Microbial Decontamination of Food by Light-Based Technologies: Ultraviolet (UV) Light, Pulsed UV Light (PUV), and UV Light-Emitting Diodes (UV-LED)

A double-sided freeform lens is proposed for collimating light emitted from light emitting diodes (LEDs). The surface profiles of the lens are mathematically characterized and precisely determined based on a point-source assumption and differential geometry theory. The proposed lens design method is straightforward, flexible, and effective. Moreover, the optical performance of the lens can be intuitively adjusted by tuning just a small number of design parameters. The simulation results showed that the proposed lens achieved an excellent collimating effect for a commercial ultraviolet (UV) LED. A prototype lens is fabricated in UV-grade poly(methyl methacrylate) material using a standard injection molding process. The light collimating effect of the lens/UV-LED assembly was measured experimentally and was shown to be in good agreement with the simulation results. The collimating angle at the half-energy level was equal to 1.88°. The performance of the UV-LED is thus comparable to that of conventional lithography UV light sources based on mercury arc lamps. Consequently, the proposed double freeform lens showed significant potential for photolithography applications within the industry.

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Inactivation of health-related microorganisms in water using UV light-emitting diodes

Water Science & Technology Water Supply ◽

10.2166/ws.2019.022 ◽

2019 ◽

Vol 19 (5) ◽

pp. 1507-1514 ◽

Cited By ~ 5

Author(s):

Kumiko Oguma ◽

Surapong Rattanakul ◽

Mie Masaike

Keyword(s):

Spectral Sensitivity ◽

Legionella Pneumophila ◽

Light Emitting Diodes ◽

Uv Light ◽

Feline Calicivirus ◽

Response Curves ◽

K Value ◽

Light Emitting ◽

Uv Led ◽

Uv Leds

Abstract UV light-emitting diodes (UV-LEDs) offer various wavelength options, while microorganisms have spectral sensitivity, or so-called action spectra, which can be different among species. Accordingly, matching properly the emission spectra of UV-LEDs and the spectral sensitivity of microorganisms is a reasonable strategy to enhance inactivation. In this study, UV-LEDs with nominal peak emissions at 265, 280 and 300 nm were applied to pathogens including Legionella pneumophila, Pseudomonas aeruginosa, Vibrio parahaemolyticus and feline calicivirus, in comparison with indicator species including Escherichia coli, Bacillus subtilis spores, bacteriophage Qβ and MS2. The results indicated that, for all species tested, 265 nm UV-LED was highest in the fluence-based inactivation rate constant k, followed by 280 nm and 300 nm was much lower. The k value at 280 nm was close to that at 265 nm for feline calicivirus and MS2, suggesting that 280 nm UV-LED can be as good an option as 265 nm UV-LED to inactivate these viruses. Bacteria tended to show fluence-response curves with shoulder and tailing, while viruses followed log-linear profiles at all wavelengths tested. This study indicates the fluence-response profiles and the fluence required for a target inactivation of microorganisms, which would serve as reference data for future study and applications of UV-LEDs.

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Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese

Applied and Environmental Microbiology ◽

10.1128/aem.02092-15 ◽

2015 ◽

Vol 82 (1) ◽

pp. 11-17 ◽

Cited By ~ 41

Author(s):

Soo-Ji Kim ◽

Do-Kyun Kim ◽

Dong-Hyun Kang

Keyword(s):

Foodborne Pathogens ◽

Light Emitting Diodes ◽

Uv Light ◽

Content Type ◽

Warm Up ◽

Light Emitting ◽

Uv Led ◽

Serovar Typhimurium ◽

Uv Lamps ◽

Uv Leds

ABSTRACTUVC light is a widely used sterilization technology. However, UV lamps have several limitations, including low activity at refrigeration temperatures, a long warm-up time, and risk of mercury exposure. UV-type lamps only emit light at 254 nm, so as an alternative, UV light-emitting diodes (UV-LEDs) which can produce the desired wavelengths have been developed. In this study, we validated the inactivation efficacy of UV-LEDs by wavelength and compared the results to those of conventional UV lamps. Selective media inoculated withEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogeneswere irradiated using UV-LEDs at 266, 270, 275, and 279 nm in the UVC spectrum at 0.1, 0.2, 0.5, and 0.7 mJ/cm2, respectively. The radiation intensity of the UV-LEDs was about 4 μW/cm2, and UV lamps were covered with polypropylene films to adjust the light intensity similar to those of UV-LEDs. In addition, we applied UV-LED to sliced cheese at doses of 1, 2, and 3 mJ/cm2. Our results showed that inactivation rates after UV-LED treatment were significantly different (P< 0.05) from those of UV lamps at a similar intensity. On microbiological media, UV-LED treatments at 266 and 270 nm showed significantly different (P< 0.05) inactivation effects than other wavelength modules. For sliced cheeses, 4- to 5-log reductions occurred after treatment at 3 mJ/cm2for all three pathogens, with negligible generation of injured cells.

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Performance of vertical type deep UV light-emitting diodes depending on the Ga-face n-contact hole density

Applied Physics Letters ◽

10.1063/5.0052416 ◽

2021 ◽

Vol 118 (23) ◽

pp. 231102

Author(s):

Youn Joon Sung ◽

Dong-Woo Kim ◽

Geun Young Yeom ◽

Kyu Sang Kim

Keyword(s):

Light Emitting Diodes ◽

Uv Light ◽

Hole Density ◽

Light Emitting ◽

Deep Uv

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New Results on Electroluminescence from Porous Silicon

MRS Proceedings ◽

10.1557/proc-283-343 ◽

1992 ◽

Vol 283 ◽

Cited By ~ 22

Author(s):

Peter Steiner ◽

Frank Kozlowski ◽

Hermann Sandmaier ◽

Walter Lang

Keyword(s):

Porous Silicon ◽

Quantum Efficiency ◽

Light Emitting Diodes ◽

Uv Light ◽

Green Light ◽

Light Emitting ◽

Porous Region ◽

First Results

ABSTRACTFirst results on light emitting diodes in porous silicon were reported in 1991. They showed a quantum efficiency of 10-7 to 10-5 and an orange spectrum. Over the last year some progress was achieved:- By applying UV-light during the etching blue and green light emitting diodes in porous silicon are fabricated.- When a p/n junction is realized within the porous region, a quantum efficiency of 10-4 is obtained.

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