scholarly journals A Critical Review on Antimicrobial Photodynamic Inactivation Using Light Emitting Diode (LED)

2021 ◽  
Vol 8 (3) ◽  
pp. 124-130
Author(s):  
T Purushothaman ◽  
K Irfana Mol
Keyword(s):  
Foodborne Pathogens ◽  
Light Emitting Diode ◽  
Food Preservation ◽  
Advanced Technology ◽  
Photodynamic Inactivation ◽  
Light Emitting ◽  
Novel Technologies ◽  
Wide Range ◽  
Micro Organisms ◽  
Promising Source

The light-emitting diode (LED) is an advanced technology with a wide range of applications in our day-to-day life. It has numerous advantages over conventional light, such as controlling the spectrum of light, the specificity of the wavelength, cool emitting surface, and cost-effectiveness. The novel technologies and developments have proved the efficacy of LEDs in eliminating microbes rather than being an effective lighting source. The LED employs Photodynamic Inactivation to eliminate micro-organisms with the help of various photo-sensitizers. Photodynamic inactivation is a non-chemical based technique that helps fight against the microbes without developing the resistant microbial strains. The illumination of LED at a specific narrow wavelength exhibits antimicrobial activity against a wide range of microbes, including resistant strains. Getting rid of harmful micro-organisms is one of the effective ways to reduce health risks and promote quality of life. Hence, the LEDs with specific narrow wavelengths can be employed to sterilize the medical equipment, healthcare environment, and food preservation without using chemicals. The Photodynamic Inactivation using LED as a light source will be a promising source for eradicating harmful micro-organisms, including nosocomial and foodborne pathogens.

scholarly journals LED Rail Signals: Full Hardware Realization of Apparatus with Independent Intensity by Temperature Changes

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1291
Author(s):  
Giuseppe Schirripa Schirripa Spagnolo ◽  
Fabio Leccese
Keyword(s):  
Temperature Sensor ◽  
Energy Efficient ◽  
Light Emitting Diode ◽  
Junction Temperature ◽  
Light Emitting ◽  
Temperature Changes ◽  
Wide Range ◽  
International Regulations ◽  
Long Lifetime ◽  
Set Up

Nowadays, signal lights are made using light-emitting diode arrays (LEDs). These devices are extremely energy efficient and have a very long lifetime. Unfortunately, especially for yellow/amber LEDs, the intensity of the light is closely related to the junction temperature. This makes it difficult to design signal lights to be used in naval, road, railway, and aeronautical sectors, capable of fully respecting national and international regulations. Furthermore, the limitations prescribed by the standards must be respected in a wide range of temperature variations. In other words, in the signaling apparatuses, a system that varies the light intensity emitted according to the operating temperature is useful/necessary. In this paper, we propose a simple and effective solution. In order to adjust the intensity of the light emitted by the LEDs, we use an LED identical to those used to emit light as a temperature sensor. The proposed system was created and tested in the laboratory. As the same device as the ones to be controlled is used as the temperature sensor, the system is very stable and easy to set up.

Changes in Lighting Source Can Produce Inaccurate Assessment of Visual Poultry Doneness and Induce Consumers To Eat Undercooked Ground Turkey Patties

2019 ◽  
Vol 82 (3) ◽  
pp. 528-534 ◽  
Author(s):  
CURTIS MAUGHAN ◽  
EDGAR CHAMBERS IV ◽  
SANDRIA GODWIN ◽  
DELORES CHAMBERS
Keyword(s):  
Foodborne Pathogens ◽  
Light Emitting Diode ◽  
The United States ◽  
Extrinsic Factors ◽  
Visual Appearance ◽  
Light Emitting ◽  
End Point ◽  
Lighting Conditions ◽  
Compact Fluorescent Lamp ◽  
End Point Temperature

