Research And Design Of High Frequency Characteristics Of Graphene Gas Sensor

In recent years,with the rapid development of society and the continuous advance-ment of technology,everyone's requirements for the quality of daily life and the sur-rounding living environment have also been continuously improved.Social production,air quality monitoring,medical and health environment and other fields have put for-ward higher requirements for the performance of gas sensors.The selection of high-performance gas-sensitive materials is crucial to the development of gas sensors.Most of the common gas sensors at home and abroad use metal oxide materials,which have the disadvantages of large volume,high power consumption,slow response,and poor repeatability.Graphene is widely used in the field of gas sensors due to its special two-dimensional planar structure and electrical characteristics.Graphene has a high carrier mobility,a large specific surface area,stable physical and chemical properties,and good adsorption performance,which can make up for the shortcomings of traditional semi-conductor gas-sensitive materials.At present,researchers'research on graphene gas sensors is mainly based on the resistance change when responding to gas,but there is little research on the influence of gas response on the high-frequency nonlinearity of graphene.In response to this problem,this paper carried out related research work on the high-frequency characteristics of graphene gas sensors,and explored the feasibility of high-frequency graphene gas sensors.Through the investigation of graphene gas sensors at home and abroad,this paper analyzes the principle of gas sensors and the high-frequency nonlinear characteristics of graphene,and expounds the researchability of the high-frequency characteristics of graphene gas sensors.Based on the traditional resistive graphene gas sensor,a graphene gas sensor with high frequency characteristics was developed.Use ADS software to design and simulate the high-frequency circuit of the sensor,and combine the signal source and spectrum analyzer to test.The main work content is as follows:(1)Research and design of graphene gas sensors with high frequency characteris-tics,including graphene microstrip gap,microstrip transmission line,DC bias,etc.Through the principle analysis and calculation of microstrip line,the microstrip line with characteristic impedance Z_L=50?and the dielectric substrate of Rogers 5880 were designed using HFSS software.Graphene microstrip gaps with different lengths D and characteristic impedance values Z_L were fabricated and tested.The results showed that:when the gap length D=0.3 mm and the characteristic impedance Z_L=50?,the mi-crostrip line has the smallest loss and the output harmonic component has the highest power.Analyze the DC bias,it can prevent the DC voltage from leaking into subsequent circuits or test instruments,the electromagnetic wave signal from leaking into the power supply system,and can change the nonlinear operating point of graphene,effectively outputting even harmonics with larger power wave component.(2)Graphene gas sensor design for recycling network.Based on the high-fre-quency graphene gas sensor,a recovery network is added to the input and output ends of the graphene microstrip gap.The recovery network is used to retain the required harmonic components,and the remaining harmonic components are reflected back to the graphene for secondary transmission,and finally the two harmonic components ob-tained are superimposed and output.The test results show that:When the input power is 14 d Bm,the third harmonic output power of the graphene gas sensor without a re-covery network is-16.5 d Bm,and the third harmonic output power of the graphene gas sensor with a recovery network is-10.1 d Bm,and the output power is approximately increased 6.4d Bm,proves that the recovery network effectively improves the output power and efficiency of the harmonic components of the graphene gas sensor.(3)Testing and verification of high-frequency characteristics of graphene gas sen-sors.Use a DC power supply,signal source,spectrum analyzer and other equipment to build a gas test system to test the output power changes of DC resistance and harmonic components after being charged with different concentrations of ammonia gas.Sort out and analyze the experimental data to get:When filled with ammonia at different con-centrations,the DC resistance of the graphene gas sensor increases,the output power of the second and third harmonics decreases,and the rate of change of the output power of the harmonic component is higher than the rate of change of the DC resistance about20%.This paper studies and designs the high-frequency characteristics of graphene gas sensors,and proves that graphene's high-frequency nonlinearity can be used for gas detection,and its gas response and sensitivity are higher than those of DC resistance detection.This research result laid the foundation for the research in the field of gra-phene sensors,demonstrated new achievements,and achieved new breakthroughs.