Natural Material-Based Biodegradable Flexible Pressure Sensor for Fall Detection and Rehabilitation Monitoring in Elderly Care
Flexible pressure sensors (FPSs) are pivotal for fall detection and rehabilitation training, yet conventional synthetic-based sensors suffer from resource-intensive manufacturing, high costs, and environmental pollution. This study introduces a sustainable fabrication strategy for FPSs using natural materials. Electrodes were fabricated by treating natural wood strips with a flame retardant, converting them into high-quality graphene via cost-effective infrared laser processing, and transferring onto starch-based substrates. The dielectric layer comprised an electrospun composite nanofiber membrane of cyclodextrin and carbon nanotubes. The resultant capacitive FPS exhibited high sensitivity (2.15 kPa⁻¹ within 0–10 kPa), a low detection limit (~6.5 Pa), rapid response and recovery times (29 ms and 39 ms), and excellent long-term stability exceeding 5000 cycles. Biocompatibility was outstanding (cell viability >98%), and the sensor fully degraded within 6 hours. Integrated with wireless technology, the sensor enabled a fall detection and rehabilitation monitoring system. Data processing utilized a Tiny Machine Learning module on a mobile platform, transmitting data to a cloud-based system. The system accurately identified five common fall postures and assisted clinicians in guiding rehabilitation exercises, achieving recognition accuracies of 99% and 100%, respectively. This work offers a sustainable healthcare solution for elderly care, addressing environmental and economic limitations of existing FPS technologies.