Effects of temperature and UV irradiation on picosecond laser fabricated flexible graphene microsensor for NO detection

In this study, a flexible graphene microsensor with an embedded microheater was fabricated for nitrogen monoxide (NO) detection. The microsensor and heater were fabricated on a polyethylene terephthalate (PET) substrate through picosecond laser ablation. The results of this study indicated that sensor temperature could be precisely and quickly controlled by adjusting the driving voltage of the microheater. The NO recovery time decreased from 1520 to 283 s (a drastic reduction of 81%) as the sensor temperature increased from 20 to 100 °C. Under ultraviolet (UV) irradiation, the recovery time decreased with the increase in input power of the LEDs. The recovery time decreased by 78% when the distance was 5 mm. In addition, the light-activation of UV-C light-emitting diodes (LED) revealed the promising gas sensing characteristics and visualized their possibility and capabilities. Furthermore, the gas sensor exhibited outstanding durability during cyclic bending tests. An increase in the bending angle decreased sensor response and increased NO recovery time, because sensor deformation influenced sensor conductivity. This study demonstrated the picosecond laser technique to the fabricated flexible graphene microsensor with the heating rate and UV-C irradiation, helping to design next-generation advanced devices for gas detection.