No abstract

In this work, we examined the biocompatibility of electrospun chitosan microfibers as a scaffold. The chitosan microfibers showed a three-dimensional pore structure by SEM. The chitosan microfibers supported attachment and viability of rat muscle-derived stem cells (rMDSCs). Subcutaneous implantation of the chitosan microfibers demonstrated that implantation of rMDSCs containing chitosan microfibers induced lower host tissue responses with decreased macrophage accumulation than did the chitosan microfibers alone, probably due to the immunosuppression of the transplanted rMDSCs. Our results collectively show that chitosan microfibers could serve as a biocompatible in vivo scaffold for rMDSCs in rats.

No abstract

Smart textiles have wide applications in various sensing systems since they have the advantage of maintaining the inherent properties of textile such as light weight, flexibility, comfort, and breathability. Therefore, textile-based pressure sensors, one of the smart textiles, have attracted considerable interest in wearable electronics and homecare systems. In this study, to construct a textile-based pressure sensor, a poly(3,4-ethylenedioxythiophene) (PEDOT) thin film was fabricated on a polyethylene terephthalate microfiber fabric by vapor phase polymerization with various concentrations of the oxidant, FeCl 3 . The PEDOT conductive textile showed a change in conductivity depending on the applied pressure. We confirmed the excellent washing and physical durability of the sensor from the stable electrical properties of the PEDOT conductive textile after washing and repeated folding tests. Furthermore, a fully textile-based pressure sensor was successfully fabricated using the highly durable PEDOT, which could simultaneously measure both static and dynamic pressures even during physical deformation, thus suggesting great potential in smart textiles, especially textile-based homecare systems.

Poly(l-lactic acid) (PLLA) based piezoelectric polymers are gradually becoming the substitute for the conventional piezoelectric ceramic and polymeric materials due to their low cost and biodegradable, non-toxic, piezoelectric and non-pyroelectric nature. To improve the piezoelectric properties of melt-spun poly(l-lactic acid) (PLLA)/BaTiO3, we optimized the post-processing conditions to increase the proportion of the β crystalline phase. The α → β phase transition behaviour was determined by two-dimensional wide-angle x-ray diffraction and differential scanning calorimetry. The piezoelectric properties of PLLA/BaTiO3 fibres were characterised in their yarn and textile form through a tapping method. From these results, we confirmed that the crystalline phase transition of PLLA/BaTiO3 fibres was significantly enhanced under the optimised post-processing conditions at a draw ratio of 3 and temperature of 120 °C during the melt-spinning process. The results indicated that PLLA/BaTiO3 fibres could be a one of the material for organic-based piezoelectric sensors for application in textile-based wearable piezoelectric devices.

The combination of the triboelectric effect and static electricity as a triboelectric nanogenerator (TENG) has been extensively studied. TENGs using nanofibers have advantages such as high surface roughness, porous structure, and ease of production by electrospinning; however, their shortcomings include high-cost, limited yield, and poor mechanical properties. Microfibers are produced on mass scale at low cost; they are solvent-free, their thickness can be easily controlled, and they have relatively better mechanical properties than nanofiber webs. Herein, a nano-and micro-fiber-based TENG (NMF-TENG) was fabricated using a nylon 6 nanofiber mat and melt blown nonwoven polypropylene (PP) as triboelectric layers. Hence, the advantages of nanofibers and microfibers are maintained and mutually complemented. The NMF-TENG was manufactured by electrospinning nylon 6 on the nonwoven PP, and then attaching Ni coated fabric electrodes on the top and bottom of the triboelectric layers. The morphology, porosity, pore size distribution, and fiber diameters of the triboelectric layers were investigated. The triboelectric output performances were confirmed by controlling the pressure area and basis weight of the nonwoven PP. This study proposes a low-cost fabrication process of NMF-TENGs with high air-permeability, durability, and productivity, which makes them applicable to a variety of wearable electronics.

No abstract

Electronic textile (E-textile) with excellent electrical/mechanical properties in large area is an essential component for wearable electronics. We herein demonstrated that brush-painting is a promising printing technique of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on fabric substrates to prepare ultra-flexible, stretchable, and highly conductive E-textiles. The brush-painting allows uniform film surface with much lower sheet resistance which is opposite to agglomerated particulates of the film from the drop-casting. As a result, the PEDOT:PSS-based E-textiles achieve high conductivity of 6.4 S cm−1 after successive bush-painting up to 50 times with excellent mechanical properties including bending, stretching, and washing stability. The brush-painted E-textiles exhibit excellent Joule heating properties with low operative voltage and quick response time. In addition, the large-area piezoresistive sensors have been realized by the brush-painted E-textiles, suggesting its great potential of the brush-painting PEDOT:PSS toward multi-functional smart textiles or wearable electronics.