Study On The Preparation Of Graphene And Its Strain Sensing Properties

Since the discovery of graphene in 2004,it is expected to be widely widespread due to its unique mechanical,electrical,optical and magnetic characteristics,and is expected to become the next generation of electronics and optoelectronic materials.There are many preparations for graphene,but the surface of the single-layer graphene obtained is prone to folds.The preparation of less graphene is not perfect.It is difficult to accurately control the number of layers and coverage of graphene.Essence Therefore,large-scale preparation of fold-free graphene single crystal and controllable graphene film with several layers is a key problem that needs to be solved urgently.The excellent flexibility and high transparency of graphene make it an ideal candidate material for making strain sensors.However,research has found that graphene is more difficult to obtain higher GF factor,so it cannot be used to monitor tiny deformation and detects human fine activity.Although studies have shown that the strain sensor based on graphene and other materials has high sensitivity,it cannot maintain a high light transmission rate of graphene.Focusing on the preparation of graphene and its strain nature,the research content of this article mainly includes the following three aspects:（1）The mechanical stripping method and atmospheric pressure chemical vapor deposition（APCVD）method were used to prepare low layer graphene and investigate the properties of graphene.Research has found that the quality of graphene prepared by mechanical stripping method is higher,and the G and 2D peaks of graphene are more sensitive to changes in the number of layers.As the number of graphene layers increases,blue shifts occur,and the G peak is enhanced.The number of graphene layers can be determined by the ratio of I_2D/I_G.Single layer graphene grown by APCVD method can be precisely controlled by adjusting the flow ratio,humidity,and pre oxidation substrate of H₂ to CH₄.Single crystal graphene（SCG）with regular hexagonal morphology on the surface of copper foil substrate has been prepared in millimeter scale without wrinkles.（2）Fewer layer graphene was prepared on Cu/Ni（111）surface by APCVD method.Research has found that single crystal Cu/Ni（111）alloy foils with controllable Ni concentration can be prepared on the surface of Cu foil substrates by changing the electrochemical deposition time and current magnitude.The Ni content in Cu/Ni alloy foils can be accurately calibrated through XRD patterns.By increasing the growth temperature and Ni element content,it is beneficial for the growth of multi-layer graphene,and a few layer graphene film with high coverage（3-5 layers）has been successfully prepared.（3）A flexible strain sensor based on SCG was prepared by encapsulating the grown SCG in a flexible substrate,and its sensing performance was studied.Research has found that SCG strain sensors have a high GF factor（16.9）and high transmittance（up to 82%transmittance）.It has been proven that SCG strain sensors can be used to accurately detect human activities such as finger bending and distinguish small vibrations of different sounds and pulses and have good cycling stability（>3000cycles）.