The Research On Wearable Sensing Based On Fabric Fibers

With the acceleration of economic and social development,the problems of environmental pollution,water pollution,air pollution and light pollution are becoming more and more serious.The sub-health population surges and the population aging is aggravating.And then people's concern and attention about their own health and the quality of the surrounding environment have also reached an unprecedented level.In this background,the demand for real-time monitoring of human physiological activities and changes of the external environment is increasing.As an effective underlying monitoring approach,the wearable sensor as well as the related technology has drawn wide attention of researchers and industry due to its characteristics of small size,light weight and easy wearing.Usually,wearable sensing devices use flat substrates(rigid or flexible)and are coated with sensing materials such as metals,organic materials,or semiconductors.In recent years,the integration of flexible wearable sensors based on fabric fibers and high-performance sensing materials has become a new hot research field.Related researches have shown promising technical characteristics of good fit,good comfort and no need of external function modules to achieve the intelligent perception.However,those researches are mostly focused on a single function(strain sensing),which has limited the further development and application of wearable sensing technology based on fabric fibers.Therefore,this study is focused on the technology of multi-functional wearable sensing based on highly elastic fabric fibers.By combining a single sensing material with highly elastic fabric fibers,we can achieve multifunctional wearable sensing under the premise of ensuring strain sensing.Related works and results have been carried out as follows:1.This study selects a kind of double covered yarn as the sensing function carrier,which is commercial and highly elastic.Several processes have been adopted,including air plasma treatment,dip-coating in graphene oxide aqueous solution and chemical reduction by hydrobromic acid,to finally obtain the wearable sensors based on fabric fibers coated with reduced graphene oxide.2.The wearable sensor based on rGO coated fabric fiber achieves multi-function sensing including strain,humidity and light sensing.Testing results show that:(1)The sensor has a wide detection range and can effectively monitor the full range of human activities(knee,elbow and finger joint bending as well as the wrist pulse beat).(2)The sensor impedance has a relatively regular change(an unstable downtrend)along with the relative humidity variation(11-33-54-75-85-95%).And the sensitivity achieves the highest(about 10%)at the relative humidity of 95%.(3)The sensors have shown short response time(about 2s)and high sensitivity to common light sources(about 0.4%at the distance of 0.5cm to white LED,and up to 4%to the sunlight).3.To explor multi-functional sensing,we have used several steps to prepare the composite of tin dioxide and reduced graphene oxide,including air plasma treatment,dip coating in graphene oxide aqueous solution,and immersing in a mixed solution of stannous chloride dihydrate,hydrochloric acid and graphene oxide aqueous solution for microwave radiation.After combining the tin dioxide/reduced graphene oxide composite with fabric fibers,the multifunctional sensors are realized.4.The wearable sensor based on rGO coated fabric fiber achieves multi-function sensing including strain,gas and light sensing.Testing results show that:(1)The sensor device is still capable of detecting a full range of human activities(knee,elbow and finger joint bending as well as the wrist pulse beat)and excellent sensing performances.(2)The device shows good sensitivity and low detection concentration to ethanol(about the sensitivity of 5%at the concentration of 20ppm).(3)The device has good sensitivity and rapid response as well as recovery time(about 2s)to visible light LEDs and the sunlight,and can distinguish different optical wavelength bands and optical powers without a strict test condition.Besides,a strict experiment condition is not necessary.