio of the nanowires. Through the mechanism of Fe3+ being gradually reduced to Fe2+, which reduces the dissolved oxygen in the system, the nanowire surface corrosion is inhibited and preferential growth along the longitudinal axis is promoted, forming nanowires with lengths in the micrometer range and diameters in the nanometer range. This high geometry ratio shifts the longitudinal plasmon resonance frequency of the silver nanowires into the infrared region, creating the necessary spectral overlap to effectively amplify the SEIRA signal. Nanowire surface. Silver coated with polyvinylpyrrolidone (PVP) acts as a stabilizer for anisotropic growth during the synthesis phase and enhances adhesion to the filter paper substrate during the substrate fabrication phase.Thanks to the randomly distributed nanowire network structure on the porous filter paper substrate, plasmon hotspots are naturally formed at the pointed ends and narrow intersections between the wires without the need for orderly arrangement or orientation. This random nanowire network responds effectively to non-polarized infrared light, creating a high hotspot density across the entire substrate surface, strongly amplifying the molecular vibration signals of the analyte and enabling the detection of organic chemical residues at extremely low concentrations. The sensor substrate is fabricated using a simple, repeatable immersion and drying process to achieve the desired nanowire density on the substrate, requiring no specialized micro / nano equipment, is low-cost, and suitable for large-scale deployment. The invention has broad application potential in the analysis of organic chemical residues, environmental quality control, and disposable field sensor systems.