ABSTRACT Undercooked poultry is a potential source of foodborne pathogens, such as Salmonella and Campylobacter. The best way to avoid eating undercooked poultry is to use a food thermometer during cooking. However, consumers who cook poultry often use visual appearance for determining doneness, which relies on extrinsic factors, including lighting conditions. Because the United States recently mandated changes in lighting to promote energy conservation, this study evaluated the effect of lighting sources on consumer perceptions of doneness and willingness to eat cooked poultry patties. Consumers (n = 104) evaluated validated photographs of turkey patties cooked to different end point temperatures (57 to 79°C) and rated the level of perceived doneness and willingness to eat each sample. Evaluations were conducted under different lighting sources: incandescent (60 W, soft white), halogen (43 W, soft white), compact fluorescent lamp (13 W, soft white), light-emitting diode (LED; 10.5 W, soft white), and daylight LED (14 W). Lighting changed perception of doneness and willingness to eat the patties, with some of the energy-efficient options, such as LED and halogen making samples appear more done than they actually were, increasing the willingness to eat undercooked samples. This poses a risk of consuming meat that could contain bacteria not killed by heat treatment. Recent changes in lighting regulations can affect lighting in homes that affects perceptions of poultry doneness, requiring that educators place extra emphasis on the message that properly using a meat thermometer is the only way to ensure meat is cooked to a safe end point temperature.

scholarly journals Spectroscopy Transmittance by LED Calibration

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 2951 ◽  
Author(s):  
Daniel Carreres-Prieto ◽  
Juan T. García ◽  
Fernando Cerdán-Cartagena ◽  
Juan Suardiaz-Muro
Keyword(s):  
Real Time ◽  
Light Emitting Diode ◽  
Research Work ◽  
Cost Effective ◽  
Spectral Width ◽  
Calibration Procedure ◽  
Pollution Monitoring ◽  
Light Emitting ◽  
Wide Range ◽  
Incandescent Lamps

Local administrations demand real-time and continuous pollution monitoring in sewer networks. Spectroscopy is a non-destructive technique that can be used to continuously monitor quality in sewers. Covering a wide range of wavelengths can be useful for improving pollution characterization in wastewater. Cost-effective and in-sewer spectrophotometers would contribute to accomplishing discharge requirements. Nevertheless, most available spectrometers are based on incandescent lamps, which makes it unfeasible to place them in a sewerage network for real-time monitoring. This research work shows an innovative calibration procedure that allows (Light-Emitting Diode) LED technology to be used as a replacement for traditional incandescent lamps in the development of spectrophotometry equipment. This involves firstly obtaining transmittance values similar to those provided by incandescent lamps, without using any optical components. Secondly, this calibration process enables an increase in the range of wavelengths available (working range) through a better use of the LED’s spectral width, resulting in a significant reduction in the number of LEDs required. Thirdly, this method allows important reductions in costs, dimensions and consumptions to be achieved, making its implementation in a wide variety of environments possible.

A High Efficiency Step-Up WLED Driver with Wide Range PWM Dimming

2012 ◽  
Vol 588-589 ◽  
pp. 884-887
Author(s):  
Fei Xu ◽  
Le Nian He
Keyword(s):  
Pulse Width Modulation ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
System Efficiency ◽  
Current Sensing ◽  
Light Emitting ◽  
Wide Range ◽  
Simulation Results ◽  
Peak Value ◽  
Pwm Dimming

A high efficiency step-up White Light Emitting-diode (WLED) driver with PWM dimming is presented in this paper. An integrated current sensing technique is used to improve system efficiency. Meanwhile, a novel PWM(pulse width modulation) dimming scheme is proposed to achieve wide range dimming frequency, which can be adaptive to dimming frequency from 200Hz to 200 KHz. The proposed driver is designed with CSMC 0.5um 40V bipolar-CMOS-DMOS process. Simulation results verify the functionality of the design and high efficiency is realized, with a peak value of 94.12% at 5.5V-input and 200mA-load.

