Wearable Optical Fiber Sensors for Biomechanical Measurement in Medical Rehabilitation: A Review

With the increasing demand for rehabilitation of the elderly population and patients with limb injuries, it is imperative to develop new wearable health monitoring system and assistive rehabilitation equipment. Optical fiber sensing has the advantages of lightweight, anti-electromagnetic interference, higher strain and elastic limit, safety, and dependableness. It has been significantly used in engineering prospecting, building structure monitoring, and medical and health fields. At present, the application of optical fiber sensing in medical rehabilitation has been developed rapidly; however, the discussion and summary of its key theories and technologies are insufficient. This review details different types of optical fiber sensing mechanisms and devices, as well as the measurement of physical parameters using optical fiber sensors and application examples in the field of medical rehabilitation. This review systematically analyzes the advance of the sensitivity, flexibility, accuracy, and wearability of the optical fiber sensing in the monitoring of human body sign information. This review also discusses the challenges of making a new generation of optical fiber sensors that fit human joints, muscles, and rehabilitation equipment. Finally, this review provides a research direction for the realization of flexible, comfortable, safe, stable monitoring of human biomechanical parameters, and real-time precise control of rehabilitation equipment in the future.

I. Introduction

On May 11, 2021, the National Bureau of Statistics announced the data of the seventh census. The population of China age 60 years and above is 264 million, accounting for 18.7% of the total population. Compared with the sixth national census in 2010, the population age 60 years and above ratio increased by 5.44% points, and the aging situation is becoming increasingly severe [1]. The aging population’s physiological functions degenerate, inflicting health problems such as diabetes, stroke, cerebral palsy, spinal cord injury, and Parkinson’s disease, which have a great impact on their daily life. On the other hand, the proportion of individuals with limb or joint injuries is also increasing. For the basic living needs of these two groups of people, medical rehabilitation methods are indispensable, while traditional rehabilitation treatment is limited to clinical environments. With the continuous development of sensing technology, wireless communication technology, and signal processing methods, wearable sensor technology can provide patients with more flexible and free dynamic monitoring and can provide real-time monitoring data for rehabilitation therapists, so that the rehabilitation treatment process can be remote and not limited by the fixed environment.