ALLPCB
Research background
Over recent decades, electronics and artificial intelligence have advanced significantly. The emergence of intelligent sensing devices enables dynamic capture and digital display of physical, chemical, and biological signals. With the arrival of 5G, wearable textiles are evolving toward compatibility with AI, IoT, multi-tier cloud services, and big data to provide improved human-machine interaction. An ideal smart textile requires multiple technical capabilities: multi-modal signal recognition sensors, rapid data analysis aided by cloud layers, and feedback from terminal intelligent systems. As the front-end information collector, key sensor performance metrics include light weight, flexibility, wide working range, good stability, high sensitivity, and multifunctionality. Sensors should be portable and comfortable to wear. Traditional electronic devices, typically built from rigid metals and composite materials, cannot meet requirements for lightness and flexibility, and their limited working range restricts use in human motion detection. To address these limitations, one-dimensional (fibers/yarns) and two-dimensional textile sensors have been developed. Due to their structures and weave flexibility, textiles in fiber/yarn (1D) and fabric (2D) forms offer good flexibility, low weight, breathability, and ease of integration with garments. Reported textile-based sensors—such as capacitive pressure sensors with woven structures, thermochromic sensors woven from optical fibers, and multifunctional sensors based on nanowire-coated fibers for pressure, Joule heating, particle filtration, and thermal insulation—show strong application potential. Notably, strain is a fundamental textile property, and textile-based strain sensors are widely applied in artificial electronic skin and health monitoring.
Conventional metal strain sensors typically provide a single sensing mode and have a narrow stretch range of about 5–10%. In contrast, textile strain sensors can bend, fold, and stretch, and their weave designs facilitate garment integration. For example, a helical structure in CNT/PU strain fibers extended the strain range to 1700%. Given the large application potential of textile strain sensors, research efforts have focused on advanced fabrication, multifunctional integration, and intelligent system construction. In the pursuit of ultra-sensitive strain sensors, most work emphasizes new materials and structures. Besides these approaches, sensing mechanisms also critically affect sensor sensitivity. Fundamentally, a sensor's sensitivity, often expressed by the gauge factor (GF), depends on the magnitude of signal change under external stimuli—for example, the resistance change of a resistive strain sensor is closely related to structural deformation. Theoretically, if the relationship between intrinsic material properties and resistance change can be clarified, sensitivity can be improved by enhancing a specific mechanical property of the material rather than constantly seeking new materials. Unfortunately, existing studies mainly focus on material and fabrication advances and give limited attention to the sensing mechanisms of textile-based strain sensors, lacking systematic classification and discussion.
Key findings
Fiber- (1D) and fabric- (2D) based textile strain sensors are strong candidates for wearable devices. Their flexible weave methods and unique structures provide flexibility, light weight, breathability, and feasibility for garment integration. In response to the rise of novel textile strain sensors, research teams from Donghua University (Qilin Wu) and the University of Manitoba (Mengqiu Xing) described new materials and fabrication methods from spatial 1D and 2D perspectives. Intrinsic sensing mechanisms are primary factors influencing sensor sensitivity, and the trend of sensing signal variation is closely related to these mechanisms. Although various sensing mechanisms have been reported, systematic classification and discussion are still lacking. Therefore, the work categorizes sensing mechanisms of textile-based strain sensors from a spatial perspective. Considering that most strain sensors rely on resistance change, the focus is on resistive textile strain sensor mechanisms, including fiber deformation, tunneling effect, crack propagation, fabric deformation, electrical contact, and bridging. Corresponding resistance prediction models commonly used for data fitting are reviewed; these models can reproduce resistance change trends and provide guidance for sensor performance. Finally, the multifunctionality of textile-based strain sensors is summarized, covering multi-mode signal detection, visual interaction, energy harvesting, thermal management, and medical applications.
The related study, titled "Fabrication Techniques and Sensing Mechanisms of Textile-Based Strain Sensors: From Spatial 1D and 2D Perspectives," was published in the journal Advanced Fiber Materials.
Summary and outlook
Textile-based smart strain sensors offer light weight, flexibility, good stability, wide working range, and high sensitivity, enabling health monitoring while maintaining wearer comfort. From a spatial perspective, textile strain sensors can be classified into 1D fibers/yarns and 2D fabrics. Common conductive materials and fabrication methods for both 1D and 2D sensors are classified and discussed, including coating, spinning, microstructure design, weaving, knitting, printing, and fabric carbonization. Given the complex sensing mechanisms of various textile sensors and the lack of comprehensive classification, intrinsic sensing mechanisms are categorized from a spatial viewpoint and corresponding predictive models are collected.
The sensing mechanism of a fabric sensor determines signal strength and variation trends. A complete framework for interpreting signal changes has not yet been established, particularly for complex 2D fabrics. Signals from some specialized fabrics may involve multiple mechanisms and require careful analysis of changes in conductive pathways during stretching. Most existing models reproduce experimental resistance but do not serve as true predictive models. A predictive model that relies only on material characteristic parameters is desirable; achieving this requires sensors with good repeatability.
Wearable robotics is a likely future direction for textile sensors. Textiles covering robotic surfaces can monitor motion and external stimuli like biomimetic skin. Optical, electrical, thermal, and humidity responses can be achieved by material selection and structural design, not limited to strain sensing. A key challenge during functional integration is signal interference. One effective strategy is to select materials with distinct response signals; another is to optimize signal decoupling, for example by building a database of characteristic signals. Functional integration also requires stable interconnects between device components. Welding joints and wiring can affect wearer comfort, and excessive contact points may not withstand prolonged mechanical deformation, eventually causing sensor failure.
Large-scale manufacturing is another critical step for sensor adoption. Currently, most integrated sensors remain at the laboratory scale, relying on time-consuming fabrication methods and precision equipment. Typical integrated sensors are short in length, from centimeters to meters, and reports of continuous industrial-scale production are scarce. Continuous manufacturing platforms are needed, which will require collaboration between materials science and mechanical automation. Research should also address the relationship between manufacturing parameters and device performance to facilitate industrial production.
Biomedical applications of fabric sensors present another promising direction. Ideal sensors could act as drug carriers, delivering drugs to the skin when cardiac monitoring detects anomalies. Tiny fiber sensors could be injected subcutaneously to serve as scaffolds for tissue support and cell growth, ultimately enabling therapeutic applications. These functions require materials with good biocompatibility, supported by extensive biological testing. Although textile sensors have received limited attention in biomedical contexts so far, wider adoption is expected in the near future.