scholarly journals Light-Emitting Diode Based Photoacoustic Imaging System

2020 ◽  
Author(s):  
Ebrahim Najafzadeh ◽  
Parastoo Farnia ◽  
Alireza Ahmadian ◽  
Hossein Ghadiri
Keyword(s):  
Imaging System ◽  
Photoacoustic Imaging ◽  
Light Emitting Diode ◽  
Imaging Modality ◽  
Optical Excitation ◽  
Poly Vinyl Alcohol ◽  
Ultrasound Images ◽  
Light Emitting ◽  
Non Invasive ◽  
Wide Range

Purpose: A Photoacoustic Imaging (PAI) as a non-invasive hybrid imaging modality has the potential to be used in a wide range of pre-clinical and clinical applications. There are different optical excitation sources that affect the performance of PAI systems. Our goal is proving the capability of the Light-Emitting Diode (LED) based PAI system for imaging of objects in different depths. Materials and Methods: In this study the Full Width of Half Maximum (FWHM) and Contrast to Noise Ratio (CNR) of LED-based PAI system is evaluated using agar, and Poly-Vinyl Alcohol Cryogel (PVA-C) phantoms. Results: The results show that axial and lateral FWHM of the photoacoustic image in agar phantom 1%, are 0.59 and 1.16 mm, respectively. It is capable of distinguishing objects about 250 µm. Furthermore, one of the main improvements of photoacoustic images is achieved by proposed LED-based system that is a 26% higher CNR versus the ultrasound images. Conclusion: Therefore, the provided technical characteristics in this study have made designed LED-based PAI system as a suitable tool for preclinical and clinical imaging.

Towards a Novel Broadband Spectrally Dynamic Solid State Light Source

2005 ◽  
Vol 892 ◽  
Author(s):  
David Nicol ◽  
Shalini Gupta ◽  
Nola Li ◽  
Ali Asghar ◽  
Elton Graugnard ◽  
...  
Keyword(s):  
Solid State ◽  
Real Time ◽  
Light Source ◽  
Tunnel Junction ◽  
Light Emitting Diode ◽  
Contact Layer ◽  
Light Emitting ◽  
Wide Range ◽  
Multiple Wavelengths ◽  
Dynamic Source

AbstractThe developments of two major components of a three terminal dual wavelength LED for excitation of multiple phosphors are described. Such a configuration will be novel Broadband Spectrally Dynamic Light Emitting Diode (BSDLED). First, work towards a functional tunnel junction in the GaN system is discussed. The developments of p+ and n+ GaN layers are specifically discussed in relation to their use in a buried current spreading contact layer. Second, the analysis of several phosphors and their application in a spectrally dynamic source is explored. The response to multiple wavelengths of the phosphors is analyzed to create a light source that can be tuned in “real time” to a wide range of correlated color temperatures.

scholarly journals A Comparison of Porphyrin Photosensitizers in Photodynamic Inactivation of RNA and DNA Bacteriophages

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 530
Author(s):  
Joe Heffron ◽  
Matthew Bork ◽  
Brooke K. Mayer ◽  
Troy Skwor
Keyword(s):  
Light Emitting Diode ◽  
Photodynamic Inactivation ◽  
Oxygen Species ◽  
Resistant Virus ◽  
Human Virus ◽  
Light Emitting ◽  
Porphyrin Photosensitizers ◽  
Therapeutic Alternatives ◽  
Palladium Ion ◽  
Rna And Dna

Effective broad-spectrum antiviral treatments are in dire need as disinfectants and therapeutic alternatives. One such method of disinfection is photodynamic inactivation, which involves the production of reactive oxygen species from dissolved oxygen in response to light-stimulated photosensitizers. This study evaluated the efficacy of functionalized porphyrin compounds for photodynamic inactivation of bacteriophages as human virus surrogates. A blue-light light emitting diode (LED) lamp was used to activate porphyrin compounds in aqueous solution (phosphate buffer). The DNA bacteriophages ΦX174 and P22 were more resistant to porphyrin TMPyP photodynamic inactivation than RNA bacteriophage fr, with increasing rates of inactivation in the order: ΦX174 << P22 << fr. Bacteriophage ΦX174 was therefore considered a resistant virus suitable for the evaluation of three additional porphyrins. These porphyrins were synthesized from TMPyP by inclusion of a central palladium ion (PdT4) and/or the addition of a hydrophobic C14 chain (PdC14 or C14). While the inactivation rate of bacteriophage ΦX174 via TMPyP was similar to previous reports of resistant viruses, ΦX174 inactivation increased by a factor of approximately 2.5 using the metalloporphyrins PdT4 and PdC14. The order of porphyrin effectiveness was TMPyP < C14 < PdT4 < PdC14, indicating that both Pd2+ ligation and C14 functionalization aided virus inactivation.

