The LED spectral power distribution modelled by different functions - how spectral matching quality affected computed LED color parameters

Supronowicz, Robert; Fryc, Irena

doi:10.1109/blj.2019.8883564

Cited by 8 publications

(9 citation statements)

References 5 publications

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“…The spectrometer was calibrated with a wavelength calibration source (mercury–argon HG-2, Ocean Insights). To characterize the spectral power distribution, the peak shape was modeled with a sum of Gaussian functions ( Reifegerste and Lienig, 2008 ; Supronowicz and Fryc, 2019 ). By fitting the sum of Gaussian functions to the spectral data, the wavelength where the intensity maximum occurs (peak wavelength in nm), the full width at half of the intensity maximum (FWHM in nm) and the full width at 10% of the intensity maximum (FW 0.1⋅ I max in nm) were calculated.…”

Section: Methodsmentioning

confidence: 99%

A New High-Throughput-Screening-Assay for Photoantimicrobials Based on EUCAST Revealed Unknown Photoantimicrobials in Cortinariaceae

et al. 2021

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Antimicrobial resistance is one of the biggest health and subsequent economic threat humanity faces. Next to massive global awareness campaigns, governments and NGOs alike stress the need for new innovative strategies to treat microbial infections. One of such innovative strategies is the photodynamic antimicrobial chemotherapy (PACT) in which the synergistic effects of photons and drugs are exploited. While many promising reports are available, PACT – and especially the drug-design part behind – is still in its infancy. Common best-practice rules, such as the EUCAST or CLSI protocols for classic antibiotics as well as high-throughput screenings, are missing, and this, in turn, hampers the identification of hit structures. Hit-like structures might come from synthetic approaches or from natural sources. They are identified via activity-guided synthesis or isolation strategies. As source for new antimicrobials, fungi are highly ranked. They share the same ecological niche with many other microbes and consequently established chemical strategies to combat with the others. Recently, in members of the Cortinariaceae, especially of the subgenus Dermocybe, photoactive metabolites were detected. To study their putative photoantimicrobial effect, a photoantimicrobial high-throughput screening (HTS) based on The European Committee on Antimicrobial Susceptibility Testing (EUCAST) was established. After validation, the established HTS was used to evaluate a sample set containing six colorful representatives from the genus Cortinarius (i.e., Cortinarius callisteus, C. rufo-olivaceus, C. traganus, C. trivialis, C. venetus, and C. xanthophyllus). The assay is built on a uniform, light-emitting diode (LED)-based light irradiation across a 96-well microtiter plate, which was achieved by a pioneering arrangement of the LEDs. The validation of the assay was accomplished with well-known photoactive drugs, so-called photosensitizers, utilizing six distinct emission wavelengths (λexc = 428, 478, 523, 598, or 640 nm) and three microbial strains (Candida albicans, Staphylococcus aureus, and Escherichia coli). Evaluating the extracts of six Cortinarius species revealed two highly promising species, i.e., C. rufo-olivaceus and C. xanthophyllus. Extracts from the latter were photoactive against the Gram-positive S. aureus (c = 7.5 μg/ml, H = 30 J/cm2, λ = 478 nm) and the fungus C. albicans (c = 75 μg/ml, H = 30 J/cm2, λ = 478 nm).

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Section: Methodsmentioning

confidence: 99%

A New High-Throughput-Screening-Assay for Photoantimicrobials Based on EUCAST Revealed Unknown Photoantimicrobials in Cortinariaceae

et al. 2021

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“…Future work may also include a more accurate representation of LED emission distribution to better model the complexity of the spectrum and its variations [50,58]. The photodetector's sensitivity may also incorporate more complexity, starting with photo-response non-uniformity.…”

