Fabrication And Properties Of Textile-based Visualized Strain Sensing Materials

Textile-based strain sensing material is a kind of composite textile material which can monitor the external strain in real time.It usually relies on loaded conductive components for achieving electrical feedback to strain stimuli.However,the weak physical interactions between conductive components and textile substrate will reduce its mechanical stability.Furthermore,the visualized sensing ability of textile-based materials to external strain has been paid more and more attention.To address the above problems,this paper aims to enhance the structure stability of the materials by introducing chemical bondings between conductive components and textiles.Moreover,taking advantage of mechanochromic property of photonic crystal elastic materials and dynamic exchange capacity of dynamic covalent networks,textile-based strain sensing materials with mechanochromic and self-healing abilities were constructed.The specific research contents are as follows.Based on the chemical reaction between the active groups introduced on weft-knitted polyester fabric（WPF）by plasma treatment and Al-doped ZnO（Al-ZnO）precursors,Al-ZnO coated WPF（WPF@Al-ZnO）textile-based strain sensing materials were prepared by using WPF as flexible substrate.Under the external force,the resistance of WPF@Al-ZnO decreased with increasing strain.The gauge factor（GF）in the strain ranges of 0%-30%,30%-90%and90%-200%are-1.84,-0.45,-0.05,respectively.Due to the chemical bondings between Al-ZnO film and fibers of WPF,the WPF@Al-ZnO textile-based strain sensing material still had stable and consistent electrical response performances after reciprocating rubbing（50 k Pa load pressure,30 cycles）,washing（200 min soaping）and light fastness（accelerated light aging test for 7 days）,showing excellent mechanical and light stabilities.The constructed WPF@Al-ZnO strain sensor can monitor human motions,showing good motion tracking performance.To endow WPF@Al-ZnO visualized sensing function,polytetramethylene ether glycol（PTMG）/isophorone diisocyanate（IPDI）/pentanediol（PDO）/silica coated polystyrene（PS@Si O₂）（abbreviated as PTIP）photonic crystal elastic materials were designed and synthesized.PTIP photonic crystal/WPF@Al-ZnO textile-based visualized strain sensing materials were then fabricated by integrating with WPF@Al-ZnO in the form of semi-embedded structure.When stretching（0%-65.0%）,the lower layer WPF@Al-ZnO generated synchronous relative resistance changes（-68%）through conductive path reconstruction,while the upper photonic crystal elastic materials produced structural color changes（604-557 nm）through lattice spacing variation.Under 15%strain,the mechanochromism and electrical response time are 0.34 s,realizing the fast and synchronous visualized monitoring and electrical response to external strain.The visualized strain sensor was constructed based on the above textile-based materials,which showed good electrical response and visualized monitoring ability in human motion monitoring.To obtain textile-based strain sensing material with long service life,using carbonized textile（CCT）as conductive component,PTMG/poly（1,4-butanediol）bis（4-aminobenzoate）（PBDAB）/IPDI/glycerin（GLY）/PS@Si O₂（abbreviated as PPIG）photonic crystal elastic materials were designed and synthesized.The PPIG photonic crystal/CCT-based visualized strain sensing materials were fabricated by embedding CCT into the elastic materials.When stretching（0%-65.0%）,they can produce synchronous structural color changes（626-557 nm）and relative resistance changes（730%）.Based on the dynamic exchange capacity of the urethane bonds in elastomeric network at high temperature,the structure of the outer photonic elastic material could be self-healed after being damaged,realizing the self-repair of visualized function.Meanwhile,depending on the fully-embedded structure,the inner CCT was not subjected to external interference,ensuring the long-term stability of electrical response performance of material.A visualized wireless strain sensor was constructed by integrating with wireless sensing technology,realizing remote electrical monitoring and visual perception of human motions.