Research And Application On Flexible Fiber Strain Sensor Based On Ringlike Laminated Construction

With the continuous development of flexible electronics,flexible strain sensors that can sense environmental information and simulate skin characteristics are receiving more and more attention,showing important applications in the fields of intelligent robots,artificial prosthetics,wearable devices and physiological health monitoring,and it is significant for the development of flexible wearable sensing and human-machine interaction.In this work,a ring-like double conductive layers structure was designed based on one-dimensional threadiness structure of polyurethane substrate.The effect of different mechanisms on the bonding effect between the substrate and conductive layer was studied.The carbon-based nanomaterials with excellent electrical properties and conducting polymers were used as conductive fillers,different sensitive material system was designed,the strain sensor with high stretchability and high linearity based on carbon black(CB)/single-walled carbon nanotubes(SWCNT)and the strain sensor with high sensitivity and high resolution based on graphene(GNPs)/polyaniline were prepared.Research Contents of the Thesis are as follows:(1)Polyurethane fiber with excellent tensile properties was selected as the substrate,and the polyethylene glycol modified layer was constructed on the surface of the substrate by dip coating process.The influence mechanism of hydrogen bonding on the surface structure of the substrate was studied.The inner graphene layer with uniform distribution and stable structure was constructed,and the bonding mechanism between the substrate and the inner layer was analyzed,and the good adhesion between the substrate and inner layer was achieved.The outer conductive network layer based on CB/SWCNT/silicon rubber(SR)composite system was constructed,and the strain-sensitive elements with excellent mechanical and electrical properties were designed.The prepared sensor possesses good stretchability(350%),resolution and linearity(adjusted R~2>0.990);combined with the microscopic characterization,the strain-sensing mechanism of the flexible strain sensor was analyzed,and the influence of the dual-mode synergistic conductive mechanism on the electrical conductivity was revealed.The application of the tiny motion and physiological activity monitoring in human body was studied and flexible wearable sensing capability was achieved.(2)The polyurethane fiber was selected as the substrate,the influence of physical adhesion on the surface structure of the substrate was studied,and the inner layer basedonthephysicaladhesionmechanismwasconstructed.The GNPs/polyaniline/SR composite system was designed.The outer conductive network layer adopted multi-layer dip coating and layer-by-layer assembly process to prepare a highly sensitive strain sensor and the performance such as sensitivity and repeatability was analyzed and optimized.The flexible electronic skin based on the above strain sensor and breathable waterproof film was developed,influence of environmental factors such as temperature and humidity on its performance was studied.The electronic skin monitoring system was constructed,the application of human body movements and micro-expressions was evaluated,so the posture monitoring and identification based on flexible wearable sensing features was realized.The research shows that the flexible strain sensor has the characteristics of simple process,high cost performance and excellent sensing performance,and possess important application value and significance in the fields of flexible wearable sensing and human-machine interaction.