Trace Chromium Ion Detection Based on 4-Mercaptobenzoic Acid Functionalized Plasmonic Fiber-Optic Spectral Combs

This is the authors' abstract. We don't add key points for this paper.

High sensitivity chromium ions (Cr3+) sensor was developed based on the combination of gold nanomaterials-coated tilted fiber Bragg grating (TFBG) and 4-mercaptobenzoic acid (4-MBA). The TFBG was first deposited with a 50 nm gold film to excite sensitive surface plasmonic resonance (SPR) spectral combs and then functionalized with a 4-MBA layer that is available for specifically capturing Cr3+ions. To further enhance the SPR-Cr3+interaction, additional gold nanoparticles (AuNPs)-4-MBA composite was prepared and bonded with the Cr3+captured by the TFBG. Thus, the SPR response to the capture of Cr3+and the sensing performance were greatly enhanced. Experimental results show that the sensor exhibits a high sensitivity of 1.23 dB/log(nM) for Cr3+with a detection limit of 0.04 nM, which is lower than that of the current similar optical Cr3+detection sensor by one order of magnitude.