Design,Performances And Applications Of Flexible Strain Sensor Based On The CNTs/Ecoflex

In recent years,the flexible electronic devices,especially the stretchable and flexible strain sensors,have attracted wide attentions for their potential applications in wearable devices and implantable biomedical devices.When the force are loaded the flexible strain sensors,which leads to the change of electrical properties as a sensing function of the applied strain due to deformation of sensor.The flexible strain sensors can be classified into resistive-type and capacitive-type sensors depending on the strain-responsive mechanism.Compared with capacitive-type strain sensors,resistive-type strain sensors have the advantages of relatively simple structure and low requirement on working environment,wide strain-measurement range so that the sensors are widely researched,which Resistive-type strain sensors are typically composed of conductive material coupled with flexible polymer.In this article,the flexible Ecoflex is used as the substrate,and carbon nanotubes(CNTs)with excellent mechanical and electrical properties are used as the conductive material to acquire the preparation of CNTs/Ecoflex flexible strain sensor and CNTs mesh/Ecoflex flexible strain sensor,which are synthesized by transfer printing of CNTs.And the sensing performance and applications of flexible strain sensors are researched.The main research contens and details are shown as follows:(1)Preparations and investigations of properties of CNTs/Ecoflex flexible strain sensorCNTs/Ecoflex flexible strain sensor was successfully synthesized by transfer printing method,which exhibited high stretchability.The samples prepared with different CNTs layers showed high responses to stretchable and bending strain,among which the device with 20-layer CNTs had the highest response and sensitivity(up to 23.09),but the response equilibrium time was long.The sensor can detect the movement of finger bending and pulse signals in real time,and the CNTs/Ecoflex can be used as a flexible electrode.The results show that the composite device can be used as a wearable sensor,as well as an electrode of a wearable device,showing broad applications in the field of portable medical devices and detection of motion.(2)Preparations and investigations of properties CNTs mesh/Ecoflex flexible strain sensorCNTs were sprayed on the mesh of different specifications.CNTs mesh/Ecoflex flexible strain sensors were successfully synthesized by transferring CNTs from mesh to Ecoflex flexible film.The influence of these synthetic parameters on performances of device was studied.The response and sensitivity of the device made by mesh size of 75,and 25 layers CNTs(~10 μm in length)were the highest,with the highest sensitivity of 4.20.The response speed of the sensor with mesh structure of CNTs was significantly improved,and the response time of the device with 20-layer CNTs was 0.27 s.The CNTs mesh/Ecoflex flexible strain sensors can realize the detection of finger movement as well as the recognition of motion amplitude,the real-time detection of pulse,which have potential applications in the fields of wearable medical devices and electronic skin.The CNTs mesh/Ecoflex flexible strain sensors have clear signals for different facial expressions and can distinguish a variety of facial expressions,which are of application value in human-computer interaction and facial expression recognition.In addition,the sensors can detect different sound vibration and distinguish different pronunciations of words,which have a good application prospect in the fields of artificial intercom and artificial intelligence.