scholarly journals Low-cost photoacoustic imaging systems based on laser diode and light-emitting diode excitation

2017 ◽  
Vol 10 (04) ◽  
pp. 1730003 ◽  
Author(s):  
Qingkai Yao ◽  
Yu Ding ◽  
Guodong Liu ◽  
Lvming Zeng
Keyword(s):  
Laser Diode ◽  
Near Infrared ◽  
Photoacoustic Imaging ◽  
Light Emitting Diode ◽  
Imaging Modality ◽  
Low Cost ◽  
Laser System ◽  
Great Promise ◽  
Light Emitting ◽  
Wide Range

Photoacoustic imaging, an emerging biomedical imaging modality, holds great promise for preclinical and clinical researches. It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission. In order to generate photoacoustic signal efficiently, bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization. As an alternative, the miniaturized semiconductor laser system has the advantages of being inexpensive, compact, and robust, which makes a significant effect on production-forming design. It is also desirable to obtain a wavelength in a wide range from visible to near-infrared spectrum for multispectral applications. Focussing on practical aspect, this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.

Optical fibre systems

1978 ◽  
Vol 289 (1356) ◽  
pp. 135-150 ◽  
Keyword(s):  
Semiconductor Lasers ◽  
Optical Fibre ◽  
Light Emitting Diode ◽  
Beam Quality ◽  
Single Mode ◽  
Laser Source ◽  
Fibre Strength ◽  
Optical Source ◽  
Light Emitting ◽  
Wide Range

The present state of research and development into optical fibre systems for applications in telecommunications is reviewed and some of the principal problems remaining are discussed. Attenuations close to the intrinsic limits of the materials available have been reached in laboratory fibres and losses in optical cables installed under normal working conditions are below 5 dB/km. Bandwidths available range from 20 MHz km, in step-index multimode fibres with light emitting diode sources, to 10 GHz km with single-mode fibres and semiconductor lasers. If a truly monochromatic laser source operating in the region of minimum material dispersion becomes available then individual fibre capacities up to, or beyond, 100 GHz km are feasible. The major problems in cabling have already been largely overcome but further improvements in fibre strength, homogeneity and reproducibility are awaited. The difficulties are technological rather than fundamental and will succumb to good innovative engineering within the next few years. The same may be said of the requirements for such mundane, but vitally important, components as splices, connectors, couplers and even the lowly jack plug. Excellent and encouraging progress is being made with all of these items. Of the major hurdles remaining, that of a suitable optical source is by far the most difficult. The lifetime and reliability of existing semiconductor lasers are improving only slowly and need to be increased by at least an order of magnitude. It would also be an advantage if their line width, coherence and beam quality could be made to approximate more closely those of an ideal laser. Fortunately light emitting diodes can also be used if adequate lasers do not become available, but at the expense of system bandwidth and repeater spacing. Technological forecasting is fraught with hazards for the unwary but it is reasonable to expect systems to be operating in the telephone network in the 1980s at capacities from 140 Mbit/s to 500 Mbit/s at repeater spacings of at least 5 km and perhaps as high as 20 km. Serious study of the application of optical fibres to underwater cables will also have begun. If simple fibre cables can be made cheaply enough for use in installations to individual subscribers a wide range of new developments become possible, but these problems are more relevant to the 1990s.

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