Battery-Free, Wireless, Multilevel Structure Fabric Pressure Sensing Belt for Imperceptible Sleep Monitoring

Abstract

Mechanical fiber sensors that can be seamlessly integrated into traditional fabrics have significant potential for imperceptible sleep monitoring. Wet-spinning techniques are an effective method for fabricating fiber sensors. However, the sensors produced by this process have a single, homogeneous linear structure, which limits their high sensitivity and linearity to low-pressure ranges and presents challenges for stability. To address this issue, we propose an improved wet-spinning process for the large-scale production of a capacitive sensor that features both multilevel structure of varying heights and a core-sheath configuration (with commercial conductive yarn as the core and TPU as the sheath).Thanks to its multilevel structure, a multilevel structure fabric pressure sensing belt (MSFPSB) woven from this fiber sensor exhibits excellent linearity (R² = 0.998) and sensitivity (0.077 kPa⁻¹) over a pressure range of 3.3–30 kPa. Furthermore, the commercial conductive core ensures the sensor's stability after 4000 compression cycles. Additionally, we have developed a battery-free, wireless, stick-on-and-use-immediately data acquisition tag based on near-field communication (NFC). The tag works with a reader placed 5 cm away to imperceptibly monitor breathing, ballistocardiogram (BCG), and body motion signals during both work and sleep. This approach enhances the comfort of sleep monitoring and helps detect potential sleep disorders.

Graphical Abstract