LED Light Source Research Articles

Optimizing microlens arrays for incoherent HiLo microscopy

HiLo microscopy is a powerful, low-cost, and easily configurable technique for acquiring high-contrast optically-sectioned images. However, traditional HiLo microscopes are based on coherent light sources with diffusive glass plates or incoherent light sources with digital mirror devices (DMD) and spatial light modulators (SLM), which are more expensive. Here, we propose a new low-cost HiLo microscopy technique using MLAs and incoherent LED light sources. We simulated structured illumination (SI) patterns and HiLo image generation. To observe how MLAs affect HiLo images, we used three common MLAs with specific microlens pitch and numerical aperture (NA) to generate periodic illumination patterns. Our simulations concluded that the MLA's NA does not significantly affect HiLo images, and a larger lens pitch can bring a higher image contrast. However, there is an optimized lens pitch. If the lens pitch is equal to or higher than 140 μm, artifacts are observed in HiLo images. Based on our simulations, employing the cross-type MLA with a 0.01NA and a period of 120 μm yields the optimal HiLo image (94.6 % contrast). In our quantitative analysis with the traditional HiLo, where SI patterns were set with the same period, we calculated the SSIM index between each HiLo-Ground Truth image pair. The cross-type MLA HiLo performed slightly better (SSIM = 0.9554) than the traditional HiLo (SSIM = 0.9396). However, when using the hexagon-type MLA, artifacts were evident in the final HiLo image (SSIM = 0.9054). The cylinder-type MLA HiLo result (SSIM = 0.9366) is similar to the traditional HiLo. To our knowledge, this is the first numerical study about MLA-based HiLo microscopy. This study can benefit researchers using MLAs and incoherent light sources to configure their low-cost HiLo microscopes.

Study on photoluminescence properties of Er2O3 materials as irradiation damage and temperature sensors

Photoluminescence (PL) properties of Er2O3 specimens were examined by using visible lasers (532 nm and 635 nm) and a UV LED light source (365 nm) to investigate the applicability for irradiation damage monitoring of materials in fusion reactors. Both in the laser induced and UV light induced PL spectra, green (510–590 nm) and red (630–725 nm) luminescence was observed. In the spectrum measurements on specimens with different crystallinities, it was confirmed that an intensity of the red luminescence weakened significantly compared with that of the green luminescence in an Er2O3 specimen with a lower crystallinity. The results indicate that the PL measurements of Er2O3 materials could be applicable for the irradiation damage monitoring in fusion reactors. The luminescence property of ion beam irradiated Er2O3 showed that information of irradiation damages could be kept up to ∼ 300 ℃ and almost recovered at 700 ℃. Based on the obtained luminescence properties, positions in a fusion reactor where Er2O3 materials could be used as irradiation damage sensors are proposed. Changes in PL spectra at high temperatures up to ∼ 400 ℃ indicate the possibility that the Er2O3 materials might be applicable also for temperature monitoring of in-vessel components during reactor maintenance periods.

Evaluation of the amount of residual monomer released from different flowable composite resins

Today, resin materials are used in the restoration of permanent and deciduous teeth or as fissure sealants. The materials can contain different types of monomers (Bis-GMA, UDMA, TEGDMA). These monomers can be released into the oral cavity after polymerization. Residual monomers released from resin-containing restorative materials after polymerization have been reported to have negative effects on mechanical properties. The aim of our study is to evaluate the amount of residual monomers released after polymerization of different flowable composite resin materials using two different modes of LED light source. Composite disc samples (8 mm diameter/2 mm depth) prepared for each material group were polymerized using two different modes of the LED light device (Standard mode and extra power mode). HPLC (High Performance Liquid Chromatography) device was used to measure the amount of residual monomer release at 1 h, 1 day, 3 days and 7 days periods. Pairwise comparison of the differences between the materials was performed by Post-hoc test. For each residual monomer, the Kruskal Wallis test was used to analyze the difference between the materials in standard mode and the difference between the materials in extra power mode. According to the results of the study; Grandio flow flowable composite showed the highest release of TEGDMA and Bis-GMA while SDR® Flow flowable composite showed the lowest release of TEGDMA, Bis-GMA and UDMA. For all materials, the extra power mode resulted in more residual monomer release. TEGDMA and Bis-GMA release was detected in all tested flowable composites at all time periods.

