Research Of Flexible Strain Sensor Based On Carbon-based Nanomaterials

Flexible strain sensors with unique properties such as ultra-thinness,low modulus,light weight,high flexibility and stretchability have attracted great interest.Strain sensors can be attached to the surface of the organ or the skin to measure and to quantify the electrical signals generated by human activities,providing new opportunities for human motion monitoring and implantable organ tissue assistive devices.Since carbon-based nanomaterials,with excellent mechanical properties and mechanical properties were prepared,their preparation methods and applications in composite materials and flexible electronic devices have been extensively studied,providing favorable conditions for manufacture and research of flexible strain sensors.This paper mainly studies the flexible strain sensor that can be used for human health monitoring,discusses the optimal process for preparing carbon-based nanomaterials,and characterizes carbon nanotubes and graphene respectively,and analyzes their feasibility for preparing flexible strain sensors.Three types of strain sensors were designed and fabricated,including strain sensors based on pure carbon-based nanomaterial films(carbon nanotube films,graphene films),carbon nanotube strain sensors based on pre-stretched microstructures,and strain sensors based on graphene nanosheets hybrid carbon nanotubes,systematically analyzed the effect of graphene nanosheet hybridization on the mechanical and electrical properties of carbon nanotube conductive networks.Firstly,the paper analyzes the preparation method of carbon-based nanomaterials,and prepare graphene by the low-cost and high-scalability liquid phase exfoliation,which is a three-dimensional layered material graphite powder dissolved in organic solvent by physical action such as ultrasonication and centrifugation.The graphite is peeled off into a two-dimensional structure to obtain a graphene dispersion.The stripped graphene was characterized by optical microscopy,Raman spectroscopy,atomic force microscopy and high-resolution transmission electron microscopy to detect the peeling effect,and the best parameters for preparing graphene were obtained.In order to improve the sensitivity of the flexible strain sensor,two types of sensors were designed,one was a carbon nanotube film strain sensor based on pre-stretching to produce microstructure,and the other was strain sensor based on three-dimensional conductivity of graphene nanosheet hybrid carbon nanotubes,and the actual sensors were fabricated.The experimental results of the strain sensor show that the microstructured strain sensor has high sensitivity(170 at 1% strain)and ultra high stability(more than 1000 times cycles);graphene hybrid carbon nanotube strain sensor has super high sensitivity,which is 50 times of pure carbon nanotube strain sensor,up to 197,sensor response time is less than 497 ms,and the number of stretching/releasing is more than 1000 times,showing long-term durability.At practical applications,strain sensors based on graphene nanosheet hybrid carbon nanotube networks can monitor and identify human activities such as finger bending,vocalization and swallowing,indicating that flexible strain sensors have application prospects in flexible and wearable devices for human motion monitoring.