Flexible Strain Sensors Based On Self-assembled Graphene Film

Strain sensor is a kind of sensor which can convert physical stimulation signals such as strain,pressure and torque into readable signals and output them.Generally,strain sensors are divided into rigid strain sensors and flexible strain sensors.The application of strain sensors on complex surfaces limits the development of rigid sensors.Flexible strain sensor is a kind of sensor made of flexible material,which has good flexibility,ductility,even free bending and folding.Carbon materials have many advantages,such as good flexibility,good conductivity,high stability,which can be easily designed into a variety of shapes and so on.However,the quality defects of graphene prepared by reduction method have been reported.The process of preparing graphene by chemical vapor deposition(CVD)is complex and the cost is high.These problems limit the development of graphene based flexible strain sensors.In order to overcome the shortcomings of the existing graphene based flexible strain sensors,a flexible strain sensor based on self-assembled graphene film and a flexible tattoo dry electrode were designed.The self-assembly graphene nano film was prepared by the marangeni effect,The flexible material polyimide(PI)is used as the substrate of the flexible tattoo strain sensor.A flexible tattoo strain sensor was fabricated by micromachined engraving and transfer printing technology.Finally,the performance of the flexible strain sensor is analyzed and tested.The test results show that the sensitivity of the strain sensor is 2.5% under 1% strain,which can withstand2000 fatigue tests,and can detect human pulse signal and respiratory signal.In addition,a novel graphene tattoo dry electrode was prepared by this process.The graphene dry electrode prepared by the same process has higher stability than the commercially available Ag/Ag Cl gel electrode(the detection ability is not attenuated within 24 hours).The dry electrode with graphene nano film has lower skin contact impedance,and the detection ability of human body electrocardiogram(ECG)is higher than that of Ag/Ag Cl gel electrode 55%.At the same time,it can be used for the accurate detection of EMG of different movements.