Fiberscope-Based Measurement of Coaptation Height for Intraoperative Assessment of Mitral Valve Repair.

Restoring adequate coaptation height is a key principle of mitral valve (MV) repair. This study aimed to evaluate the utility of fiberscope (FS) technology to assess MV coaptation height for intraoperative use. Ex-vivo testing was performed on five adult porcine hearts. The left atrium (LA) was resected, and the left ventricle (LV) was pressurized retrograde to 27 ± 1mm Hg. An endoscope was inserted into the LV apex, centered under the MV orifice. An FS system (Milliscope II camera, LED light source, and 0.7 mm diameter × 15 cm long) 90° semirigid scope with 1.2 mm focal length) was mounted above the MV annulus in a custom alignment and measuring fixture. Three blinded measurements were taken at two locations on each MV, A2 and P2 segment, from the top of coaptation to the leaflet edge identified by the FS. Accurate positioning was verified using the LV endoscope. A control (metal rod of similar thickness) was used for comparison, with coaptation height recorded when the control was seen via the endoscope. Coaptation heights were similar for the control and FS methods across all hearts at A2 (11.6 ± 2.6 mm control vs 11.8 ± 2.2 mm FS) and P2 (13.3 ± 2.6 mm control vs 13.4 ± 2.9 mm FS) segments, with similar measurement variability (control SD 0.1-1.0 mm; FS SD 0.1-0.9 mm). One outlier was excluded from analysis (n = 19/20). The maximum absolute difference and percent error between measurement methods were less than 1.1 mm (median [IQR], 0.6 [0.3-0.9] mm) and less than 14% (4.1 [2.2-7.6]%). Utilization of a miniaturized FS enabled precise and accurate quantification of MV coaptation. This technique is promising for evaluating post-repair valve competence and coaptation height.

Optical Management of Perovskite Solar Cells by Biomimetic‐Structured Polydimethylsiloxane Films

The application of antireflective (AR) films is a promising optical management strategy to improve the light utilization of perovskite solar cells (PSCs). Plumeria petals of different colors are employed as the master mold for the first time to prepare biomimetic AR films. Hierarchical morphologies replicated from the petals have a primary characteristic size in tens of micrometer scale. A strong scattering effect happens when the incident light hits the AR films, leading to a remarkably reduced reflectance with broadband enhancement of the transmission over the entire visible range. With the incorporation of the biomimetic AR film, the highest power conversion efficiency for PSCs reaches 23.56% with a large short‐circuit density (Jsc) of 26.54 mA cm−2, corresponding to an average enhancement of 6.17%. The enhancement effect is verified under 1.5G AM radiation with different tilted angles and warm white LED light source with different light intensities. Furthermore, optical simulations are performed to illustrate the structure–effective relationship. This work offers an interesting experience by learning from nature and provides valuable references for further refining the design of the AR films in micrometer scale.

Flow and heat transfer performance of microchannel heat sinks with circular concave cavities and ribs for water cooling LEDs

