Multimodal E-Textile Enabled by One-Step Maskless Patterning of Femtosecond-Laser-Induced Graphene on Nonwoven, Knit, and Woven Textiles.

Personal wearable devices are considered important in advanced healthcare, military, and sports applications. Among them, e-textiles are the best candidates because of their intrinsic conformability without any additional device installation. However, e-textile manufacturing to date has a high process complexity and low design flexibility. Here, we report the direct laser writing of e-textiles by converting raw Kevlar textiles to electrically conductive laser-induced graphene (LIG) via femtosecond laser pulses in ambient air. The resulting LIG has high electrical conductivity and chemical reliability with a low sheet resistance of 2.86 Ω/□. Wearable multimodal e-textile sensors and supercapacitors are realized on different types of Kevlar textiles, including nonwoven, knit, and woven structures, by considering their structural textile characteristics. The nonwoven textile exhibits high mechanical stability, making it suitable for applications in temperature sensors and micro-supercapacitors. On the other hand, the knit textile possesses inherent spring-like stretchability, enabling its use in the fabrication of strain sensors for human motion detection. Additionally, the woven textile offers special sensitive pressure-sensing networks between the warp and weft parts, making it suitable for the fabrication of bending sensors used in detecting human voices. This direct laser synthesis of arbitrarily patterned LIGs from various textile structures could result in the facile realization of wearable electronic sensors and energy storage.

Radio-frequency and optically transparent radome de-icing materials: fluorine-doped tin oxide.

Ice-elimination systems are very common in radio-frequency (RF) structures like radomes. For a radome application, the de-icing materials must be predominantly transparent to broadband RF radiation and have an adequate heating performance to remove the ice. The current development of high-performance radome de-icing materials is limited with a trade-off between the sheet resistance and RF transmission because one cannot be improved without sacrificing the other. We report for the first time a transparent conductive oxide (TCO) film as a lightweight and high optically transparent radome de-icing material. In this research, we prepared fluorine-doped tin oxide (FTO) films by horizontal ultrasonic spray pyrolysis (USP) deposition and found that the sheet resistance varied from 9 to 5000 Ω sq-1 with 0.219 to 90.0% RF transmission. Dassault CST software was used to validate the RF transmission at the X-band (8.2 to 12.4 GHz) region. The FTO films also exhibited sufficient optical transparency with efficient voltage-induced heating performance. With optimized electrical properties and RF transparency, FTO films will be good candidates for next-generation radome de-icing materials.