Research On Flexible Strain Sensor Based On Conductive Composites

Flexible wearable devices have attracted widespread attention due to their huge application potential in human health monitoring,telemedicine,artificial intelligence and other fields.Flexible strain sensors occupy an important position in flexible wearable devices.They have the characteristics of good flexibility,high sensitivity and comfortable fit with the skin,and can convert physical deformation into measurable signals such as resistance and capacitance.It can be designed to be attached to the target flexible object to accurately measure its deformation,monitor the surface tension of the human skin caused by joint movement,muscle vibration,and even emotional expression.It is generally considered to have broad application prospects in the fields of human motion monitoring,remote health diagnosis,motion control of industrial robots,and human-computer interaction.In recent years,researchers have done a lot of work on flexible strain sensors.However,most of the flexible strain sensors reported in these studies still have the problem that sensitivity and stretchability cannot be improved at the same time.Moreover,the development of flexible strain sensor is restricted by the complex fabrication process and high cost.This subject proposes two flexible strain sensors based on conductive composite materials to solve the above problems.The preparation technology,sensing mechanism,performance and potential applications of the two sensors are introduced respectively.The research content of this topic mainly includes the following parts:(1)Since toluene is similar with Ecoflex in solubility,the Ecoflex is immersed in toluene to swell it,and microstructures such as wrinkles and protrusions are formed on the surface,which increases the specific surface area and adsorption capacity of Ecoflex.As a result,more conductive carbon black is uniformly and stably adsorbed to the pleated Ecoflex surface,increasing the conductive path,and successfully preparing highly sensitive conductive carbon black/wrinkle Ecoflex composite flexible strain sensor without affecting the tensile properties.The mechanical and electrical characteristics of the strain sensor are studied.The sensor has a good strain detection range(0-500%)and a high sensitivity of up to 67.7.At the same time,it has extremely fast response performance(120 ms)and high stability(can withstand 5000 times of 150% strain cycle loading).At the same time,this paper studies the potential applications of the sensor to realize human motion monitoring(such as the bending motion of hand joints,pulse vibration before and after exercise,pronunciation,etc.),manipulator motion monitoring,and car collision simulation monitoring.At the same time,we successfully integrated the sensor with the big data cloud platform to monitor the human respiratory state remotely and in real time,which proved the application prospect of the flexible strain sensor in the wearable Io T.(2)The liquid Ecoflex and ethanol are mixed and solidified,utilizing the volatile characteristics of ethanol,the surface of Ecoflex is formed with regular wrinkles.Then Ecoflex is swelled and modified with petroleum ether solution to further form dense wrinkles and protrusions on the surface.The specific surface area and adsorption characteristics of Ecoflex were greatly increased.In addition,considering the superior electrical properties of graphene,graphene was selected as the conductive material to realize the preparation of an ultra-high sensitivity graphene/modified Ecoflex composite flexible strain sensor.The research results show that the sensor has a sensitivity of up to 1078.1,a wide strain detection range(650%),good durability(can withstand 1200 cycles of 300% strain loading)and fast response(140 ms).At the same time,the strain sensing mechanism of the sensor is analyzed and explained.In addition,the potential of the sensor is demonstrated,and it can be applied to human motion monitoring,gesture recognition and robot control.