ABSTRACT The poor heat dissipation of LED light sources limits their applications in plant factories. This paper combines a microchannel heat sink (MHS) with circular concave cavities and ribs with the water irrigation system of an LED plant factory to develop water-cooled LEDs. By using this approach, four types of MHSs were designed: circular concave cavities (circular), circular concave cavities and single-sided ribs (circular-single), circular concave cavities and odd-symmetric ribs (circular-odd), and circular concave cavities and double symmetric ribs (circular-double). The influence of the arrangement of circular concave cavities and ribs on the flow and heat transfer performance was numerically investigated by ANSYS Fluent 21.0 R1. Corresponding MHSs with circular concave cavities and ribs were manufactured, and an experimental platform was built to experimentally verify the numerical results. The results showed that a circular concave cavity in the microchannel caused the fluid to form a secondary flow, which led to the continuous destruction and reconstruction of the flow and thermal boundary layer in the microchannel. This contributed to heat and mass transfer, while the presence of ribs altered the flow direction of the fluid and enhanced mass and heat transfer within the cavities. The pressure drop at the inlet and outlet of the MHS increased in the case of circular concave cavities and ribs as the inlet flow rate increased. Compared with MHSs with circular concave cavities, the ribs increased the pressure drop at the inlet and outlet. The inlet and outlet pressure drop of MHS with circular concave cavities and double-symmetric ribs was the highest, followed by MHS with circular concave cavities and odd-symmetric ribs, and the smallest was the MHS with circular concave cavities and single-sided ribs. As the inlet flow rate increased from 10 ml/min to 60 ml/min, the pressure drop between the inlet and outlet of the MHS with circular concave cavities increased from 22.54 Pa to 165.98 Pa (an increase of 143.44 Pa); the pressure drop of the MHS with circular concave cavities and single-sided ribs increased from 24.72 Pa to 187.31 Pa (an increase of 162.59 Pa); the pressure drop of the MHS with circular concave cavities and odd-symmetric ribs increased from 27.92 Pa to 212.12 Pa (an increase of 184.20 Pa) and that of the MHS with circular concave cavities and double symmetric ribs increased from 29.32 Pa to 221.21 Pa (an increase of 191.89 Pa). Under the same inlet flow rate and LED chip input power, the cooling water outlet temperature of MHS with circular concave cavities and double symmetric ribs was the highest, followed by MHS with circular concave cavities and odd-symmetric ribs, MHS with circular concave cavities and single-sided ribs, and MHS with circular concave cavities was the lowest. These results indicated that the heat transfer performance of MHS with circular concave cavities and double-symmetric ribs was the best, followed by MHS with circular concave cavities and odd-symmetric ribs, and MHS with circular concave cavities and single-sided ribs. The MHS with circular concave cavities had the worst heat transfer performance. The outlet temperature of the MHS with concave cavities and ribs reaches the highest value at the inlet flow rate of 30 ml/min. At this flow rate, the outlet temperature is 343.89 K for the MHS with circular concave cavities, 344.73 K for the MHS with circular concave cavities and single-sided ribs, 346.53 K for the MHS with circular concave cavities and odd-symmetric ribs; and 347.58 K for the MHS with circular concave cavities and double symmetric ribs.

Tunable broadband luminescence of Bi‐ion‐doped glasses via Gd2O3 co‐doping

AbstractThe doping of bismuth (Bi) ions in borosilicate glasses has gained attention for its potential applications in LED light sources and imaging displays. Here, gadolinium oxide (Gd2O3) was introduced into the glass matrix in varying concentrations using a high‐temperature melting method to investigate its impact on the luminescence properties of Bi ions. The resulting glass exhibited bimodal emission peaks at 465 and 750 nm when excited with 325 nm light. The luminescence intensity and fluorescence half width at half height initially increased, followed by a subsequent decrease as the Gd2O3 content in the glass increased from 10 to 43 mol%. Additionally, the color of the luminescence transformed from purple–red to green under white light irradiation. The composition and excitation wavelength of the glass can be adjusted to achieve selective tuning of the luminescence.

Plasmonic Nanocomposites of ZnO-Ag Produced by Laser Ablation and Their Photocatalytic Destruction of Rhodamine, Tetracycline and Phenol.

Hydrosphere pollution by organic pollutants of different nature (persistent dyes, phenols, herbicides, antibiotics, etc.) is one of the urgent ecological problems facing humankind these days. The task of water purification from such pollutants can be effectively solved with the help of modern photocatalytic technologies. This article is devoted to the study of photocatalytic properties of composite catalysts based on ZnO modified with plasmonic Ag nanoparticles. All materials were obtained by laser synthesis in liquid and differed by their silver content and preparation conditions, such as additional laser irradiation and/or annealing of produced powders. The prepared ZnO-Ag powders were investigated by electron microscopy, X-ray diffraction and UV-Vis spectroscopy. Photocatalytic tests were carried out with well- known test molecules in water (persistent dye rhodamine B, phenol and common antibiotic tetracycline) using LED light sources with wavelengths of 375 and 410 nm. The introduction of small concentrations (up to 1%) of plasmonic Ag nanoparticles is shown to increase the efficiency of the ZnO photocatalyst by expanding its spectral range. Both the preparation conditions and material composition were optimized to obtain composite photocatalysts with the highest efficiency. Finally, the operation mechanisms of the material with different distribution of silver are discussed.

