An invisibility cloak based on visible rays with a refractive index similar to that of air can effectively conceal people or objects from human eyes. However, even if an invisibility cloak based on visible rays is used, an infrared (IR) thermography camera can detect the heat (thermal radiation) emitted from different types of objects including living things. Therefore, both visible and IR rays should be shielded using an invisibility cloak produced by an appropriate technology. Herein, we developed a textile cloak that can almost completely conceal people or objects from IR vision. If a person or object is covered with an IR-and thermal-radiation-shielding textile woven with polyurethane (PU)−tin oxide (SnO 2 ) composite microtubes, serving as an IR invisibility cloak, IR and thermal radiation emitted from the person or object can be simultaneously blocked. Furthermore, the IR-and thermal-radiation-shielding characteristics could be improved further by filling the core of the PU−SnO 2 composite microtubes with heat-absorbing materials such as water and paraffin oil in place of air. In addition, the external surface of the IR-and thermal-radiation-shielding textile serving as an IR-reflecting cloak can be waterproofed to enable certain IR-and thermal-radiation-shielding functions under various environmental conditions.

Here, we investigate a wearable-based IR and thermal stealth structure that effectively blocks IR and thermal radiation from a human body or device using a polyurethane-antimony tin oxide (PU-ATO) composite fiber. The aging time of the ATO sol prepared by a sol-gel method, and the concentration of ATO with respect to that of the PU matrix were optimized to prepare PU-ATO composite fibers that simultaneously have an appropriate mechanical strength (strength of~4 MPa and strain of~340%) and IR-and thermal radiation-shielding properties with~98% IR light, as determined by Fourier transform IR spectroscopic studies. The fabricated PU-ATO composite fiber showed stable IRand thermal radiation-shielding properties even when exposed to ten cycles of repeated temperature changes of −20 and +80°C and long-term temperature changes for 30 days. In addition, the surface of the PU-ATO composite fiber was rendered hydrophobic to prevent the distortion of the IR and thermal radiation due to the wetting of the PU-ATO composite fiber with absorbed water. The PU-ATO composite fiber-based textile proposed herein can be applied in wearable IR-and thermal radiation-shielding technologies to shield IR signals generated by objects of diverse and complex shapes.

Wearable textile colorimetric sensors are extremely effective for expressing danger or warning, as they are non‐invasive and exhibit easily recognizable color changes. However, unlike conventional sensors, these devices are actually worn by individuals and should, therefore, not only detect hazardous chemicals in real time but also maintain the reversibility, durability, and stability of color change upon exposure to sweat, repetitive movement, and environments involving continuous exposure to chemical substances. Herein, a halochromic fiber maintaining excellent pH sensing properties upon continuous exposure to chemical and physical stimuli is fabricated. The fiber surface is rendered hydrophobic by phosphonic acid treatment, and a composite pH indicator dye capable of simultaneously detecting acids and bases is embedded into the fiber pores. The halochromic fiber could accurately detect pH while maintaining a clear color transition even after repeated changes in the acidic–basic environment, returning to the neutral state within several seconds after termination of exposure to the test solution. Thus, the presented technique allows one to significantly improve the reversibility, durability, and stability of color change—a problem faced by conventional wearable sensors—and, thus, greatly contributes to the development of halochromic textile sensors applicable to real‐life work environments.

Flexible fibers composed of a conductive material mixed with a polymer matrix are useful in wearable electronic devices. However, the presence of the conductive material often reduces the flexibility of the fiber, while the conductivity may be affected by environmental factors such as water and moisture. To address these issues, we developed a new conductive fiber by mixing carbon nanotubes (CNT) with a polyurethane (PU) matrix. A silane ((heptadecafluoro–1,1,2,2–tetra–hydrodecyl)trichlorosilane) was added to improve the strain value of the fiber from 155% to 228%. Moreover, silica aerogel particles were embedded on the fiber surface to increase the water contact angle (WCA) and minimize the effect of water on the conductivity of the fiber. As a result, the fabricated PU-CNT-silane-aerogel composite microfiber maintained a WCA of ~140° even after heating at 250 °C for 30 min. We expect this method of incorporating silane and aerogel to help the development of conductive fibers with high flexibility that are capable of stable operation in wet or humid environments.