MWCNT/PDMS Flexible Strain Sensor And Its Patterning Study

Traditional commercial strain sensors are generally made of metal or semiconductor materials.Limited by the nature of the metal or semiconductor material itself,the strain range is generally not more than 5%,and the flexibility is poor.Traditional strain sensors cannot meet the requirements of large strain range,flexibility,and wearability required by wearable sensors.The flexible strain sensor developed rapidly in recent years has shown great application prospects in the fields of motion monitoring and human-computer interaction due to its large sensing range,high sensitivity,lightness and softness.In this paper,aiming at the problems of stretchable lead,strain sensitive layer preparation and strain direction identification in flexible strain sensor:a flexible structure with spring lead is designed and prepared.Multi-Walled Carbon Nanotube(MWCNT)was added to Polydimethylsiloxane(PDMS)to prepare MWCNT/PDMS strain sensitive layer.The performance of resistive flexible strain sensor with MWCNT/PDMS as strain sensitive layer was tested and analyzed.The flexible strain sensor is patterned to achieve the purpose of simultaneously identifying the size and direction of the plane strain.The specific research contents are as follows:1)A H65 brass wire spring-like lead with a diameter of 0.2 mm was designed and prepared,and it was packaged by PDMS to prepare a PDMS flexible structure that can be used as a lead.The PDMS flexible structure with spring lead was optimized from three aspects:the mass ratio of PDMS prepolymer to curing agent,the thickness of flexible structure and the spacing of spring lead.Finally,the flexible structure had excellent tensile properties(maximum tensile strain of 95%).Through experimental tests,it is proved that a large number of spring-like leads can be arranged in parallel in PDMS under the premise of ensuring stable mechanical properties and good conductive stability.2)A resistive flexible strain sensor with MWCNT/PDMS composite as strain sensitive layer was designed and fabricated.By adding a variety of additives to MWCNT/PDMS,the dispersion effect of MWCNT in the composite and the performance of the composite were optimized,and the optimal content of MWCNT in the composite was determined to be 6wt%.The maximum tensile elongation of the prepared strain sensitive layer reaches 96.67%,which has excellent tensile properties,sensitivity and linearity.The strain sensitive layer and the spring lead are packaged by PDMS.The packaged flexible strain sensor has a sensitivity of 5.18 in the response range,and has good linearity and stability,which can realize the monitoring of human motion signals.3)Patterning on the basis of MWCNT/PDMS flexible strain sensor.With the help of simulation software,the "cross" snake structure is simulated and optimized to determine the optimal geometric structure parameters,and the "cross" snake structure flexible strain sensor is prepared.The sensor has good cyclic stability and high sensitivity,and can identify the size and direction of plane strain.The experimental results show that the designed PDMS flexible structure with springlike lead can be applied to flexible sensors.The MWCNT/PDMS flexible strain sensor can meet the actual needs of human motion monitoring.The patterned sensor can realize the identification of strain size and direction.The preparation method and test method studied in this paper provide a reference for the subsequent research of flexible strain sensor.