The Evolution of Spinal Endoscopy: Design and Image Analysis of a Single-Use Digital Endoscope Versus Traditional Optic Endoscope.

Spinal endoscopy has evolved significantly since its inception, offering minimally invasive solutions for various spinal pathologies. This study introduces a promising innovation in spinal endoscopy-a single-use digital endoscope designed to overcome the drawbacks of traditional optic endoscopes. Traditional endoscopes, despite their utility, present challenges such as fragility, complex disinfection processes, weight issues, and susceptibility to mechanical malfunctions. The digital endoscope, with its disposable nature, lighter weight, and improved image quality, aims to enhance surgical procedures and patient safety. The digital endoscope system comprises a 30-degree 1000 × 1000 pixel resolution camera sensor with a 4.3 mm working channel, and LED light sources replacing optical fibers. The all-in-one touch screen tablet serves as the host computer, providing portability and simplified operation. Image comparisons between the digital and optic endoscopes revealed advantages in the form of increased field of view, lesser distortion, greater close-range resolution, and enhanced luminance. The single-use digital endoscope demonstrates great potential for revolutionizing spine endoscopic surgeries, offering convenience, safety, and superior imaging capabilities compared to traditional optic endoscopes.

Thermally Stable NIR Emission from Disordered Ba5La3MgAl3O15:Cr3+ with Peak Wavelength Beyond 900 nm

AbstractBroadband near‐infrared (NIR) emissions in the long wavelength region with simultaneous high efficiency and thermal stability are desirable for NIR phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) light sources. Herein, a novel broadband NIR‐emitting phosphor is reported, Ba5La3MgAl3O15:Cr3+ (BLMAO:Cr3+), which exhibits a NIR emission band spanning 700–1300 nm with maximum peak wavelength (λmax) at 925 nm and full width at half maximum of 160 nm. The optimized phosphor achieves an internal quantum efficiency of 66%, and the integrated emission intensity at 423 K remains 61% of that at room temperature, which surpasses most Cr3+‐activated phosphors emitting in the long‐wavelength NIR region (λmax > 900 nm). The NIR luminescence properties are elucidated on the basis of density functional calculations of the multiple Cr3+ local structures as generated by the Ba/La occupation disorder in the host material. The applications of the NIR phosphor in pc‐LED devices are demonstrated, showing potential in night‐vision and nondestructive examination. The results indicate that BLMAO:Cr3+ is a promising phosphor with highly efficient and thermally stable broadband NIR emission for NIR LED light sources.

Push–pull biphenyl–based iodonium salts: Highly sensitive one-component photoinitiators for photopolymerization under UV–visible LEDs

Diaryliodonium salts play an important role as highly efficient photoinitiators in the field of photopolymerizations. They can rapidly photodecompose to produce free radicals and super acids; thus, can initiate highly efficient photocuring of acrylic and epoxy monomers and resins. However, the absorption of commercialized diphenyliodonium salts is poorly matched with popular LED light sources, and the participation of sensitizers is usually required to achieve efficient photoexcitation. Here, we synthesized five new phenyl biphenyl iodonium salts with different electron-pushing and electron-withdrawing substituents, e.g., methoxy and CN, at the biphenyl substituent. Our results demonstrate that all synthesized iodonium salts have strong absorption in the range (λmax = 258–352 nm; εmax = 21,300–29,900 M−1 cm−1). The photochemistry of these synthesized iodonium salt is strongly influenced by substituents on the biphenyl ring. All iodonium salts can undergo rapid photolysis under light excitation, with higher quantum yield of photoacid generation reaching 0.25 and can quickly initiate cationic photopolymerization of epoxy monomers. Furthermore, free radicals are generated during photolysis, which can successfully trigger free radical polymerization. These iodonium salts with good absorbance in the UVA band demonstrate their potential as excellent photoinitiators under 365–405 nm LED excitation.

