Fabrication And Application Of Iron Nanowire/Carbon Microsphere Flexible Fabric Strain Sensor

Strain sensing is one of the key research topics in the field of mechanical engineering.As people pay increasing attention to sports health,especially the goal of sports recovery and scientific sports becomes more and more clear,in order to avoid human injury caused by unreasonable sports,it is necessary to conduct real-time detection of human motion state.Researchers at home and abroad have carried out extensive research on the flexible wearable strain sensor for human motion state detection,but how to improve the sensitivity,repeatability and wearable comfort of the flexible wearable strain sensor is still a key issue to be solved.In this paper,the motion state of human body was taken as the detection object,and the flexible strain sensitive material combining iron nanowires and carbon microspheres was proposed.The research method combining theory and experiment was adopted to carry out three aspects of research:finite element simulation analysis of the stress characteristics of the flexible strain sensor,the mechanism of the mechanical sensor was described from the theoretical level,and the optimization strategy of the sensor was proposed.The high performance strain sensitive material of iron nanowires/carbon microspheres was prepared,and polyester fabric was introduced as the sensor substrate to construct the sandwich fabric strain sensor.The mechanical testing platform was built,and the mechanical property testing and practical application verification were carried out.The specific work and research results of this paper are as follows:(1)The axisymmetric model of flexible strain sensor with sandwich structure is established by finite element simulation.Firstly,the deformation of the sensor model under the action of small force is analyzed.The deformation of the sensor under the action of small force is small,and the overall deformation of the sensor is obvious when a relatively large force is applied,and there is no fracture phenomenon under the maximum force.Then,the strain of the sensor is studied when the thickness of the sensitive layer changes.The simulation results show that the thicker the sensitive layer is,the more obvious the deformation trend of the flexible strain sensor is.(2)The preparation of iron nanowires,carbon microspheres and their composite materials was completed.At the same time,the corresponding sensitive layers of polyester fabric were prepared,and the flexible fabric strain sensor of "PDMS-polyester fabric sensitive layer-PDMS" sandwich structure was constructed.The iron nanowires were prepared by magnetic field assisted in-situ reduction method,and the carbon microspheres were prepared by hydrothermal method.After preparation,the morphologies of the carbon microspheres and iron nanowires were observed by scanning electron microscopy.Then,the composite material of iron nanowires and carbon microspheres was prepared under the condition of ultrasonic dispersion,and the three materials were assembled on the pretreated polyester fabric based on the layer self-assembly technology(LbL).After drying,the polyester fabric sensitive layer of the three materials was obtained.Finally,the sandwich fabric strain sensor was constructed on the basis of PDMS.(3)A flexible fabric strain sensor made of iron nanowire,carbon microspheres and their composite materials was prepared.The linearity and sensitivity of the flexible fabric strain sensor were tested based on the mechanical test platform.The test results show that the performance of the composite flexible fabric strain sensor is significantly better than that of the carbon microspheres or iron nanowires flexible fabric strain sensor.Then,the repeatability,hysteresis,flexural and stability of the two composite flexible fabric strain sensors are tested.The test results show that the composite flexible fabric strain sensor not only has low hysteresis,but also has low hysteresis.At the same time,it also has good bending and stability.Subsequently,the composite flexible fabric strain sensor was used to detect the motion of human knuckles,neck,larynx,arms,knees and elbows.The test results show that the iron nanowires/carbon microspheres flexible fabric strain sensor prepared in this paper has great potential and application prospect in human movement health monitoring.