Smart sock: innovative system with embroidered textile electrodes for EMG monitoring of foot and leg muscles

Wearable biopotential monitoring is a promising technology for continuous, non-invasive assessment of physiological signs. Traditional gel-based electromyography (EMG) electrodes maintain gold-standard signal quality, yet skin preparation requirements and irritation issues restrict their use to short-term, clinic-based sessions, leaving a gap between laboratory precision and home monitoring. To address this gap, we developed and evaluated a smart sock system for continuous lower limb EMG monitoring. Four EMG acquisition systems were compared, ranging from conventional gel electrodes to an embroidered textile electrode integrated within a smart sock, with the conductive path formed by stainless steel conductive thread sewn into the cotton fabric, enabling seamless recording from three lower limb muscles without skin preparation. System type significantly affected signal-to-noise ratio (SNR) in the tibialis anterior (p = 0.0009) and abductor hallucis (p = 0.0162), as well as error metrics across all three muscles, most notably mean absolute error (MAE) in the gastrocnemius lateralis (η2 = 0.360). The 20 mm embroidered electrode achieved higher tibialis anterior SNR than the 30 mm variant (p = 0.0002) while requiring less material and fabrication time, and Bland–Altman analysis confirmed clinically acceptable agreement with gel electrodes. These findings demonstrate a smart sock system balancing clinical precision with real-world usability, with the 20 mm embroidered design (System C) showing the most favorable overall balance of signal fidelity, comfort, and manufacturing efficiency, supporting its potential for extended wearable monitoring.