Plasma enhanced planar crystal growth of laser induced graphene

•Cold Argon plasma treatment increases surface wettability of Polyimide surface.•Surface wettability was controlled by varying the plasma-tool scan speed.•Plasma treatment at low scan speed improves the crystallite size of LIG. The effect of wettability of Polyimide (PI) surface on the crystallite size and electrical conductivity of Laser-Induced Graphene (LIG) was studied for the first time. The wettability of PI was increased by varying the scan speed of a localised Argon cold plasma pen. The surface energy of PI increases with wettability which reduces the activation energy of diffusion of graphene nuclei and improves the crystallinity of LIG. The effect of plasma exposure was studied by contact angle measurement using two liquid solvents such as water and Ethylene Glycol (EG). Raman spectra of LIG showed that the crystallite size increased by 21 % at lower CO2 laser power (0.77 W) on PI pre-treated at a lower plasma scan speed (200 mm/min) which improved the conductivity by 51.13%. This study demonstrated that increased wettability of PI surface assists in the planar growth of LIG crystallites.