Bio-inspired High-performance and Multi-functional Surfaces Tailored by Atmospheric Pressure Plasmas
Example of organization, memory, and density control of plasma streamers in our DBD plasma reactor using carefully controlled AC frequency and voltage. Argon (top row) and air (bottom row) discharges were excited at 20 kHz and 16 kHz, respectively, using the voltages shown. Photos (~500 ms exposure) were taken through the transparent FTO-coated (grounded) electrode side of the DBD plasma; bright spots are locations where multiple streamers are repeatedly initiated in a sequential fashion due to residual charge on the dielectric barrier surface. The field of view of all images is 4” diameter.
Our aim is to enhance the performance, utility and effectiveness of protective and other mission materials used by the soldier through systematic, micro- and nanoscale modification and control of the morphology and chemical functionality of surfaces. This endeavor involves the development of novel plasma-based processing tools and methods to impart bio-inspired multifunctionality to all manner of Army-relevant materials, e.g., (protective) materials with engineered wettability, chemical/fouling resistance, or anti-microbial action; chemical and biological agent sensing and defense capabilities; or energy generation and/or catalytic properties. In the first year of the project, we developed an atmospheric-pressure, dielectric barrier discharge (DBD) plasma tool for localized and user-definable structural and chemical modification of surfaces (Objective 1) and demonstrated, for the first time, that it is possible to spatially direct the formation of plasma microdischarges (also known as ‘streamers’), and hence location of surface modification, using patterned dielectric electrodes (Objective 2, patent pending [1a]). We have also studied and correlated how plasma streamers can modify the wettability (hydrophilic vs. phobic character) and chemistry of various material surfaces (polymers: PMMA, nylon, Teflon; glass; metals), as well as etch and modify surface roughness (Objective 3). We are collaborating with CCDC-NSC and have carried out initial experiments to create polymer surfaces with orthogonal multifunctionality (simultaneously hydrophilic and hydrophobic, Objective 4) as a platform to immobilize and test the bioactivity of CCDC-NSC’s enzyme catalysts for threat detection.
