Research On Structure Design And Test Of High Performance Flexible Strain Sensor

In recent years,due to the flexibility and ductility,flexible strain sensors have potential applications in the fields of health care,robotics,and human-computer interaction.Among them,the resistive flexible strain sensor has become one of the current research hotspots because of its simple structure,convenient manufacturing and excellent performance,and has been extensively studied in the material properties,preparation methods and performance of the sensor.However,there are still many technical problems: for example,how to solve the contradiction between sensor sensitivity,measurement range and linearity;and how to improve the applicability of the preparation method to meet the needs of various application scenarios;is the current research focus and difficulty.This paper proposes a flexible strain sensor with a porous structure,using polyurethane(PU)sponge as a porous micro-framework structure,carbon nanotubes(CNT)and titanium carbide nanosheets(MXene)as conductive composite materials,deposited conductive composite material on the porous frame of PU sponge,complete the preparation of the sensitive structure layer,and use conductive tape and polyimide(PI)film to complete the electrode extraction assembly,and finally use the silicone rubber(Ecoflex)to complete the package of the sensor to realize the preparation of the sensor.In order to improve the convenience and comfort of human wearing,the prepared samples can be cut to any size according to the needs to conformal attachment.Specifically,flexible tensile strain sensors and flexible compression strain sensors with porous structures are prepared to meet the requirements of tension and compression application,effectively expanding the application range of the sensor,and the sensor has an excellent overall performance.The specific research content is as follows:(1)The microscopic morphology characterization of the CNT/MXene-PU-Ecoflex flexible strain sensor shows that the sponge skeleton has a stable porous micro-framework structure and uniform pore size distribution.The sponge skeleton is completely covered by conductive sensitive materials,and the conductive path gradually changes from partial open circuit to stable conductive loop with the proportion of CNTs increasing.(2)Performe various performance tests on the tensile and compressive strain sensors,analyze the influence of CNT/MXene with different mass ratios on the sensor performance,and obtain the best ratio scheme.Comprehensive sensitivity,measurement range,stability and other key performance indicators,the flexible tensile strain sensor has a high comprehensive performance when the mass ratio of CNT and MXene is 5:1(GF value within 0-24% strain is 0.56,linearity is 0.98 and GF value within 24-60% strain is 1.19,the linearity is 0.99);the flexible compression strain sensor has a high comprehensive performance when the mass ratio of CNT and MXene is 10:1(the GF value within 0-3% strain is 2.29,linearity is 0.99;GF value within 3%-17% strain is-3.34,linearity is 0.99;GF value within 17%-65% strain is-0.47,linearity is 0.98;GF value within 65%-80% strain is-1.53,and the linearity is 0.99).In addition,both types of sensors exhibit good volt-ampere characteristics,and exhibit stable output characteristics in variable speed tests of 10 to 200 mm/min and 5000 times of repeatability tests.(3)Combine the characteristics and performance of the CNT/MXene-PU-Ecoflex flexible tensile strain sensor to monitor the application of stretching-related human motion.Specific applications include small-strain human motion monitoring and large-strain human motion monitoring.The sensor can sensitively monitor various small-strain and large-strain motions,and has the prospect of being applied to human motion monitoring.(4)Combine the characteristics and performance of the CNT/MXene-PU-Ecoflex flexible compression strain sensor to monitor compression-related human motion applications.The sensor can sensitively monitor related small strain and large strain movement,and has the prospect of being applied to human motion monitoring.In addition,this paper also combines the characteristics of compression sensors to realize the regulation of the brightness and color changes of LED lights.In summary,this paper proposes and prepares a resistive flexible sensor based on PU sponge as a porous micro-framework structure and CNT and MXene as conductive composite materials,which can realize the functional sensing of tension and compression.Through microscopic characterization,performance testing,and application testing,it can be verified that the sensor has excellent performance in sensitivity,linearity,stability,etc.,and can effectively monitor human movement,fully demonstrating its application prospects in the fields of health monitoring,remote medical diagnosis and human-machine interaction.