Robotic Plasma System for Rapid Activation of Mass-Produced Electrochemical Sensors

Polishing, cleaning, and activation of solid electrode surfaces are common in electrochemistry; however, they are often labor-intensive, operator-dependent, and poorly reproducible. In the context of large-scale production of disposable solid-state sensors, such as screen-printed electrodes (SPEs), traditional surface conditioning procedures have proven to be impractical and incompatible with automated workflows. Here, we report the development of a low-cost robotic system that integrates a Tesla coil-based air-plasma generator with a Python-controlled XY motion platform for rapid (∼15 s per 0.11 cm²) and reproducible surface activation of SPEs. The main novelty of this study lies in the mechanization and reproducibility of the plasma activation process, achieved through the integration of a robotic platform with an air-plasma generator to enable standardized and scalable electrode conditioning. Morphological and Raman spectroscopic analyses revealed significant surface restructuring after plasma activation, leading to reduced charge-transfer resistance (from 7.10 to 0.45 kΩ), increased electron-transfer kinetics (∼4-fold increase in k⁰), increased electroactive area (from 0.073 to 0.270 cm²), and improved interelectrode reproducibility (RSD from 9.7 to 0.8%). The treatment also restored the voltammetric performance of carbon, gold, and platinum SPEs stored for over ten years. Plasma-treated carbon SPEs enabled the voltammetric determination of picric acid in simulated explosive samples (linear range: 0.5-50.0 μmol L^-1; LOD: 0.1 μmol L^-1). Moreover, 3D-printed electrodes were also successfully treated by using this system. This robotic plasma system provides a low-cost, scalable, and ecofriendly strategy for standardized activation of disposable electrodes, enhancing or restoring their electrochemical performance for routine analytical and industrial applications.