Preparation Of Flexible Carbon-based Materials And Their Sensor Applications

The carbon nanomaterials represented by carbon nanotubes(CNTs)and the biomass microcrystalline graphite carbon material represented by the silk have excellent performances and exhibit potential applications in many fields.Flexible sensors can be used to detect signals such as the body’s own motion and physiological information,as well as the stimulation of the external environment.Sensors have broad application and development prospects in the fields of real-time health monitoring,telehealth care,human-machine interface interaction,and environmental monitoring.Due to carbon materials generally have rich and varied morphology,excellent electrical conductivity,adjustability of multi-level structure and good flexibility,they have significant and unique application advantages in the field of flexible sensing electronic devices.The controllable preparation of the above carbon materials and their performance characterizations are the key factors for in the development of their application in the field of flexible sensing.Aiming at the application of flexible sensing,this paper systematically studied the growth preparation,structural characterization and visualization manipulation of ultralong carbon nanotubes.In situ growth of carbon nanotubes on silk-based carbon materials and application to flexibility sensor construction.The main research contents and results are summarized as follows:(1)Horizontal arrays of ultralong carbon nanotubes were prepared by chemical vapor deposition and labeled by loading sulfur nanoparticles to achieve localization and manipulation.Based on this optical visualization technology,the free extraction and recovery between carbon nanotube layers in the atmosphere is realized under the probe station,and the electrical properties of the carbon nanotubes during this manipulation are tested.The current variation law of carbon nanotubes extracted and recovered between the tube layers under constant voltage was found.In addition,after improving the growth conditions of the ultra-long carbon nanotubes,a floc sample of the carbon-coated carbon nanotubes visible to the naked eye was obtained.The unique structure of this carbon nanotube wrapped with a layer of onion-like carbon may have potential applications in areas such as flexible electronics.(2)A method of growing carbon nanotubes on silk-based fabric materials has been developed and this method has been further optimized.The optimized method is called one-step chemical vapor deposition.The morphology and quality of the sample prepared by this method are optimized,and the method is simpler,more efficient and cost-effective.We further studied the effects of catalyst types and catalyst concentrations on the morphology of carbon nanotubes grown on carbonized silk fabric substrates,which is important for regulating the growth of samples according to people’s needs.In addition,the composite material of the carbon nanotubes and the silk-based carbon fabric can be used as a sensing material,and has an important significance in constructing a flexible sensor.(3)The composite material of the carbon nanotubes and the silk-based carbon fabric is a kind of flexible conductive hierarchical carbon material,and the carbon material sensing material to construct a high-performance flexible pressure sensor.The multi-stage microstructure of the carbon material provides a large number of contact sites with the electrodes,giving the flexible sensors high sensitivity(1.2 kPa-1),fast response(50 ms),high stability and reliability.The flexible pressure sensor can be used to detect human motion and physiological signals and exhibits application potential in the field of wearable electronic devices.In addition,we have built an airflow sensor based on the unique structure of this material,which can sense changes of the outside airflow size.The airflow sensor has a very low detection limit(0.05 m/s)and a fast response time(1.3 s).The flexible airflow sensor is expected to play an important role in environmental areas such as medical clean rooms and mine ventilation areas.