Low-Defect Laser-Induced\nGraphene from Lignin for\nSmart Triboelectric Touch Sensors

Laser-induced graphene (LIG) has\nemerged as a versatile\ncarbon\nmaterial for broad applications. However, the synthesis of high-quality\nLIG materials, especially with low defects, remains underexplored.\nThis study was thus focused on developing a facile and cost-effective\nalternative to producing low-defect LIG, especially using lignin as\na renewable precursor. The results showed that lignin treated by methyl\nethyl ketone yielded LIG with a markedly low-defect level (<i>I</i><sub>D</sub>/<i>I</i><sub>G</sub> ratio of 0.12)\nby direct laser writing under ambient conditions. The triboelectric\ntactile sensor fabricated from low-defect LIG electrodes exhibited\nexceptional durability (over 15,000 cycles), accurate and real-time\nresponsiveness (<0.01 s), wide-ranged touch frequencies (1–6\nHz), and ultrasensitivity to pressure (5–300 kPa). Moreover,\nthe sensor was successfully demonstrated for the wireless control\nof LEDs. This work indicated that lignin-derived low-defect LIG has\ngreat potential for smart electronics applications.