| Laser direct writing technology(LDW)uses high-energy laser as local heat source to heat,sinter,ablate and induce reaction.Due to the characteristics of high machining precision,fast speed,strong controllability and wide material adaptability,laser direct writing technology has gradually become a method of flexible sensor preparation.Although the temperature,gas,humidity and other flexible sensors prepared by laser direct writing have been applied to health monitoring,smart home and other fields,these research work mostly focuses on the synthesis of single functional materials or the preparation of single functional devices.There is little exploration on the laser direct preparation of integrated flexible sensor array,which fails to give full play to the advantages of rich types of materials,wide adaptability and simple process flow.Taking the flexible temperature pressure sensor array as the research object,this paper studies the all laser direct writing preparation of the device.By establishing a finite element model with phase transformation mechanism and dynamic parameters varying with temperature,the temperature field distribution of laser processed materials is effectively simulated,and then the structural morphology is predicted;The influence of laser parameters on electrode performance is explored from the perspective of microstructure,and the performance regulation law of laser direct writing of each functional layer is clarified;Through laser direct writing of silver electrode,carbon sensing layer and microstructure layer,a flexible temperature pressure sensor array is constructed.The main contents of this paper are as follows:(1)Laser direct writing carbon based materials and their properties.Carbon based temperature sensing layer was prepared by laser direct writing carbonized polyimide(PI).The resistivity can be adjusted between 0.084-560 Ω·m,and the temperature coefficient of resistance(TCR)can reach-0.62%/℃.The photothermal model with phase transition mechanism and dynamic parameters is established.The pre simulation error of transverse and longitudinal dimensions of carbon electrode within the range of preparation process parameters is less than 5%.(2)Study on laser direct writing silver electrode and its properties.The highly conductive silver electrode was prepared by laser direct writing,with a minimum resistivity of 120 μΩ·m,and is insensitive to temperature,pressure and bending.Through the combination of numerical simulation and experimental characterization,the regulation law of composition and Gradient Morphology of silver electrode prepared by laser was explored.(3)A flexible temperature pressure sensor was fabricated by all laser direct writing.The temperature measurement structure is constructed by using silver electrode and carbon sensing layer,and the response sensitivity to temperature can reach-0.62%/℃;A pressure sensor with high sensitivity is constructed by using silver electrode and microstructure.The sensitivity is-1.6 kPa-1 in the range of<0.3 kPa and-0.31 kPa-1 in the low pressure section(0.3-3 kPa). |
