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We report on developing a wearable infrared (IR) display based on stretchable conductive fibers fabricated through an expansion–contraction process. The expansion process creates a gap between the strands of spandex fibers. This is achieved by immersing the fibers in a solvent where carbon nanotubes (CNTs) are dispersed, thereby embedding the CNTs. Contraction is achieved through a drying process, which removes the gap between the strands of the spandex fibers. This ensures that the CNTs remain embedded, even after repeated stretching. The CNT-embedded spandex fibers are arranged into a 5 × 7 pixel array. The intensity of the IR rays emitted from the fibers can be controlled by adjusting their temperature, which is achieved by varying the driving voltage. Full-color IR images and displays of letters and numbers are realized through precise control of the IR light intensity. The wearable IR display developed in this study opens up exciting possibilities for integration into advanced systems such as military identification, artificial intelligence robots, autonomous driving, and aerospace industry applications. [ABSTRACT FROM AUTHOR]

Halochromic sensors, which allow users to visually recognize exposure to acid/base chemicals that are harmful to the human body, are routinely used in a wide range of industries, such as pharmaceuticals, biotechnology, cosmetics, and environmental/human monitoring systems. In this study, halochromic fibers that operate stably, even when exposed to rain or sweat and repeated stretching–releasing, were investigated. While the halochromic mesoporous silica was synthesized using tetraethylorthosilicate and cetyltrimethylammonium bromide, methyl yellow (MY) and bromothymol blue (BTB) as halochromic dyes were added so that MY and BTB were chemically or physically immobilized on the siloxane network structure of the halochromic mesoporous silica. Using the swelling and shrinking properties of the polymer, the halochromic mesoporous silica was embedded in a highly elastic spandex fiber composed of multiple strands. Because of the strong ionic and hydrogen bonding between the dye and the silica matrix, the dyes can be immobilized even in an aqueous solution without the leaching of the dyes. The stretchable halochromic fiber reversibly changed its color even after repeated exposure to acidic/basic conditions five times and could sense acid/base concentrations in the range of 0.5–10 wt %. In addition, because the halochromic mesoporous silica is tightly adhered between the stands of spandex fibers, stable color conversion properties were maintained even after stretching to 150% of the fibers and repeated 100 times. Because the halochromic fiber can be applied to lab coats, work clothes, and gloves, it is expected to be used as a wearable colorimetric sensor for daily life and industrial applications. [ABSTRACT FROM AUTHOR]

Herein, we have proposed a method that uses a highly stretchable and conductive fiber-based multi-angle fiber array, which precisely measures human joint motion in various degrees of freedom (flexion and rotation) at the shoulders, knees, and wrists in real time. By embedding conductive carbon nanotubes (CNTs) within spandex fibers of high elasticity and shape recovery ratio, we monitored joint motion stably without degrading the fiber's conductivity even during repeated stretching and contraction of different lengths. The strain occurring in a specific direction was monitored using mapping images generated due to the change in resistance that occurred when 12 CNT-embedded spandex fibers arranged in radial lines at intervals of 15° were stretched or contracted by an external force. The proposed high-precision joint-monitoring technology measures human motion accurately and is applicable for use in wearable healthcare devices that require precise measurements. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Light-Liquid Selective Filters: Light-Liquid Selective Filter-Mounted Nanowire-Networked Polyurethane Fiber for an Ultraviolet Sensor (Adv. The SnO SB 2 sb nanowire-networked polyurethane fiber covered with a (1 I H i ,1 I H i ,2 I H i ,2 I H i -heptadecafluorodec-1-yl) phosphonic acid-coated Al SB 2 sb O SB 3 sb nanoparticles can stably detect ultraviolet intensity even when exposed to liquids. Fiber, light-liquid selective filters, nanowires, network, ultraviolet sensors. [Extracted from the article]

Fiber‐sensor‐based real‐time monitoring of the degree of exposure of the human body to ultraviolet (UV) rays is one of the technologies in the field of smart healthcare‐based wearable devices. With the development of wearable UV sensors, it is essential to build technologies with stable durability and excellent sensing capabilities for continuous movement and with water, sweat, and external contaminants. In this study, a fiber sensor is investigated that can stably detect UV intensity even when exposed to liquids such as water. The device consists of SnO2 nanowires, which are sensitive to UV intensity, arranged on a polyurethane (PU) fiber in a random network pattern, with the aim to minimize the amount of current change caused by various tensile and compressive stresses encountered by the wearable sensor. To prevent the distortion of the measured current that may occur in the semiconductor sensing channel as a result of external water exposure, a (1H,1H,2H,2H‐heptadecafluorodec‐1‐yl) phosphonic acid (HDF‐PA)‐coated Al2O3 nanoparticles (NPs) with a UV transmittance of 77% are coated on the networked SnO2 nanowire channel. The SnO2 nanowire‐networked PU fiber covered with the HDF‐PA coated Al2O3 NPs is confirmed to be sensitive only to UV, without reacting to external water under various bending conditions. [ABSTRACT FROM AUTHOR]