Abstract
This paper proposes a Fabry–Perot pressure sensor based on AB epoxy adhesive with ultra-high sensitivity under low pressure. Fabry–Perot interference, located between single-mode fiber (SMF) and hollow-core fiber (HCF), is an ultra-thin AB epoxy film formed by capillary action. Then the thick HCF was used to fix the HCF and SMF at both ends with AB epoxy adhesive. Experimental results show that when the thickness of AB epoxy film is 8.74 μm, and the cavity length is 30 μm, the sensor has the highest sensitivity. The sensitivity is 257.79 nm/MPa within the pressure range of 0–70 kPa. It also investigated the influence of the curing time of AB epoxy on the interference spectrum. Experiments showed that the interference spectrum peak is blue-shifted with the increase of curing time. Our study also demonstrated the humidity stability of this pressure sensor. These characteristics mean that our sensor has potential applications in the biomedical field and ocean exploration.
Highlights
Experimental results show that when the thickness of AB epoxy film is 8.74 μm, and the cavity length is 30 μm, the sensor has the highest sensitivity
The pressure sensor based on AB epoxy adhesive film is mainly composed of singlemode optical fiber (SMF, Corning SMF28 e+), hollow-core fiber (HCF, TSP075150, with a core diameter of 75 μm and a cladding diameter of 150 μm), AB epoxy adhesive, thick
When external pressure is loaded, due to the pressure difference between the inside and outside of the sealed air cavity, the AB epoxy adhesive ultra-thin film layer is elastically deformed, which in turn changes the length of the Fabry–Perot interference (FPI) cavity, causing the corresponding interference spectrum to shift
Summary
Fabry–Perot (FP) sensors have drawn attention due to many outstanding advantages, such as high sensitivity, small size, high measurement accuracy, high resolution, and extensive dynamic range [1,2,3,4,5,6]. More and more high sensors have been developed that use different materials to form an FP cavity [18,19,20,21,22]. Luo et al [25] reduced the thickness of the optimized PDMS film to 20 μm, and the sensitivity of the optical fiber pressure sensor could reach 100 pm/MPa. the sensitivity is not large enough. When the external air pressure was between 100 and 1600 kPa, the sensitivity of the FP cavity was 6790 pm/MPa. The sensor has the advantages of the working range being much more extensive and low cost; the process is very complicated, and the sensitivity is not large enough. Our work mainly studied the sensitivity measurement of fiber optic pressure sensors under low-pressure conditions. The particular structure based on the sensor can be applied to biological penetration detection and has some potential applications for marine engineering
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