scholarly journals Estimation of the Ultraviolet-C Doses from Mercury Lamps and Light-Emitting Diodes Required to Disinfect Surfaces

2021 ◽  
Vol 126 ◽  
Author(s):  
Pablo Fredes ◽  
Ulrich Raff ◽  
Ernesto Gramsch ◽  
Marcelo Tarkowski
Keyword(s):  
Light Emitting Diodes ◽  
Optical Power ◽  
Computational Procedure ◽  
Light Sources ◽  
Dose Distributions ◽  
Light Emitting ◽  
Radiant Efficiency ◽  
Ultraviolet C ◽  
Simulation Results ◽  
Uv C

Disinfection of surfaces by ultraviolet-C (UV-C) radiation is gaining importance in diverse applications. However, there is generally no accepted computational procedure to determine the minimum irradiation times and UV-C doses required for reliable and secure disinfection of surfaces. UV-C dose distributions must be comparable for devices presently on the market and future ones, as well as for the diverse surfaces of objects to be disinfected. A mathematical model is presented to estimate irradiance distributions. To this end, the relevant parameters are defined. These parameters are the optical properties of the UV-C light sources, such as wavelength and emitted optical power, as well as electrical features, like radiant efficiency and consumed power. Furthermore, the characteristics and geometry of the irradiated surfaces as well as the positions of the irradiated surfaces in relation to the UV-C light sources are considered. Because mercury (Hg) lamps are competitive with UV-C light-emitting diodes, a comparative analysis between these two light sources based on the simulation results is also discussed.

scholarly journals Double-Sided Freeform Lens for Light Collimation of Light Emitting Diodes

2019 ◽  
Vol 9 (24) ◽  
pp. 5452
Author(s):  
Yong-Sin Syu ◽  
Chun-Ying Wu ◽  
Yung-Chun Lee
Keyword(s):  
Light Emitting Diodes ◽  
Uv Light ◽  
Design Parameters ◽  
Injection Molding Process ◽  
Light Sources ◽  
Molding Process ◽  
Light Emitting ◽  
Uv Led ◽  
Simulation Results ◽  
Freeform Lens

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.

Improving AlGaN-based ultraviolet-C (UV–C) light-emitting diodes by introducing quaternary-graded AlInGaN final quantum barrier

2021 ◽  
Vol 112 ◽  
pp. 110745
Author(s):  
Muhammad Usman ◽  
Shahzeb Malik ◽  
Masroor Hussain ◽  
Habibullah Jamal ◽  
M. Ajmal Khan
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Ultraviolet C ◽  
Uv C

scholarly journals Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1477
Author(s):  
Woo-Suk Jung ◽  
Ill-Min Chung ◽  
Myeong Ha Hwang ◽  
Seung-Hyun Kim ◽  
Chang Yeon Yu ◽  
...  
Keyword(s):  
Plant Growth ◽  
In Vitro Culture ◽  
Light Emitting Diodes ◽  
Photosynthetic Pigment ◽  
Antioxidant Properties ◽  
Light Sources ◽  
Light Emitting ◽  
Cell Defense ◽  
Led Irradiation

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mingming Jiang ◽  
Fupeng Zhang ◽  
Kai Tang ◽  
Peng Wan ◽  
Caixia Kan
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Coherent Light ◽  
Light Emitting ◽  
Exciton Polaritons ◽  
Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

Four color stacked white organic light-emitting diodes utilizing the concept of triplet harvesting

2011 ◽  
Vol 1286 ◽  
Author(s):  
Th. C. Rosenow ◽  
S. Olthof ◽  
S. Reineke ◽  
B. Lüssem ◽  
K. Leo
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
Light Sources ◽  
Emission Layer ◽  
Light Emitting ◽  
Organic Light ◽  
Blue Emitters ◽  
Color Rendering ◽  
Triplet Harvesting

ABSTRACTOrganic light-emitting diodes (OLEDs) are developing into a competitive alternative to conventional light sources. Nevertheless, OLEDs need further improvement in terms of efficiency and color rendering for lighting applications. Fluorescent blue emitters allow deep blue emission and high stability, while phosphorescent blue emitter still suffer from insufficient stability. The concept of triplet harvesting is the key for achieving internal quantum efficiencies up to 100 % and simultaneously benefiting from the advantages of fluorescent blue emitters. Here, we present a stacked OLED consisting of two units comprising four different emitters in total. The first unit takes advantage of the concept of triplet harvesting and combines the light emission of a fluorescent blue and a phosphorescent red emitter. The second unit emits light from a single emission layer consisting of a matrix doped with phosphorescent green and yellow emitters. With this approach, we reach white color coordinates close to the standard illuminant A and a color rendering index of above 75. The presented devices are characterized by high luminous efficacies of above 30 lm/W on standard glass substrates without outcoupling enhancement.

Centers for Disease Control-type light traps equipped with high-intensity light-emitting diodes as light sources for monitoring Anopheles mosquitoes

Acta Tropica ◽  
2018 ◽  
Vol 183 ◽  
pp. 61-63 ◽  
Author(s):  
Benedita Maria Costa-Neta ◽  
Abdias Ribeiro Lima-Neto ◽  
Apoliana Araújo da Silva ◽  
Jefferson Mesquita Brito ◽  
João Vitor Castro Aguiar ◽  
...  
Keyword(s):  
Disease Control ◽  
High Intensity ◽  
Light Emitting Diodes ◽  
Light Sources ◽  
Light Traps ◽  
Light Emitting ◽  
Anopheles Mosquitoes ◽  
Centers For Disease Control ◽  
High Intensity Light

Manufacturability of high power ultraviolet-C light emitting diodes on bulk aluminum nitride substrates

2012 ◽  
Vol 78 ◽  
pp. 127-130 ◽  
Author(s):  
James R. Grandusky ◽  
Zhibai Zhong ◽  
Jasson Chen ◽  
Charles Leung ◽  
Leo J. Schowalter
Keyword(s):  
Aluminum Nitride ◽  
High Power ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Ultraviolet C

scholarly journals Three-Method Hybrid Numerical Simulation for Surface-Plasmon-Enhanced GaInN-Based Light-Emitting Diodes with Metal-Embedded Nanostructures

2021 ◽  
Vol 9 ◽  
Author(s):  
Ryoya Hiramatsu ◽  
Ryo Takahashi ◽  
Ryoto Fujiki ◽  
Keisuke Hozo ◽  
Kanato Sawai ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Light Emitting Diodes ◽  
Simulation Tool ◽  
Wave Analysis ◽  
Light Emitting ◽  
Rigorous Coupled Wave Analysis ◽  
Physical Background ◽  
Simulation Results ◽  
Rigorous Coupled Wave ◽  
Difference Time

In this paper, a hybrid numerical simulation tool is introduced and performed for GaInN-based light-emitting diodes (LEDs) with metal-embedded nanostructure to theoretically predict external quantum efficiency (EQE), which composed of finite-difference time-domain, rigorous coupled wave analysis, and ray tracing. The advantage is that the proposed method provides results supported by sufficient physical background within a reasonable calculation time. From the simulation results, the EQE of LED with Ag-nanoparticles embedded nanostructure is expected to be enhanced by as high as ∼1.6 times the conventional LED device in theory.

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