Research On Performance Of Flexible Pressure Sensors Based On Graphene Films With Different Structures

With the increasing demand of intelligent wearable electronic devices and medical devices,the development of flexible pressure sensor devices is attracting much attention.The wearable pressure sensor can not only detect subtle pressure changes caused by physiological signals,but also be designed as a multifunctional medical detector.In recent years,how to improve the sensitivity,response time,recovery time and stability of pressure sensors is a hot research at home and abroad.In this paper,three different micro-structural sensitive layers are designed based on graphene films to improve the performance of pressure sensors.The specific research contents are as follows:（1）A sensitive layer of r GO film with honeycomb-structure was designed.The prepared pressure sensor has high sensitivity at room temperature（25℃）and low temperature（-196℃）.The honeycomb-structure of the film was controlled by hydrazine hydrate reduction and the sensitivity of the pressure sensor prepared which based on different thickness of the r GO film.The structure of the pressure sensor showed low temperature foldability and excellent performance.When the room temperature was 25℃,the sensitivity was 0.009k Pa^-1,the response time and recovery time were 16 ms and 22 ms,respectively.Beside,it showed good cyclic stability（>1200 times）.At ultra-low temperature-196℃,the sensitivity increased to 0.05 k Pa^-1,and the response time and recovery time were 13 ms and 25 ms,respectively.On this basis,the potential application of flexible wearable pressure sensor in healthcare and integrated devices is explored.（2）A sensitive layer of r GO thin film with synaptic structure was designed.The GO thin film with synaptic structure was prepared by template,the r GO thin film was prepared by thermal reduction method which was applied in sensor.The effect of different thermal reduction temperature on the sensitivity of the prepared pressure sensor was discussed.The results show that the optimum reduction temperature was 180℃.At this point,the sensitivity can reach 4.19 k Pa^-1,the response time and recovery time of the sensor were 52 ms and 62ms,respectively.Beside,it showed good cycle stability（>25000 times）.In addition,the pressure sensor can be used as a reliable health detection device to monitor the comprehensive physiological signals of the human body.Multiple sensors were composed of 3×3 array to realize mapping spatial pressure distribution.（3）A sensitive layer of r GO film with wave-structure was designed.The GO film with wavy-structure was prepared by stretching-scaling method,and the r GO film was prepared by HI acid reduction as the sensitive layer,and then assembled into a pressure sensor.The effect of different tensile ratios on the sensitivity of the pressure sensor was also discussed.The results showed that the sensitivity increased with the increased of the stretching ratio,and the sensor had the best performance when the stretching ratio was 180%.At this point,the sensitivity can reach 2.64 k Pa^-1.At the same time,the response time and recovery time of the sensor were 6 ms and 20 ms,respectively.Beside,it showed good cycle stability（>12000 s）.The structure of the pressure sensor can be used to detect physiological signals of the human body,and the 3×3 array sensor assembled on this basis realizes the mapping of spatial pressure distribution.