Search

The feasibility of using InGaN/GaN multiple-quantum-well light-emitting diode arrays (LED arrays) as photodiodes (PDs) is investigated experimentally in addition to their light emitting function. Two discrete LED arrays are produced from one 4 × 4 LED array with a parallel-connected pixel configuration. Such compact designs are useful for light emission or detection at the transmitting/receiving terminals of optical wireless communication systems. Despite 4 × 2 LED arrays achieving a light output power of 67.4 mW at 250 mA, they exhibit an optical responsivity (detectivity) of 0.183 A/W (1.61 × 1012 cm Hz1/2W−1) under ultraviolet light illumination (λ = 380 nm) at zero bias. For 4 × 2 LED arrays, the presence of an appreciable ultraviolet light response, together with a high 3-dB bandwidth (∼8 MHz) for modulated light detection, allowed us to build a 15 Mbit/s directed optical link with these LEDs functioning as both the optical transmitter and the receiver. Finally, the unitary LED array-based optical link is capable of real-time transmission of digital audio signals (data rate = 6 Mbit/s) at a propagation distance of 100 cm in free space even though some of the constituent pixels are inactive for light detection.

The optical properties of nonpolar AlGaN multiple quantum wells (MQWs) emitting at 280 nm were investigated intensively using temperature-dependent and time-resolved photoluminescence spectra associated with the characterization of structural properties. The densities of superficial pits and basal-plane stacking faults (BSFs) were reduced by 33.8% and 35.9%, respectively, for nonpolar AlGaN MQWs due to the carefully optimized dual nitridation. It was found that the nonpolar MQWs emission can be significantly improved by reducing the BSFs density as the BSFs emission was the main competing channels. Moreover, an internal quantum efficiency of 39% for nonpolar Al0.43Ga0.57N MQWs at emission wavelength of 279 nm was achieved even the full width at half maximum values of X-ray rocking curves were 0.565° for c-direction and 0.797° for m-direction. This fact means that a highly efficient deep ultraviolet light sources can be expected by means of nonpolar AlGaN due to the elimination of quantum confined Stark effect induced the decrease in radiative lifetime.

Robots are being increasingly used in the fight against highly-infectious diseases such as Ebola, MERS, and SARS-CoV-2. Many of these robots use ultraviolet lights mounted on a mobile base to inactivate the pathogens. While the lights are generally effective at irradiating open spaces and walls, they are less effective when it comes to horizontal surfaces, because of the orientation of the light sources. This can be problematic for pathogens such as Ebola, where transmission via contaminated work surfaces, which are often horizontal, is a concern. In this paper, we describe the design, implementation, and testing of an ultraviolet light disinfection system implemented on a mobile manipulator robot designed to address the problem of horizontal surface disinfection. A human supervisor designates a surface for disinfection, the robot autonomously plans and executes an end-effector trajectory to disinfect the surface to the required certainty, and then displays the results for the supervisor to verify. We also provide some background information on Ultraviolet Germicidal Irradiation (UVGI) and describe how we constructed and validated models of ultraviolet radiation propagation and accumulation in our system. Finally, we describe our implementation on a Fetch mobile manipulation platform, and discuss how the practicalities of implementation on a real robot affect our models.

There is a need for UV based sanitization in automobiles. In this pandemic automobiles are currently sanitized with alcohol based sanitization. For automobiles conventional methods for sanitisation can’t be used. Both vapour based sanitization and alcohol based sanitization are dangerous to use in automobiles. The main component of the alcohol sanitizer is ethanol. Ethanol is highly flammable in nature. There is a requirement for alternative method. The best method to kill the microorganisms in effective way is with the use of Ultraviolet light. [5] UV-C is known for disinfection as it kills viruses, bacteria and other microorganisms. UVC have a wavelength of 200-280nm. This Energy is found naturally in sunlight. It is produced in strong intensity with the help of high intensity lamp. In this project an IOT device which uses UV-C light is used to produce UV light and motion detector is used to detect any motion near the light and immediately switching the light off in case of any motion. Thus preventing any person contact with UV light. This helps to minimize the fire accidents caused by alcohol based sanitization in automobiles.

