This article presents a prototype design and experimental validation of intelligent control of a street light luminaire containing CW (cool white) and WW (warm white) LED based on human or object detection, motion, and weather conditions. The system is mainly controlled by a Raspberry Pi 5(RPi 5) integrated with a wireless CCTV camera for obtaining real-time object presence and speed estimation, along with a DHT11 sensor and LDR for temperature, humidity, and light level detection, and sensing of fog and rain from a weather application programming interface (API). The designed system uses vision-based object detection, determines the type and speed of object movement, and then dynamically adjusts the LED light output, consists of alternate array of CW and WW LED arrays, based on the required illuminance on road surface corresponding to the object's speed. On the other hand, it senses weather behaviour from weather API data to generate control signal and transfer via IoT network to ESP8266 to switch between CW and WW LEDs in a single LED module. In this system, sensor fusion techniques are used to correlate environmental parameters to actuate the situation demanded light level. A hardware prototype is designed and experimentally tested in a controlled environmental scenario to evaluate system response time, light output adjustment variation with speed, and lighting performance under dynamic weather conditions. This control setup helps to develop a smart street lighting solution as well as to provide suitable visual conditions and safety to support the development of a smart city.

Inkjet printing offers a mask-free route to large-area electronics, yet achieving uniformity in micron-scale organic light-emitting diode (µ-OLED) arrays remains challenging. Presented here is a photolithography-free, solvent-programmed, single-step inkjet micro-inlay process in which lateral phase separation self-confines each emissive pixel. Guided by solubility parameters, a trichloromethane (TCM)/1,2-dichloroethane (DCE) binary solvent is designed to optimize interactions among the solvents, emissive solutes, and the poly(4-vinylpyridine) (P4VP) underlayer. Micro-Raman mapping, cross-sectional SEM, and AFM phase analysis support lateral phase separation between the emissive region and the displaced P4VP phase, selective restructuring of P4VP while preserving the underlying transport layer, and no detectable nanoscale phase segregation within the emissive interior, yielding self-confined pixels of approximately 100µm. High-speed imaging shows that the blend yields reproducible 180 dpi arrays without jetting instability or nonuniform deposition. Green µ-OLED arrays printed with the blend achieve a peak luminance of 2400cd m-2, a peak current efficiency of 3.5cd A-1, and a peak external quantum efficiency of 1.0%. The figure of merit and luminance uniformity improve by 2.6- and 6.9-fold, and by 3.9- and 2.9-fold, respectively, relative to neat TCM and neat DCE. This strategy enables scalable fabrication of flexible and three-dimensional conformal OLED platforms.

Ag2Te has emerged as a promising n-type flexible thermoelectric material for harvesting body heat in wearable electronics. However, previously reported thin films have suffered from low carrier mobility and limited power factor of < 10 µW cm-1 K-2. Here, we present a two-step evaporation strategy on polyimide substrates at 280°C, followed by post-annealing at 250°C, enabling precise microstructural and stoichiometric control. This approach yields Ag2Te films with an exceptional room-temperature carrier mobility of 4756 cm2 V-1 s-1 and a power factor of 17.9 µW cm-1 K-2, outperforming both prior thin-film and bulk counterparts. The resulting devices exhibit excellent flexibility and rapid transient voltage response across temperature differences of 10-40 K, delivering power density up to 11W m-2. Integrated into robotic systems and light emitting diode arrays, these films enable thermally triggered actuation and sensing, underscoring their potential for efficient, adaptable, and self-powered applications in next-generation Internet of Things devices and sensor networks.

Multimodal tactile sensing is crucial for next-generation robotics and human-machine interaction, but conventional solutions based on discrete sensor arrays suffer from complexity, limited flexibility, and high fabrication costs. Here, we introduce a continuum sensing paradigm based on a continuous liquid metal enabled flexible tactile sensing (CLiMETS) platform. This approach eliminates the need for sensor arrays by decoding tactile information from a single, unstructured liquid metal (LM) surface. We reveal a key mechanism where the deformation-induced voltage of the LM's electric double layer (EDL) is synergistically amplified by over two orders of magnitude upon contact with a conductive rod. Our geometrically encoded, dual-channel scheme enables precise 5by5 localization and eight-directional sliding recognition. We further demonstrate the platform's feasibility by realizing postprocessing visual feedback of an LED array, effectively translating complex tactile inputs into corresponding optical outputs. The CLiMETS platform offers a minimalist yet highly versatile proof-of-concept sensing modality, laying a strong foundation for more adaptive and interactive tactile technologies.

