Plasma sterilization

Furthermore, the EtO process presents wide effectiveness and possibility of validation in industrial sterilizators, when compared to the plasma sterilization process. It also shows advantages in comparison to other sterilant gases (formaldehyde and hydrogen peroxide) related to permeability, diffusion, volatilization, polimerization, and compatibility. 

NON-THERMAL PLASMA STERILIZATION OF DIFFERENT SURFACES MECHANISMS OF PLASMA STERILIZATION... 

Plasma sterilization is a quite complicated process determined by multiple plasma species and factors, including charged and excited species, reactive neutrals, and UV radiation. The contribution of these factors differs in different types and regimes of non-equilibrium plasma discharges also it differs from the point of view of induced biological pathways. The synergistic nature of the interaction between the plasma factors is important in sterilization similarly to the plasma treatment of polymers (see Section 9.7). First consider the... 

Low-pressure plasma discharges are able to provide significant UV radiation in the range of wavelengths effective in sterilization. It explains the important contribution of UV radiation in plasma sterilization at low pressnres, which has been discnssed in Section... 

A comparison of direct (without the mesh) and indirect (with the mesh) plasma sterilization is shown in Fig. 12-10. It is clearly visible that plasma that comes in direct contact with bacteria is able to sterilize significantly faster than an afterglow or jet. Only 5 s of direct plasma treatment resrrlts in the appearance of a sterihzation region (spot near the center). Complete sterilization occms within 15 s when direct treatment is employed and only partial disinfection can be achieved within the same time frame with indirect treatment. Over 5 min of indirect treatment is reqtrired to achieve sterihzation resrrlts similar to direct treatment obtained within 15 s. Therefore, even with substantial UV radiation, indirect plasma treatment is substantially weaker than the direct treatment provided by charged particles (see Section 12.1.3). 

Surface Versus In-Depth Plasma Sterilization Penetration of DBD Treatment into Fluid for Biomedical Applications... 

NON-THERMAL PLASMA STERILIZATION OF AIR STREAMS KINETICS OF PLASMA INACTIVATION OF BIOLOGICAL MICRO-ORGANISMS... 

Pathogen Detection and Remediation Facility for Plasma Sterilization of Air Streams... 

Table 12-2. Phenomenological Reaction Rate Coefficients for Plasma Sterilization of Bacteria (E. coli) using Ozone O3, Hydroxyl Radicals (OH), and UV Radiation...

In the framework of the aforementioned kinetic model of plasma sterilization, the following formula describes the rate of inactivation of airborne micro-organisms inside a DBD from the combination of effects of ozone, hydroxyl, and UV radiation ... 

Plasma sterilization data collected by treatment of E. coli in the described pulsed spark discharge (Campbell et al., 2006) are presented in Table 12 for two different initial conditions. When the initial cell count was high (1.8- 10 cfu/mL), the spark discharge could produce a 4-log reduction at 100 pulses and 2-log reduction at about 65-70 pulses. When the initial cell count was at an intermediate level (2 10 cfu/mL), the spark discharge produced a 2-log reduction at 50 pulses. Taking into account the energy of one pulse and volume of water, the minimum energy per 1L of water for 1-log reduction in... 

E. coli concentration is as low as 77 J/L. It should be mentioned that similar but much more detailed experiments with spark discharge treatment of E. coli in water at lower bacterial concentrations (Aijunan et al., 2007) results in similar very low values of the plasma sterilization energy cost (about 100 J/L). Table 12-5 compares major plasmas applied for water sterilization. The properties of spark discharges are beneficial for water treatment. The spark discharges in water investigated by Campbell et al. (2006) and Aijunan et al. 

Kinetic Modei of Non-Thermai Piasma Steriiization of Air Flow. Based on kinetic data presented in Table 12-1 and on comparison of experimental and simulation data on direct plasma deactivation of E. coli bacteria in air stream using a DBD discharge (Fig. 12-18), estimate reaction rate coefficient of plasma sterilization attributed to effect of charged particles. Assume that plasma density in the discharge is rig = lO cm, and that the charged particles are responsible for the discrepancy between experimental and simulation results presented in the Fig. 12-18. 

Remarkably, such peroxide plasma-sterilized articles also retain their advantageous multiaxial impact energies as well as tensile strength and elongation after being exposed to numerous sterilization cycles. These sterilized articles may be components of medical devices, sterilization devices, and food and beverage devices. 

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