Fiber-Optic SPR pH Sensor Based on MMF-NCF-MMF Structure and Self-Assembled Nanofilm

A fiber-optic pH sensor, based on layer-by-layer (LBL) self-assembly and surface plasmon resonance (SPR) technology, is proposed and experimentally confirmed. This article proposes poly (diallyldimethylammonium chloride) (PDDA) as the pretreatment solution for the surface of the gold film and the highly sensitive polyacrylic acid/chitosan (PAA/CS) self-assembled nanomembrane as the pH-sensitive film. It has been experimentally verified that the sensor can detect pH from 3.18 to 11.84 and it exhibits a high average sensitivity of 32.31 nm/pH in this range. In addition, experiments have confirmed that the sensor has attractive stability, repeatability, and hysteresis characteristics.

Automated summary

The fiber-optic pH sensor proposed in this study utilizes layer-by-layer self-assembly and surface plasmon resonance technology to achieve high sensitivity of 32.31 nm/pH. It can detect pH values in the range of 3.18 to 11.84, with confirmed stability, repeatability, and hysteresis characteristics.