Multispectral imaging (MSI) systems leverage the differing optical absorption properties of oxygenated and deoxygenated haemoglobin across various wavelengths to enable non-invasive dynamic monitoring of relative blood oxygen saturation. Existing systems struggle to meet demands for portable, efficient monitoring due to high costs and slow response times. This study developed a compact MSI system utilising a multi-band light-emitting diode array as its light source. Combined with a triple-isosbestic point calibration algorithm, it rapidly generates pseudo-colour maps of blood oxygen distribution. The system was validated in human finger and rabbit small intestine ischemia-reperfusion models. Following occlusion, relative blood oxygen saturation in the ischaemic regions decreased to 66.3% (finger) and 29.5% (small intestine), both significantly distinct from normal areas. Post-reperfusion, the ischaemic regions exhibited marked recovery with characteristic reperfusion response patterns. These findings demonstrate the system's capability to accurately identify hypoxemic zones, indicating its potential for dynamicin vivoblood oxygen monitoring applications.

To assess the feasibility of a light emitting diode (LED) solid-state lamp that mimics the extraterrestrial solar near ultraviolet (NUV) spectrum between 250 and 400 nm, we present the design and experimental results of a prototype LED solar simulator. It consists of a matrix of 109 LEDs, selected based on wavelength, emission angle, and radiative power, in order to mimic the solar NUV spectrum outside the Earth’s atmosphere, with irradiance ranging from one to four times that of solar radiation. Such an LED lamp is suitable, for example, for testing the resistance of space materials to the NUV radiation. Based on our experimental tests, we analyze the advantages and drawbacks of the multichannel NUV LED solar simulator compared to traditional arc-lamps-based simulators.

Abstract Nano-scale light-emitting diodes (LEDs) are crucial for realizing ultra-high-resolution displays and have attracted significant attention. This paper reports a blue-emitting nanopillar LED display with a resolution up to 500 × 150 and a pixel density of 6336 PPI. The display area is 2 × 0.6 mm 2 , with individual pixels with a diameter of approximately 800 nm. Key steps in the device fabrication include precise etching to define nano-scale pixels, tetramethylammonium hydroxide treatment to repair etching-induced damage and smooth the sidewalls, followed by planarization using polyimide to facilitate the subsequent fabrication processes and to ensure electrical isolation between the p- and n-regions. Furthermore, a passive matrix-driven 6 × 6 nanopillar array was fabricated, achieving independent addressing of individual pixels through spatially separated p- and n-type electrodes. This work presents a feasible technical pathway for the scalable manufacturing of ultra-high-resolution displays.

To address opto-thermal crosstalk in high-density LED arrays, this study develops a physics-informed photo-thermal scalar model. Combined with spatially resolved micro-photoluminescence mapping and calibrated DC electro-thermal characterization, the model extracts key opto-thermal parameters of AlGaInP and InGaN chips under 405/470 nm single/dual-wavelength excitation. It separates direct photoluminescence gain from indirect photo-thermal attenuation, quantifying material-specific responses: InGaN achieves radiative enhancement via quantum-confined Stark effect (QCSE) screening and band-filling mitigation, while AlGaInP shows thermal quenching due to higher temperature sensitivity-providing material-level design and calibration guidance for integrated LED systems.

Triboelectric nanogenerators (TENGs) can effectively harvest mechanical energy from the environment, offering a promising solution for a sustainable power supply in wearable electronics. However, their widespread application is often hindered by expensive raw materials and complex fabrication processes. This study develops a simple and efficient integrated ultrasonic-shear process to exfoliate low-cost flake graphite (FG) into multi-layer flake graphite (MLFG), which is then embedded into polydimethylsiloxane (PDMS) to fabricate a novel composite triboelectric layer. The multi-layered structure of MLFG provides a larger specific surface area and more charge trapping sites, significantly enhancing capacitive behavior. The optimized 2 wt% MLFG-TENG achieved an open-circuit voltage of 90.3 V and a short-circuit current of 4.6 μA, which are 1.2 times and 1.6 times higher than those of the 3 wt% FG-TENG and 3.1 times and 4.2 times higher than those of the pure PDMS-TENG, respectively. This method delivers superior output performance with lower doping levels and maintains stable output after 20 000 cycles, demonstrating exceptional scalability. Furthermore, by integrating a rectifier circuit, the MLFG-TENGs successfully power small electronic devices such as LED arrays and electronic clocks. Concurrently, when integrated with machine learning, the MLFG-TENGs achieve 100% accurate recognition of five distinct hand motion patterns, highlighting their great potential in the fields of self-powered wearable devices and motion sensing.

