Design And Performance Study Of Self-repairing Flexible Strain Senso

With the rapid development of digital age and science and technology,compared with traditional bulky sensors,flexible strain sensors have more application prospects because of their high adaptability and stretchability,especially in the field of electronic skin.Direction recognition and self-healing function are two important features of human skin,and they are also the development direction of future electronic skin.On one hand,the direction recognition function is the basis for the application of flexible strain sensor in complex strain environments;on the other hand,the self-healing function can effectively solve the problems of the performance deterioration or even failure of flexible sensors caused by mechanical damage,thereby reducing maintenance costs and electronic waste.However,most of the flexible strain sensors used in electronic skin do not have multi-directional strain recognition and self-healing functions.In addition,the next generation of flexible sensors as electronic skin also need to meet the ’invisible’ and ’unsensible’ requirements,thus improving comfort and aesthetic when wearing,which require high transparency and flexibility.Based on the above requirements,this paper aims to develop a transparent flexible strain sensor with direction recognition and self-healing functions.Firstly,a transparent flexible strain sensor with direction recognition function was developed by using highly oriented antimony tin oxide(ATO)nanofibers and polydimethylsiloxane(PDMS).Then,the self-healing function of the flexible strain sensor was further developed by introducing self-healing transparent polyurethane instead of PDMS for encapsulating ATO nanofibers.The detailed research contents are as follows:The first part aims to prepare transparent flexible sensors with directional recognition function and excellent sensing performance.Firstly,highly oriented ATO nanofiber membrane was prepared by high-speed electrospinning and high-temperature calcination,and then PDMS was used to encapsulate it to obtain a monolayer flexible strain sensor.The sensor showed obvious anisotropy along the parallel and vertical nanofiber orientation directions,and the GF values were 250 and 1.2,respectively.Based on the anisotropic characteristic of monolayer ATO sensor,two ATO films were stacked orthogonally and encapsulation with PDMS to prepare a flexible directionaware strain sensor.According to the signals of the two ATO films,the magnitude and direction of the strain could be successfully calculated.These results show a great potential of the developed strain sensor in the fields of human motion monitoring,human-machine interaction and smart textiles.The second part aims to endow the flexible sensor with self-healing function and improve the service life of the flexible sensor and even the entire electronic device.Firstly,self-healing polyurethane was synthesized based on multiple hydrogen bonds,and then ATO nanofiber membrane was encapsulated by self-healing polyurethane instead of PDMS to prepare transparent flexible strain sensor with self-healing function.Compared with the flexible sensor in the previous chapter,the sensor not only inherited its excellent sensing performance and high transparency(80%),but also showed higher stretchability and working range.More importantly,the flexible sensor has excellent self-healing function.It could effectively restore the sensing performance and mechanical properties of the damaged sensor by being healed at room temperature,60 ℃ and 80 ℃.With the increase of the healing temperature,the self-healing efficiency has been significantly improved and the healing time decreased,e.g.,only10 min at 80 ℃.