This paper aims to study the leakage current characteristics of outdoor insulators exposed to pollution after a long dry season. This study observed the insulating phenomenon using the natural tropical climate of the Gowa Makassar region in Indonesia and the effect of NSDD, humidity, temperature, ultraviolet light, and rainfall in real-time. A microcontroller was used to collect data on leakage current and environmental-climate conditions over 23 months. Silicon rubber-type line posts and suspensions were used in the test sample, mounted on a 20 kV distribution network. The illustration of this test can represent actual conditions in the field. This leakage current test refers to the IEC 60060 standard with a real-time monitoring system for leakage current and tropical climatic conditions. For hydrophobic measurements using the spray method according to IEC 62073 and STRI 92/1 standards. The tests show that the leakage current and hydrophobic properties are influenced by changes in the tropical climate with temperature, humidity, ultraviolet radiation, and rainfall parameters. Changes in hydrophobic properties are also controlled by the mechanism for cleaning pollutants during rain and experiencing recovery when climatic conditions return to normal due to the hydrophobic transfer of contaminants. In addition, laboratory-based flashover mechanism testing was also carried out to determine the reliability of the insulator. This test demonstrates that the flashover voltage is affected by the number of pollutants and wetting on the silicone rubber polymer insulator's surface.

We present a rib waveguide design in beta-barium borate-on-insulator platform for coherent deep-ultraviolet generation down to a wavelength of 230 nm via nonlinear frequency conversion.

Deep ultraviolet light-emitting diodes (DUV-LEDs) have been considered as the most potential ultraviolet light sources, however, the traditional packaging with flat quartz glass has severe total internal reflection (TIR) loss, largely reducing the efficiency of DUV-LED. It is an efficient method to address this problem using organic lens, but traditional organic materials cannot be applied in DUV-LEDs because they are easily cracked by short-wave ultraviolet light. In this report, solid-liquid mixing state (SLMS) organic lens is proposed to enhance the light extraction efficiency and reliability of DUV-LEDs. Results show that the radiant power of DUV-LEDs using SLMS organic lens is enhanced by 53.86% under the injection current of 150 mA compared to DUV-LEDs (275nm)encapsulated with conventional flat quartz glass. Moreover, after 279 hours continuous operation, DUV-LEDs encapsulated with SLMS organice lens can still radiate 8.289 mW, which is only 3.94% lower than the initial power. Consequently, an efficient, low-cost and universal strategy has been proposed to enhance the light-extraction efficiency of DUV-LEDs, which has a great application prospect in packaging industry of DUV-LEDs.

In this study, rare earth doped infrared (IR) to visible, up-converting particles along-with efficient ultraviolet (UV) to visible fluorescent molecules were imbedded in proteins and were used as a mean for increasing the human vision range to infrared and ultraviolet wavelengths. Stilbene-420 fluorescent molecules which convert near UV light to blue light, were chosen for the strong overlap of their fluorescence emission with the sensitivity region of blue cone cells and for the ability of blue light to increase the regeneration of bleached visual pigments. Our data show that the up-conversion efficiency of the IR up-converting particles and blue fluorescing molecules efficiencies remained unchanged when these material are imbedded in proteins compared to their efficiencies in water solutions. Addition of up-converting particles to rod visual cells resulted in the bleaching of the visual pigments, rods, when irradiated with infrared light (980 nm) whereas no bleaching was observed, under the same conditions, without the presence of up-converting particles. This suggests that the up-converted green light induced visual process in the rod visual pigments. In addition, we describe the design and present data of a novel optical device, which can be used as eye glasses, utilizing up-converting particles that allows the wearer to see rather intense infrared light.

