Ultrasoft Zwitterionic Eutectogels for Adaptive and Durable Sensing at Dynamic Skin Interfaces

Zwitterionic hydrogels have attracted considerable interest as promising candidates for next-generation bioelectronic interfaces due to their intrinsic antifouling characteristics and efficient ionic conductivity. However, their practical use is often limited by low mechanical compliance, poor adhesion to biological substrates, and environmental vulnerability. Herein, we report a new class of zwitterionic eutectogels synthesized through a one-pot photopolymerization of zwitterionic and polar monomers in a deep eutectic solvent (DES). The DES phase not only serves as a nonvolatile medium but also promotes multivalent hydrogen bonding and electrostatic coordination, resulting in a skin-compliant yet tough polymer network. The resulting eutectogels exhibit an ultralow modulus (∼10 kPa), toughness of 160 kJ m^-3, stretchability of 850%, and ionic conductivity of 70 mS m^-1. Crucially, they also maintain environmentally tolerant and strain-adaptive interfacial adhesion, enabling reliable and conformal contact with dynamically deforming skin. These features collectively enable robust electrophysiological signal acquisition and high-fidelity strain sensing, highlighting their potential as a versatile platform for wearable bioelectronics and soft human-machine interfaces.