A Simple, Low-Cost Multi-Sensor-Based Smart Wearable Knee Monitoring System

Maintaining good mobility with ease and freedom of movement is important for an individual's health and active aging. The knee joint, being the primary bearer of the body weight, plays a vital role in mobility. Continuous monitoring of the knee joint can potentially provide important information related to knee health and mobility which can be used for health assessment, early diagnoses of mobility-related problems, and monitoring recovery from injury or surgery. Therefore, we developed a simple, low-cost multi-sensor-based smart wearable device to monitor and assess the knee joint and mobility. The system is composed of miniaturized sensors (motion, temperature, pressure and galvanic skin response) to measure acceleration, angular velocity, skin temperature, muscle pressure and sweat rate of the knee joint during different activities. A database is constructed from 70 healthy adults aged 18-86 years that contains sensor data measured using the proposed knee joint monitoring system. To extract key knee and gait features from the datasets, we employed computationally efficient methods such as complementary filter and wavelet packet decomposition. The variations in the characteristics of the obtained parameters were analyzed in terms of gender and age groups. This simple, easy-to-use, cost-effective, non-invasive and unobtrusive knee monitoring system can be used for real-time monitoring, evaluation and early diagnoses of joint disorders, fall detection, mobility monitoring and rehabilitation.