Preparation And Application Of Wearable And Flexible Pressure Sensor Based On Electrospinning Nanofiber

Implantable flexible sensors and wearable smart portable devices have gradually been used in medical equipment,military security,artificial intelligence and other fields.Among them,the flexible pressure sensor can adapt to a variety of complex contact situations.The integration of such electronic devices on clothing,machinery,organisms,medical equipment and other substrates can realize real-time monitoring of limb movement,physical sign parameters,and environmental perception.Electrospinning,as a new technology for preparing nanofibers under the action of a high-voltage electrostatic field,uses the unique characteristics of nanofibers,such as high porosity,high specific surface area,low cost,good mechanical flexibility and strength,to prepare pressure sensors.Cast film sensors of the same material are more sensitive.The electroless plating metallization finish gives the nanofibers excellent conductivity while ensuring the characteristic structure of the fiber itself.At present,the traditional electroless plating process often uses Sn Cl₂and Pd Cl₂ to sensitize and activate the substrate.The process is cumbersome and often consumes a large amount of precious metals,which causes cost increase and environmental pollution problems.However,the modification treatment of dopamine may cause It destroys the physical properties of the membrane such as porosity,air permeability,and hand feeling,so it is a problem worth exploring to design a simple and low-polluting process to prepare conductive nanofiber electrodes.This topic uses polyacrylonitrile nanofiber nanofibers as a flexible substrate,and fully considers the chemical resistance and good thermal stability of polyacrylonitrile nanofibers;through the electroless metal plating process,the reduction of activated nanofiber membranes is further Realize the conductive metallization of materials,which can be used as the sensitive element of the sensor.First,take 0.17 mg of PdCl₂ and 100 ml of DMF to prepare a 1.7 ppm solution,and then take0.8 g of PAN powder and dissolve it in 10 ml of palladium solution to prepare a spinning solution.Add the spinning solution to the syringe,the spinning needle and The distance of the receiving plate is 15cm,the advancing speed is set to 0.65ml/h,a voltage of 18k V is applied,and the electrospinning time is 10h to obtain a nanofiber membrane.Then,electrospinning the palladium ion(Pd2+)/polyacrylonitrile(PAN)solution under high pressure to obtain activated polyacrylonitrile nanofibers,and then electroless silver plating to obtain composite nanofiber membrane electrodes.The formula of electroless silver plating:Dissolve 1.5g glucose and 60mg polyethylene glycol with3ml ethanol and 47ml deionized water to prepare 50ml reducing solution.Use 0.8g silver nitrate(AgNO₃)and deionized water to configure 8g/L AgNO₃ solution,add ammonia dropwise(about0.6ml),the clear solution becomes turbid until it becomes clear again to obtain silver ammonia solution,then add 1ml ethylene amine.The activated nanofiber membrane was placed in the A and B solution for 40 minutes to obtain the silver-plated nanofiber electrode,and then a series of test and characterization were carried out.The FESEM image showed that the obtained result was the correct conductive nanofiber film covering A coral-like silver layer with high porosity and good conductivity.The surface morphology was observed by scanning electron microscope(SEM),energy dispersive spectroscopy(EDS)was used to explore the content and distribution of surface elements,X-ray diffraction analysis(XRD)was used to test the nano-silver crystal structure,and thermogravimetric analysis(TGA)was used to The thermal stability of the membrane was tested,and the electronic binding state on the surface of the nanofiber membrane was measured by X-ray photoelectron spectroscopy(XPS).The above characterization test results fully prove the rationality and feasibility of the functional nanomaterial preparation.At the same time,the conductivity of the conductive nanofiber membrane measured by a four-point probe square resistance meter is0.825?/sq,which means that the prepared material has great application potential in the field of smart wearable textiles.The capacitive pressure sensor was prepared by assembling a pair of silver-plated nanofiber electrodes with porous nylon mesh and encapsulated by polyimide tape.Through the analysis of the signal curves of different pressures and capacitances,it was found that the sensor had 1.49 k Pa-1High sensitivity,fast response time of 48 ms,low hysteresis of 7.55%,stable performance and durability over 1000 times.In addition,the detection of human movement(finger movement,wrist joint,knee flexion movement,etc.)can also be realized by the wearable pressure sensor.At the same time,the mechanism of the sensor is explained through the simulation of finite element analysis.The method is simple,low cost,and low in metal pollution.It provides new ideas for microstructure design,improves the performance of capacitive pressure sensors,and indicates a broad prospect for industrial development.