Preparation And Study Of Capillary Tube Gas Sensor Based On Doped Polyaniline

Polyaniline?PANI?gas sensor is one of the important sensors for detecting and analyzing gas samples.It has great applications in various industries including environmental monitoring,home safety,medical diagnosis,artificial intelligence and so on.The detection of large-volume,high-concentration ammonia gas samples has made great progress,and it has achieved some practical applications.At present,with the advancement of various applications such as human medical diagnosis,scientific experiment atmosphere detection,food safety and quality monitoring,the development of a new structure polyaniline gas sensor capable for rapid detection of small volume and low concentration ammonia samples is imperative.In this paper,a doped polyaniline gas sensor with capillary tube structure is proposed,and the preparation and sensing performances are studied.We established a DLPD method to grow a sensitive film,namely PANI-CSA/TiO₂or PANI-SSA/HCl material,on the inner wall of a silica glass capillary tube.A doped polyaniline capillary tube gas sensor was obtained by painting electrodes to build an electrical signal extraction device.With the assistance of scanning electron microscope?SEM?,Energy dispersive spectrometer?EDS?,Fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?and self-built gas sensor detection system,etc.,the morphology,composition,phase structure,electrochemical performance and gas sensing performance were studied.The optimized preparation process parameters have been investigate.Under the optimal liquid flow rate of 0.62 mL/min,PANI-CSA/TiO₂and PANI-SSA/HCl capillary tube sensors?core diameter 1 mm,length 7 cm?with better performances than planar sensors can be obtained.Among them,the comprehensive performance of PANI-CSA/TiO₂ capillary sensor is better,the response time for detecting 3 ppm NH₃ gas is 84 s,the sensitivity is up to 877%,the recovery time is 55 s,and the response time of the corresponding planar sensor sample is 152 s,the sensitivity is 17.8%,and the recovery time is 367 s.For a small volume,low concentration?1 mL,0.1 ppm?NH₃ gas sample,the response time of the PANI-CSA/TiO₂ capillary sensor is 54 s,and the sensitivity is 454%,while the planar sensor fails to detect.The feasibility of using Eu³⁺doped polyaniline to further enhance the sensing performance of the capillary tube gas sensor was explored.With Eu?NO₃?₃ as a structure guiding agent,Eu³⁺doped PANI sensitive material was prepared inside the capillary tube by DLPD process.The analysis shows that the Eu³⁺doped PANI has a nanofiber porous network structure.This porous film shows a large specific surface area.The self-built sensing performance test system can detect small volume and low concentration NH₃ gas samples?0.3 mL,0.25 ppm?.The Eu³⁺doped PANI capillary tube sensor has showed high sensitivity?435%?,short response time?5 s?and recovery time?5 s?.The reproducibility and selectivity of the sensor are good.