BandEI: A Flexible Electrical Impedance Sensing Bandage for Deep Muscles and Tendons

Monitoring deep muscles and tissues is critical for rehabilitation, training, and fine motor control. In this work, we propose BandEI, a flexible, bandage-like wearable sensor for electrical impedance sensing. BandEI utilizes woven conductive fabric as the core material for its electrodes and leverages digital fabrication, including laser cutting, to enable scalable and customizable fabrication. To streamline the design process, we provide a user interface that allows users to freely select the deployment location of BandEI. The interface automatically generates fabrication-ready design files that accommodate for the curvature and shape of the selected area. We evaluate BandEI and validate its ability to detect signals from actively engaged large muscles, such as the biceps and triceps. Additionally, it can capture signals from deep or passively activated muscles, like those in the hand, which are typically difficult to detect with conventional surface electromyography (sEMG). We design and implement BandEI for muscles in the fingers, neck, and ankle, demonstrating its capability for diverse applications, including real-time gesture recognition, neck motion monitoring, and gait tracking.