Comparative evaluation of the virucidal effect of remote and direct cold air plasmas with UV‐C

Abstract

Cold atmospheric pressure plasma is an emerging nonthermal processing technology for the decontamination of foodborne pathogens. This study presents a comparative evaluation of the energy efficiency of the decontamination by three different dielectric barrier discharge (DBD) setups operating in air against Feline calicivirus with a UV‐C lamp. Significant enhancement of the energy efficiency was achieved with a lab‐scale batch reactor prototype, which employed surface DBD, leading to similar energy per unit area requirements as that for UV‐C. A key advantage of plasma over UV‐based disinfection systems is that plasmas are not limited by shadowing effects. Nonetheless, unlike UV‐C, the virucidal efficacy of plasma is significantly reduced for dry samples and remote plasma treatment is only effective against wet samples.

Non-Thermal Plasma as a Novel Strategy for Treating or Preventing Viral Infection and Associated Disease

“…Because plasma can flow around complex 3D surfaces, decontamination by plasma technology is not limited by shadowing. A recent study compared UV-C with plasmabased inactivation of feline calicivirus (FCV) on surfaces and showed that the energy cost of plasma-based inactivation can be similar to UV-C [67]. However, UV-C was effective both on dry and humid surfaces, while plasma was shown to be less effective on dry substrates [67].…”

“…DBDs are generated by time varying voltage excitation approaches with varying geometries. Examples include nanosecond-pulsed direct DBDs (Figure 6A) [67,95], surface DBDs (Figure 6H) [67,96,99], and a 2D array of integrated coaxial microhollow DBD (Figure 6G) [95, 100,101].…”

“…In general, the direct treatment modality is more effective against viruses compared to remote treatment. In particular, it was found that remote DBD treatments were not effective for dry virus, while direct treatment could inactivate virus on both dry and humid substrates [67,101]. Although complete inactivation (>4 log 10 reductions) was achieved for both treatment modalities, the inactivation could be reduced from a minute to a second time scale with direct treatment [95] (Figure 7A).…”

“…When aerosolized virus was sent through the plasma, the virus inactivation timescale was further reduced to 10 ms [115]. While the direct treatment modality is more effective, it does not always entail larger energy efficiency for surface decontamination expressed as energy per unit area [67]. In first order approximation, this unanticipated result is due to the potential of a remote plasma source to treat surfaces that are much larger than its crosssectional area.…”

“…Plasma will directly inactivate the airborne virus with efficacies in excess of 99.9%, comparable to HEPA efficacies. The small pressure-drop across the plasma systems when mounted in air handling systems compared to HEPA filters will potentially require smaller [67,94,95,101,162] and are normalized to the reference virus titer. The short dashed colored lines represent the detection limit for each of the corresponding plasma treatment.…”