Micro-nano Structure For The Property Modulation Of The Capacitive Pressure Sensor

With the development of the information society and internet of things,the demand for variety and depth of collecting information steadily increased.Flexible pressure sensors have been applied in more and more information collecting fields.The consumption of flexible pressure sensors cannot be overlooked.It was applied in e-skin,wearable device,human-machine interface,robots and mobile health and so on.Although many exciting progress has been achieved in the field of flexible pressure sensor,this field is still immature.In this thesis,we conducted a deep research in these aspects of micro-nanostructure design,mechanical model analysis and fabrication technology in flexible pressure sensors.At present,the mechanical model analysis of flexible capacitive pressure sensor is infrequent.We used the numerical analysis software(MATLAB)to calculate the effect of parameter in the microstructure of dielectric layer on sensitivity.In addition,the research about the effects of the microstructure of electrodes on sensitivity was infrequent.Through simulated analysis based on the simulation software(COMSOL),we conducted a research on the reason why the microstructure of electrode is good for sensitivity of pressure sensor,respectively in electricity and mechanism.We found the law about microstructure design and gave some guides for the design of capacitive pressure sensor.We fabricated a few kinds of electrodes with different structure to verify correctness of our simulation and we fabricated a kind of highly sensitive flexible pressure sensor with the help of our simulation.The sensitivity of our devices were 2.3 kPa'1,which was better than most of capacitive pressure sensors.and the response time of our devices is very fast(23 ms),which is better than most of capacitive pressure sensors.The flexibility of our device is proved to be very excellent by bending test.This characteristic is suitable for working environment of e-skin and wearable devices.In addition,we conducted some experiments about collecting biological signal based on the high sensitivity of our device,such as pulse extraction and insect crawling monitoring.These experiments indicate that flexible pressure sensor has a huge potential in the field of collecting biological signal.In addition,we fabricated a few kinds of dielectric layer with different spacing structure according to our simulation and assemble those dielectric layer into pressure sensor.We verified the correctness of our simulation by mechanical test for our device and it indicated that our numerical analysis had a guide function for subsequent device design.We compare flexibility of graphene and indium tin oxide(ITO)electrodes by bending test and prove that graphene had a better flexibility.