Research On Graphene-based Sound Generator And Acoustic Wave Amplifier

Graphene’s small heat capacity per unit area and large thermal conductivity make it show great potential in sound generators,and now it has begun to be used in artificial throats,graphene earphones and other fields.The high carrier mobility of graphene makes it possible for graphene to be used in surface acoustic wave devices.However,the current research on both is not comprehensive enough: the research on the factors affecting the sound emission efficiency of graphene sound generators is not complete;the research on graphene amplifying surface acoustic waves is still relatively less,especially research on factors affecting amplification efficiency of graphene amplifying surface acoustic waves.Therefore,in view of the problems above,this paper studies the factors that affect the sound generation efficiency of graphene,establishes a theoretical model of graphene amplifying surface acoustic waves,and further explores the factors that affect the efficiency of graphene amplifying surface acoustic waves.The main contents in this research include:(1)The theoretical model of the output sound pressure of the graphene sound generator is established.Firstly,the thermoacoustic effect is divided into two processes,electro-thermal and thermal-acoustic.The corresponding theoretical model is established,and the analytical expression of the output sound pressure of the sound generator is obtained.Then,the influencing factors of the output sound pressure of the graphene sound generator are analyzed by MATLAB simulation tool:the higher the frequency,the smaller the measurement distance,the larger the input power,the smaller the heat storage coefficient of the substrate,the thinner the graphene film,and the higher output sound pressure.When the measurement distance is 3cm,the input power is 1W,and the input frequency is 25 k Hz,the output sound pressure of the graphene sound generator reaches the highest,the maximum value is 58.7d B.(2)A graphene sound generator is fabricated and experimentally tested to explore the effects of AC input power and substrate types on the output sound pressure of the graphene sound generator.The graphene film is prepared by laser scribing method,and the graphene sound generator is fabricated.The output sound pressure of the sound generator in the frequency range of 100Hz-20 k Hz is tested in the anechoic chamber environment,which verified the correctness of the theoretical model.Among them,the output sound pressure of the sounder is tested when the AC input amplitude is 0.5V,1.5V,2.5V,3.5V,and 4.5V.When the amplitude is 4.5V,the output sound pressure of the sounder is the largest,and the maximum value is 47.1d B.In addition,the output sound pressure of the graphene sounder is tested when the substrate is PI film,PET film,and PDMS film.The results show that the output sound pressure of the graphene sounder is the highest when the substrate is PI film,and the maximum output sound pressure is 47.1d B.(3)The variable electrical conductivity of graphene carriers under an applied electric field is analyzed,and the amplification performance of multilayer graphene SAW amplifiers under different substrates is studied.The graphene surface acoustic wave amplifiers are comparatively studied with ZnO and Cd S as substrates,and their magnifications under different carrier drift velocities are studied,respectively.The results show that when ZnO is used as the substrate,the amplifying performance is the best with the carrier drift velocity greater than and close to the surface acoustic wave phase velocity,which can reach 34.92 dB.