Study Of Strain Sensors Based On Wrinkled Microstructure

Flexible strain sensors have received a lot of attention in health care and other fields because of their many features such as good flexibility,high sensitivity and good wearable characteristics.However,the trade-off between sensitivity and flexibility of the sensors still faces a relatively large challenge.In order to make strain sensors with both wide strain range and high sensitivity characteristics,we combine the high tensile property of wrinkled structures and the high sensitivity of microcrack strain sensors,and propose two methods to construct wrinkled microstructure strain sensors,and investigate the sensing characteristics and working mechanism of the sensors,and finally test the sensors in practical application scenarios.The research of this thesis contains the following two main parts:(1)Design and preparation of a wrinkled microstructure strain sensorWe prepared the wrinkled microstructure using the compressive stress of the thermal expansion method.In this chapter,strain sensors with wrinkled microstructures were prepared using the thermal expansion method and transfer printing technique.The morphological,mechanical and electrical properties of the sensors were tested and investigated,and the experimental results showed that the response range of the sensors can be effectively improved and the high sensitivity can be maintained by introducing the wrinkled microstructures into the strain sensing system.The strain sensor with wrinkled microstructure has excellent properties such as isotropic stretchability,ultra-high sensitivity(GF=6 657)and wide working range(75%).Based on these excellent properties,the sensor can be applied to application scenarios such as human physiological signal monitoring(including cough,finger flexion and pulse)and speech recognition.(2)Design and preparation of nested wrinkled microstructure strain sensorsBased on the strategy of preparing single wrinkled microstructure strain sensors in the previous section,this section adopts a combination of template method and thermal expansion method to prepare nested wrinkled microstructure strain sensors.The morphological,mechanical,and electrical properties of the sensor were tested,and the experimental results showed that the nested wrinkled microstructures were also effective in improving the sensor performance,with 65% of the response range,up to 7 805.9 sensitivity,and 1 000 tensile-release cycles of the nested wrinkled microstructures.The nested wrinkled microstructure pressure sensors prepared based on such different scales of wrinkled microstructures also exhibit ultra-high sensitivity and mechanical cycling stability.Finally,we characterized the nested wrinkled microstructure sensors for applications such as facial expression recognition,human pulse monitoring,and speech recognition.