Leveraging 3-D Printer With 2.8-W Blue Laser Diode to Form Laser-Induced Graphene for Microfluidic Fuel Cell and Electrochemical Sensor

Realization of laser-induced graphene (LIG) by ablating laser on several substrates, like polyamide (PI), has gained huge attention. Generally, a CO₂ laser, with a 10.6- $\mu \text{m}$ wavelength, has been reported to form LIG. However, higher build area, the requirement of a higher power, limited LIG conductivity values, infrared wavelength, and cost are several drawbacks of the CO₂ laser-based process. Herein, a 3-D printer, loaded with a low-power (2.8 W) blue (450 nm) laser diode, has been demonstrated to create such LIGs with higher conductivity on PI sheets. The LIGs, with varying conductivity values, have been fabricated by diversified laser parameters achieving maximum conductivity of 2572.19 S/m, which was more than seven times higher than the one achieved by a CO₂ laser. Subsequently, such LIG was transferred to a lamination sheet, named T-LIG, using a laminator. Finally, T-LIG based microfluidic device was developed with a microchannel and three integrated electrodes for electrochemical detection of folic acid, achieving a limit of detection of $10 ~\mu \text{M}$ . Similarly, a microfluidic fuel cell was developed using T-LIG which provided a maximum power density of $5.06 ~\mu \text{W}$ / cm² with a maximum open-circuit voltage of 50 mV. Overall, such T-LIG-based microfluidic devices have huge potential for diverse applications.