Search Results (173)

A novel four-in-one (4-in-series) MicroLED-in-Package (MiP4) architecture is demonstrated for the first time, integrating four sub-85 µm blue micro-LED (µ-LED) dies on a transparent glass substrate through a redistribution-layer (RDL) interconnection process. The MiP4 device operates natively at 16 V, eliminating the need for step-down converters and simplifying high-voltage backlight driving circuits. The transparent glass carrier enables efficient light extraction, excellent thermal dissipation, and uniform emission. Electrical and optical characterization of dual- (B2), triple- (B3), and quad-chip (B4) devices shows ideal voltage scalability (8 V, 12 V, 16 V) and stable emission at 450 ± 2 nm with minimal FWHM broadening (22–29 nm). Compared with a commercial LED, the MiP4 delivers 1.8× higher optical power (~41.8 mW) despite its active area being only ~1/70 that of the reference device (20,000 µm² vs. 1,350,000 µm²), yielding a dramatically enhanced luminous flux density of 64 lm/mm² at 50 mA. Furthermore, pulse-driven measurements under 2%, 5%, and 10% duty cycles verify excellent thermal stability and minimal spectral shift (<1 nm), confirming the device’s robustness and energy efficiency. This first-of-its-kind 4-in-1 high-voltage glass-based µ-LED package provides a scalable and manufacturable route toward next-generation ultra-thin, high-brightness Mini-LED backlight and optical communication systems. Full article

Ultraviolet-A light-emitting diode (UVA-LED) irradiation is an emerging technology for biofortifying plants with enhanced nutraceuticals. This study firstly investigated effects of various doses (0-control, 16, 32, 48 J/cm²) on Chinese cabbage microgreens (CCM) quality, identifying 32 J/cm² as the suitable dose for improving total antioxidant capacity (TAC) of CCM. Based on this dosage, the following two irradiation patterns were compared: single irradiation (SI, single pulse of 32 J/cm²) and fractionated irradiation (FI; four pulses of 8 J/cm² each). Both FI and SI significantly enhanced CCM quality, though through distinct mechanisms. FI effectively promoted accumulation of biomass and vitamin C, with increases by 9.25% and 13.20%, respectively. Meanwhile, SI markedly enhanced 20.90% higher TAC than FI. This was achieved by elevating enzymatic (7.71% superoxide dismutase-SOD, 9.03% peroxidase-POD, 40% catalase-CAT, and 52.17% ascorbate peroxidase-APX) and non-enzymatic (18.89% total phenolics-TPC, 10.04% total flavonoids-TF, and 18.99% carotenoids) antioxidants. Additionally, both FI and SI significantly reduced the nitrate content. To our knowledge, this is the first study to demonstrate the effect of UVA-LED irradiation pattern on microgreens quality. These findings provide basic information for UVA-LED application in indoor agriculture and the food industry, emphasizing the importance of strategically selecting irradiation patterns to achieve specific production goals. Full article

This paper presents a CMOS-based hybrid system capable of noninvasively quantifying the total hemoglobin (tHb), the oxygen saturation (SpO₂), and the heart rate (HR) by utilizing five-wavelength (670, 770, 810, 850, and 950 nm) photoplethysmography. Conventional pulse oximeters are limited to the measurements of SpO₂ and heart rate, therefore hindering the real-time estimation of tHb that is clinically essential for monitoring anemia, chronic diseases, and postoperative recovery. Therefore, the proposed hybrid system enables us to distinguish between the concentrations of oxygenated (HbO₂) and deoxygenated hemoglobin (Hb) by using the absorption characteristics of five wavelengths from the visible to near-infrared range. This CMOS hybrid mixed-signal architecture includes a light emitting diode (LED) driver as a transmitter and an optoelectronic receiver with on-chip avalanche photodiodes, followed by a field-programmable gate array (FPGA) for a real-time signal processing pipeline. The proposed hybrid system, validated through post-layout simulations and algorithmic verification, achieves high precision with ±0.3 g/dL accuracy for tHb and ±1.5% for SpO₂, while the heart rate is extracted via 1024-point Fast Fourier Transform (FFT) with an error below ±0.2%. These results demonstrate the potential of a CMOS-based hybrid system as a feasible solution to achieve real-time, low-power, and high-accuracy analysis of bio-signals for clinical and home-use applications. Full article

