Plasma
Plasma Sterilization – Medical Equipment
Ethylene Oxide (EtO) is the most common method of sterilant used in medical equipment facilities because it is universally effective on any medical equipment containing heat-sensitive polymers and/or having high aspect ratios, like long lumens. However, due to the high cost of EtO, high toxicity, and the length of time it takes to perform sterilization using this method, the FDA SBIR program is funding research to develop alternative sterilization solutions. ACT and Rutgers University have identified an ozone plasma sterilization system with plasma-in-lumen technology (Figure 1) to be one innovative alternative solution offering many improvements over EtO. Compared to other low-temperature sterilization approaches such as Vaporous Hydrogen Peroxide (VHP), ACT’s technology can sterilize lumens with arbitrary lengths.
Plasma-Powder De-Oxidation
Plasma, the fourth state of matter, is a highly reactive state that can be used to enhance or assist various chemical processes. Low-temperature plasma (LTP) creates a set of circumstances that enable chemical reactions without the adverse effects of material decomposition, melting, agglomeration, or sintering. One such chemical reaction is the reduction of metal oxides to form metal and water (MxOy → M+ H2O). Metal particles are used in a host of applications including energetic materials and 3D printing (i.e., additive manufacturing). When used (or even stored or transported) for these applications, the inherently thin layer of metal oxide on each particle surface grows, thereby changing the chemical and mechanical properties of the powders and any macro-scale parts manufactured from those powders. ACT is currently developing an LTP process that can reduce metal oxides from metal powders. Oxide content can be reduced as a pre-treatment prior to utilization/fabrication processes or as a post-treatment recycling process afterward. Oxides can be removed from metals and metalloids including copper, aluminum, steel, nickel alloys, and boron. If desired, ACT can also apply a plasma-enhanced chemical vapor deposition (PECVD) technique immediately after the LTP metal oxide reduction to passivate the reduced oxide particles. This PECVD passivation layer protects the particles from reoxidation during transport and storage in ambient conditions.
Publications:
- 1. P. Agrawal, D. Jensen, C.-H. Chen, R. M. Rioux, T. Matsoukas. “Surface-functionalized Boron Nanoparticles with Reduced Oxide Content by Non-thermal Plasma Processing for Nanoenergetic Applications.” ACS Appl. Mater. Interf. 13 (2021) 6844-6855.
- Dency, M. A.; Kintzer, J.; Schmitt, T.; Troop, G.; Balkhandia, P.; Chen, Chien-Hua; Jensen, D. Nonthermal Hydrogen Plasma Process for the Reuse of Metal Additive Manufacturing Feedstock Powder. Ind. Eng. Chem. Res. 2024, 63, 21890–21900.