Biofilms are comprised of diverse bacteria and fungi with slime material especially in high humidity condition. Since surface of the evaporator in an automobile is relatively high humidity condition due to the compression and relaxation of refrigerant, biofilms can be established easily on the surface, resulting in bad smell. In this work, we present a novel automotive air hygiene system based on inhibition of biofilm growth on the evaporator. A bioelectric current technology has been integrated on the system which is an optimized electromagnetic current for biofilm removal.The surface of biofilms is electrically polarized. Thus, when an electric field applies for biofilms, it induces electrostatic force by a direct current (DC) and electrical oscillation by an alternating current (AC). Based on these electrical interference principles of the biofilms, a new electromagnetic wave, named TROMATZ, has been optimized. The TROMATZ wave is characterized simultaneous application of both DC and AC signals with scale of 10uA that do not create an interference with other electronics. A prototype device has been fabricated and tested in an automotive evaporator part. Biofilms are cultured for 67 hours in a standard growth media on the surface of the evaporator, followed application of the electromagnetic wave for one hour. The total biomass of biofilms has been characterized by a standard staining method and analyzed via a fluorescence microscopy. The results demonstrate that approximately 81.8% of total biofilm were removed when the TROMATZ was applied. Furthermore, after 1 hours application of the electrical wave, live cell in biofilms has been reduced approximately 71.4% compared to non-treated biofilms.

PAIST: Young Wook Kim, Seungmo Lim; Korea Institute of Industrial Technology: Sang Kuy Han, Hae Won Choi; Korea Research Institute of Bioscience and Biotechnology: Bon-Sang Koo