Chronic wound healing is a complex and tightly regulated process requiring coordinated epithelial and stromal regeneration. Photobiomodulation (PBM) using low-level red light-emitting diode (LED) therapy has emerged as a non-invasive approach to enhancing skin repair. In this study, we evaluated the therapeutic efficacy of a pulsed, multi-wavelength LED system on full-thickness excisional wound healing in a normal murine model. Daily LED treatment significantly accelerated wound closure, promoted re-epithelialization, and improved dermal architecture. Histological and immunohistochemical analyses revealed enhanced epidermal stratification, reduced inflammation, and improved collagen organization. Molecular profiling demonstrated increased expression of proliferation marker Ki67, keratins CK14 and CK17, and extracellular matrix-related genes including MMPs, Col1a1, and Col3a1. In vitro assays using HaCaT keratinocytes showed accelerated scratch wound closure and cytoskeletal remodeling following PBM exposure. These findings suggest that pulsed PBM promotes coordinated epithelial regeneration and matrix remodeling, highlighting its potential as a tunable and effective therapeutic modality for accelerating cutaneous wound healing under physiological conditions. Full article

A finite element simulation was conducted to analyze the thermal damage caused by a 532nm nanosecond pulsed laser on a CCD detector. A three-dimensional model was developed to study the temperature field variations within the detector. The simulation was centered on the laser-induced temporal progression of thermal damage in the CCD. Results showed that higher laser fluence led to increased heat accumulation, resulting in the expansion of the thermal damage area. Different thermal damage patterns were observed in the light sensor region and the light-shielded region. In the light sensor region, the melting of the silicon substrate expanded more in the transverse direction compared to the longitudinal direction with increasing laser fluence, while damage in the light-shielded region extended from the edges towards the center as laser fluence increased. These distinct damage patterns were attributed to different energy deposition patterns and structural differences between the light sensor region and the light-shielded region. Full article

Visible Light Positioning (VLP), leveraging Light-Emitting Diodes (LEDs) and smartphone CMOS cameras, provides a high-precision solution for indoor localization. However, existing systems face challenges in accuracy, latency, and robustness due to line-of-sight (LOS) limitations and inefficient signal encoding. To overcome these constraints, this paper introduces a real-time VLP framework that integrates Multi-Pulse Position Modulation (MPPM) with smartphone multi-sensor fusion. By employing MPPM, a high-efficiency encoding scheme, the proposed system transmits LED identifiers (LED-IDs) with reduced inter-symbol interference, enabling robust signal detection even under dynamic lighting conditions and at extended distances. The smartphone’s camera is a receiver that decodes the MPPM-encoded LED-ID, while accelerometer and magnetometer data compensate for device orientation and motion-induced errors. Experimental results demonstrate that the MPPM-driven approach achieves a decoding success rate of over 97% at distances up to 2.4 m, while maintaining a frame processing rate of 30 FPS and sub-35 ms latency. Furthermore, the method reduces angular errors through sensor fusion, yielding 2D positioning accuracy below 10 cm and vertical errors under 16 cm across diverse smartphone orientations. The synergy of MPPM’s spectral efficiency and multi-sensor correction establishes a new benchmark for VLP systems, enabling scalable deployment in real-world environments without requiring complex infrastructure. Full article

