Cold plasma technology is an emerging and promising technology both in the medical field and in the agricultural sector (Han et al., 2020; Maisch et al., 2012; Schmidt et al., 2020). The technology effectively decontaminates various spoilage and pathogenic microorganisms using plasma discharges to generate reactive species (Jyung et al., 2022; Liao et al., 2019; Wang et al., 2016). Plasma-activated water (PAW) has also gained attention alongside cold plasma technology as a novel and chemical-free disinfectant (Gao et al., 2015). Diverse reactive oxygen and nitrogen species (RONS) generated from cold plasma discharges interact with the solution, undergoing multiple chemical reactions and transforming into long-lived species, such as H2O2, O3, or nitric acids, which contribute to microbial inactivation (Kim et al., 2010; Man et al., 2022; Zhou et al., 2020). Unlike chlorinated sanitizers, various reactive species in PAW do not produce harmful byproducts, increasing its attraction as an alternative disinfectant (Patange et al., 2018). Therefore, the generation of sufficient amounts of RONS is crucial to ensure the efficacy of PAW-based decontamination.

The effectiveness of microbial inactivation in PAW varies depending on the type of plasma discharge, electrode shape, working gas, chemical composition, discharge time, treatment time, and dissolved RONS (Jiang et al., 2014; Thirumdas et al., 2018). Among these factors, electrode geometry has been studied extensively (Nau-Hix et al., 2022; Trosan et al., 2024; Perinban et al., 2019). Dielectric barrier discharge (DBD) is one of the most widely applied plasma sources due to its compatibility, reliability, and scalability (Kogelschatz, 2003; Zhou et al., 2020). Recently, DBD plasma sources have attracted attention in various fields related to environmental chemistry, such as methane reforming, biomedical applications, and food processing (Kuchenbecker et al., 2009).

Surface dielectric barrier discharge (SDBD) has a basic set up similar to that of DBD, as both consist of a pair of electrodes and a dielectric barrier (Portugal et al., 2022). However, SDBD differs in that it has an asymmetrical configuration of the two electrodes, and the discharge is generated along the surface of the profile, which is exposed to surrounding air or gas (Han et al., 2019). The structural differences provide SDBD advantages that overcome several limitations of current cold plasma sources. The surface electrode partially covers the dielectric or the ground electrode, allowing SDBD to operate at lower applied voltages or input powers compared with conventional DBD, which has a large gap distance (Misra et al., 2019). Because SDBD can be ignited and sustained without a substrate, the discharge remains stable (Pai et al., 2018; Trosan et al., 2024). SDBD electrodes can also be produced with flexible materials that can form diverse geometries and maintain a constant distance between uneven samples (Yong et al., 2017). These advantages have led to increased attempts to apply SDBD to numerous applications, including microbial inactivation or in-package plasma processing for food decontamination (Gershman et al., 2021; Jayasena et al., 2015).

Despite the advantages of SDBD, the impact of electrode geometry on microbial inactivation and the concentration of plasma-generated RONS has yet to be well defined. As previously described, the microbial inactivation of PAW can be attributed to dissolved RONS (Zhao et al., 2020), and it is essential to determine whether the geometry of the SDBD electrode influences the generation of RONS. Furthermore, RONS generation conditions in PAW need to be optimized for maximizing microbial inactivation and the concentration of RONS. The objectives of this study were to evaluate microbial inactivation in PAW and the concentrations of RONS generated by SDBD using different electrode geometries, optimize the bacterial inactivation of PAW by adjusting the operating parameters, and measure the concentrations of RONS from SDBD discharge and dissolved reactive species in PAW to understand their role in bacterial inactivation.