Section: Discussionmentioning

confidence: 99%

“…However, the different terms used to mathematically shape the tail and the decay do not fit all cases. Thus, it is still recommended to use a bell curve as best overall representation [50]. Nonetheless, in the absence of a fit for all skewed models, we used the manufacturer's spectral sensitivity data available for three typical cases of silicon photodiodes with our measured spectra of the LEDs to evaluate the impact on the typical computation of oxygen saturation.…”

Section: Selected Componentsmentioning

confidence: 99%

Source–Detector Spectral Pairing-Related Inaccuracies in Pulse Oximetry: Evaluation of the Wavelength Shift

Tsiakaka

Gosselin

2020

Sensors

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Pulse oximetry enables oxygen saturation estimation ( S p O 2) non-invasively in real time with few components and modest processing power. With the advent of affordable development kits dedicated to the monitoring of biosignals, capabilities once reserved to hospitals and high-end research laboratories are becoming accessible for rapid prototyping. While one may think that medical-grade equipment differs greatly in quality, surprisingly, we found that the performance requirements are not widely different from available consumer-grade components, especially regarding the photodetection module in pulse oximetry. This study investigates how the use of candidate light sources and photodetectors for the development of a custom S p O 2 monitoring system can lead to inaccuracies when using the standard computational model for oxygen saturation without calibration. Following the optical characterization of selected light sources, we compare the extracted parameters to the key features in their respective datasheet. We then quantify the wavelength shift caused by spectral pairing of light sources in association with photodetectors. Finally, using the widely used approximation, we report the resulting absolute error in S p O 2 estimation and show that it can lead up to 8% of the critical 90–100% saturation window.

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“…The spectrometer was calibrated with a wavelength calibration source (mercury-argon HG-2, Ocean Insights). To characterize the spectral power distribution, the peak shape was modeled with a sum of Gaussian functions (Reifegerste and Lienig, 2008; Supronowicz and Fryc, 2019). By fitting the sum of Gaussian functions to the spectral data, the wavelength where the intensity maximum occurs (peak wavelength in nm), the full width at half of the intensity maximum (FWHM in nm), and the full width at ten percent of the intensity maximum (FW 0.1 · I max in nm) were calculated.…”

Section: Methodsmentioning

confidence: 99%

A new High-Throughput-Screening-assay for Photoantimicrobials Based on EUCAST Revealed Photoantimicrobials in Cortinariaceae

Fiala

Schoebel

Vrabl

et al. 2021

Preprint

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A spark of light might unravel antimicrobial activity of colored compounds, which otherwise would have been classified as inactive. While many mushrooms contain such colorful pigments but lack antimicrobial activity, we wondered if a controlled irradiation is needed to unleash their effect. To explore such photoantimicrobial actions in the Kingdom Fungi, an efficient high-throughput-screening (HTS) assay is needed. Here we report on the establishment of a reliable photoantimicrobial assay based on the EUCAST recommendations, which was validated with known photosensitzers (i.e., curcumin, phenalenone, rose bengal, an hypericum extract, and methylene blue). Furthermore, an improved LED-irradiation setup enabling with only 24 LEDs a homogenous irradiation of a 96-well plate is presented. The established HTS-assay was utilized to screen six colorful Cortinarius extracts unrevealing C. xanthophyllus and C. rufo-olivaceus as promising sources for new photoantimicrobials.

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The LED spectral power distribution modelled by different functions - how spectral matching quality affected computed LED color parameters

Cited by 8 publications

References 5 publications

A New High-Throughput-Screening-Assay for Photoantimicrobials Based on EUCAST Revealed Unknown Photoantimicrobials in Cortinariaceae

A New High-Throughput-Screening-Assay for Photoantimicrobials Based on EUCAST Revealed Unknown Photoantimicrobials in Cortinariaceae

Source–Detector Spectral Pairing-Related Inaccuracies in Pulse Oximetry: Evaluation of the Wavelength Shift

A new High-Throughput-Screening-assay for Photoantimicrobials Based on EUCAST Revealed Photoantimicrobials in Cortinariaceae

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