Polarized on-chip lensless microscopy provides a cost-effective diagnostic solution for large field-of-view (FOV) imaging. However, conventional designs often rely on a 3-dimensional and rotational motorized stage for the sensor, a configuration that necessitates an additional image registration process, increases system bulkiness, and extends image acquisition time. In this work, we present a polarized lensless microscope based on illumination diversity. The proposed system integrates a two-LED multiplexed pixel super-resolution and multi-wavelength phase retrieval framework based on an RGB-LED matrix, as well as illumination polarization-state modulation, enabling high-resolution polarized microscopic imaging without mechanical movement in the detection optics, including the specimen. Our system achieves sub-micron resolution across a wide FOV while featuring a compact, cost-effective design with rapid image acquisition and reconstruction. We expect that our proposed polarized lensless microscope design will enhance the applicability of lensless imaging systems in the biomedical field.

Flexible electronics demand stretchable, high-performance interconnects for wearable and implantable applications. However, conventional methods such as direct-ink writing or doped-activator metallization face challenges including thermal degradation risks from high-temperature sintering, complex multi-step chemical procedures with toxic precursors. Here, we introduce an updated laser-induced selective metallization (LISM) for fabricating stretchable copper electrodes directly on a commercial polysiloxane rubber. This approach employs a spray-coated copper carbonate hydroxide activator, followed by near-infrared laser activating. Laser irradiation leads to the reduction of copper ions, along with the formation of amorphous carbon domains and micro-nanoscale surface structures. Electroless copper plating (ECP) and electroplating (EP) are subsequently performed to form continuous, low-resistivity serpentine traces. Comprehensive characterization verifies the successful reduction of copper and the robust integration of the electrode into the substrate. Mechanical testing shows that the structure maintains its electrical performance under repeated cyclic deformation. Functional demonstrations including electrocardiogram (ECG) patch, LED arrays, and wireless antennas showcase practical applicability of the proposed approach. Additionally, LISM operates at ambient temperature without toxic precursors and it minimizes chemical consumption and provides exceptional durability. This method advances next-generation electronics requiring both mechanical flexibility and electrical reliability.

Precise and independent control of illumination and temperature is essential for photobiological experiments and mammalian cell culture. To overcome the limited throughput and thermal instability of existing lighting incubators, we developed a high-throughput lighting incubator comprising eight independently controlled light-exposure chambers within a shared physiological environment. The integration of high-density LED arrays in such a confined architecture, however, leads to severe heat accumulation, making it difficult to maintain the required 37 °C operating condition. Here, we report the design, optimization, and experimental validation of an active liquid-cooling thermal management system tailored for this multi-chamber instrument platform. Guided by three-dimensional computational fluid dynamics simulations, a serpentine liquid cooling plate was optimized and implemented to replace conventional passive fin heat sinks, which were found to cause substrate temperatures exceeding 45 °C under high-power operation. The assembled instrument, coupled with an industrial chiller for precise coolant temperature control, was systematically characterized. Experimental results demonstrate that the chamber temperature can be stably maintained at 37 ± 0.5 °C under continuous high-power illumination, with minimal inter-chamber variation over long-term operation. This instrument provides a robust and reproducible platform for high-throughput photobiological experiments requiring strict thermal stability and independent multi-parameter optical control.

To solve the problems of severe reflection caused by local high illumination and shadow areas in the visual inspection of IC (Integrated Circuit) devices, this paper innovatively designs a multi-annular array light-emitting diode (LED) light source system based on freeform surface reflectors. A comprehensive evaluation function that simultaneously optimizes the illumination uniformity and illumination efficiency on the receiving surface is established. The Taguchi method is applied to optimize four parameters of the system. Furthermore, the ANOVA method is used to confirm the effectiveness of the optimization experiment. Finally, the optimized light source system was experimentally validated in the IC chip detection system. The results showed that the illumination uniformity and the illuminating efficiency of the optimized multi-annular array LED light source system were improved by 13.6% and 48.5%, respectively, compared to the traditional LED light source. The verification in the IC chip detection system shows that the average accuracy of character recognition, pin shortage detection and weak scratch detection reaches 99.74%, 100% and 99.97%, respectively, which can fully meet the visual inspection lighting of IC devices.

