Copyright © 2022 Foshan MBRT Nanofiberlabs Technology Co., Ltd All rights reserved.Site Map
The development of wearable electronic products has become one of the hottest research directions at present. Compared with traditional rigid devices, integrated fabric-based wearable electronic products are considered to be the most effective materials for flexible conductive sensing and electronic skin due to their outstanding flexibility and lightness. However, the low bonding force between fabrics and conductive materials, small adhesion, and discontinuous spatial conductive networks restrict the development of fabric sensors.
Recently, Professor Li Jialin and Associate Professor Hong Xinghua of Zhejiang Sci-Tech University published a research result entitled "Highly Conductive and Elastic Electronic Silk Fabrics via 3D Textile Macro-design and Microscopic Plasma Activation for Personal Care and Information Interaction" in Advanced Fiber Materials. This work forms a macroscopic three-dimensional silk fabric structure through a jacquard process, combines microscopic plasma-activated iron oxyhydroxide scaffolds and in-situ polymerized polypyrrole, and develops a general strategy to design a fabric wearable device with high conductivity and high sensing sensitivity for motion recognition and health monitoring. The fabric exhibits high conductivity (resistivity of 0.3 Ω·cm), fast sensing response (50 ms), excellent durability (>1500 cycles), and a maximum tensile strain of 30%. In addition, the possible mechanism of plasma-activated iron oxyhydroxide scaffolds to produce zero-valent iron and induce pyrrole polymerization was analyzed. This work provides a new way to construct advanced fabric-based conductive sensor devices, which is expected to be applied in health monitoring, smart homes, virtual reality interaction and other fields.
The main point of this paper
The preparation and application of 3D highly conductive silk wearable device (3D-CSWD) are shown in Figure 1. The device is designed following two key processes: (1) Through advanced jacquard weaving technology, a high-precision silk flexible matrix with two-dimensional plane continuity and three-dimensional spatial interlacing is realized, which enhances the elastic deformation ability and thus improves the sensing sensitivity. (2) Two low-temperature plasma treatments are used: (a) oxygen-containing functional groups are introduced in situ on the silk surface to stably construct FeOOH scaffolds under the action of hydrogen bonds; (b) the scaffolds are activated again. During polymerization, PPy preferentially grows on the fabric/FeOOH surface and does not fall off in the reaction solution, which improves the polymerization efficiency and enhances the conductivity and washability.
After the fabric is treated with cold plasma for the second time, a large number of negatively charged particles and free electrons are generated. These negative charges reduce Fe3+; at the same time, during the oxidation polymerization of the fabric with Py monomer to form PPy, Fe3+ acts as an oxidant and is also reduced to produce Fe(0). Finally, the surface of 3D-CSWD not only has conductive polymer PPy, but also Fe(0), which makes the fabric have better conductivity. Figure 2 is the XPS characterization and analysis results of 3D-CSWD.
The surface of the fabric treated with β-FeOOH is rice-like, which is due to the stacking of polycrystalline β-FeOOH to form a dense layer wrapped on the surface of the fiber. After the in-situ assembly reaction of PPy, β-FeOOH as a scaffold provides growth space for PPy
The warp and weft of the woven fabric are perpendicular to each other, with small bending degree and weak resilience. The weaving structure designed in this study introduces a binding structure, which plays the role of a "coil-like spring". When the double-layer structure is stretched, the binding structure connects the upper and lower layers of weft, slides relatively, and gradually changes from a bent state to a straight state, providing greater elasticity and ductility.
3D-CSWD can monitor human movement in real time, and its application range can range from weak physiological signals to large-scale motion signals. By attaching the fabric to the wrist, throat and inside the mask, different ranges of motion signals such as pulse, swallowing and breathing can be detected. For finger movement, the resistance change rate of the fabric can reach 200%, and the movement of the joint can reach 400%. In addition, when swallowing, the fabric sensor can produce a sharp narrow response peak; when the wrist is bent, a stable and strong wide response peak is generated. By identifying and analyzing different response peaks, the human body's movement state can be judged in real time, which has broad application prospects in non-invasive biomedical monitoring and personal medical diagnosis.
In summary, the 3D highly conductive silk wearable device is prepared by combining the macroscopic multi-dimensional fabric structure design, microscopic plasma activation and in-situ polymerization of polypyrrole strategy, showing excellent durability and washability. Due to the certain thickness and stretchability of the specific fabric structure (3 times that of ordinary conductive silk woven fabrics), the human body's movement state, such as pulse, breathing, swallowing movements, and wrist and finger bending, can be monitored; in addition, the device can also transmit Morse code signals for information exchange. This study provides a new design idea for the preparation of fabric-based flexible conductive sensing textiles.
Electrospinning Nanofibers Article Source:
https://link.springer.com/article/10.1007/s42765-024-00471-z
