Research On Preparation And Application Of Ionic Flexible Strain Sensor Based On MXene Composite Structure

Flexible strain sensors are characterized by light weight,bendable,attachable,curved surface compatibility,etc.,which can be applied to flexible wearable devices and play an important role in the fields of human movement,medical health,and human-machine interaction.Ionic strain sensor is one important type of flexible strain sensors.Under the action of external stress,the internal ions of the sensor move in a directional direction,resulting in potential difference between the electrodes,realizing the force electric energy conversion,so it can sense the strain.At the same time,the ionic strain sensor also has the ability to identify different strain directions and self powered characteristic,so it has attracted much attention.However,limited by the performance of electrode materials and the interface between the electrodes materials and the polyelectrolyte layer,the sensitivity and stability of the ionic sensors studied at present have some shortcomings,which limits the further development of the sensor in the wearable soft sensing application field.Therefore,it has important significance and application value for the further development of ionic sensors.In this project,we used two-dimensional transition metal carbides(MXene)and carbon nanotubes(CNTs)composite structure as electrode material,TPU / ionic liquid composite as polyelectrolyte layer,through high-temperature hot pressing method to prepare highperformance three-layer structure ionic sensor,and further fabricated wearable flexible sensor by packaging.The main research contents are as follows:(1)MXene electrode material is mixed with CNTs to improve the electrical and mechanical properties of the electrode;TPU and ionic liquid are used as polyelectrolyte materials;The MXene/CNT ionic sensor with three-layer structure was prepared by hightemperature hot pressing method;the micro-morphology of the sensor was characterized and its performance was tested.(2)A mechanical sensing test platform was built to test the force-electric sensing performance of the ionic sensor.The test results show that the sensor has high sensitivity(4.78 m V/1% strain),long-term cycle stability(6000 s),fast response(less than 100 ms),and good strain direction recognition.(3)A wearable mechanical sensor was fabricated by simply encapsulating the ionic sensor with polymer.The sensor can be attached to the human body and sense the multiscale activities of the human body in real time.It can not only recognize the large-scale joint bending deformation with different amplitude and direction,but also detect the weak pulse signal of the human body.(4)Finally,we designed a data acquisition control system,and realized the application of controlling LED lights,mechanical claws and artificial muscle intelligent drivers by using ionic sensors.The research results show that the MXene/CNT ionic sensor prepared by us has excellent self-sensing characteristics and recognition of deformation direction,which can be used as a wearable device with very broad application potential in human motion,medical health,flexible control,human-computer interaction,and intelligent prosthesis and so on.