Structural Design And Performance Study Of Smart Clothing Flexible Sensor

Clothing is essential in life.Costume is asked not only to cover the body and keep human warm but also to be more functional,personalized and intelligent.Wearable smart clothing refers to the clothing and accessories which have the built-in electronic detection system and can be achieved in the use of human physiological signal detection in the daily life.Clothing as a "second skin" close to the human body,with light and comfortable,portable,large coverage and other advantages,is the best medium to obtain the human body signal.The knitted garments,because of its special structure,showing soft,comfortable,flexible elastic and convenient to line conducting sensing material,so often used to study the carrier intelligent flexible sensor,can detect the user’s body temperature,heartbeat,respiration and other physiological parameters of human body,but also can realize the monitoring of muscle activity and the motion state of human body.Worldwide there have been many research institutions in the study of smart clothing,but in order to realize the intelligent garment industry there are still many problems to be solved,such as knitted flexible sensor sensitivity and stability,durability and large scale production,and the effects of different braiding structure,knitted coil,wearing pressure,washing conditions and other factors on the physiological parameters detection is also no systematic theoretical research.This topic starts from the study of conductive material about the structure and properties.Choosing the appropriate structural conductive yarn fabric embedded in seamless knitted products,and then focus on the research of conductive properties of knitted fabric from raw material,structure,size and other factors.Analyzing the stability of conductive fabric after washing.With the fabric resistance as the characteristic value,the design and preparation technology of the flexible sensor were analyzed and optimized by the orthogonal test.The specific research contents are as follows:1、Analysis of seven kinds of conductive fiber micro-structure and conductive principle,testing of the mechanical properties and electrical conductivity of the conductive fibers,and selecting the suitable conductive yarn materials.2、Select silver plated fiber and carbon fiber as conductive plaiting,knit the flexible sensor sample on theseamless underwear machine.Conductive fabric structure for 1+1,2+2,2+1 three kinds of mock rib,design dimensions 10,20,30 rows of longitudinal,40,60,80 rows of transversal.3、Design a method for the determination of equivalent resistance of fabric,test respectively equivalent resistance of conductive fabric in natural state and under tension,analysis the effects of raw materials,yarn structure,fabric size and other factors on the flexible conductive fabric equivalent resistance value.4、To explore the impact of washing on knitted flexible sensor apparent structure and conductive properties,focusing on the resistance stability of silver and carbon black conductive fabric after 30 times after washing treatment.Compared with fabric washing resistant performance,find out the stable performance fabric for flexible sensor.5、Design mixed orthogonal testing to research the influence of various factors on the conductive properties of the silver plated fabric.Combined process parameters for the optimization of electrical conductivity and washing stability of flexible sensors.Through this a series of experiments,analysis and research,Copper wire,stainless steel wire and wool nitrile conductive yarn are limited to the requirement of yarn for seamless weaving machine,copper fiber and carbon grew conductive fiber limited by resistance measurement stability,while the silver conductive fiber and carbon black conductive fiber with good conductive continuity and weaving performance was selected for conductive fabric knitting.Testing the conductive fabric,it is found that,with the increase of the number of longitudinal conductive plating,row with the same number of fabric resistance increase,and row number is less,the greater the degree of resistance change;with the increase of conductive plating is the same as the number of rows,the longitudinal resistance of the fabric is reduced,and the less the number of longitudinal,resistance change the smaller the degree.When wearing clothing,conductive fabric under low tensile stress,equivalent resistance decreased.But the reduction of resistance of 100 D silver plated fabric is smaller than70 D silver plated fabrics,and the conductivity of 100 D silver plated fabric is more stable with different structure.After 30 times washing treatment,silver fiber oxidizes in different degrees,and the resistance of fabric in tension increased.But resistance discreteness is almost unchanged,the washing resistant performance of silver conductive yarn and fabric is good.After washing,the conductivity of carbon black fabric become more stable.However,the equivalent resistance of carbon black conductive fabric is still in MΩ level,and the conductive fabric in tensile state,fabric equivalent resistance varies greatly and scattered.Before and afterwashing,the resistance stability of 1+1 mock rib is the best,and the second is 2+2 mock rib fabric.The resistance stability of 2+1 mock rib fabric is slightly unstable.Four factors of silver plated conductive fabric were analyzed by using the comprehensive balance method.Before and after washing,the fabric in nature and under tensile condition,the impact of various factors: plating row number> wale number> yarn fineness> ratio in the coil.Factors of plating row number and wale number are closely related to the resistance of flexible conductive fabric.The factor of yarn fineness has some effects on the conductive properties of fabric,but the factor of ratio in the coil has little effect on the conductivity of the fabric.Through the deviation analysis,knitting a conductive fabric,by using 100 D silver conductive yarn,2+1 mock rib,sizing 30 row and 40 vertical wale,as a flexible sensor,can reduce the resistance of flexible sensor and the power consumption.This paper experiment analysis and research for the follow-up research and development to provide certain theoretical reference basis,based on the conductive fiber knitted fabric of the development of intelligent textile has important practical significance.