Preparation And Properties Of Flexible Film Sensor Based On Carbon System Composite Slurry

Flexible thin film sensor is an important area in the field of sensor research.In recent years,many sensor technologies for bending,temperature and pressure monitoring have made major achievements.However,there are still many technical problems in the development of thin film sensors such as low cost,simple preparation,small pollution and mass production.Carbon system composite conductive slurry(composite graphite,conductive carbon black,carbon nanotubes and graphene in resin)is the most commonly used core material of sensitive functional layer for flexible film sensor.It has the advantages of large elasticity,large strain,large measurement range and low cost.In this study,three kinds of flexible thin film sensors,i.e.thin film bending sensor,thin film pressure sensor and thin film temperature sensor,were prepared by using carbon based composite slurry.The thin film bending / pressure / temperature sensors were studied.This paper mainly completed the following work:1.Preparation and properties of thin film bending sensorThe optimal low temperature plasma treatment time of PI film substrate was 25 s.The bending sensitive composite paste was prepared by using the film bending sensor as the research object,and the bending sensitive functional layer and the film bending sensor were prepared by silk printing the bending sensitive composite paste on the Ag electrode.The results show that when the grinding times were 3 times,the drying temperature was 100℃,and the dispersant was EFKA-4310,the performance of the bend sensitive functional layer was the best.The linearity of the film bending sensor was 0.9847 in the range of 0 ~ 90 ° bending angle,and it had good repeatability and short response time.2.Preparation and properties of thin film pressure sensorIn this study,the best time to treat PI film with alkali solution was 50 min,and the best sintering temperature of Ag electrode was 150℃.Carbon based pressure-sensitive composite slurry with different carbon content was prepared by using carbon based conductive particles,polyphenoxy resin,DBE solvent and EFKA-4310 dispersant as raw materials.The pressure-sensitive composite functional layer was prepared by silk printing carbon based pressure-sensitive composite slurry on Ag electrode.Finally,three kinds of film pressure sensors with different carbon content were made.The sensitivity,hysteresis and repeatability of the membrane pressure sensor with different carbon content were analyzed.Finally,it was concluded that the film pressure sensor with 12.97% carbon content has good sensitivity,good repeatability and low hysteresis.3.Preparation and properties of thin film temperature sensorIn this paper,we showed a method of mass production of thin film temperature sensor.Firstly,Ag micro pattern was designed and deposited on PI substrate by using high-precision screen printing technology,and a temperature sensitive composite composed of PDMS doped low-temperature carbon black and graphene was coated on the electrode surface.Finally,the film temperature sensor was fabricated by cutting and packaging.The effect of sintering temperature on the microstructure and conductivity of Ag interdigital electrode was studied.The performance of the flexible temperature sensor in a large dynamic range was studied.The experimental results showed that the temperature coefficient of the resistance of the thin film temperature sensor was 0.0139/℃,which had higher sensitivity,smaller lag,better linearity and faster response speed.