Flexible Segmented Assemblable Fiber Optic Sensor for Human Multi-Joint Monitoring

Human joint motion monitoring is essential for disease diagnosis, rehabilitation, health management, and enhancing human-computer interaction experiences. This work presents the development and validation of a flexible segmented assemblable fiber optic sensor (FSAFOS) specifically designed for human multi-joint monitoring. The FSAFOS is composed of miniature LEDs, segmented polymethyl methacrylate optical fibers, and photoconductive chips encapsulated in a flexible cladding, allowing it to accurately sense joint bending angles while maintaining high flexibility and comfort. The modularity of the FSAFOS enables rapid customization and assembly through magnetic connectors, adapting to various joint configurations and sizes. Experimental results demonstrate that the sensor exhibits good stability, low hysteresis (<5%), and high linearity (<i>R</i>² = 0.996) in measuring bending angles. In validation experiments, the FSAFOS accurately measured finger joint and spinal bending angles with errors less than 1.85° compared to ground truth. The FSAFOS represents a significant advancement in the field of biomechanical monitoring, offering potential applications in personalized posture monitoring and human-machine interfaces.The study protocol was approved by the Medical Ethics Committee from the Department of Psychology and Behavioral Sciences, Zhejiang University, China (reference number: [2022]098).