Optimizing Lasing Parameters for Fabricating an Efficient Flexible Electrothermal Heater Based on Laser-Induced Graphene

This work involved fabrication of an efficient thin film heater from 100 μm thick polyimide (PI) sheet by scribing it using a carbon dioxide lasing machine through optimizing laser power (P), scanning speed (SS), and pulses per inch (PPI). A 15 mm × 15 mm square pattern was designed using CorelDRAW software and scribed in a rastering mode on top of PI with the help of Universal Control Panel (UCP) software of the laser machine. Laser power of 8 %, SS of 4 % and PPI of 1000 were obtained as optimal parameters for producing laser induced graphene (LIG). This LIG exhibited a low sheet resistance of approximately 16.64 Ω/sq and was thermally stable on the PI substrate even after 30 cycles of repeated heating and cooling. The LIG was found to be highly porous with the aid of scanning electron microscope (SEM) and its structure was crystalline from XRD patterns. FTIR was conducted and showed disappearance of functional groups in PI after treatment with the laser beam. Our developed LIG heater showed great electrothermal performance with maximum temperature of approximately 288.7 °C, rate of temperature rise of 107.06 °Cs -1 , and time of 1.85 s to reach 63 % of temperature difference at a low input voltage of 6 V with homogeneous temperature distribution seen in the thermal images taken using FLIR camera. This LIG heating element can be placed in confined spaces because of its flexibility, thinness, and lightness. Additionally, its efficient joule heating effect attracts many applications such as seat warmers, anti-fogging equipment, food shelf displays, etc.