Anisotropic thin films are widely used in sensors, optical devices and other fields. Ordered CdSe@CdS nanorods anisotropic film was fabricated by a simple and low cost self-assembly technology. Both parallel arrangement and hexagonal close-packed arrangement of the nanorods were observed due to the entropy driven mechanism. Green fluorescence centered at 535 nm can be obtained under an excitation of 325 nm ultraviolet light. The photoluminescence intensity of the CdSe@CdS nanorods film periodically varied with the polarization angle. The polarization ratio of the photoluminescence is $0.16\pm 0.02$ , which indicates the film can be used in ultraviolet polarization detection.

In this work, we discuss the molecular beam epitaxial growth of AlGaN nanowires on Si for ultraviolet light emitting. It is found that, although using a relatively low substrate temperature, AlGaN nanowires with different Al contents can still have a reasonably good optical quality. The reduced substrate temperature could favor the development of electrically injected ultraviolet light emitting devices.

UV light sources have many applications in science and technology. Generation of ultraviolet light from near-infrared lasers requires twice frequency conversion processes, such as the third- or fourth-harmonic generations (THG or FHG). In recent years, however, due to the increase in power of InGaN laser diode (InGaN-LD) and the emergence of primary visible solid-state lasers, it has become possible to generate ultraviolet laser light by once second-harmonic generation (SHG) [1] . In order to develop a more compact and simpler UV laser light source, we have been developing a single-mode primary visible fiber laser. Firstly, we successfully drew a single-mode double-clad structured Pr-doped waterproof fluoride glass fiber (Pr:SM-DC-WPFGF) and demonstrated laser oscillation with the power of 251.7 mW in 2016 [2] , then output power was improved to 2-W in 2019 [3] . We think that this kind of visible light source can be applied for a generation of UV laser.

In this work, we demonstrate AlGaN nanowire deep ultraviolet light-emitting diodes emitting at 280 nm with the transferred monolayer graphene as a transparent conductive electrode.

Regular irradiation of indoor environments with ultraviolet C (UVC) light has become a regular task for many indoor settings as a result of COVID-19, but current robotic systems attempting to automate it suffer from high costs and inefficient irradiation. In this paper, we propose a purpose-made inexpensive robotic platform with off-the-shelf components and standard navigation software that, with a novel algorithm for finding optimal irradiation locations, addresses both shortcomings to offer affordable and efficient solutions for UVC irradiation. We demonstrate in simulations the efficacy of the algorithm and show a prototypical run of the autonomous integrated robotic system in an indoor environment. In our sample instances, our proposed algorithm reduces the time needed by roughly 30\% while it increases the coverage by a factor of 35\% (when compared to the best possible placement of a static light)., Preliminary version of this paper will be published in the ICRA 2021 conference

We here present a DMD based low-cost digital lithography system, and report the results of microstructure fabrication experiments on both glass slide substrates and single mode optical fiber end faces. The system possesses the ability to rapidly fabricate microstructures in sub-micron scale, and the characteristic of fabricating on unconventional substrates such as optical fiber end faces. Through the processing procedure of “visible light – chromatic aberration and optical path difference correction – ultraviolet light”, the function of visual focusing was supported, without sacrificing part of the photoresist film. With above-mentioned features, the system is promising to accelerate the processing and construction of experimental sub-micron scale microstructure prototypes, especially micro-element prototypes on fiber end faces.

We report a direct and facile method to study the limit resolution of optical fiber microlithography, which is based on DMD (digital micromirror device) the fiber end face of submicron uv lithography system, with 365 nm uv light, supplemented by 620–630 nm red light for focusing the reference light source, using the Reduced projection objective lens will focus the DMD modulation of the ultraviolet light on the spin of the photoresist fiber end face, realize the optical fiber end surface microstructure (single exposure precision 900 nanometers, single exposure area of more than hundred microns) preparation. By changing the magnification of the objective and Number of pixels in a single cycle of digital mask, the influence of the Objectives with different magnification and the pixel point on the precision and integrity of the microstructure was analyzed, and the lithography experiment was carried out to verify and get the optimal solution between the two factors.

