Research On Flexible And Stretchable Strain Sensors Based On Silver Nanowires And Multi-walled Carbon Nanotubes

Flexible conductive thin films prepared by high aspect ratio silver nanowires and multi-walled carbon nanotubes combined with flexible substrate PDMS show good application prospects in the field of flexible wearable sensors.Flexible tensile strain sensors are one of the most important components of wearable electronic sensors.They are widely used in health monitoring systems due to their good mechanical properties,sensitivity,linearity,hysteresis and stability.The silver nanowires with uniform morphology and high aspect ratio were prepared by modified polyol method and copper chloride as nucleation control agent.The nanowires were characterized by SEM,EDS,XRD and ultraviolet-visible.Subsequently,using self-made silver nanowires and multi-walled carbon nanotubes as conductive materials and PDMS as flexible substrates,silver nanowires and multi-walled carbon nanotubes were uniformly deposited on PDMS to form flexible conductive films,and a simple flexible stretchable strain sensor was assembled.By changing the concentration of silver nanowires(Omg/cm2,0.025/cm2,0.05mg/cm2,0.1 mg/cm2,0.2 mg/cm2,0.3 mg/cm2),to discuss the effect of the addition of silver nanowires on the performance of a flexible tensile strain sensor.The strain resistance,mechanical properties,sensitivity,linearity,hysteresis and stability of the sensor are analyzed by digital multimeter and universal testing machine.The flexible stretchable strain sensor is installed in the throat,finger,wrist,elbow and knee of human body to test.Through characterization and analysis of silver nanowires,it is proved that silver nanowires with uniform morphology and high aspect ratio are successfully prepared by improved polyol method.The silver nanowires have an average diameter of 130±10 nm,a length of 37±5 μm,and a length to diameter ratio of 284.The addition of silver nanowires improves the sensing performance of flexible tensile strain sensors.With the addition of different silver nanowire content,the initial resistance of flexible tensible strain sensor decreases from 1008 ohms to 96 ohms.When the concentration of silver nanowires is 0.2 mg/cm2,the elongation at break of flexible tensible strain sensor reaches 197.2%.When the concentration of silver nanowires is 0.3mg/cm2,the flexible tensible strain sensor has good sensitivity,and the maximum sensitivity can reach 110.7.The linearity of the flexible tensile strain sensor is greatly improved,and the maximum nonlinear error is 3.54%.The hysteresis error of the flexible tensile strain sensor is decreasing,and the minimum hysteresis error is 5.18%.At the same time,the flexible tensile strain sensor has good stability during 1000 stretching cycle tests.The flexible stretchable strain sensor is installed in the moving part of the human body for monitoring,and the sensor can convert the motion signal of each part into an electric signal curve,and can recognize the moving part of the human body and the moving state of the moving part according to the electric signal curve.Therefore,the flexible tensile strain sensor has a good application prospect in human health monitoring,motion monitoring,rehabilitation entertainment and human-computer interaction.