Ultrafast Fabrication of Lignin-Encapsulated Silica Nanoparticles Reinforced Conductive Hydrogels with High Elasticity and Self-Adhesion for Strain Sensors

Abstract

Conductive hydrogels are receiving considerable attention because of their important applications, such as flexible wearable electronic, human-machine interfaces, and smart/soft robotics. However, the insufficient mechanical performance and inferior adhesive capability severely hinder the potential applications in such an emerging field. Herein, a highly elastic conductive hydrogel that integrated mechanical robustness, selfadhesiveness, UV-filtering, and stable electrical performance was achieved by the synergistic effect of sulfonated lignin-coated silica nanoparticles (LSNs), polyacrylamide (PAM) chains, and ferric ions (Fe 3+ ). In detail, the dynamic redox reaction was constructed between the catechol groups of LSNs and Fe 3+ , which could promote the rapid gelation of the acrylamide (AM) monomers in 60 s. The optimized conductive hydrogels containing 1.5 wt % LSNs as the dynamic junction points exhibited the excellent elasticity (<15% hysteresis ratio), high stretchability (∼1100% elongation), and improved mechanical robustness (tensile and compressive strength of ∼180 kPa and ∼480 kPa). Notably, the abundant catechol groups of LSNs endowed the conductive hydrogels with the long-lasting and robust self-adhesion, enabling seamless adhesion to the human skin. Meanwhile, the catechol groups also provided an exceptional UV-blocking capability (∼95.1%) for the conductive hydrogels. The combined advantages of the conductive hydrogels were manifested in flexible sensors for the high-fidelity detection of various mechanical deformations over a wide range of strain (10−200%) with good repeatability and stability. We believed that the designed conductive hydrogels may become a promising candidate material in future flexible wearable electronics for long-term and stable human movements monitoring.

Porous AgNWs/Poly(vinylidene fluoride) Composite-Based Flexible Piezoresistive Sensor with High Sensitivity and Wide Pressure Ranges

“…A comparison of the sensing performances of the PAPC- x based piezoresistive sensors is shown in Table S1. Such a sensitivity variation is typical for flexible piezoresistive sensors based on porous materials. , Figure c and Table S2 compare the sensing performances of the PAPC-based flexible piezoresistive sensor with other porous-based piezoresistive sensors reported in the previous literature, demonstrating the higher sensitivity and broader sensing range for the PAPC-based sensor simultaneously. ,− …”

Self-Adhesive and Conductive Dual-Network Polyacrylamide Hydrogels Reinforced by Aminated Lignin, Dopamine, and Biomass Carbon Aerogel for Ultrasensitive Pressure Sensor

“…As illustrated in Figure e–i, the pressure sensitivity ( S ), defined as S = (Δ I / I 0 )/Δ P , which was calculated from the slope of relative current change–pressure curve, was 170 kPa –1 (from 0 to 20 kPa), 110 kPa –1 (from 20 to 50 kPa), 46.3 kPa –1 (from 50 to 100 kPa), and 30.9 kPa –1 (>100 kPa). Such ultrahigh pressure sensitivity was near 4 orders of magnitude higher than that of conventional lignin-modified PAM hydrogels and was superior to the hydrogels derived from other biomass materials (Table S6). Moreover, the sensor possessed acceptable fatigue resistance and exhibited a stable electrosignal at 500 times reciprocating compression under 30% strain (Figure S8).…”

Synergy of Host–Guest and Cation−π Interactions for an Ultrastretchable, pH-Tunable, Surface-Adaptive, and Salt-Resistant Hydrogel Adhesive

“…Functional hydrogels are widely concerned by researchers because of their promising applications in flexible electronic devices, − wound dressings, − tissue repairing, and other fields. − Benefiting from their soft and wet nature, hydrogel adhesives display advantages such as biocompatibility, − controllable adhesiveness, − and moist environment for wound healing. − However, the applications of these materials on biointerfaces are limited by their brittleness. Another shortcoming of hydrogel adhesives is their deteriorated adhesion strength in a wet biological environment since their ionic attraction with the substrate would be screened by the electrolytes in the biological fluids.…”