Research on the Fabrication of Ultrasensitive Fabry–Pérot Pressure Sensor Based on Dip-Coating Method

To effectively control the thickness of polymer diaphragms and enhance the sensitivity of the Fabry–Pérot (FP) pressure sensor, the research of the relevant parameters based on the dip-coating method is carried out. By experimentally investigating the relationship between the immersion depth and dipping time, solution viscosity, dipping angle, lifting speed, and dipping speed, the effect of the intracavity pressure on the thickness of diaphragm formation is found to be predominant. Extremely thin diaphragm thicknesses can be obtained by controlling the dipping parameters when the hollow-core fiber (HCF) is immersed in the polydimethylsiloxane (PDMS) polymer solution. Experimental results show that the optimized diaphragm thickness can be reduced to $4.9~\mu \text{m}$ . Correspondingly, the FP pressure sensor has a sensitivity of up to 5.01 nm/kPa, which is about two times that reported in previous studies.