All 3D-Printed Conducting Polymer Hydrogel-Based Soft Surface Electromyography Electrode Array for Noninvasive Fatigue Assessment.

Abstract

High-density surface electromyography (sEMG) electrode arrays allow the recording of rich myoelectric signals and provide a useful approach for monitoring exercise-induced muscle fatigue. However, existing sEMG electrode arrays often suffer from mechanical mismatches between conventional rigid electrodes and soft tissues, as well as complex fabrication processes and limited programmability, which severely constrain the rational design and practical application of sEMG electrode arrays. Herein, we successfully fabricate an eight-channel PEDOT:PSS-PVA hydrogel-based soft sEMG electrode array via a multi-material 3D printing. Through systematic rheological characterization of the composite inks and rational design of a printable three-layer electrode architecture, we achieve seamless interfacial integration and integrated sequential fabrication. The as-prepared sEMG electrode array exhibits exceptional softness comparable to that of human soft tissues (Young's modulus ∼ 10 kPa), low electrochemical impedance (∼22 Ω), and good electrochemical stability. Leveraging these advantageous properties, our sEMG electrode array enables noninvasive sEMG signal recording and monitoring of fatigue-associated sEMG changes with a high signal-to-noise ratio (SNR > 20 dB) under various grip forces before and after exercise, and captures sEMG changes associated with fatigue progression during repetitive movements. These results validate the capability of our electrode array for high-quality sEMG monitoring of fatigue-associated electrophysiological features and open up promising avenues for future applications such as scientific athletic training.

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