A Multi-model,Large-range Flexible Strain Sensor Based on Carbonized Silk Habotai for Human Health Monitoring

In recent years,flexible strain sensors have received considerable attention owing to their excellent flexibility and multifunctionality.However,it is still a great challenge for them to accurately monitor multi-model deformations with high sensitivity and linearity.In this study,the industrial insulating silk habotai was successfully converted into carbonized silk habotai(CSH)for use in strain sensors.A strain sensor created using CSH exhibited excellent sensing performance under multi-model deformations,including stretching,twist and bending.The maximum tensile strain was 434%.The gauge factors were 14.6 in the wide tensile range of 0%–400%with a high linearity of 0.959.In addition,the CSH strain sensor exhibited an extremely fast response time(110 ms)and could accurately detect bending(0°–180°)and torsional(0°–180°)strains.High durability and repeatability were observed for the multi-model strains.Finally,a new type of smart pillow was developed to accurately record head movement and breathing during sleep.The sensor may also be used for auxiliary training in table tennis.The proposed CSH strain sensor has shown great potential for applications in smart devices and human-machine interactions.

Facile and Large-scale Fabrication of Biodegradable Thermochromic Fibers Based on Poly(lactic acid)

To investigate the feasibility of developing biobased and biodegradable thermochromic fibers,poly(lactic acid)(PLA)fibers with visual temperature indicator functionality were fabricated using a scalable melt spinning technique(spinning speed 800 m/min),where PLA and thermochromic microcapsules were used as fiber-forming polymers and color indicators,respectively.The effect of thermochromic microcapsules on the mechanical properties and reversible color-changing function of PLA fibers was systematically investigated to achieve high tenacity and sensitive color-changing function.The difference in the fiber performance was connected to changes in the multilayer structure.The results show that PLA fibers exhibit excellent tenacity of 3.7-4.7 cN/dtex and reversible and stable thermochromic behavior over 31℃.The high fraction of mesophase within TPLA-1 fiber plays an important role in its tenacity.Meanwhile,the low-concentration of microcapsules(~1 wt%)with good dispersion could act as a nucleating agent inside the PLA matrix and contribute to the formation of microcrystals in the amorphous between primary lamellae,which is also beneficial to maintain the tenacity of the fibers.The agglomeration of high-concentration microcapsules within PLA fibers hampered the formation of mesophase,resulting in a decrease in fiber tenacity.Aside from the content of microcapsules,the agglomeration of high-concentration microcapsules(>5 wt%)is the main reason that limits the substantial increase in fiber color depth.This study opens up new possibilities for degradable thermochromic fibers produced using standard industrial spinning technology.

Facile and Large-scale Fabrication of Self-crimping Elastic Fibers for Large Strain Sensors

Stretchable conductive fibers offer unparalleled advantages in the development of wearable strain sensors for smart textiles due to their excellent flexibility and weaveability.However,the practical applications of these fibers in wearable devices are hindered by either contradictory properties of conductive fibers(high stretchability versus high sensing stability),or lack of manufacturing scalability.Herein,we present a facile approach for highly stretchable self-crimping fiber strain sensors based on a polyether-ester(TPEE)elastomer matrix using a side-by-side bicomponent melt-spinning process involving two parallel but attached components with different shrinkage properties.The TPEE component serves as a highly elastic mechanical support layer within the bicomponent fibers,while the conductive component(E-TPEE)of carbon black(CB),multiwalled carbon nanotubes(MWCNTs)and TPEE works as a strain-sensitive layer.In addition to the intrinsic elasticity of the matrix,theTPEE/E-TPEE bicomponent fibers present an excellent form of elasticity due to self-crimping.The self-crimping elongation of the fibers can provide a large deformation,and after the crimp disappears,the intrinsic elastic deformation is responsible for monitoring the strain sensing.The reliable strain sensing range of theTPEE/E-TPEE composite fibers was 160%-270%and could be regulated by adjusting the crimp structure.More importantly,the TPEE/E-TPEE fibers had a diameter of 30-40 pm and tenacity of 40-50 MPa,showing the necessary practicality.This work introduces new possibilities for fiber strain sensors produced in standard industrial spinning machines.