Hydrogen Sensitivity And Signal Modulation Circuit For Palladium Loaded Composite Fiber Membrane

In recent years,with the progress of electronic technology,the demand of sensors is also increasing year by year.In order to deal with the sensor in the complex environment,it is necessary to develop the sensor with low cost,easy preparation and strong anti-interference ability.In recent years,clean energy based on hydrogen has been paid attention to and developed,so hydrogen sensors are widely needed.Because the sensor consists of sensitive material and its signal modulation circuit.Therefore,the paper is divided into two parts,the first part is the research of hydrogen sensor,the second part is the design of sensor circuit.Although palladium based hydrogen sensors have been studied for decades,the displacement of palladium particles is caused by the volume expansion of palladium due to hydrogen absorption,which affects the performance of the sensors.In order to improve the stability and sensitivity of the sensor,it is suggested to use polymer support to adapt to the displacement caused by palladium expansion,but the mechanical properties of polymer support is still a perplexing problem.Therefore,in this study,palladium nanoparticles were synthesized and attached to polyvinylidene fluoride(PVDF)nanofibers.The effects of initial hydrogen concentration,base resistance and relative humidity on the hydrogen sensor are studied.Through the calculation of activation energy,it is found that the resistance of hydrogen sensor is the best(512k ?)when the conduction path is controlled by the grain barrier of palladium.At the same time,humidity has a significant impact on the sensor response,and it is recommended to control it below 10% relative humidity.The initial exposure can greatly improve the sensitivity of the sensor,and the detection limit is 25 ppm.Combined with X-ray photoelectron spectroscopy and COMSOL multiphysical simulation,the effect of viscoplastic PVDF on the sensitivity of the sensor was studied.The hardening process of polyvinylidene fluoride(PVDF)is caused by the volume expansion of palladium nanoparticles in the initial adsorption of hydrogen.The hardened PVDF can inhibit the femtoscale oscillation of palladium nanoparticles and resist their deformation.The most stable conducting path of Pd nanoparticles can be obtained when the sensor is initially placed in.Therefore,the highest sensitivity was obtained by immobilizing palladium nanoparticles with PVDF.In this study,the influence of the mechanical properties of polymer substrate on palladium based hydrogen sensor is proved,which can not be ignored in the design of palladium based hydrogen sensor.The hydrogen sensor prepared by this method has the advantages of high response,fast recovery,simple preparation,low cost and suitable for large-scale production.For the sensor circuit,this paper proposes a LC resonant circuit based on the impedance conversion circuit,which is different from the conventional DC circuit.The impedance conversion circuit can indirectly control the resonance frequency offset through the resistance,and the electromagnetic wave generated by the circuit can be directly transmitted wirelessly.First of all,an impedance conversion circuit is designed,and the simulation experiment is carried out on the circuit,and the experiment is carried out on the circuit through the actual commercial formaldehyde sensor.It is found that the parasitic effect of the circuit makes the simulation and the measured data different.At the same time,the sensitivity of the circuit is discussed deeply.It is found that the change of sensitivity decreases with the increase of sensor resistance.Through theoretical analysis,the sensitivity not only depends on the parameters of the initial resonant circuit,but also depends on the electrical resistance of the sensor itself,and the sensitivity is inversely proportional to the sensor resistance.Therefore,the initial circuit can be designed The initial value adjusts the sensitivity.Therefore,the anti-interference ability of the sensor is explored by studying the sensor circuit and sensor respectively.Therefore,the anti-interference ability of the sensor is explored by studying the hydrogen sensor and the sensor circuit respectively.