Research On The Pressure Sensing Technology Based On Micro-Nano Hollow FP Cavity On Fiber

Barometric pressure measurement has always been the focus of measurement in engineering applications,especially in hazardous areas such as flammable and explosive.Traditional air pressure measurement methods usually use electrical sensors to detect signals,but electrical sensor units have poor mechanical performance and signal transmission stability,and cannot accurately collect pressure and strain information,nor can they meet the needs of air pressure measurement in complex environments.The optical fiber-based pressure sensor is small in size and light in weight.At the same time,it is not susceptible to electromagnetic signal interference,and its sensitivity and measurement accuracy are relatively high.In the field of complex environmental pressure measurement,such as oil pipeline pressure measurement,deep sea pressure measurement.The pressure measurement of oil storage tanks shows great application potential.In this paper,based on the principle of Fabry-Perot multi-beam interference,combined with precision cutting,bubble blowing,discharge-assisted expansion method and CO2 laser heating method,three fiber Fabry-Perot sensors based on the hollow structure on the fiber are designed and prepared.By establishing a mechanical simulation model for the sensor,the parameter design range of the sensor is optimized,and the pressure measurement sensitivity of the optical fiber Fabry Perot sensor is significantly improved.Compared with the research status of other research groups at home and abroad,the barometric pressure measurement structure proposed in this paper has greater advantages in sensitivity and resolution.The main innovations of this paper:(1)A new type of optical fiber pressure sensor filled with AB epoxy adhesive film based on the blowing method.In the case of small pressure changes,colloids are generally used to prepare FP microcavities to obtain high-sensitivity test results.However,the traditional preparation of colloidal microcavities is inevitably affected by the capillary phenomenon,and thinner colloidal films cannot be prepared.In order to overcome the capillary phenomenon during the preparation of the colloid microcavity.A new type of optical fiber pressure sensor filled with AB epoxy adhesive film based on the blowing method is proposed.The liquid AB epoxy glue is pressurized and bubbled by a pressure pump,and the air pressure is controlled by the air pump,which can control the size of the bubble,and then control the bubble wall thickness.By controlling the quality of the colloid,a very thin bubble film can be prepared.The FP sensor structure on the optical fiber is realized by film layer transfer.The pressure sensitivity in the range of 100kpa-400kpa is about 264.0pm/kPa.At the same time,the temperature drift of the sensor is also greatly reduced due to the decrease of the film thickness.14%previously reported in the literature.The structure has the advantages of ultra-thin film thickness,ultra-high pressure sensitivity,low cost,good repeatability,etc.,indicating that it has good application value in high-sensitivity pressure and acoustic wave detection.(2)Preparation and sensing of FP cavity on optical fiber based on discharge-assisted expansion method.When preparing hollow microbubble cavities,when the filling pressure is relatively too high,the radius of the microbubbles will expand(that is,the expanded state),but when the filling pressure is relatively too low,the shrinkage effect(that is,the contracted state)will occur.Assuming that the exhaust pressure and the filling pressure are controlled in a reasonable state,there is a transition critical state between expansion and contraction.We repeatedly adjust and control the discharge intensity parameters,the inflation pressure value,and the position of the microbubbles under the condition of the critical state pressure-assisted arc discharge.The microbubble membrane layer can be gradually thinned while retaining the smooth,uniform and symmetrical advantages of the traditional solid microsphere cavity.A uniform microbubble with a thickness of 2?m was prepared,and the film layer was transferred to form an FP cavity.In the pressure range of 100kpa-1600kpa,the sensor sensitivity can reach 6790 pm/MPa,which is 1.5 times higher than previous reports.The special stable structure of the microcavity makes it more suitable for applications in high-pressure harsh environments.(3)Optical fiber FP hollow microcavity air pressure sensor based on thin film shaping and sensitization.In order to overcome the problem of structural deviation and cracking caused by uneven heating in the preparation of microbubbles,the discharge expansion method and the CO2 laser heating expansion method are combined to prepare a hollow glass capillary with an outer diameter of 150 ?m and an inner diameter of 128 ?m,with a diameter of 500 ?m and a spherical wall.Ultra-thin hollow glass bubble cavity with a thickness of 300nm.The film layer is transferred to form an FP cavity,which optimizes the design of the sensing structure and precisely controls the cavity length.In the air pressure range of 100kpa-1600kpa,the sensor peak offset-pressure sensitivity is about 20.12pm/kPa.The sensitivity is increased by 4 times compared with the FP cavity on the fiber based on the discharge assisted expansion method in(2).