Mechanism And Fabrication Of Graphene-based Flexible Strain Sensor

The unmanned variant aircraft is an important carrier of the future military struggle,and the accurate perception of the deformation of its body structure is an important factor affecting the success of its mission.Traditional strain sensors have many limitations such as large rigidity and large volume when applied to unmanned variant aircraft.It is urgent to study a new type of strain sensor with flexibility and adhesion.In recent years,the emerging material graphene film has become a research hotspot in the field of flexible strain sensing due to its excellent mechanical and electrical properties.However,at present,most of the research in this field focuses on the structure and process of the graphene devices,and the strain-sensing mechanism is still unclear.At the same time,the preparation conditions of graphene materials are severe,the process is complicated,and the cost is high,which is difficult to be practically applied in engineering.Aiming at these problems,the paper studies the strain mechanism of graphene film obtained by two low-cost preparation methods and the design and manufacturing process of the sensor from the perspective of low cost and the balance between sensitivity and range.The main research contents of this paper include:1.Strain sensing mechanism of thin film based on theory of conductive paths destruction and the structure and the fabrication process design of sensor.Based on the investigation of the strain-sensing mechanism of the film and the internal structure of the graphene film material,combined with the research results of the existing sensitivity mechanism of the film strain sensor,the strain-sensitive mechanism of graphene film based on the theory of nanosheet overlap and the theory of conductive paths destruction is proposed.From the statistical point of view,the trend change model of the resistance is obtained,and the characteristic description of the film type strain sensitive material with different internal structure is realized.2.Flexible strain sensor based on nickel-based CVD graphene filmNickel-based CVD(Chemical Vapor Deposition)graphene film was used as the sensitive material to study the fabrication process and process of the flexible strain sensor,and a novel graphene transfer process was explored.Flexible strain sensors based on 3M tape-CVD graphene structure and PDMS-CVD graphene structure were designed and fabricated with 3M tape and polydimethylsiloxane(PDMS)as flexible substrates.The performance of the two types of sensor was tested and compared.The results show that the overall performance of the PDMS-CVD graphene structure is superior to the 3M tape-CVD graphene structure.3.Flexible strain sensor based on vacuum-filtered graphene filmThe preparation process of vacuum-filtered graphene film was studied,and vacuum-filtered graphene film was prepared.On the basis of this,a flexible strain sensor based on PDMS-vacuum suction-filtered graphene structure was designed and fabricated with PDMS material as flexible substrate,and the characteristics of the sensor were tested and compared.The results show that the PDMS-vacuum-filtered graphene structure has a relatively high gauge factor compared with the PDMS-CVD graphene structure,but the stability is not good.On conclusion,the mechanism of graphene flexible strain sensor proposed in this article,and the three graphene flexible strain sensors designed and manufactured during this study,can provide theoretical basis and basic sensing approaches for the further exploration of the precise sensing technology of the unmanned variant aircraft body structure deformation.