This work reports, for the first time, the use of spark ablation with impaction printing to selectively deposit silver (Ag) and gold (Au) nanoparticle (NP) functionalization on single-layer graphene (SLG) based gas sensors. This method avoids lithography and chemical processes, maintaining the device's quality while potentially lowering the fabrication costs. Ag-decorated sensors reveal a three-fold improvement in nitrogen dioxide (NO₂) gas response over pristine-SLG sensors. We demonstrate detection capabilities down to 50 ppb at room temperature, negating the requirement for external thermal or photoactivation. In contrast to pristine or Au-decorated SLG sensors, Ag-decorated devices exhibit 96% recovery at room temperature (RT). These results highlight the potential of using spark ablation with impaction printing for functionalizing graphene-based sensors.

Packaging is an indispensable part in microelectronics manufacturing industry, where transfer molding as an essential step is typically included for encapsulation. Recently, with the fruitful achievements of research on graphene in gas sensing, there is also urgent need for study on how the packaging process will affect the graphene, to develop compatible manufacture protocol for practical graphene-based gas sensor. In this work, we carried out experiments on how molding compound outgassing affects graphene for gas sensing. Our results show that although there is some impact on the electrical properties of the graphene, there is no change in the microstructure, and only a slight and manageable change in gas sensing abilities. This work suggests that graphene could maintain performances after epoxy molding packaging processes.