Preparation And Performance Study Of Flexible Strain Sensors Based On Low Dimensional Nanomaterials/SEBS

With the rapid development of flexible electronic devices,people’s demand for the performance of wearable flexible sensors is increasing.While having stable sensing performance,it also needs to have a wide strain range and biocompatibility.At present,flexible sensors based on a single nanomaterial often find it difficult to balance high sensitivity and wide strain range.Researchers usually approach these issues from two aspects: sensitive materials and flexible substrates to improve the overall performance of flexible sensors.Triple block copolymer poly(styrene ethylene butene styrene)(SEBS)has ultra-high tensile strength and biocompatibility,which can be used as an elastic substrate to improve the strain range of sensors.Low dimensional nanomaterials(such as carbon nanotubes,graphite oxide,etc.)have high specific surface area,high strength and excellent conductivity,and are commonly used as sensing unit materials for flexible strain sensors.This article uses SEBS as a flexible substrate material and utilizes the high elasticity of SEBS to expand the strain range of the sensor;Using low dimensional nanomaterials such as carbon nanotubes(CNTs),silver nanowires(Ag NWs),graphite oxide(GO),and metal carbonitrides(MXene)as sensitive materials,the sensitivity of the sensor is improved through a binary nanomaterial composite system to prepare a flexible strain sensor,and explore the synergistic effect of the binary nanomaterial composite system on the performance of the sensor.The main research contents are as follows:1.A series of CNTs/SEBS flexible tensile sensors were prepared by changing the amount of CNTs added,using SEBS as a flexible substrate and CNTs as a single sensitive material.Research has shown that as the content of CNTs increases,the sensitivity of the sensor increases.However,when the amount of CNTs added is too high,the effective strain range of the sensor decreases.The sensitivity of this sensor can reach 71.96 in the0-80% strain range,and decreases to 34.68 in the 80-200% strain range.CNTs/SEB flexible tensile sensors can work stably under different strain levels and strain rates,and maintain good sensing performance after 1500 cycles,with good cycling stability.2.In order to improve the sensitivity of the sensor,sensitive materials were further compounded on the basis of CNTs/SEBS flexible sensors.Ag NWs and MXene were respectively coated on the surface of CNTs/SEBS films as the second sensitive layer by blending and dipping methods.Ag NWs/CNTs/SEBS and MXene/CNTs/SEBS flexible tensile sensors with dual sensitive layers were prepared,and the influence of binary nanomaterial composite systems on sensor performance indicators was compared and analyzed.Research has shown that the mechanical performance of MXene/CNTs/SEBS flexible strain sensors is better,with a sensitivity of up to 566.24 in the 0-10% strain range and 147.61 in the 10-35% strain range;The sensitivity is 37.02 within the strain range of35-80%.In addition,the sensor can operate stably in a strain range of 0-80% and a strain rate of 10-50 mm/min,and can still operate stably after 1500 cycles.3.A dual functional flexible strain sensor with sponge structure was prepared by template sacrifice method,which can be used as both a compression sensor and a tension sensor.Adding Na Cl to SEBS solution,SEBS sponge was prepared using template sacrificial method.GO/SEBS and CNTs/SEBS flexible strain sensors were prepared using CNTs and GO as single sensitive layers,respectively;GO/CNTs/SEBS flexible strain sensors were prepared by further adsorbing GO on CNTs/SEBS sponges.Research has shown that GO/CNTs/SEBS flexible strain sensors have the best performance.Whether applied to tensile sensors or compression sensors,GO/CNTs/SEBS sponges exhibit high sensitivity and a wide strain range,and exhibit excellent stability under cyclic testing of0-4000 seconds.When used as a tensile sensor,the maximum tensile strain can reach150% and the maximum sensitivity is 45.45;When used as a compression sensor,the maximum compressive strain can reach 35% and the maximum sensitivity is 145.16.