UV-LED의 살균효과 연구

Abstract

The main theme in this study is checking the sterilizing effect using UV LEDs. Among UV LEDs being currently produced, UV-A, -B, -C having wavelengthes 365 ㎚, 310 ㎚, 265 ㎚ have been analyzed to know about the sterilizing effect for various bacteria. Escherichia coli (E. coli), salmonella, staphylococcus, bacillus, and vibrio are used as bacterium to do study, and luria-bertani (LB) is used to cultivate bacterium. Sterilizing system is made of UV LED box installed with UV LEDs having 265 ㎚, 310 ㎚, 365 ㎚ wavelengths, and the change of the amount of bacteria has been checked for various times according to the study schedule. For E. coli, this study uses two ways to check the amount of the bacteria. The first way is making UV-LED to irradiate directly on LB broth that E. coli is injected. The second way is making UV-LED to irradiate on the ampicillin plate covered with a regularly diluted LB broth. For salmonella, staphylococcus, bacillus, and vibrio, only the second way is used due to a dangerousness. According to the result from the test for E. coli, bacteria on the LB broth being irradiated by UV LED with wavelength 265 ㎚, and 310 ㎚, do not increase as times goes, but bacteria on the LB broth with wavelength 365 ㎚ significantly increase. On the ampicilliin plate being irradiated by UV-LED with wavelength 265 ㎚, bacteria decreases with 15 seconds half-life, and the bacteria are perfectly sterilized 5 minute after the irradiation. In the case of the irradiation with wavelength 310 ㎚, bacteria decrease with 15 minute half-life, and all the bacteria are sterilized 4 hours after irradiation. However, the result from the irradiation with wavelength 365 ㎚ is different from the others. Although, bacteria increase at the beginning, it keeps 90% of the initial amounts as time goes and it does not increase more than that. For the staphylococcus, bacteria decrease with 1.5 hours half-life, and all the bacteria are sterilized 6 hours after irradiation with wavelength 265 ㎚. In the case of the irradiation with wavelength 310 ㎚, the amount of bacteria keeps 80% of the initial amounts, and it does not show big variation. With the irradiation of wave length 360 ㎚, it does not show any sterilizing effect. For the bacillus, bacteria irradiated with wavelength 265 ㎚ decrease with 45 minute half-life, and those are perfectly sterilized 3 hours radiation. However, UV-LEDs with wavelength 310 ㎚ and 365 ㎚ do not show any sterilizing effect. For the vibrio, bacteria irradiated with wave length 265 ㎚ decrease with 5 minute half-life, and those are perfectly sterilized 50 minute after the irradiation. With wavelength 310 ㎚, bacteria decrease with 6 hours half-life, and UV-LED with wavelength 365 ㎚ does not show any sterilizing effect.