Sustainable Poly(lactic acid) Smart Mattress Surface Fabrics With Integrated Capacitive Sensors for Real-Time Sleep Monitoring

Smart mattress surface fabrics for real-time sleep monitoring have attracted significant interest, yet scalable and eco-friendly fabrication methods remain underdeveloped. In this work, a textile capacitive pressure sensor (TCPS) was seamlessly integrated into poly(lactic acid) (PLA) weft-knitted inlaid fabrics using a single-step intarsia knitting technique, eliminating the need for post-lamination or adhesives. The fabricated TCPS exhibited high sensitivity (1.73–0.09 kPa-1across 0–15 kPa), outperforming many previously reported textile-based capacitive sensors, while maintaining stable sensing performance under varied compressive pressures, compression rates, and repeated washing. The TCPS showed a hysteresis error of 14.02% at 6 kPa and maintained high repeatability over 5000 compression cycles at 15 kPa. Environmental tests indicated that baseline drift was mainly influenced by humidity, whereas the capacitance change ratio (ΔC/C0) remained relatively stable. In addition, the PLA-based TCPS fabric demonstrated superior comfort properties, including thermal insulation, air permeability, and water vapor permeability, compared to commercial mattress surface fabrics. Furthermore, a 4 × 4 TCPS array was embedded into the PLA fabric and wirelessly interfaced with a data acquisition module to acquire and record capacitance signals in real time for sleep monitoring. As a proof-of-concept demonstration, an offline deep learning model achieved an overall accuracy of 88.2% for classifying five typical sleep behaviors and 96% for identifying ten participants, validated under strict Leave-One-Subject-Out (LOSO) and stratified 70/30 protocols, respectively. This work presents a promising and scalable route to sustainable smart textile systems for personalized sleep monitoring.