Research On Fabrication And Characteristics Of Flexible Strain Sensors Based On SEBS And Lowdimensional Nanomaterials

With the rapid development of flexible strain sensors,numerous people have begun to put forward more requirements on flexible sensors,especially highly elastic strain sensors.For flexible strain sensors,improving the detection range of the sensor usually includes methods such as changing the sensitive unit material,improving the stretchability of the substrate,and changing the geometry of the sensor.This article aims to expand the stretchable range of the sensor and improve the gauge factor(GF)of the sensor under a wide range of stretch conditions.In view of the fact that the thermoplastic elastomer styrene ethylene butylene styrene(SEBS)is a kind of elasticity and environmental protection,this work adopts the blending heating method of SEBS and liquid paraffin to prepare the elastic substrate.By changing the mass ratio of reactants to prepare 7flexible substrate samples,the stress-strain performance test results show that the elastomer with a mass ratio of 1:3 has good toughness and consistency,and experiments have proved that the substrate has good adhesion to sensitive materials.The CNT/graphene/fullerene-SEBS flexible strain sensor was prepared by using a mixture of carbon nanotube(CNT),graphene(Graphene)and Fullerene(Fullerene)as the sensitive unit material.In order to further improve the stretchability and consistency of the sensor,the method of blending and heating was adopted to mix the sensitive unit material CNT/Ag flakes with SEBS and liquid paraffin,and the preparation of a shapeable sensor was realized by changing the reaction vessel.The specific results of the test are as follows:(1)It is characterized by scanning electron microscope(SEM)and transmission electron microscope(TEM)that the sensitive unit materials of the CNT/graphene/fullerene-SEBS flexible strain sensor are tightly arranged,and the sensitive unit materials are tightly bonded to the flexible substrate.The volt-ampere characteristics results show that the conductivity of flexible sensors based on CNT,CNT/graphene and CNT/graphene/fullerene are 1.684 S/m,2.932 S/m and 5.179 S/m,respectively.The results indicate the good conductivity of Graphene and the bridge of fullerene.The stretch range of the CNT sensor is up to 120%,and the GF is86.When Graphene is added to the sensitive unit material system,the GF of the CNT/graphene sensor is increased to 148 when the stretch range of the CNT/graphene sensor is maintained at120%,which reflects the good interlayer sliding characteristics and crack propagation mechanism of Graphene.When Fullerene is added to CNT/graphene,the lubricating properties of Fullerene alleviate the crack expansion of Graphene,resulting in an increase in the sensing range of the CNT/graphene/fullerene sensor to 203%and 136%(R~2=0.998)linear range,so the joint action of the three carbon materials can cause the sensitive unit material to not fracture under the condition of large strain.Through the comparison of the sensor under different speed and different strain tensile conditions,the repeatability and long-term anti-fatigue properties of the sensor under different speed and different strain are proved.(2)Through the characterization of energy spectrum analysis(EDS)mapping and SEM,the composition of the CNT/Ag flakes&SEBS flexible strain sensor and the dispersion of sensitive materials are determined.Strain characteristic test for sensors is performed based on the four components of CNT/Ag 2:1,CNT/Ag 4:1,CNT/Ag 1:0 and CNT/graphene 4:1,due to the conductive path of carbon nanotubes and silver nanosheets with the characteristics of sheet structure and small filling volume,and the results show that the sensor based on CNT/Ag 4:1has excellent sensing characteristics,realizing strain detection with a range of 540%and a GF of 5.197.The cyclic test results of the flexible sensor under the conditions of 50%,100%and150%strain at three rates of 3mm/s,5mm/s and 7mm/s show that the sensor has good repeatability and the resistance changes with the increase of strain.The rate increases accordingly,showing good rate adaptation characteristics and strain resistance dependence.The cycle test under 3600s time proved that the sensor maintains almost the same resistance change regulation,which exhibits good anti-fatigue characteristics.A ring-shaped strain sensor is prepared to realize real-time measurement of resistance changes in different application scenarios using this method,such as cross-section measurement,wrist bending measurement,sealing ring measurement,and balloon inflation.The experimental results show that the sensor has potential application value.