A damping hydrogel with high water retention and strong adhesion for precise bioelectric signal detection†

Bioelectric signals are important for understanding biological patterns and treating diseases. However, the detection of bioelectric signals is often interfered with by artifacts caused by unintentional human movements, therefore, the damping of the interface experiencing vibrations is crucial for obtaining clear bioelectric signals. Herein, we propose a hydrogen bond-engineered dual-network hydrogel damper via a photopolymerization strategy, incorporating acetamide (AC) molecules as dynamic bonding regulators. Because of the amphiphilic nature of AC, it can act as both a hydrogen bond donor and acceptor, contributing to the construction of a high-density interpenetrating hydrogen bond network in chitosan/acrylic matrices. The hydrogel damper exhibits a high water retention (8% water loss for 5 days at 25 °C, 54% RH), a strong adhesion (93.42 kPa on skin), and a high damping performance (tan δ > 0.3) in the human movement frequency range (1–50 Hz). Due to these properties, the hydrogel is firmly attached to the human skin, reducing the interface impedance between the hydrogel damper and the skin, and can be stored at room temperature for a long time without losing water. In addition, the hydrogel damper has a frequency-dependent dynamic mechanical behaviour that selectively removes motion artifacts to improve the stability and reliability of bioelectric signals.