Ambient-Air Plasma Prototype: Proof-of- Concept E. coli Inactivation and PAW Characterisation

Abstract

Cold atmospheric plasma (CAP) is increasingly explored for antimicrobial wound care because reactive oxygen and nitrogen species (RONS) can be generated locally at low gas temperatures. However, many clinically used systems remain bulky and dependent on external gas and mains power, limiting their use in mobile or resource-limited settings. This work presents the development of a compact, battery-powered ambient-air cold plasma prototype integrating microcontroller-controlled high-voltage generation and guided airflow in a handheld housing based on paper 144 (BMT 2026). Optical emission spectroscopy (200- 440 nm) revealed a pronounced emission feature at 337 nm, consistent with excited nitrogen species and typical for air plasma, indicating the formation of bioactive plasma chemistry. Initial in-vitro testing on Escherichia coli DSM 613 demonstrated a clear exposure-time dependent reduction in bacterial growth on agar under non-thermal conditions. In addition, plasma-activated water (PAW) was characterized as a chemical process fingerprint using the summary parameters pH, electrical conductivity (EC), and oxidation-reduction potential (ORP) in deionized water, tap water, and 0.9% sodium chloride. At a standardized activation time (8 min, t1), the air-plasma “Wolke” source produced the strongest EC increase across matrices, highlighting its potential for efficient liquid activation.