Non-Thermal Plasma Induced Wettability Changes on Marina Wool via Atmospheric Dielectric Barrier Discharges

Water and detergents are used to deodorize and sanitize soiled fabrics on Earth. However, onboard the International Space Station (ISS) and future space missions to Mars, this solution is impractical. Launching more sets of clothing into space is also impractical, since it costs anywhere between $5,000 and $10,000 per pound to launch into space. Presently, no solution to deodorize and sanitize clothing onboard spacecraft exists. The purpose of this project is to analyze the prospect of using non-thermal, atmospheric dielectric barrier discharges (DBD) in the deodorization and sanitization of soiled fabric onboard spacecraft. Since astronauts commonly wear marina wool, this fabric was selected for all experiments. Preliminary findings show that surface modification of marina wool was achieved via direct exposure to DBD generated plasmas. The dielectric barrier discharge (DBD) reactor was positioned 1mm above a 1.50” diameter sample of marina wool and powered by an Amazing1 PVM500 AC Power Supply for a duration of 2 minutes per fabric sample at a frequency range of 14–22 kHz. Surface modification was determined by measuring the contact angle change of a 10 uL distilled water droplet on plasma-treated marina wool. The 10uL water contact angle on untreated marina wool is estimated to be greater than 160 ± 15°. Plasma treatment time of 2 minutes or more is required to obtain complete wettability (0°). During these 2 minutes, marina wool temperatures increased on average by 22.7 °F. Once complete wettability was obtained, the water contact angle on plasma-treated marina wool was nonexistent (0°) for a duration of 50 minutes. At 50 minutes, marina wool showed an estimated water contact angle of 48 ± 15°. A day later, the same fabric sample had an estimated water contact angle of 127 ± 15°. These preliminary results show that while surface modification was initially achieved, it was temporary with respect to the surface’s wettability. This signals that plasma will not permanently interfere with the fabric’s original anti-wetting properties—an important property in anti-fouling coatings. The degree of permanent, microscopic plasma-etching on the surface of the marina wool fabric samples remains to be seen. A set of plasma conditions (i.e. power, treatment time, gas type, pressure) will be investigated that can potentially eliminate transferred bacteria and odorous compounds, while maintaining the fabric’s structural integrity and anti-wetting properties. An in-space laundry solution—such as the one proposed here—would make astronauts more comfortable during long-duration space missions and significantly reduce the cost of launching a 6-man crew with the necessary clothing for a future 2.5 year trip to Mars.