Influence of dynamic LED irradiation mode on the content of nitrates, structural and functional characteristics of lettuce plants

One of the promising irradiation modes for plant is dynamic, when parameters change throughout the growing process depending on certain factors. In this work, lettuce plants were illuminated under different LED light sources, including white (2700 K), 30% white (2700 K) + 70% red (660 nm), 15% blue (445 nm) + 85% red (660 nm), 40% blue (445 nm) + 20% red (630 nm) + 40% red (660 nm) and dynamic mode for 35 days to investigate the effects. Photosynthetically active flux density was the same for all lettuce samples during the experiment (210 µmol m−2 s−1). The results showed the effects of photoregulation on the growth and development of lettuce plants. Optimal irradiation regime for lettuce plants was a dynamic regime formed using two colour components: white (2700 K) and red (660 nm) LEDs. Lettuce grown under dynamic conditions had a lower content of nitrates and developed faster than under stationary conditions.

16-channel snapshot multispectral imaging based on integrated Fabry Perot microcavity array

<sec>By designing and fabricating a narrow-band Fabry-Perot multi-beam interference spectroscopic microcavity array, and integrating it with a visible light detector focal plane array, we demonstrate a small compact multispectral imaging detector. The micro-cavity filter array with 4×4 basic repeating units and a total of 2048×2048 pixels is obtained on a quartz substrate by the four-fractal combination lithograph-etching process. Then the micro miniatured multispectral imaging detector is formed by fitting with the detector chip. The depth and precision of the etching will determine the distribution and offset of the central wavelength of the narrowband spectral channel respectively. The results show that the etching rate of reactive ion is (3.6 ± 0.2) Å/s, and the process is stable and controllable. Due to the different etching depths, the basic repeating unit forms 16 different levels of steps, and the process achieves the design expectation well.</sec><sec>The results are obtained as follows: the response spectrum peak of the microcavity array sample varies from 520 to 680 nm, the free spectrum range is 160 nm, the full width at the half-peak is less than 10 nm, the transmittance is about 70%, the relative half-width of the transmittance peak at 590 nm is 1.19%, and the waveform coefficient is 2.78. A 16-channel multispectral camera is constructed by using the optical micro-precision assembly device to realize the precise alignment and the fitting of the micro-cavity filter array and the image sensor. Xenon lamp and monochromator are used as tunable wavelength monochromatic cooperative light source to detect the effect of 16-channel snapshot multispectral imaging on a pixel scale. The results show that the multispectral imaging detector has 16 different narrow-band response spectra. The characteristic spectrum of the target can be clearly distinguished by spectral channel.</sec><sec>When imaging the target with known spectral characteristics, for a certain frame of multi-spectral image, selecting a suitable spectral channel can eliminate the background in the field of view through image subtraction and improve the contrast of the target. In the dark room condition, we take the LED light source with center wavelength varying in a range between 528 and 589 nm as the target (the wavelength coincides with the working wavelength of the spectral channel), and effectively suppress the background through the spectral differential intensity subtraction, which can improve the accuracy and sensitivity of the target capture. The 16-channel snapshot multi-spectral imaging detector based on integrated Fabry-Perot microcavity array has the advantages of small size, high integration and strong environmental adaptability, and is expected to play a role in realizing the real-time detection of weak moving targets, auxiliary diagnosis of skin surface observation, and high dynamic range imaging of target observation under backlight conditions.</sec>

Комплексная модель распределения температуры для контроля тепловых характеристик бытовых светодиодных ламп

The study covers the question of the dynamics of heat transfer in a household LED lamp and scenarios for simplifying the modeling of thermal distribution, including the account of heat conduction, convection and the influence of several LED light sources. A comprehensive analysis of heat distribution processes in household LED lamps and the development of a mathematical model of the thermal radiation of an LED light source using the finite difference method are presented. The developed model takes into account the lamp geometry, material properties and environmental conditions. Special attention is paid to the influence of the location of the LEDs in the lamp system. The novelty of the study lies in the fact that the volumetric geometry of the lamp and light source, scenarios to account for various parameters of the model are included in the mathematical model. Verification of the model has shown accuracy up to 93 %. The study aims to create a more realistic and accurate method for modeling and analyzing thermal management in multilight LED household lighting fixtures.

