Natural material-based biodegradable flexible pressure sensor for fall detection and rehabilitation monitoring in elderly care

Flexible pressure sensors (FPSs) offer unique benefits for fall detection and rehabilitation training, but conventional FPSs made from synthetic materials have drawbacks, including resource-heavy manufacturing, high costs, and environmental pollution. To address these limitations, this study proposes an innovative fabrication strategy for FPS based on natural materials. The upper and lower electrodes were made by treating a natural wood strip with a flame retardant, converting it into high-quality graphene via a cost-effective infrared laser, and transferring it onto starch-based substrates. The dielectric layer was created by electrospinning a composite nanofiber membrane with cyclodextrin and carbon nanotubes. The resulting capacitive FPS shows high sensitivity (2.15 kPa−1 within 0–10 kPa), a low detection limit (~6.5 Pa), fast response and recovery times (29 and 39 ms), and excellent long-term stability (over 5000 cycles). It also demonstrates excellent biocompatibility (cell viability >98%) and fully degrades within 6 h. By integrating this sensor with wireless technology, a fall detection and rehabilitation monitoring system was developed. Data processing was handled by a Tiny Machine Learning module on a mobile platform, which transmitted relevant data to a cloud-based platform. The system accurately identified five common fall postures and assisted clinicians in guiding rehabilitation exercises, achieving recognition accuracies of 99% and 100%, respectively, offering a sustainable healthcare solution for the elderly.