Preparation And Performance Of Flexible High-Temperature Resistant Fiber Membrane-Based Piezoresistive Sensor

Lightweight,flexible pressure sensors working under high temperatures have intrigued great research interest owing to their potential in firefighting,aerospace technology,automotive,and petroleum industries.However,most pressure sensors currently in use are made of polymers,carbon materials,and other components that cannot withstand high temperatures,which limits their functionality in hightemperature environments.Here,a strategy is proposed in this study to tackle the problem of unstable operation of sensors at high temperatures.In Chapter 1,through our research,we discovered that an orthogonal ordered fiber network structure can further enhance the performance of nanofiber membrane-based resistive pressure sensors,improving their sensitivity and accuracy.We employed various orientation fiber electrospinning methods for fiber fabrication.After examining possible methods for improving the sensitivity and accuracy of fiber sensors,it was discovered that oriented fiber network structures could enhance the performance of piezoresistive sensors within nanofiber membrane structures.To achieve this,various fiber orientation electrospinning techniques were used to acquire the oriented fibers.The reduction treatment of the nanofiber membrane promotes the in-situ reduction of AgNO3 into Ag seeds,which further grow as Ag nanoparticles in the following wetchemical treatment.Then a protective silica layer is fabricated on the Ag nanoparticles,which effectively prevents the nanoparticle’s migration and fusion;we propose that metal-support interaction(MSI)may help to form the silica coatings on the Ag nanoparticles.As formed,Ag nanoparticles with a SiO2 coating layer are sinter-resistant and show much higher thermal stability than bare Ag nanoparticles on the nanofibers.In Chapter 2,we compared fiber membranes with different aluminum-silicon mole ratios and experimented with various orientation fiber spinning methods.Eventually,we selected a flexible and stable amorphous SiO2 fiber membrane as the substrate for our sensors.Additionally,we chose Ag as the metal resistive sensing layer due to its stable properties at high temperatures.Through a multi-step chemical reduction process,we uniformly deposited an Ag metal layer onto the SiO2 fiber membrane.Finally,we coated the surface of the Ag metal layer with a protective SiO2 layer by immersing the sample in a TEOS hydrolysis solution,creating the SC-Ag/SiO2 SNF sample.To demonstrate the stability of the SC-Ag/SiO2 SNF sample at high temperatures,we compared it with an Ag/SiO2 SNF sample without the SiO2 protective layer using insitu high-temperature XRD,XPS,and thermogravimetric analysis.We found that the SiO2 protective layer effectively shielded the Ag metal nanoparticle layer on the SCAg/SiO2 SNF sample from the influence of high temperatures,preventing the migration,fusion,and subsequent oxidation of the metal nanoparticles.This lays a foundation for its sensing applications at high temperatures.In Chapter 3,we assembled the SC-Ag/SiO2 SNF sensor device and conducted stability tests using a programmable and computer-controlled cyclic stability testing platform.Data acquisition was performed using a multimeter and a multi-channel data acquisition card.We successfully demonstrated the excellent operational stability of the SC-Ag/SiO2 SNF sensor device.The sensor was capable of stable operation under heating at 350℃,and even after annealing at 600℃ for 2 hours,the SNF maintained its performance as a pressure sensor.The high flexibility,high temperature-resistant,and robust SNF may provide a platform for unconventional pressure sensor construction.And the strategies used in this study may bring insights into both the design and the application of these sinterresistant nanostructures.