This paper presents the process of sterilizing water with help of ultraviolet lights of a certain wavelength. This sterilization of water destroys bacteria and microorganisms in the water because their DNA absorbs UV light, so they can no longer reproduce. Absorption in DNA has a peak at 254nm. For sterilization to be fast and efficient, a power LED is needed, but there are no LEDs available on the market that are accessible at this wavelength. For this reason, this application uses a power LED of 365nm, and one of 420nm, so we can compare their power to clean the water of bacteria. The water samples resulting from the tests performed were analyzed at a specialized laboratory. Thus, the final measurements showed that this type of setup can be used as water sterilizer. The 365nm LED achieved an efficiency of 15.4%, while the 420nm LED achieved an efficiency of 10.5%. This shows that the absorption of UV light is higher at shorter wavelengths. The efficiencies of the LEDs were calculated after exposing the water probes to the UV light for 5 minutes.

High-performance Ga-doped In 2 O 3 nanowire phototransistor based on top-gate structure was fabricated with gate dielectric is SiO 2 . By adjusting gate voltage of the phototransistor, the device can detect extremely weak ultraviolet light, with high responsivity (R) and large light-dark current ratio $(\mathrm{I}_{\text{ph}}/\mathrm{I}_{\text{dark}})$ . For example, its responsivity can reach 580 $\mathrm{A}/\mu \mathrm{W}$ and $\mathrm{I}_{\text{ph}}/\mathrm{I}_{\text{dark}}$ is maintained at~ 10^5 with 300 nm illumination (0.0 15 $\mu\mathrm{W}/$ cm2)

This research presents the effect of the constant current density on nanoporous silicon formation by double tank electrochemical etching cell without coating aluminum on the backside of silicon wafer. In this paper, the constant current density is increased from 10 mA/cm2 to 25 mA/cm2 during the anodization process by using hydrofluoric acid and ethanol at ratio 4:1 and the etching time are 10 minute. Gravimetric and Photoluminescence measurement were performed to investigate the porosity and the uniform distribution of nanoporous silicon layer respectively. The result shows that the porosity of nanoporous silicon layer was increased when the constant current density increased. The range of the porosity 46% to 80% and it is dependent on constant current density. The photoluminescence measurement with irradiate ultraviolet light on the surface of samples it was observed that hight uniformity of photoluminescence intensity. Indicates that the nanoporous silicon surface are more uniform distribution. This research discovers that the constant current density has large effect on the porosity of nanoporous silicon layer. Results show good improvement the nanoporous silicon formation by double tank electrochemical etching cell without coating aluminum on the backside of silicon.

The purpose of the work is to evaluate the performance of titanium dioxide nanoparticles based Ultraviolet photodetector decorated with Au nanoparticles (NPs) under 375 nm wavelength Ultraviolet light and at room temperature. The fabricated device shows an important responsivity about 100A/W. Moreover, it achieved the highest detectivity of 10 14 Jones and high response speed (rise/ decay time of 0.96 s/9.6s).

In the research project AVerdi the influence of photonic sintering methods on the resulting electrical conductivity, sintering duration and adhesion of digitally printed silver nanoparticle inks was investigated and compared to convective sintering. Conductor paths with film thicknesses below $1 \mu \mathrm{m}$ were applied on flexible polymer substrates via inkjet printing. Aerosoljet printing was used to generate thicker lines up to $11 \mu \mathrm{m}$ on injection molded substrates. Photonic sintering was carried out with near infrared emitters or ultraviolet light emitting diodes. For inkjet printed structures on polyimide a conductivity up to 24 % relative to bulk silver was achieved after a sintering duration of 2 s and 5 s for the near infrared and the ultraviolet light source, respectively. Oven sintered samples showed an electrical conductivity of 14 % after 1 h at 200° C. On polyethylene terephthalate a conductivity around 7 % was achieved after irradiation with near infrared light for 1 s, whereas convectively sintered samples showed a conductivity around 4 %. All material combinations sintered by the different methods showed good adhesion. The overall results of long-term behavior after thermal-cycling, regarding electrical conductivity and adhesion, show that the photonically sintered structures achieve similar results compared to the reference. The photonically sintered structures generated with the aerosoljet on polyamide 6 achieved conductivity values up to 19 %, which were comparable to the furnace sintered reference samples. On liquid crystal polymer substrates conductivity values reached up to 35 % after sintering with ultraviolet light emitting diodes for 60 s. Oven sintered samples showed a conductivity around 25 % after 1 h at 150° C. The adhesion of the silver nanoparticle ink on liquid crystal polymer and polyamide 6 substrates is better than with the reference samples. The reliability tests show fewer failures with alternative sintered samples. In this study only the results for inkjet printed structures are presented.

