Biocompatible Lignin-Containing Hydrogels with Self-Adhesion, Conductivity, UV Shielding, and Antioxidant Activity as Wearable Sensors

Hydrogels have drawn intensive attention as emerging materials for various applications in wearable sensors, soft robotics, and implantable devices. However, fabricating hydrogels with UV-shielding and antioxidant properties still remains a challenge. Herein, we prepared biocompatible 3-allyloxy-2-hydroxypropyl-lignin/polyacrylic acid (AHP-lignin/PAA) hydrogels with self-adhesion, conductivity, UV shielding, and antioxidant activity as wearable sensors by the incorporation of lignin into PAA. The structure, lap shear strength, and biocompatibility were characterized using the UV–vis spectrometer, universal testing machine, and cell test. The hydrogels showed strong adhesion to various substrates. The AHP-lignin/PAA hydrogels had excellent UV shielding and free radical scavenging capacity. Meanwhile, AHP-lignin/PAA hydrogels exhibited excellent sensitivity to tiny changes in low pressure. Notably, the hydrogels could adhere to the skin well without any other adhesives to monitor the movement signals of the body motion accurately. The biocompatible AHP-lignin/PAA hydrogels with self-adhesion, conductivity, UV shielding, and antioxidant activity offer great potential applications in wearable sensors.