Preparation And Application Of Flexible Pressure Sensor Based On Micro-array Electrode And Composite Dielectric Layer

Flexible pressure sensor has been extensively researched in the fields of wearable electronics,health care and smart terminals,including rapidly evolving technology areas such as artificial intelligence?AI?and Internet of Things?IoT?technology.So the flexible pressure sensor,as an important sensing element among various electronic devices,is of more and more interests,as revealed by recently research.For the above technology to play a better role in human life,there are strict requirements for the preparation of flexible pressure sensors with low-cost manufacture and over-all properties.Researchers around the world have carried out many pioneering works on the improvement of the sensitivity of capacitive pressure sensors from the following aspects,including structural optimization of the electrodes and dielectric layers.The reason is that the deformation of the micro-array structure electrode and dielectric layer increase under the same pressure conditions,which will result in an increase in sensitivity.However,the conventional method for preparing microstructures includes chemical etching,photolithography,etc.,the process is complicated and the cost is high,which is not conducive to large-scale production.In this thesis,a simple technological process is proposed to prepare the micro-array structure template,and then a flexible electrode with micro-array structure is obtained by transferring method.The flexible microstructure electrode is used as the response sensitive layer for the sensor,A type of resistive and capacitive flexible pressure sensor were separately prepared.In addition,the deformation process of the micro-array structure is simulated by finite element method.We also regulate the sensitivity of the sensor by adjusting the dielectric constant of the capacitive flexible pressure sensor dielectric layer.The main research contents of this paper are as follows:?1?Preparation and characterization of a resistive flexible pressure sensor based on a micro-array electrode.In this experiment,firstly,a PDMS plate electrode with silver nanowires?AgNWs?attached by suction filtration was prepared,and adjust the electrical conductivity of the plate electrode by changing the amount of AgNWs added to the suction filter device to.Secondly,a plasma etching process is used to prepare the micro-array structure electrode,and the pre-stretched PDMS substrate is treated by plasma etching at a low pressure,and when the pre-stretched PDMS substrate returns to its original length,the micro-array structure will form on the surface of PDMS substrate.And it will use as a template in the next step,then the template is spin-coated with AgNWs and filled with liquid PDMS,and the micro-array flexible PDMS electrode embedded with AgNWs is obtained by transferring process.Finally,the PDMS plate electrode is superimposed on the micro-array flexible PDMS electrode to prepare a resistive flexible pressure sensor.By investigating the performance of the sensor,we found that the prepared resistive flexible pressure sensor has a high sensitivity of up to 2.1 kPa^-1 at low pressure and the response time less than 100 ms.In addition,the effect of AgNWs size on micro-array flexible PDMS electrodes was also explored.?2?Preparation and application of flexible pressure sensor based on composite dielectric layer.The micro-array structure of the flexible capacitive pressure sensor is still obtained by the aforementioned method.The difference is that the conductive layer of the electrode in this experiment is prepared by a magnetron sputtering method to obtain a more uniform gold layer.The substrate of the dielectric layer is made of polyvinylidene fluoride?PVDF?,and the Barium titanate?BT?nanoparticles are added to PVDF as high dielectric constant fillers to adjust the dielectric constant of the dielectric layer,to achieve the purpose of adjusting the performance of the sensor.The dielectric layer is prepared by spin coating onto the plate electrode and then superposed on the micro-array structure electrode to produce a capacitive flexible pressure sensor.Subsequently,we conducted a comprehensive test on the comprehensive performance and application of the sensor.The results show that the flexible pressure sensor has an excellent performance.The sensitivity is up to 4.09 kPa^-1 at low pressure?0-2500 Pa?,and low detection limit?<1.5 Pa?,fast response time?<50 ms?,high pressure cycling stability?>5000 times?and high bending stability?>1000 times?.In addition,the flexible pressure sensor can also be used to monitor water droplet movement and human behavior.Finally,the microstructure deformation process is described by finite element analysis,and the mechanism of microstructure improvement sensor performance is explored.