This study examined the membrane permeability of E. coli, which were exposed to a moderate pulsed electric field (PEF) (3.3 kV/cm). The membrane permeability of E. coli was examined as a function of time after exposure to PEF. When comparing the percentage of propidium iodide (PI) permeability at a given time from PEF exposure, it appeared that as the bacterial density increased, there was a decrease in PI permeability. The permeability to PI in the bacterial suspensions of 0.05, 0.1, and 0.5 OD, 90 min after exposure, was 56.4 ± 4.08%, 43.91 ± 0.75%, and 29.47 ± 3.31%, respectively. Membrane permeability was also examined in different phosphate-buffered saline (PBS) concentrations. At 0.05 OD there was a linear correlation between PBS concentrations (0.56, 0.75, and 1 mM) and PI permeability (28.36 ± 2.22%, 61.08 ± 3.17%, and 98.2 ± 0.9%, respectively). At the higher bacterial densities of 0.1 and 0.5 OD, this phenomenon was not evident. Examination of bacterial membrane permeability using 4, 70, and 250 kDa fluorescein isothiocyanate (FITC)-dextran revealed that PEF led to 4kDa FITC-dextran permeabilization of 27.94 ± 3.76%. The PEF parameters used did not influence the bacterial cell size and viability. This study shed light on bacterial membrane permeability as a function of conductivity and bacterial density under PEF exposure. Full article

Alumina ceramic substrates are ideal materials for next-generation microelectronic systems and devices, widely used in aerospace, 5G communications, and LED lighting. High-quality hole processing is essential for system interconnection and device packaging. Millisecond lasers have emerged as a promising choice for hole processing in alumina ceramic due to their high processing efficiency. However, existing research has rarely explored the mechanisms and processing techniques of millisecond laser oblique hole formation. This study systematically investigates the dynamic evolution of oblique hole processing in alumina ceramic through theoretical simulations, online detection, and process experiments. Through the simulation model, we have established the relationship between material temperature and hole depth. By analyzing the ablation phenomena on the upper and lower surfaces of the ceramic during the transient interaction process between the millisecond laser and the ceramic, the material removal mechanism in this process is elucidated. Additionally, this study examines the millisecond laser oblique hole processing technology by analyzing the influence of various laser parameters on hole formation. It reveals that appropriately increasing the single-pulse energy of millisecond lasers can optimize the material removal rate and hole taper. Ultimately, the formation mechanism of millisecond laser oblique hole processing in alumina ceramics is comprehensively summarized. The results provide theoretical and methodological guidance for high-speed laser drilling of alumina ceramic substrates. Full article

Pulse-width modulation (PWM) and pulse-density modulation (PDM) are widely used in applications where electrical energy is delivered in a pulsed manner. Typical examples include LED (light-emitting diode) control, DC motor control, switched-mode power supplies (SMPS), and electric heating control. However, the pulsed operation of power switches is often associated with significant electromagnetic interference (EMI). As an alternative, stochastic pulse-density modulation (SPDM), also referred to as stochastic signal density modulation (SSDM), can be considered. This technique distributes the energy of generated harmonics over a broader frequency spectrum, thereby reducing the amplitude of individual frequency components. As a result, unwanted frequencies become easier to filter out, mitigating EMI more effectively. Full article

Recently, the urgency of combating antibiotic-resistant bacteria, viruses, and other pathogens has dramatically increased. With the development of nanotechnology, significant hopes are placed on nanoparticles with antimicrobial properties. The efficiency of such materials can be significantly enhanced through light-activated processes. In this study, we prepared composite ZnO-Ag nanoparticles and tested their ability to inhibit Staphylococcus aureus bacteria. The composite ZnO-Ag nanoparticles were fabricated using pulsed laser ablation of Zn and Ag targets in water using a nanosecond pulsed laser. During antibacterial tests, light-enhanced activation of the nanoparticles was achieved using low-power near UV (375 nm) and blue visible (410 nm) LED irradiation. For comparison, similar laser-fabricated ZnO nanoparticles were also tested. The combined use of nanoparticles and LED irradiation significantly increased the generation of reactive oxygen species. As a result, low nanoparticle concentrations (0.05 g/L) and low-power LED irradiation (0.17–0.22 W) significantly reduced the concentration of Staphylococcus aureus bacteria, including experiments with visible light irradiation. Compared to their ZnO counterparts, the use of ZnO-Ag composite particles led to an additional increase in antimicrobial activity. Full article

