Strain-Decoupled Serpentine Heterostructured Hydrogel Electrodes for Motion-Artifact-Resistant Electrophysiology

Motion artifacts caused by mechanical mismatch at the skin-electrode interface remain a central barrier to reliable epidermal electrophysiology during dynamic activity. Here, we report a strain-decoupled serpentine heterostructured hydrogel electrode (SHGE) that integrates a laser-patterned serpentine geometry with a laminated bacterial cellulose/tannic acid supporting layer and a conductive MXene/poly(vinyl alcohol) hydrogel layer. The heterostructure provides interfacial hydrogen bonding and topological interlocking, while NaOH-induced PVA nanocrystalline domains and the serpentine layout jointly suppress crack propagation and localize deformation away from the sensing interface. As a result, the SHGE exhibits a fracture energy of 23.4 kJ m^-2, suppressed resistance drift under 0°-120° bending, stable electrical output over 50 000 bending cycles, and strain-insensitive operation up to 70% deformation. During dynamic electromyography and electrocardiography recordings, the SHGE reduces motion-induced baseline fluctuation and maintains higher signal-to-noise ratios than commercial Ag/AgCl electrodes across multi-day and outdoor exercise protocols. When integrated with a wireless acquisition module and a machine-learning classifier, the high-fidelity signals enable classification of eight representative human motions with an overall accuracy above 90% under the tested data-splitting protocol. The same heterostructure strategy enhances fracture resistance across multiple polymer matrices, indicating a general design route for deformation-resistant hydrogel bio-interfaces.