Dual-conductive hydrogels with anti-freezing and water-retaining properties for highly sensitive wearable sign language translation

With the continuous development of flexible electronics and human-computer interaction, the demand for flexible sensors in sign language recognition has further expanded. Hydrogels have emerged as promising candidate materials for flexible sensors due to their ability to efficiently convert mechanical deformation into electrical signals. To address the limitations of conventional hydrogels that suffer from insufficient service life caused by water evaporation or low-temperature freezing, this study prepared a composite hydrogel using a one-step polymerization method, in which acrylamide (AM) monomers were polymerized in situ within a system containing ionic liquid ([EMIM]Cl), polydopamine (PDA), and carbon nanotubes (CNTs), forming a polyacrylamide (PAM) network. Benefiting from multiple interaction mechanisms among PDA, [EMIM]Cl, and PAM, including hydrogen bonding, π-π stacking, and covalent bonds, the fabricated hydrogel exhibits exceptional tensile properties (elongation exceeding 2400 %), excellent water retention, antifreeze characteristics, and strong adhesion. As a strain sensor, it exhibits high sensitivity (GF = 2.38 within 0–400 % strain), fast response (< 80 ms), and durability (12,000 stretch-release cycles). By integrating the hydrogel strain sensor with peripheral circuits and a 1D-CNN algorithm, it can accurately capture hand movements, achieving a detection accuracy of 98.61 % for six complex sign language gestures. This provides an effective solution for high-performance sign language recognition.