The oxide semiconductor BiVO4 is a promising photoanode for the oxygen evolution reaction (OER) under visible light. It is a well-suited model photoanode for the time-resolved investigation of light-pulse-induced space charge layer reorganization and electron-transfer chemistry at the BiVO4–electrolyte interfaces. In order to study the different time scales of the photocapacitive and photochemical processes including the effect of defect states, a time-resolved photoelectrochemical rotating ring-disk electrode setup with a time resolution of better than 1 ms is developed. Measurements were performed under dark, continuous, and stroboscopic illumination using a LED array that simulates the AM 1.5G spectrum. Cyclic voltammetry measurements revealed four different regions for the photocurrents, which can be associated with different states of band bending and allow for the determination of the flat band potential. The photocurrent transients during switch-on and -off of the LED array show an exponential time evolution with three time constants that are attributed to (1) fast reorganization of the space charge layer, (2) slower onset/relaxation of the photocatalytic OER, and (3) very slow photocorrosion. These findings help to understand the interplay between photoinduced space charge reorganization and OER-related charge transfer in the electrochemical double layer during photocatalytic water splitting.

Photobiomodulation (PBM) has been shown to enhance cell growth and differentiation. This study investigates the effects of 810-nm PBM on the proliferation and cardiac differentiation of human-induced pluripotent stem cells (hiPSCs), utilizing a custom-made LED device. This device is compatible with standard cell incubators and features an LED array that ensures uniform light exposure to cells in each well of a 96-well plate. hiPSCs were irradiated with 810-nm light at intensities of 1.0, 1.5, and 2.0 mW/cm² for 15min daily. Outcomes assessed included cell viability, mitochondrial function and morphology, and cardiomyocyte differentiation. The results show that PBM at 1.5 mW/cm² enhanced hiPSC proliferation and cardiac differentiation, yielding a higher number of spontaneously beating cardiomyocytes compared to controls. These findings suggest that 810-nm PBM may improve the efficiency of cardiac cell generation for both research and therapeutic applications.

Abstract Hyperspectral imaging acquires spatially resolved spectral signatures, enabling a wide range of applications from scientific research to industrial processes. Traditional microelectron-mechanical systems (MEMS) Fabry–Pérot (FP) spectrometers offer a compact and simple design but are limited by single free spectral range (FSR) operation. This limitation introduces a fundamental trade-off: achieving high spectral resolution necessitates narrowing the operational bandwidth. Furthermore, maintaining such high resolution demands a larger number of sampling channels, which increases the acquisition time for a single hyperspectral image and thereby limits the frame rate. Here, we present a computational hyperspectral imaging framework that achieves broadband spectral coverage and high frame rate without sacrificing spectral resolution. By dynamically modulating the MEMS-FP cavity to span multiple FSRs, we generate a set of low-correlation spectral sampling patterns as spectral encoders. When combined with a tailored reconstruction algorithm, the system accurately decodes spectral information from a significantly reduced number of sampling channels. We experimentally validate the effectiveness of our system through LED array inspection, demonstrating its potential for high-throughput defect detection in LEDs or screen manufacturing lines. Our work presents a strategy that leverages rapidly advancing computational techniques to overcome the limitations of conventional hardware architectures in hyperspectral imaging. This compact and integrable solution is particularly well-suited for deployment in resource-constrained environments.

LED luminaires with apertures containing visually resolvable bright spots are commonly used to illuminate outdoor environments. However, the impact of the distance between LEDs, which determines spatial frequency at a given viewing distance, on perceived discomfort caused by these luminaires remains unclear. This study involved 29 participants who were shown 68 stimuli varying in spatial frequency, intensity, diffusion level and ambient lighting in a dark laboratory setting. Participants reported their experiences of discomfort from glare, ability to resolve individual LEDs and afterimages. The findings revealed that increased spatial frequency heightened both discomfort and the likelihood of experiencing afterimages. It is hypothesized that the point spread function of the eye contributed to these effects, where sources began to be perceived as a single larger source with equal or greater intensity. These results suggest that LED luminaire designs should favour configurations with lower spatial frequencies to minimize discomfort. A simple quantity, direct illuminance at the eye, is recommended for use to predict discomfort from glare because it performed like other more complex models.

