Research On Flexible Stretchable Strain Sensors Based On Ecoflex/AgNWs/MWCNTs

In recent years,flexible electronic devices have been widely concerned,among which flexible strain sensor has shown broad application prospects in wearable devices,flexible electronic skin,man-machine exchange,intelligent medical treatment,flexible display screen and other fields due to its wearable,high-performance,portable,comfortable and other characteristics,and has become a research hotspot.However,there are some problems to be solved in the flexible strain sensor based on nanomaterials and polymer flexible substrates,such as low sensitivity,small tensile range,poor stability and durability,etc.The results of this study show that after the multi-wall carbon nanotubes(MWCNTs)was doped with the silver nanowires(Ag NWs)with high length-diameter ratio,the flexible stretch-strain sensor prepared by combining multi-wall carbon nanotubes(MWCNTs)with the platinum-catalyzed silicone rubber(Ecoflex)can effectively improve the performance indicators of the sensor.In this study,the multi-wall carbon nanotubes doped with silver nanowires is used as conductive materials for the flexible sensor,and the platinum-catalyzed silicone rubber(Ecoflex)is used as the flexible substrate.Preparation methods of silver nanowires is the improved method of polyol,with Cu Cl₂as the control agent,the silver nanowires has uniform morphology,and high length-diameter ratio.Making flexible substrate cured at low temperature to form a film.By means of deposition,silver nanowires and multi-walled carbon nanotubes is uniformly deposited on the Ecoflex film to make a flexible conductive film and assembled into a simple flexible stretchable strain sensor.By changing the content of silver nanowires(0.05 mg/cm²,0.1 mg/cm²,0.15 mg/cm²,0.2 mg/cm²),the effect of silver nanowires on the performance of flexible strain sensor is investigated.Use flexible sensing test instruments to analyze the mechanical properties,sensitivity,linearity,hysteresis and stability of the sensor,and combine the flexible stretchable sensor with gloves to make a simple smart glove.The sensor is also tested when it is worn in the cervical spine,wrist,elbow and knee parts of the body.The characterization analysis of the silver nanowires prepared in the laboratory proved that the improved polyol method has successfully prepared the silver nanowires with uniform morphology,average diameter of 130±13 nm,length of 35±6?m and aspect ratio of 269.The addition of silver nanowires effectively improved the sensing performance of the flexible stretcher strain sensor,and the Ecoflex as the flexible substrate increased the stretching range of the flexible strain sensor,which is up to 70%in this study.When the content of silver nanowires is 0.15 mg/cm²,the elongation at break of the flexible stretchable strain sensor is 817%,and the sensitivity reaches 118.19,the linearity conforms to the quadratic fitting,and the linear correlation coefficient R² is close to 1.At the same time,the flexible stretchable strain sensor showed good stability in 1000 tensile cycle tests.After the flexible stretchable strain sensor is worn on the moving part of the human body for monitoring,the sensor can convert the movement signal of each part into an electric signal,and then identify the movement state of each part according to the electric signal curve,therefore,flexible stretchable strain sensors have good application prospects in human health monitoring,rehabilitation training,motion monitoring and human-computer interaction.