From the past couple of years, the rate of pathogen infections is increasing rapidly which is affecting our daily life. Reason behind the continuous increment of these infections in humans is due to rapid multiplication of harmful pathogens being transmitted from non-living surface to human body due to incomplete sanitization of surrounding area. Up till now many autonomous robots are designed for cleaning purpose but are either inbuilt with lesser cleaning processes or involve direct human efforts. Hence, an Automatic Disinfectant Robot which is capable of Cleaning, Sanitizing, and Disinfecting the floor surface by killing harmful pathogens with the help of vacuum cleaner, sanitizer and ultraviolet ray disinfection methodology, respectively without any direct involvement of human beings is becoming an undeniable need. Besides floor dusting, the robot must also capable of sanitizing the wall up to maximum possible height. The designed robot is intelligent enough to cover both simple and complex path as per requirement, which makes it usable in all possible conditions. For security purposes, ultraviolet light is adjusted in a way that does not harm human while it is exposed to a particular section of the surface for an allowable time. All these working mechanisms are assembled in such a way that enables robot to work round the clock with maximum cleaning efficiency and trouble-free control. In case manual operation is needed there must be a handy solution for the controlling action of the bot.

Ultraviolet is a vital spectrum in wireless optical communication. There are a lot of studies have been done in wireless ultraviolet communication. However, Ultraviolet communication networking mainly focuses on self-organizing networks and multi-hop networks. We proposed a new multi-access scheme of star topology network for confidential communications in semi-open spaces on the surface of ships. We verified the feasibility of the scheme through theoretical analysis and system simulation. It is proved that the scheme is suitable for ultraviolet communication and has better performance in a multi-user network. This scheme could be a sub-scheme for the next generation communication network combined with ultraviolet light communication.

Because the spacecraft in orbit are exposed to intense solar radiation, it will be affected by factors such as cosmic rays and high-energy particles, causing its material surface to be charged and damaged. And compared to the various currents captured on the surface of the spacecraft, when the incident energy is higher than the photoelectric threshold, the damage of the emitted photocurrent to the material is more serious. Because of the significant threat of particle radiation to the charged protection and operational life of spacecraft material, this paper studied the test method of photoelectron emission yield (PEEY) and developed the corresponding system. During the test, firstly, a deuterium lamp and a vacuum ultraviolet (VUV) monochromator are used to generate light. After splitting, it uses a focusing and collimating device to modulate the light into a parallel beam. Secondly, we use a photodiode to detect the incident light flux to obtain the number of incident photons. Thirdly, the collection plate is applied to realize the useful collection of electrons emitted from the material surface. The response current is read by electrometer with high accuracy and low noise. Finally, the ratio of the number of photoelectrons to the incident photons at a single wavelength is calculated to obtain the PEEY. The result shows that the minimum detectable range of the PEEY of the gold is 10-2 ~ 10-4 el/ph. under VUV radiation, and the reliability of the system is proved by comparative with the literature.

In the theoretical calculation of the photoemission yield spectrum of space metal materials, the mathematical model is found based upon three steps process of photoemission combined with the metal free-electron gas model. We take Cu as an example, the variation of photoemission yield spectrum caused by the electric field with different field strength and different incidence angle is calculated. This paper shows that the regions of quantum efficiency of Cu and Au when the materials are in the vacuum, under certain conditions, are respectively calculated between 8×10–8 and 2.6×10–3, 8.53×10–6 and 3.8 × 10–3, corresponding to the regions of incident ultraviolet wavelength are respectively between 138nm and 287nm,108nm and 249nm. Its quantum efficiency decreases with the increase of incident wavelength. The greater the intensity of the applied electric field, which is perpendicular to the copper surface, the greater the value of the calculated copper yield spectrum. The greater the angle formed by the incident ultraviolet light with the copper surface, the smaller the value of the calculated copper yield spectrum.

