Recently, the research group led by Professor Zhao Tao from the College of Chemistry and Chemical Engineering has made significant progress in the field of integrated fire-warning and sensing wearable equipment. The work was recently published in Advanced Functional Materials under the title "Extra-Protective-Layer-Free Integrated Textile for Robust Protection and Highly Sensitive Bimodal Sensing in Firefighting."
A key future trend in the design of modern firefighting apparel is the integration of physical protection with physiological and environmental sensing capabilities. However, the extreme conditions of fire scenes mean that conventional fabrication strategies typically involve stacking additional functional protective layers—such as waterproof and flame-retardant coatings—on top of the conductive sensing layer. This traditional "layer-stacking" multilayer structure severely impedes the transmission of external physical stimuli (e.g., mechanical force and heat) to the internal sensing layer, significantly compromising sensor sensitivity and response speed. Therefore, how to resolve the inherent conflict between passive external physical protection and active internal sensing sensitivity remains a critical scientific challenge for the practical application of integrated firefighting equipment.
This work proposes a new design strategy for integrated textiles (i-Textile) that eliminates the need for additional protective layers. Inspired by the structure of human skin, the research team endowed conventional cotton fabrics with asymmetric functional architectures through spatially selective deposition. Specifically, they first uniformly deposited complexes of 1,4,7,10-tetraazacyclododecane (Cyclen) and copper sulfate onto the cotton fabric, followed by the in situ growth of vertically aligned micron-sized copper hydroxide platelets, which were firmly encapsulated by a crosslinked polymer network. Finally, nanoscale polypyrrole (PPy) particles were deposited on one side of the fabric via single-face interfacial polymerization. This sophisticated micro–nano hierarchical design endows the asymmetric cotton fabric (ACF) with excellent electrical conductivity on one side (serving as the inner electrode) and superior superhydrophobicity, flame retardancy, and electrical insulation on the other side (serving as the outer protective layer).
As an integrated device designed for firefighting and rescue operations, the external protective capability serves as the cornerstone for ensuring stable sensor performance in fire environments. Tests show that the superhydrophobic surface on the outer side of the modified fabric exhibits water contact angles exceeding 160° for both deionized water and artificial sweat, demonstrating excellent water-repellent and self-cleaning functions. Moreover, the incorporation of phosphorus-containing polymers and metal species endows the fabric with a limiting oxygen index (LOI) as high as 30.7%, enabling it to withstand repeated and prolonged flame exposure without ignition. Through density functional theory (DFT) calculations and IGMH analysis, the team revealed that the hydrogen-bonding network contributes up to 63.61% of the total binding energy at the interface between the fiber substrate and the functional coating. This strong interfacial interaction ensures that the fabric maintains stable superhydrophobic and flame-retardant properties even after 50 standard washing cycles.
On the basis of robust physical protection, the research team placed a porous thermosensitive chitosan interlayer between two layers of the asymmetric fabric to construct a complete bimodal integrated textile. In capacitive mode (for mechanical monitoring), the device exhibits ultrahigh sensitivity to subtle mechanical stimuli (GF = 41.59 N⁻¹) and an ultrafast response time (0.25 s), enabling accurate detection of physiological motion signals such as breathing and running of firefighters. In resistive mode (for overtemperature warning), thanks to the absence of additional physical thermal insulation layers, the device achieves a response time of only 1.89 s to high-temperature flame, far superior to that of conventional smoke alarms. To address the severe electrical crosstalk caused by direct parallel connection of the two sensing circuits, the team innovatively introduced an asymmetric time-division multiplexing (TDM) circuit strategy, successfully achieving interference-free and stable parallel operation of highly sensitive physiological motion monitoring and rapid overtemperature warning on a cloud platform.
This work not only achieves, on a single piece of fabric, the seamless integration of extremely robust multi-effect protection (superhydrophobicity and durable flame retardancy) with highly sensitive bimodal sensing, while successfully eliminating the bulky "extra protective layers" in traditional integrated garments, but also establishes the TDM circuit decoupling strategy as a feasible methodological platform for resolving multimodal sensing signal interference. This study holds significant implications for deepening the understanding of internal stimulus-transmission mechanisms in wearable devices and for the rational design of next-generation high-performance, multifunctional integrated firefighting wearable equipment.
Chen Zexin, a master's student at the College of Chemistry and Chemical Engineering, is the first author of this paper, with Professor Zhao Tao serving as the corresponding author. Donghua University is the sole corresponding institution for this paper.
Original link to this aricle：https://doi.org/10.1002/adfm.76070
