The Study On Preparation And Performance Of High Sensitive Flexible Pressure Sensor

In this thesis,two highly sensitive and flexible pressure sensors were successfully prepared.For the first time,regenerated silk fibroin/polyurethane composite material was used as the substrate for a highly biocompatible pressure sensor,which improved the test comfort while supporting and protecting the sensor.The preparation and performance of two different optimization methods(surface structuring and material functionalization)were studied.The main research contents and conclusions are as follows:1.This thesis obtains sandwich-structured multi-walled carbon nanotubes/styrene-ethylene-butylene-styrene(MWCNTs/SEBS)by simulating the irregular protrusion microstructured MWCNTs/SEBS pressure sensitive layer on the human skin surface as the core,the composite membrane of regenerated silk fibroin and polyurethane protein as the substrate,and the magnetron sputtering silver electrode.Pressure sensor,its sensitivity reaches 0.156 kPa-1,the minimum can detect a pressure of 0.01 N,the pressure response time is 500 ms,after 1700 pressure cycles at a pressure of 0.01 N,the relative resistance change is reduced from 10%to 8%;Applied to wearable devices,it can detect the degree of bending of the finger and the pulse wave signal at the radial artery.The array sensor is used to simulate the pulse of traditional Chinese medicine,and the pulse wave signals at different positions of the radial artery are obtained.2.Three different fillers of perovskite structure barium titanate(BaTiO3),activated carbon(C),and multi-walled carbon nanotubes(MWCNTs)improve the dielectric properties of Polydimethylsiloxane(PDMS)polymer-based composites due to their own structure and physics There are obvious gaps in nature.When the content of BaTiO3 is as high as 40%,the dielectric constant of the composite is only 157%higher than that of pure PDMS.When the activated carbon with a spherical structure is added to PDMS,the dielectric constant of the composite is not obvious when the amount is less than 5%The multi-walled carbon nanotubes have a high aspect ratio.When the carbon tube content is 3%,the dielectric constant of the composite material is as high as 64.24,which is 2020.12%more than that of pure PDMS.This shows that multiwalled carbon nanotubes(MWCNTs)can achieve a higher dielectric constant increase with a smaller amount of addition,which is an ideal high-dielectric composite filler.3.Based on the results of the research and discussion in Chapter 3,a dielectricregulated dielectric voltage-sensitive layer is designed from the perspective of materials,and MWCNTs/PDMS composite films can be prepared on a large area and at low cost by using a simple grinding process.The experimental analysis obtained the 3%MWCNTs/PDMS dielectric layer with the highest pressure sensitivity,which is used to prepare a high-sensitivity tactile pressure sensor with a sensitivity of 3.801 kPa-1,a pressure response time of only 200 ms,and a minimum of one can be detected.The weight of ants(0.66 mg)can withstand more than 20,000 cycles of testing.Such a highsensitivity sensor can be used to detect breathing,vocalization signals at the throat,and pulse beat signals at the radial artery,which is of great significance for the detection of human health in the biomedical field.4.Comparing two flexible pressure sensors with different optimization methods(surface structuring and material functionalization),the pressure sensitivity of the sensor through the functional design of the material reaches 3.801 kPa-1,and the smallest can measure the weight of an ant(0.66 Pa),The response time is shorter,and the processing and preparation steps are greatly reduced,so that a low-cost flexible pressure sensor can be prepared in a large area to meet the use of different functions.The flat surface structure enables the sensor to withstand more than 20,000 cycles of testing,which is the cyclic stability capability that a surface-structured sensor cannot achieve.