Flexible Microplasma Discharge Device for Treating Burn Wound Injuries Against Fungal Infections Parinaz Eskandari 1* , Carol L. Beaver 2 , Silvia Rossbach 2 , Dinesh Maddipatla 1 , Massood Atashbar 1 1 Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, USA 2 Department of Biological Sciences, Western Michigan University, Kalamazoo, USA * parinaz.eskandari@wmich.edu Abstract—A flexible microplasma discharge device (MDD) was fabricated for the eradication of Candida albicans, an opportunistic pathogenic yeast, using ambient air as the sterilization agent. To fabricate the MDD, silver ink was deposited on flexible polyethylene terephthalate (PET) films in a honeycomb and circular design using screen-printing process to fabricate the top and bottom electrodes. Then the MDD was assembled by attaching the top and bottom electrode using a two-sided Kapton tape (dielectric layer). The antifungal efficacy of the MDD was investigated by varying parameters including treatment time (60, 90 and 120 seconds) and applied voltage (6, 8 and 10 V). The antifungal efficacies of 12.5% and 100% were achieved for applied voltage ranging from 6 V to 10 V for a treatment time of 60 seconds respectively. Similarly, as the treatment time increased from 60 seconds to 120 seconds for an applied voltage of 6 V, an efficacy rate of 3% to 95% was obtained, respectively. In addition, a surface temperature of 22.4 ◦C was measured at an applied voltage of 6 V which is safe to the wound area. This clearly demonstrated that the MDD can eliminate the C. albicans with an efficacy rate of 95% at a low voltage of 6 V and treatment time of 120 seconds. Keywords—Microplasma; flexible; sterilization; yeast; screen- printing; fungal infection; burn wound injuries; candida albicans. I. INTRODUCTION Sterilization describes a process that eliminates all microbial lifeforms including bacteria, viruses, spores and fungi. Microbial lifeforms that causes infections are called pathogens and many of these pathogens may cause irreparable problems specially when they enter through wounded skin preventing from healing. Infections also increase the patient’s risk of scars; in some cases, the pathogens spread to other parts of the body resulting in severe disabilities [1]. Therefore, elimination of pathogens from infected wounds, in other words, sterilization of wound is considered to be the first and important step in treating the wounds and promoting healing process. The National Center for Injury Prevention and Control in the United States reported that approximately 2 million fires occur each year causing 1.2 million patients with burn wound injuries (BWI) requiring hospitalization, and about 5,000 deaths each year from burn-related complexities [1]. The most common microorganisms that infects BWI are bacteria (70%), and fungi (20-25%) [2]. Topical and systemic antimicrobial agents have been used in treating BWIs. However, presence of fungal infection in burn wounds has been observed [1]. This is because, fungi, which are omnipresent microorganisms may lead to fungal superinfection when the normal bacteria biota is suppressed [2]. A prospective study was conducted with 70 burned patients to elucidate the pattern of microbial colonization of burn wounds and eight different species of bacteria along with one species of fungi (C. albicans) were found [2]. C. albicans is considered as an opportunistic fungi pathogen caused by yeast and became resistant to currently used azole compounds that exerts antifungal activity [3, 4]. Burn wounds are prone to invasive fungal infection and they are misrecognized due to the lack of clinical awareness and mycology laboratories [5]. Therefore, an early detection and an efficient approach for elimination of C. albicans, rather than using antifungal drugs, is necessary to potentially decrease the anti-fungal infections and mortality rate in immunocompromised hosts [5- 7]. In the last decade, the emergence of atmospheric pressure non-thermal plasma has led to powerful sterilization methods [8, 9]. Plasma is the fourth state of matter which is an electrically neutral, highly ionized gas containing ions, electrons, excited atoms, and ultraviolet (UV) irradiation, free radicals, and chemically reactive neutral particles. In non-thermal plasma, the energy is accumulated in the electrons and the temperature of electrons is in the order of 10 5 K and ions is about 300 K [10- 12]. In contrast to a thermal plasma based on coagulative and ablative properties, non-thermal plasma is known for medicinal effects on exposed tissue due to its minimal tissue damage [13- 16]. Different approaches are available such as plasma jets, corona discharge plasma sources and dielectric barrier discharge (DBD) plasma sources to produce nonthermal plasma at atmospheric pressure for biomedical applications [17- 19]. Both plasma jet and corona discharge are point based plasma sources (covering small regions) and requires arrays of devices to effectively inactivate pathogens leading to a significant wound-healing benefits. Plasma devices made of DBD are practically viable for wound healing applications since they can generate plasma over large areas and are easy to apply as a wearable bandage on the wound region in comparison with plasma jet and corona discharge approaches [20- 25]. In this work, a nonthermal flexible DBD based microplasma discharge device (MDD) was fabricated on flexible PET film using screen printing process to generate plasma at atmospheric pressure. C. albicans were cultured on agar plates. The antifungal efficacy of the MDD was investigated by exposing the C. albicans to microplasma discharge generated from the fabricated MDD and the results are analyzed and presented. U.S. Government work not protected by U.S. copyright 2022 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) | 978-1-6654-4273-2/22/$31.00 ©2022 IEEE | DOI: 10.1109/FLEPS53764.2022.9781581