Wound healing with nonthermal microplasma jets generated in arrays of hourglass microcavity devices

• Published in: Journal of physics. D, Applied physics Applied physics, 2014-10, Vol.47 (43), p.435402-7
• Main Authors: Park, Chan Hum, Lee, Joong Seob, Kim, Ji Heui, Kim, Dong-Kyu, Lee, Ok Joo, Ju, Hyung Woo, Moon, Bo Mi, Cho, Jin Hoon, Kim, Min Hwan, Sun, Peter Peng, Park, Sung-Jin, Eden, J Gary
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Arrays; Devices; Equivalence; Microcavities; microplasma; Microplasmas; Plasma (physics); plasma device; Radicals; wound healing
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/47/43/435402

Clinical studies are reported in which artificial wounds in rat epidermal and dermal tissue have been treated by arrays of sub-500 µm diameter, low temperature plasma microjets. Fabricated in Al/nanoporous alumina (Al2O3) by wet chemical and microablation processes, each plasma jet device has a double parabolic (hourglass) structure, and arrays as large as 6  ×  6 devices with 500 µm diameter apertures have been tested to date. Treatment of 1 cm2 acute epidermal wounds for 20-40 s daily with an array of microplasma jets generated in He feedstock gas promoted wound recovery significantly, as evidenced by tissue histology and measured wound area. Seven days after wound formation, the wound area of the untreated control was 40  ±  2% of its initial value, whereas that for an identical wound treated twice daily for 20 s was 9  ±  2% of its original surface area. No histological distinctions were observed between wounds treated twice each day for 10 or 20 s - only the full recovery time differed. Spectra produced in the visible and ultraviolet by He jets in room air are dominated by atomic oxygen (3p 5P → 3s 5S) at 777 nm and violet fluorescence (391.4 nm) from N2+, a species produced when the He (2s 3S1) metastable is deactivated by Penning ionization of N2. Although the combined cross-sectional area of the jets in the array is only 7% of the wound area, the microplasma treatment results in spatially uniform, and accelerated, wound healing. Both effects are attributed to the increased surface area of the jet array (relative to a single jet having an equivalent diameter) and the concomitant enhancement in the generation of molecular radicals, and metastable atoms and molecules (such as ).