Research On The Preparation Of Fabric Based Conductive Composite Materials And Their Application In Wearable Sensors

In recent years,the application of sensors in medical monitoring,intelligent robots,prosthesis implantation and other aspects has attracted the attention of academic circles.Although the research related to sensors has achieved good development.But at present,the balance between the sensitivity,durability and response performance of sensor has not been well solved.In addition,as the external deformation of the acceptor and conductive material carrier,the choice of sensing substrate also has many problems.As a wearable comfort material for human body,textiles can withstand a variety of complex deformation,such as stretching,twisting,bending and tearing.In addition,textiles are also characterized by high softness,strong skin-friendliness,breathability,warmth and non-toxic and harmless.Therefore,textiles are excellent choice for wearable flexible sensors substrate.Firstly,the pressure sensor is fabricated with cotton fabric as the substrate by printing.The surface of one cotton fabric is printed with polyaniline(PANI)paint,and the surface of the other cotton fabric is printed with PANI paint and nano silver(AgNPs)paint.Then,the conductive parts of the two cotton fabrics are combined in a face-to-face manner,the aluminum foil fixed with silver paste is used as the electrodes at both ends of the fabric,and the transparent 3M tape is used for packaging and fixing.The prepared cotton-based sensor not only exhibits high tensile performance,but also can undergo deformation such as folding,stretching,and bending.Tests show that the cotton-based sensor can achieve excellent sensitivity of about 0.04-0.10 kPa^-1,and can sense slight pressure in the range of 0-20 k Pa.In addition,the sensor also has good stability and anti-fatigue performance,and can keep stable during 500 cycles of testing without significant attenuation of the electrical signal.The material is loaded and unloaded to produce a deformation response to external pressure,the response time is 0.4 s and the recovery time is 0.41 s,indicating that the material has good response performance and can quickly respond to external deformation,which further confirms the sensitivity of the sensor.A series of application tests prove that the cotton-based sensor has performance such as motion tracking and voice recognition.Then the strain sensor is prepared by electroless plating on cotton and spandex blended fabric.First,the polymerization reaction of aniline is carried on the surface of the fabric,and then the redox reaction between PANI and silver nitrate(AgNO₃)is used to promote the deposition of silver on the surface of the fabric.A small amount of silver on the surface of the fabric acts as an activation site to initiate subsequent electroless plating.Tests such as scanning electron microscope(SEM)and thermogravimetric analysis(TGA)are conducted to confirmed the presence of silver on the surface of the fabric.The tensile performance test proved that the fabric still maintained good mechanical properties after electroless plating.At the same time,it is found that the sensor had good mechanical properties.The flexibility of the product can be deformed by folding,bending and twisting.Through further testing,it is found that the sensitivity of the material can be as high as 26.11 k Pa^-1,and the cycle test of about 160 s can be realized at the same time,and the electrical signal will not be significantly attenuated,which proves that the sensor has strong stability and fatigue resistance performance.The response performance and recovery performance of the material are good,the response time is 0.04 s and recovery time is 0.08 s respectively,which further confirms the sensitivity of the sensor.At the same time,the conductivity of the fabric does not change significantly after multiple washings and tape tests,which confirms that silver deposits on the surface of the fabric has good fastness.The application test shows that the silver-plated fabric has a good sensing effect on macroscopic large deformations and small movements of the outside world.In addition,the material has excellent sterilization effects on Escherichia coli and Staphylococcus aureus.Due to the high conductivity of the material,it has a good Joule heating effect and can be used as a wearable heater,effectively expand the application of flexible wearable sensor.