Conventional machine vision architectures suffer from intrinsic energy inefficiency and latency bottlenecks due to the physical segregation of sensing, memory, and processing units. Emerging organic neuromorphic devices offer a promising solution, yet concurrently achieving strong photoresponse, ultralow-power operation, and reliable non-volatile memory remains a critical challenge. Herein, we integrate a heterostructured dielectric layer, poly (amic acid) (PAA)/hafnium oxide, into wafer-scale organic neuromorphic devices, significantly enhancing charge carrier mobility, photosensitivity, and memory performance. The optimized devices exhibit a suite of exceptional characteristics: high carrier mobility, ultralow light detection sensitivity (102 nW cm-2) with a fast response time (50 µs), minimal energy consumption (53 aJ per spike), long-term memory retention (50000 s), and robust endurance. We further demonstrate programmable organic thin-film transistors (OTFTs) driving LED arrays, enabling repeatable light/mask-induced pattern writing/erasing and integration of sensing-memory-display functions. Linear Dynamic Range Adjustment (LDRA) simulations reveal ultrahigh dynamic range and superior imaging capabilities of PAA-optimized OTFTs. This hetero-dielectric strategy establishes a universal platform for organic neuromorphic electronics, addressing key gaps in adaptive edge vision systems and human-retina-like interactive meta-displays.

Abstract Fog-related flight disruption is costing big international airports more than Rs 2.5 crores for each such event, while the traditional countermeasures, chemical seeding and thermal heating, are expensive, slow and environmentally damaging. This paper proposes the first field-validated airport fog dispersal autonomous UAV system that combines deep reinforcement learning with targeted UV-C photolysis technology. Conventional ways of fog dispersal take 30–45 min for runway clearance, cost Rs 15,000 per operation and produce 500 kg of CO2 emissions. These strategies evaporate fog droplets without tackling the condensation nuclei that are causing them and so the fog can quickly reform. We use a 4-UAV swarm with UV-C LED arrays (254 nm wavelength) for the degradation of hygroscopic aerosols which act as cloud condensation nuclei (CCN). Unlike thermal approaches that only evaporate droplets, our photolysis-based approach can reduce the efficiency of CCN by 35–45% so that the fog does not re-form. A deep Q-Network (DQN), based on 625-256-256-8 architecture, autonomously coordinates swarm positioning based on real-time sensor fusion from LiDAR (25 × 25 m resolution), thermal imaging (640 × 480 at 30fps) and meteorological arrays. 96% accuracy of fog detection. Our operational flights took place at Sri Guru Ram Dass Jee International Airport Amritsar, India, with 120 flights starting from November 2024 till March 2025. Results show: 83.1% reduction in time of fog clearance (from 30 to 5.06 min), 80% improvement of runway visibility range (from 450 to 810 m), 95% reduction in cost (from Rs 800 to Rs 15000 per sortie), 96% reduction in CO2 emission (from 20 to 500 kg per operation).Randomized complete block design using Friedman analysis (kh2 = 128.45, p &lt; 0.001, Cohen’s d effect sizes of 4.85–7.92 show very large practical significance for all of the metrics. Zero incidents during 120 flights with ground exposure from UV-C (0.008 mJ/cm 2 ) 375x below ICNIRP occupational limits. Real-time DQN inference latency (183+-27ms) is the aviation safety-critical requirement (&lt; 250ms). This research sets up a scalable paradigm for fog management at fog-prone airports anywhere in the world economically and environmentally and the potential savings is Rs. 2.5 Crores every year at major international airports.

Fabricating quantum-dot (QD) light-emitting diode (LED) arrays typically relies on direct QD patterning or costly color filters (CFs), highlighting the need for cost-effective patterning techniques to achieve high-efficiency pixelated QLEDs. This study presents a bi-color-converting cavity that transforms yellow emissions from non-patterned mixed red and green QDs into saturated red and green emissions by adjusting the thickness of the indium-zinc-oxide phase tuning layer. Excluding blue QDs with low quantum yields and high injection barriers, this approach is expected to achieve excellent device performance tailored for specific outdoor display applications. The cavity yellow QLEDs exhibit maximum current efficiencies of 28.20 and 36.32 cd/A for red and green emissions, representing enhancements of 144% and 148% over CF yellow QLEDs, respectively. These improvements stem from the bi-color-converting cavity, which enhances the forward emissions in the cavity yellow QLED and redistributes exciton energy in mixed QDs by modulating the energy transfer. Furthermore, bi-color pixelated QLEDs with a resolution of 423 pixels per inch have been demonstrated. This bi-color-converting cavity technique relies on established photolithography techniques and holds great potential in high-performance and high-resolution display applications.