Abstract
Skin-interfacing electrodes are central to health monitoring, rehabilitation, stimulation, gaming, and AR/VR. Next-generation wearables demand high signal quality, conformability, and long-term comfort, yet existing gel and dry electrodes fall short. It is presented microprinted biphasic soft electrodes whose 3D microstructure and embedded liquid-metal droplets enlarge true skin contact and reduce contact impedance to 4.7 kΩ—a 14.1-fold reduction relative to Ag/AgCl (66.1 kΩ). The electrodes enable forehead EEG detection of the Berger effect, previously impractical with conventional electrodes, and deliver robust SNR during prolonged wear and motion. A simple model links infill geometry to effective surface area, guiding optimization and validated in n = 10 subjects. These versatile electrodes enable high-fidelity monitoring of muscle, heart, and brain signals for healthcare and advanced human-machine interfaces (HMIs), establishing a transformative paradigm for wearable bioelectronics in healthcare, neuroprosthetics, and advanced HMIs.