Chronic diabetic wounds affect 15–20% of patients and are characterized by impaired healing due to disrupted hemostasis, inflammation, proliferation, and extracellular matrix (ECM) remodeling. Low-level light therapy (LLLT) has emerged as a promising noninvasive strategy for enhancing tissue regeneration. Here, we developed a multispectral pulsed LED system combining red and near-infrared light to stimulate wound healing. In vitro photostimulation of human keratinocytes and fibroblasts on biomimetic hydrogels enhanced adhesion, spreading, migration, and proliferation via increased focal adhesion kinase (pFAK), paxillin, and F-actin expression. In vivo, daily LED treatment of streptozotocin-induced diabetic wounds accelerated closure and improved ECM remodeling. Histological and molecular analyses revealed elevated levels of MMPs, interleukins, collagen, fibronectin, FGF2, and TGF-β1, supporting regenerative healing without excessive fibrosis. These findings demonstrate that multispectral pulsed photobiomodulation enhances diabetic wound healing through focal adhesion-mediated cell migration and ECM remodeling, offering a cost-effective and clinically translatable approach for chronic wound therapy. Full article

Using multimodal wearable devices to diagnose cardiovascular diseases early is essential for providing timely medical assistance, particularly in remote areas. This approach helps prevent risks and reduce mortality rates. However, prolonged use of medical devices can lead to measurement inaccuracies, necessitating calibration to maintain precision. Unfortunately, wearable devices often lack affordable calibrators that are suitable for personal use. This study introduces a low-cost simulation system for phonocardiography (PCG) and photoplethysmography (PPG) signals designed for a multimodal smart stethoscope calibration. The proposed system was developed using a multicore microprocessor (MCU), two digital-to-analog converters (DACs), an LED light, and a speaker. It synchronizes dual signals by assigning tasks based on a multitasking function. A designed time adjustment algorithm controls the pulse transit time (PTT) to simulate various cardiovascular conditions. The simulation signals are generated from preprocessed PCG and PPG signals collected during in vivo experiments. A prototype device was manufactured to evaluate performance by measuring the generated signal using an oscilloscope and a multimodal smart stethoscope. The preprocessed signals, generated signals, and measurements by the smart stethoscope were compared and evaluated through correlation analysis. The experimental results confirm that the proposed system accurately generates the features of the physiological signals and remains in phase with the original signals. Full article

The consumption of fresh produce has significantly increased in recent years, contributing to improved diets through the provision of essential nutrients, vitamins, and fiber. However, there has been a rise in foodborne illness outbreaks linked to fruits and vegetables, often caused by pathogens such as Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes. These outbreaks have led to severe health consequences, including illnesses, hospitalizations, and even deaths. Once produce is contaminated by foodborne pathogens, these pathogens are difficult to eliminate. Traditional decontamination methods, such as water washes and chlorine-based sanitizers, have been widely used to address these microbial concerns. However, these methods may not be effective against pathogens in crevices or biofilms on the surface of produce, and their effectiveness varies depending on the type of produce and pathogens. Moreover, the chemicals used may raise health and environmental concerns. As a result, novel technologies for pathogen inactivation are gaining attention. These include ozone, ultraviolet light, cold plasma, pulsed light, ultrasound, microbubbles, nanobubbles, electrolyzed water, high-pressure processing, chlorine dioxide gas, and among others. This paper reviews a range of emerging and innovative technologies for the sanitization of fresh produce. The mechanisms, advancements, and practical applications of these technologies are examined with a focus on enhancing food safety and preserving produce quality. These innovative methods provide new opportunities for both research and industry to develop practical, affordable, and safe solutions for maintaining produce safety and quality. Recent studies highlight the effectiveness of combining methods, showing that using multiple sanitization techniques can significantly improve pathogen inactivation on fresh produce. For example, more than 5 log reductions of Listeria innocua and E. coli on avocado, watermelon, and mushroom can be achieved with the combined application of pulsed light and malic acid in previous research. In this review, we recommend the application of combined sanitization methods, emphasizing that integrating multiple techniques can provide a more effective and comprehensive approach to pathogen inactivation. This combined-method strategy has become a promising and innovative trend in the ongoing efforts to improve produce safety and quality. Full article

