Preparation And Performance Research Of Superhydrophobic Flexible Strain Sensor With Microcrack Structure

Due to the lightweight,easy to process,good mechanical properties and chemical stability of conductive polymer nanocomposites based flexible strain sensors,they have been widely used in wearable electronic devices,intelligent robots,human-computer interaction,and many other fields.At the same time,the rapid development of various electronic devices also put forward higher requirements for the sensitivity and recognition accuracy of flexible sensors.Besides,the human sweat and domestic sewage that affect the stability of the sensor during use are still key problems needed to be solved.To this end,this dissertation improves the sensitivity of the sensor by structurally designing the conductive active layer,constructing a conductive network with microcrack structure,and then modifing it with micro-nano structure and low surface energy superhydrophobic coating.As a result,a high-performance flexible strain sensor with superhydrophobic properties was developed.The main research resuklts are as follows:（1）Ordinary printing paper was coated with conductive Ti3C2Tx MXene through the dip-coating process,and then paraffin soot particles with micro-nano structure and low surface energy were uniformly deposited on its surface to construct the superhydrophobic paper-based strain sensor.Based on the difference of elastic modulus and thermal expansion coefficient between Ti₃C₂T_x MXene conductive coating and paper,ultra-sensitive microcrack structure in conductive coating was successfully constructed by heat treatment.When the paper-based sensor is deformed under external force,the expansion and closure of the microcracks in the conductive layer cause a significant change in the overall resistance,thus endowing the sensor with excellent strain sensing capability.As a result,the prepared paper-based strain sensor achieves high sensitivity（gauge factor,GF=17.4）within 0-0.6%bending strain,extremely low detection limit（0.1%strain）,brillent fatigue resistance and stability over1000 bending cycles.Besides,the paraffin soot coating endows the sensor with excellent water resistance（water contact angle,WCA=157°）,chemical resistance,and good self-cleaning ability to common stains in life.As a result,the sensor can effectivly monitor various severe and weak human movements even in water environment.Finally,it can also be applied for electronic skin,showing broad application prospects in the field of wearable electronic devices.（2）Carbon nanotubes（CNTs）/reduced graphene oxide（r GO）synergistic double conductive layer was constructed on the surface of rubber band（RB）by swelling ultrasonic and dip coating processes,and then hydrophobic fumed silica（Hf-Si O₂）particles were ultrasonically loaded on the surface to prepare a superhydrophobic RB based sensor with high sensitivity and wide response range.The stability of the first conductive network formed by CNTs in a wide strain range endods the sensor with a wide strain working range.The highly sensitive microcrack structures produced in r GO synergies conductive layer during the tensile process,endowing the sensor with high strain sensitivity in the whole range（ε=0-482%,the GF is 685.3）.The sensor can real-time effectively monitor severe human activities such as arm swing and running,and extremely weak physiological signals such as heartbeat and vocal cord vibration,showing great application prospects in the field of human health monitoring.In addition,the Hf-Si O₂ superhydrophobic coating endow the sensor with excellent waterproofness（WCA=156°）and chemical corrosion resistance,ensuring its stable sensing response in harsh outdoor environments.The electronic fabric based on conductive RB can accurately sense and distinguish the position and size of external stress stimulation,showing a certain application potential in the field of tactile sensing...