Smart wearable materials and devices with multifunctional applications

Abstract

The advancement of portable and wearable electronic devices (e.g., sensors, solar cells, nanogenerators, supercapacitors, and soft robots) has attracted extensive attention to smart living applications. Particularly, versatile and sophisticated e-textiles are gaining recognition in the field of hybrid wearable electronics and energy packages owing to their high compliance and wearability to monitor and diagnose daily activities/health conditions. However, fabricating subtle and multifunctional wearable textile electronics with high performance and integrated functionalities is still a great challenge. To address the challenges, this thesis aims to design and develop smart materials and wearable devices in different platforms through innovative hybrid materials, structural designs, and facile processing. To begin with, a dual carbon-based 1D fiber e-textile was fabricated based on a bioinspired configuration utilizing heterogeneous dispersion and assembly methods. By combining hybrid-carbon materials and high elastic polymer, the stretchable conductive fibers possessed conductivity, outstanding stretchability, durability, softness, and preserved wearability. Correspondingly, fiber-shaped TENGs were developed to form a fully integrated device of sensors and energy harvesters. Owing to its one-dimensional architecture, the soft conductive fiber can be assembled with commercial garments as wearable e-textiles. Subsequently, by exploring the 2D wearable platforms, a novel conductive bio-aqueous ink consisting of bio-mediated carbon and liquid metal was proposed for printing textile electronics. The screen-printed smart electronics exhibited high wearability, aesthetic properties, and scalability, as well as good mechanical strength, stretchability, washability, breathability, abrasiveness, and durability. The as-prepared 2D e-textile could be easily fabricated into sensing and energy devices. A 3D printing-based direct ink writing was further adopted for optimizing the disposition of conductive composite on wearable substrates. Concerning conductive stability, eco-friendliness, and adhesiveness, a bio-assisted carbon-based gel ink was developed with good strength and electric performance, recyclability, waterproofing, stability, and long-term durability. With the precise and effective printing approach, green-based e-textiles with patternable conductive circuits were proposed for sensing and energy harvesting. Owing to the significant multi-properties, the obtained e-textile carries high feasibility and wearability in various practical scenarios of real-time health monitoring and self-powered sensing. The energy-driving of commercial electronics and powering LEDs were also demonstrated successfully. Moreover, a human-machine interaction (HMI) system was developed in the form of seamless integrated e-textile garments for real-time signal recognition and dexterous manipulation. In summary, this thesis carried out a systematic study on exploring and constructing truly wearable smart devices from viewpoints of advanced materials sciences, structural designs, and processing technologies. Various types of highly wearable e-textiles were designed and developed in the forms of 1D fiber, 2D planar, and 3D printing structures with satisfactory electrical performance, stability, stretchability, and durability. A new avenue was promoted to integrate soft conductive electronics with textile wearables which were versatile in real-time practical opportunities such as health monitoring, self-powering, energy harvesting, and human-machine interaction. Thus, the work is expected to have a promising benefit in the fields of fully wearable electronics for healthcare monitoring, sustainable energy sources, and artificial intelligence.