Photoacoustic tomography (PAT), also known as optoacoustic tomography, has been emerging as a biomedical imaging modality that can provide cross-sectional or three-dimensional (3D) visualization of biological tissues such as blood vessels and lymphatic vessels in vivo at high resolution. The principle behind the visualization involves the light being absorbed by the tissues which results in the generation of ultrasound. Depending on the strength of ultrasound and its decay rate, it could be used to visualize the absorber location. In general, pulsed lasers such as the Q-switched Nd-YAG and OPO lasers that provide high-energy widths in the range of a few nanoseconds operating at low repetition rates are commonly used as a light source in photoacoustic imaging. However, such lasers are expensive and occupy ample space. Therefore, PAT systems that use LED as the source instead of lasers, which have the advantage of being obtainable at low cost and portable, are gaining attention. However, LED light sources have significantly low energy, and the photoacoustic signals generated have a low signal-to-noise ratio (SNR). Therefore, in LED-based systems, one way to strengthen the signal and improve the SNR is to significantly increase the repetition rate of LED pulses and use signal processing, which can be achieved using a high-power LED along M-sequence signal decoding. M-sequence signal decoding is effective, especially under high repetition rates, thus improving the SNR. However, power supplies for high-power LEDs have a circuit jitter, resulting in random temporal fluctuations in the emitted light. Such jitters, in turn, would affect the M-sequence-based signal decoding. Therefore, we propose a new decoding algorithm which compensates for LED jitter in the M-sequence signal processing. We show that the proposed new signal processing method can significantly improve the SNR of the photoacoustic signals. Full article

Background: There is no cure for mitochondrial diseases which manifest in numerous ways including fatigue, muscle weakness, and exercise intolerance. Medical treatment varies and focuses on managing symptoms. Photobiomodulation (PBM) can decrease mitochondrial damage thereby increasing energy production and decreasing cell death. This pilot study will apply PBM to people with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) to examine the safety of application, and if changes occur in symptoms and signs after cross-over application/withdrawal of a sham or active PBM treatment including a two-week period of washout. Methods: This study is an exploratory, prospective series N-of-1 (single patient) studies. The protocol is guided by the CONSORT extension for reporting N-of-1 trials (CENT 2015), chosen due to the rarity of mitochondrial diseases, the fluctuating symptomology, and heterogeneity of the clinical presentation. The primary outcome is patient-reported fatigue assessed using the Checklist of Individual Strength and with concomitant evaluation of safety. Secondary measures are of depression, anxiety and stress, sleepiness, physical activity, blood lactate and creatine kinase, physical measures of sit-to-stand, and heel raise capability. Mitochondrial function will be evaluated using hydrogen magnetic resonance spectroscopy for lactate. PBM will be a participant-administered, home-based therapy using a multiple diode flexible array (BeniLight iLED-Pro Multi-Wave Multi-Pulse belt; 465 nm, 660 nm, 850 nm; average irradiance 5.23 mW/cm²; total joules: 770.1 J/treatment, all sites; 5 KHz; 20% duty ratio) over the anterior thigh muscles, posterior calf muscles and abdomen for 10 min to each site, three times/week. The safety of the intervention will be assessed. Descriptive statistics, causal analyses of time series data and dynamic modelling will be applied as relevant to the variables collected. Hydrogen magnetic resonance spectra will be acquired and averaged to obtain the content of the targeted hydrogen levels. Discussion: The study will provide guidance on whether and how to progress to a larger, randomised cohort study with sham control. Full article