Research On Capacitive Flexible Pressure Sensor Based On AgNMs Electrode

With the development of flexible electronic equipment,people's demand for high-performance flexible tactile sensors is very urgent.Flexible tactile sensors are developing in the direction of high sensitivity,wide detection range and array.For capacitive flexible pressure sensors,in order to improve the sensitivity and detection range of the sensor,at the present stage,more methods are used to increase the surface area of the electrode material and the roughness of the dielectric layer.For the manufacture of sensors with simple methods,high success rate and high consistency,further exploration is needed.While improving the sensitivity of the sensors,the development of sensor arrays with high consistency is realized.In this thesis,with the goal of improving the sensitivity of the sensor and widening its detection range,two capacitive flexible pressure sensors based on silver nanomaterials(Ag NMs)were designed and prepared,and their performance was tested.The specific results are as follows:(1)In order to improve the stability of the combination of sensitive materials and substrates,a flexible electrode was prepared with silver nanowires(Ag NWs)adsorbed on filter paper with microstructure,and the paper-based electrodes were characterized by scanning electron microscope(SEM).The results show that Ag NWs and the substrate are evenly and tightly bonded.A grid-shaped PDMS dielectric layer with a spacing of 2 mm was prepared by 3D printing technology,and the dielectric layer has higher force-sensitive characteristics and roughness.Then the paper-based capacitive pressure sensor is prepared by combining the above electrode and dielectric layer.(2)The performance test of the paper-based capacitive pressure sensor based on Ag NWs shows that the detection range of the sensor is 0-45000 Pa,the detection limit is less than 300 Pa,the response time is less than 50 ms,and the sensitivity reaches 0.048 k Pa^-1in the pressure range less than 3950 Pa.In addition,the sensor shows good repeatability in repeated load/unload pressure cycle tests.The sensor is used as a sensitive unit to prepare a sensor array,and the array is used to realize the shape and pressure sensing of different objects.(3)In order to further increase the high-sensitivity pressure detection range,silver-coated carbon nanotubes(Ag@CNTs)with high specific surface area are used as electrode materials,and PE tape with a microporous structure is used as a template to prepared a micro-structured Ag@CNTs electrode with high elasticity.Then based on PDMS and air layer as dielectric layers,a flexible capacitive pressure sensor based on Ag@CNTs-PDMS microstructure was developed.The SEM characterization results of the microstructured Ag@CNTs electrode show that the electrode material is tightly bound to PDMS,and the electrode surface has a complete PE tape inverted mold microstructure.(4)The performance test of the micro-structured flexible capacitive pressure sensor based on Ag@CNTs-PDMS is carried out.The results show that the sensitivity of the sensor in the range of less than 15601 Pa is approximately 0.0486 k Pa^-1,the minimum detection limit is less than 300 Pa,and the response time is less than 50 ms;And the sensor has stable performance in repeated load/unload pressure cycle tests.Further use of the highly sensitive,wide detection range of flexible pressure sensor for application testing,the results show that the sensor can be used for voice action recognition and pulse test,these functions have laid the foundation for the development of electronic skin and wearable electronic devices.