Experimental study of flexible sensors based on ultraviolet nanosecond laser induced graphene

Abstract

Current laser-induced graphene (LIG) methods encounter challenges such as subpar graphene quality and intricate manufacturing of electronic devices using graphene. In order to tackle these issues, this paper proposes a method of using an ultraviolet nanosecond pulse laser to stimulate the formation of graphene. Polyimide (PI) is subjected to laser irradiation in a single step to produce high-quality porous graphene. Subsequently, low-cost flexible pressure and strain sensors are manufactured using graphene. The Raman spectroscopy results demonstrate that the graphene generated has excellent quality (ID/IG = 0.14, I2D/IG = 0.37). Scanning electron microscopy shows that the LIG surface has a uniform porous morphology, with a patterning precision of 100 μm and a sheet resistance of 9.29 Ω/sq. The performance of the flexible pressure sensor was evaluated, demonstrating precise sensitivity (0.75 KPa−1 within 2.5 KPa range), a broad detection range (0–160 KPa), and a minimal detection limit of 20 Pa. The strain sensor exhibited a high level of sensitivity to strain (GF factor of 139), a broad linear range of strain (0–35 %), a low limit of detection (capable of detecting strains as low as 0.6 %), and outstanding durability (no signal distortion was observed even after subjecting it to over 2500 cycles of stretching). Flexible sensors can be worn as electronic skin on fingers, the neck, and the surface of robotic claws. The research results show that ultraviolet nanosecond pulsed lasers, using the LIG process, can produce graphene of higher known quality. The flexible pressure and strain sensors fabricated from this graphene exhibit outstanding performance.