Hyperspectral and Photodiode Retrievals of Nighttime LED‐Induced Chlorophyll Fluorescence (LEDIF) for Tracking Photosynthetic Phenology in a Vineyard

AbstractThe magnitude of chlorophyll fluorescence emission represents both chlorophyll content and energy quenching processes enabling its application to serve as a proxy of photosynthetic activity. Thus, there is interest in advancing methods for canopy‐scale monitoring of chlorophyll fluorescence. Remotely sensed solar‐induced fluorescence (SIF) retrievals offer daytime monitoring of chlorophyll fluorescence, which can serve as an indicator of photosynthesis. However, it represents an instantaneous measurement during the day, which is strongly influenced by incoming radiation, solar angle, and sun/shade fraction—making it difficult to tease out baseline information on plant health and potential photosynthetic capacity—which could be tracked by changes in fluorescence yield (independent of sunlight). Recent advances have demonstrated the potential for inducing nighttime chlorophyll fluorescence via LED light sources at the canopy‐scale, which can be retrieved as LED‐induced chlorophyll fluorescence (LEDIF), potentially serving as a baseline indicator of plant health and photochemical capacity, independent of daytime conditions. In this study, we explored two methods of LEDIF retrievals: (a) hyperspectral sensor (1.33 nm full‐width half max) and (b) low‐cost Red‐Far‐Red photodiode sensor. LEDIF retrieved by the hyperspectral sensor demonstrated strong correlations with daytime SIF and gross primary productivity during mid to end of season phenology (R2 > 0.70). In contrast, phenological dynamics of LEDIF retrieved by the photodiode sensor was more subtle, likely due to weaker signal‐to‐noise ratio, but still demonstrated some potential. Overall, LEDIF offers a technique to monitor nighttime chlorophyll fluorescence emissions (and changes in its spectral shape with a hyperspectral sensor) to assess canopy‐scale phenology of photosynthetic potential.

Urea-driven g-C3N4 nanostructures for highly efficient photoreduction of Cr(vi) under visible LED light: effects of calcination temperature.

Graphitic carbon nitride (g-C3N4) nanostructures were synthesized via the calcination of urea at various temperatures ranging between 400 and 600 °C and were utilized for photoreduction of Cr(vi) in aqueous medium. Due to the low adsorption of Cr(vi) on the g-C3N4 surface, a more accurate assessment of the photocatalytic performance of the samples was carried out. Although the characterization showed that the specific surface of samples increased as the calcination temperature increased, the most efficient product in terms of the photoreduction duration of Cr(vi) was produced through the calcination process carried out at 450 °C, which reduced the concentration by more than 99% in 40 minutes. These results demonstrate that the structural and surface properties of g-C3N4 are critical factors that impact the photocatalytic performance. Alongside the calcination temperatures, the concentration of citric acid as a hole scavenger, the source of illumination, pH levels, and the recycling ability of the produced specimen at 450 °C were also investigated. Conspicuously, the photocatalyst works better when more citric acid is present and the pH level decreases. Out of all the cases studied regarding the light source, the 400 nm LED light source was found to be the most efficient. Additionally, even after going through the photoreduction process four times, the photocatalyst still remained highly efficient.

Paper-based colorimetric sensor using Photoshop and a smartphone app for the quantitative detection of carbofuran.

We developed a smartphone-assisted microchemistry analyzer for the quantitative detection of carbofuran using a paper-based colorimetric sensor, Photoshop software, and a smartphone app. The changes in color of the carbofuran enzymatic reaction in the paper-based sensor were captured and analyzed using a smartphone-controlled analyzer with an LED light source and a smartphone camera. The high accuracy of this method was demonstrated for the determination of carbofuran with a linear response in the range 0.05-1.0 ppm and limits of detection (LOD) of 0.02 and 0.018 ppm using Photoshop and smartphone app colorimetric analysis, respectively. These two methods not only show the high sensitivity and highly quantitative relationships between the concentrations of commercial carbofuran and characteristic color values of the blue channel in smartphone images but were also applied to infusions of tea. Moreover, the smartphone app is able to GPS tag the location of the test and transmit the results to a website that displays quantitative results from carbofuran samples on a map.

