Continuous Fabrication Of Ultra-Fine Triboelectric Nanogenerator Yarn And Its Application In Smart Clothing

With the advancement of science and technology,clothing now serves more electronic purposes(e.g.medical treatment,physiological monitoring,and human-machine interaction)than only the classic ones(warmth and adornment).Restricted by the large size,rigidity,and heavy quality of traditional powering and sensing devices,the development of current smart clothing is meeting great challenges.Fiber electronics are urgently desired for flexible wearable technology because they are adaptable,lightweight,and comfortable.However,modern fiber electronics differ from traditional fibers in terms of fineness,flexibility,and productivity,making it challenge to integrate them with cutting-edge textile technology.Therefore,it is significant to maintain the inherent functions(sensing and powering)of electronics while keeping the morphology,mechanical properties,and continuous production of traditional fibers in flexible wearables.In view of the above problems,this paper presents an ultra-fine triboelectric nanogenerator yarn with great potential in smart clothing which is produced continuously by universal manufacturing process.The specific research content is as follows:(1)Using conjugated electrospinning and modified melt-spinning technologies,a triboelectric nanogenerator yarn with a built-in spiral structure was constructed.The triboelectric yarn has ultra-fine diameter(～250μm),outstanding mechanical property comparable to those of general fibers,and a large-scale(20 m/min)and continuous(thousand-meter-length)manufacturing process.This yarn has two working modes,i.e.,internal self-generation and external contact electrification,which is sensitive and stable to tensile strain.(2)The electronic textile based on this yarn was designed and woven,and its fabric style and wearing comfort were evaluated.This yarn is applicable with various modern textile technologies,including weaving,knitting,sewing,and embroidering.Kawabata evaluation system for fabrics(KES-FB)was systematically employed to analyze the triboelectric nanogenerator yarn enabled textile’s sensorial comfort(surface,compression,bending,stretching,and shearing),suggesting that the introduction of the yarn would not reduce the tactile sensations of textile.Moreover,the electronic textile shows electrical stability during 10 washing cycles and 3%mass loss after 5000Martindale abrasion cycles.The electronic textile has excellent air permeability(10833 mm/s)and great water vapor transmission(0.033 g/cm~2).(3)Based on the dual working mode of triboelectric nanogenerator yarn,a smart clothing system was developed for energy harvesting and physiological sensing.On the one hand,judging the external contact electrification,an energy collecting coat was developed,which can convert the bioenergy into electrical energy,and light the LCD screen and the digital watch.On the other hand,the yarn was woven into elastic knitted electronic textile,which was used to monitors human physiological signals successfully.Take respiratory signal as an example,respiratory frequency,intensity,and other information can be obtained through electrical signal.In addition,a human motion posture recognition system was developed,which can enable users to view their body posture in real time on the mobile phone.Finally,a 3×4 digital dialing keypad and a 1×3"3D touch"setting keypad were created on the clothing to control smart phone.We integrated the yarn into smart clothing system to harvest biomechanical energy,detect vital signal,recognize human motion,and realize human-machine interactions,which provides a possible solution for the future development of smart clothing.