Plasma formation using a capillary discharge in water and its application to the sterilization of E. coli

Abstract

An underwater electrical discharge in a narrow dielectric capillary provides the details of the evolution of microbubbles to plasma as formed by a tungsten electrode inserted in the capillary. An increase in the applied voltage forms microbubbles after water fills the capillary. A further increase in the voltage generates a surface discharge through the boundary of the bubble, elongating the bubble shape, and eventually forming plasma by electrical breakdown. This produces atomic oxygen, atomic hydrogen, and hydroxyl radicals from dissociation of water vapor. Also, a bactericidal test in normal saline solution showed that more than 99.6% of the bacterial cells were killed within 8 s, resulting from chlorine-containing species, in particular hypochlorous acid as a major bactericidal agent.

Visualization of Dynamic Sub-microsecond Changes in Membrane Potential

“…The model assumes that all the energy, as predicted by the FDTD model using applied voltage measured across a parallel resistor, reaches the cells as an electric field; however, ohmic losses before the electrodes, in the electrodes, or at the electrode-solution interface could decrease the electric field at the cell relative to its nominal value. Additionally, some energy may be lost in the formation of chemical species, such as the formation of hydrogen bubbles through electrolysis, from the electrical discharge from the tungsten electrodes (27). We have observed this effect through the formation of microbubbles during pulsing, albeit at higher potentials.…”

Effects of Plasma Activated Water on the Postharvest Quality of ‘Siberia’ Lily

“…There are a couple of methods of producing plasma-activated water using radicals produced in the plasma state such as a method of using microwave plasma and a method of producing plasma in water. Out of them, the underwater plasma technique resolves water with plasma that is produced by electrodes in water and creates reactive oxygen species (ROSs), and they react with water to produce hydrogen peroxide, and thus become bactericidal (Hong et al, 2010;Ma et al, 2017).…”

A Homogeneous Surface Inactivation Device Driven by a Pulse High‐Voltage Source

“…Atmospheric‐pressure cold plasmas (APCP) have recently used for surface modification, film deposition, water purification, biomedical inactivation, wound healing, and food safety protection, owing to their attractive and potential features . Compared to the conventional inactivation methods, APCP can offer a generation of UV radiation, reactive molecules/radicals (OH, O, O 3 , etc.…”