Low-Power Plasma Activation of Industrial Materials: Comparative Characterization of Gas and Substrate Effects on Surface Free Energy and Stability

Low-power plasma technologies are gaining increasing importance for industrial surface modification, particularly where energy efficiency and material integrity are critical. This work presents the design, construction, and characterization of a custom-built parallel-plate plasma system featuring micrometer-scale control of the electrode gap. The system enables stable plasma generation at low-power in milliwatt (mW) using both direct current (DC) and alternating current (AC), providing a versatile platform for controlled surface activation. The performance of the system was evaluated on a range of industrially relevant materials using different process gases. Surface characterization by atomic force microscopy (AFM) confirmed that the plasma treatment preserves the surface morphology, indicating non-destructive processing. Contact angle measurements revealed a substantial increase in surface free energy (SFE) across all tested materials, demonstrating enhanced wettability and activation. Furthermore, the modified surfaces showed stable SFE values over time, indicating durable surface functionalization.