Colorimetric aptasensor based on temporally controllable light-stimulated oxidase-mimicking fluorescein for the sensitive detection of exosomes in mild conditions.

Analysis of exosomes provides important information for rapid and non-invasive screening of tumors. However, sensitive and convenient detection of exosomes remains technically challenging to date. Herein, a colorimetric aptasensor based on the light-stimulated oxidase-mimicking activity of FITC was constructed for detecting ovarian cancer (OC) exosomes. The aptasensor contained an EpCAM aptamer to capture OC exosomes. Cholesterol and fluorescein (FITC) were used to modify either end of the DNA (DNA anchor). The DNA anchor could combine with exosomes through a hydrophobic reaction between cholesterol and the lipid membrane. FITC oxidized 3,3',5,5'-tetramethylbenzidine (TMB) under a 365 nm LED light source in a temporally controllable manner under mild conditions, causing the solution to change from colorless to blue, and the corresponding UV-vis absorbance increased. Based on this principle, the exosomes were qualitatively analyzed by observing the color change with the naked eye. In parallel, the exosome concentration was also detected using UV-vis spectrophotometry. The linear range was from 2 × 105 to 100 × 105 particles per mL with a limit of detection of 1.77 × 105 particles per mL. The developed aptasensor also exhibited favorable selectivity and could discriminate the exosomes from OC cells and normal cells. Besides, the receiver operating characteristic (ROC) curve demonstrates that it is possible to distinguish between patients with OC and healthy donors (HDs) using exosomes as the biomarker. Our technology may expand the applications of DNA-based detection method-enabled OC diagnostic tools.

Shadow Segmentation With Image Thresholding for Describing the Harshness of Light Sources.

Light sources are usually described by luminous intensity, color temperature and color rendering index, while the harshness of the light source is often overlooked. It is also referred to as the softness or light quality and can be determined by analyzing the shadows it produces. Shadow detection is often addressed in image analysis research, but the methods usually provide solutions for removing shadows. In this research, a method is proposed for isolating shadows from test images, applying thresholding for segmentation of the shadow into umbral and penumbral regions, calculating the shadow metric, and finally calculating the final numerical evaluation of the quality of the light source, i.e., the degree of its softness or harshness. The method proved to be efficient in analyzing halogen, LED and xenon light sources in conjunction with light-shaping attachments that soften the light. The method is not influenced by the intensity of the light source and focuses exclusively on the quality of the light. The method provides a single value to describe this light property and has the potential to become a standardized method for describing the quality of light sources and light-shaping attachments.

NFC-enabled photothermal-based microfluidic paper analytical device for glucose detection.

This study introduces the development of a photothermal-based microfluidic paper analytical device (PT-µPAD) integrated with near-field communication (NFC) technology and smartphone readout for enzyme-free glucose quantification in human samples. With the properties of gold nanoparticles (AuNPs) both as a nanozyme and as a photothermal substrate, there is no need for costly reagents like enzymes or a readout instrumentation for the selective and sensitive detection of glucose. In PT-µPADs, AuNPs are etched by hydrogen peroxide (H2O2) generated from glucose catalysis. Photothermal detection from the plasmonic heating of these AuNPs when illuminated by a 533nm LED light source is achieved by inserting the PT-µPAD sensor into a portable NFC platform suitable for smartphone readout. Temperature variation is directly proportional to the glucose concentration. After optimization, we acquired a linear range between 5.0 and 20.0 µmol L-1 (R2 = 0.9967) and a limit of detection (LOD) of 25.0 nmol L-1 for glucose. Additionally, while our sensor does not utilize any enzyme, it is remarkably selective to glucose with no effects from interferences. Recovery studies in various human control samples indicated a range of 99.73-102.66% with the highest RSD of 3.53%, making it highly accurate and precise. Moreover, our method is more sensitive than other methods relying on conventional µPADs for glucose sensing. By integrating the potential benefits of microfluidics, nanomaterials as nanozymes, and NFC technology for wireless readout, our sensor demonstrates great promise as an accessible, affordable, and shelf-stable device for glucose quantification. Moreover, this concept can be extended to detect other molecules of interest as a point-of-care (POC) diagnostics device.