Capacitive stretch sensors for knee motion and muscle activity tracking for gait analysis

Gait analysis is crucial for understanding human movement and has significant health monitoring and rehabilitation implications. However, current methods for analyzing walking gait often lack accuracy and comfort. While flexible sensors are typically used to measure knee angles, they do not adequately monitor muscle activity in the calf and thigh, which is essential for a comprehensive gait analysis. To address this, we developed capacitive stretch sensors using a parallel plate capacitance model, combining Ecoflex with Carbon Black as the conductive material and Ecoflex as the flexible, stretchable substrate. Three of these sensors were attached to a knee brace, resulting in a lightweight, comfortable, and user-friendly measurement system. This integration significantly reduces sensor hysteresis errors. The knee brace converts knee bending angle and muscle activity into electrical signals, allowing for detailed analysis. This enables the recognition of different walking gaits by distinguishing between knee-bending angles and muscle activities. The use of an integrated knee brace with flexible stretch sensors offers precise gait measurements and valuable data for applications in human health monitoring, rehabilitation training, sports monitoring, and human-computer interaction, presenting broad prospects for future use.