Safety assessment of a novel cold atmospheric pressure plasma multijet device for biomedical applications

Cold atmospheric pressure plasma (CAP) is gaining attention in medicine for its antimicrobial and pro-proliferative effects in wound healing, and is emerging as a promising oncological therapy with high efficacy and minimal side effects. Current CAP technologies face distinct limitations on biological surfaces. Dielectric barrier discharge devices are difficult to apply to non-uniform surfaces due to variable electrode distance, while single-outlet plasma jets, though more suitable for irregular geometries, provide limited coverage and require prolonged treatment times. This study presents a safety assessment of a novel multijet CAP device, conducted in accordance with DIN SPEC 91315:2025-07. The helium-based system demonstrates consistent, treatment time-dependent surface coverage and low liquid evaporation, attributable to its low gas flow. Ex vivo, contactless temperature measurements showed that continuous manual treatment does not increase surface temperature beyond 40 °C. Electrical characterisation revealed a stable, controlled power profile modulated by input voltage and treatment distance. In vitro genotoxicity testing showed no chromosomal damage in HaCaT keratinocytes. Prolonged continuous exposure in confluent cultures caused minimal cytotoxicity, suggesting good tolerance up to three minutes at the 70% threshold. Overall, these findings demonstrate a safe, controllable plasma delivery platform for biological applications, supporting further development toward clinical translation.