Ag/APTES/Cu<sub> <i>x</i> </sub>O (<i>x</i> = 1, 2)-MGS-Coated No-Core Fiber Surface Plasmon Resonance Gas Sensor and Its Application in Hydrogen Sulfide Detection
Cheng Li, Xiao Liu, Xiaozhan Yang, Wenlin Feng
Abstract
A novel fiber-optic surface plasmon resonance (SPR) hydrogen sulfide gas sensor based on silver/3-aminpropyltriethoxysilane/cuprous oxide modified graphene sheets (Ag/APTES/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text{Cu}}_{x}\text{O}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}=1$ </tex-math></inline-formula> , 2)-MGS) composite membrane coated no-core fiber (NCF) was proposed and fabricated. The NCF is sandwiched between two segments of multi-mode fiber (MMF), forming the fiber-optic sensing unit with MMF1-NCF-MMF2 structure. The comparative experiment of sensing performance of two sensors coated respectively by Ag/APTES and Ag/APTES/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text{Cu}}_{x}\text{O}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}=1$ </tex-math></inline-formula> , 2)-MGS film is investigated in detail. The results show that the sensor with Ag/APTES/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text{Cu}}_{x}\text{O}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}=1$ </tex-math></inline-formula> , 2)-MGS film has better sensing performance for hydrogen sulfide in the concentration range of 10–60 ppm. After adsorption of hydrogen sulfide, the resonance wavelength of the sensor with Ag/APTES/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\text{Cu}}_{x}\text{O}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}=1$ </tex-math></inline-formula> , 2)-MGS film shows the red shift, and the total shift is about 132.642 nm. In the concentration range of 10–40 ppm, the sensitivity is 3385.67 pm/ppm, the detection limit is 0.56±0.12 ppm, and the response time is 27 s. The sensor has good temperature, humidity, time stability and excellent selectivity, and can be potentially used in the trace hydrogen sulfide detection.