International Conference on Advanced Electromaterials 2011

1. International Conference on Advanced Electromaterials 2011 Effect of UVA-LED on the Sterilization Young-Sun Jeon1, Bo-An Kang1, Seung-Dai Kim1, Young-Hwan Lee2, Ju-Hyun Jeong3, Seung Hwangbo4, Kyu-Seog Hwang1,* 1Department of Biomedical Engineering & Sun Tech, Nambu University, Gwangju, Korea 2Department of Automobile, Chunnam Techno College, Jellanam-do , Korea 3Department of Ophthalmic Optics, KonyangUniversity, Daejeon , Korea 4Department of Electronic & Photonic Engineering, Honam University, Gwangju, Korea 9VDC 9VDC 3.9V 3.9V 3.4V 3.4V 3.4ohmX2 3.1ohmX2 Introduction Ultraviolet irradiation is a common disinfection option for reducing the bacteria count in the developed world. A ultraviolet-light emitting diode has developed as a simple alternative light source to mercury lamp which has the high sterilization effect at around 260 nm. Since the disinfection effect and mechanism of ultraviolet A – light emitting diode have not yet investigated exactly, we studied ultraviolet A – light emitting diode bactericidal activity. The LED used in the work for inactivation of Escherichia coli in water has an emission maximum at 375 nm. The difference of disinfection effect between ultraviolet A – light emitting diode and visible radiation at 405 nm is investigated in this work. Experimental • DH5α strain (Escherichia coli) was used as indicator bacteria. • UVA-LED module (375 nm, P8D237, 1500μW, Seoul Optodevice) was used. • Reference LED module (405 nm,P8D240, 510mW, Seoul Optodevice) was used. • The bacterial suspension (200 μL) was poured into well plate where under the LED module. • The distance between LED module and bacterial suspension was 25 mm. • Bacterial suspension inside the chamber was maintained by two fans (powered by • 3 V batteries) placed at the bottom of the chamber. • All tests were completed within 2 hours. • The number of bacteria was measured by the colony-counting method. DH5α strain (Escherichia coli) Experimental devices Experimental results 375 nm 405 nm 405 nm 375 nm Emission spectra of the LED modules. 375 nm Survival rate of E. coli after exposure to the LED modules. Survival rate (SR) = log10 (N / N0) N: Number of bacteria colonies before irradiation N0: Number of bacteria colonies after irradiation Supply voltage : 9V DC Current : Total 700mA Resistance : 3.4 ohm x 2 Supply voltage : 9V DC Current : Total 1.40A Resistance : 3.1 ohm x 2 Conclusions UV-LEDs are an effective technology to inactivate E. coli in water. Here, we suggest the use of the UVA-LED for this work on disinfection . Advantages of UVA-LED over the UVC mercury lamp were a lower level of wasted to utilized energy and safety exposure procedures. As expected, 405 nm visible radiation was no effective for sterilizing, but 375 nm has the high sterilization effect. We showed that the UVA sterilization is a feasible at 375 nm-UVA which is more commercialized and verified than UVC-LED. Corresponding address Tel: +82-62-970-0110 Fax: +82-62-970-0288 E-mail: khwang@nambu.ac.kr Home page: http://opt.nambu.ac.kr/fml/prof.htm