Significance The rapid development of flexible sensing technology drove wearable monitoring textiles to be widely applied in the fields of physiological signal monitoring, walking state recognition and human-computer interaction. Compared with traditional rigid sensor devices, fabric-based wearable monitoring systems were endowed with superior flexibility, air permeability and wearing comfort. They could be closely attached to human skin to achieve non-invasive and long-term real-time monitoring, and thus were regarded as ideal carriers in the fields of health management and intelligent interaction. However, the difficulty in their application was that most existing wearable monitoring textiles were dependent on external power supplies for operation. Restricted by factors such as power supply volume and battery life, they were unable to meet the demands of long-term, real-time and non-invasive monitoring. The introduction of self-powered technology offered a key solution to these problems. The functions of energy collection, conversion and signal transmission could be integrated into fiber or textile structures, and autonomous energy supply could be realized through human motion friction, ambient light and other means, which improved the battery life and usability of monitoring devices accordingly. Based on this, the research on self-powered technology for wearable monitoring textiles was identified as the core technology that could break through the limitations of external power supplies and propel wearable flexible sensing technology to transform from laboratory research to practical application.
Analysis In this paper, the self-powered mechanisms of wearable monitoring fabrics and the research and application progress of self-powered wearable monitoring fabrics were reviewed, which provided references for promoting the commercialization of wearable monitoring fabrics. The self-powered mechanisms of wearable monitoring fabrics were mainly dominated by triboelectricity, piezoelectricity, and photovoltaics. The energy supply performance of various energy supply mechanisms was improved through structural optimization and material modification. Among them, triboelectric energy supply was most widely applied and was sensitive to human low-frequency movements, but it had problems of humidity drift and packaging. Piezoelectric energy supply was featured with stable signals, yet the supply voltage was relatively low and the materials were prone to fatigue. Photovoltaic energy supply had high energy density, but its stability was insufficient and the packaging difficulty was high. Although ionic and humidity-driven energy supplies were applied in a small number of cases, both were found to have insufficient sweat resistance. At the application level, self-powered wearable monitoring fabrics had been applied in various fields such as physiological signal monitoring (pulse, respiration, sweat, etc.), walking states (gait recognition and analysis), and human-computer interaction. They were demonstrated to exhibit certain monitoring continuity and accuracy, but the monitoring precision was easily affected by factors such as motion artifacts, output power, and the complexity of system integration.
Conclusion As an important field of flexible wearable sensing technology, the self-powered wearable monitoring fabrics have been applied in various fields such as physiological signal monitoring, walking state recognition, and human-computer interaction. With the assistance of technologies such as machine learning, recognition resolution, monitoring accuracy and adaptability to complex application scenarios were further improved, which provided a research direction for non-invasive long-term intelligent monitoring. However, defects such as relatively low energy conversion efficiency, insufficient long-term stability, and difficulty in balancing sensing performance and comfort still existed. In the future, focus should be placed on the research and development of multi-mechanism synergistic energy supply materials, as well as the optimization of packaging and system integration, so as to promote the multi-dimensional signal monitoring of self-powered wearable monitoring fabrics.
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