The paper presents research data of the UV-radiation effect on the structure formation and physical-mechanical properties of paint coatings formed from the industrial EP-773 two-component epoxy enamel. The coatings have been modified with active hollow glass microspheres (Q-cel 6048) and have been irradiated with UV light (207 nm). A relevance of the work associated with the need of improvement coating producing technologies and development protective paints with required performance characteristics. By the method of scanning electron microscopy it was found that addition of the microspheres in the industrial EP-773 two-component epoxy enamel leads to decrease in a number of micro cracks and their extending in a volume of paint coatings. It is shown that hardness of paint coatings with the hollow glass microspheres is higher. It has been established that hollow glass microspheres improve the hiding power of the paint coatings, while maintaining a high level of an adhesion and an impact strength, thereby contributing to save paint coatings and to increase their service period due decreasing in the amount of corrosion products on their surfaces. It is obtained that effect of the UV radiation (wavelength 207 nm) on the surface of paint coatings formed from the industrial EP-773 two-component epoxy enamel modified with active fillers leads to structure destruction primarily near microspheres due to occurring extra internal stresses and promotes to derivation of polymer crosslinking due to the successive addition of free-radical building blocks. The experimental date indicate that UV irradiation of coatings surface deposited from EP-773 two-component epoxy enamel with glass microspheres promotes forming uniformly, dense and non-porous paint coatings with decreased hardness but with extra corrosion protection.

In this tutorial paper, control design aspects of wafer scanners used in the semiconductor industry will be highlighted. At the same time, challenges for control design development as to meet the ever increasing demands on accuracy and speed are presented. Mechatronic systems that will be discussed are: (a) the light source needed to generate the ultraviolet light that is used for wafer exposure, (b) the optical and metrology systems needed for accurate measurement and imaging, and (c) the reticle and wafer stage systems needed for accurate and fast positioning. The control challenges associated with these systems mainly involve dealing with: (a) rejection of high frequency aliased disturbances, (b) large-scale or fast-updated (state) reconstruction, (c) vibration control and isolation in view of structural vibrations and disturbances, (d) inherent design tradeoffs like Bode's sensitivity integral and gain-phase relationships, (e) multivariable plant identification of (quasi-static) deformations and structural dynamics for point-of-interest control, and (f) thermal modelling, model reduction, and the control of (local) time-varying deformation. Results will be discussed using representative examples.

Skin aging caused by ultraviolet light exposure is one of the serious problems from the viewpoint of beauty and healthcare. This is because ultraviolet light can cause age spot, wrinkles, at the worst case, skin cancer and so on. To evaluate skin aging, various modalities are being used, such as histopathological diagnosis, optical coherence tomography, ultrasound examination (B-mode imaging). However, they have disadvantages in terms of invasiveness, penetration depth and tissue specificity, respectively. To overcome these defects, photoacoustic imaging (PAI), a novel modality was used in this work. This modality can sense differences of tissue characteristics non-invasively. In this experiment, human skin tissues in various generations (i.e. various degrees of photoaging) were measured by using acoustic resolution photoacoustic microscopy (AR-PAM). To verify the feasibility of quantitative skin aging evaluation with PA technique, signals from sectioned human skin (cheek and buttock; female from 28 to 95 years old) were measured with PA microscopy. The effects of photoaging progress on the signal intensity were investigated. The results demonstrated that the PA signal from the dermis significantly increases with aging progress (p < 0.05). These analyses demonstrate the feasibility of quantitative skin aging evaluation with a PAI system.

Pulse discharge in water can not only produce ozone, hydrogen peroxide and other active substances with high oxidation potential, but also ultraviolet light and shockwaves, which has been widely used in biomedical, environmental, mining and other fields in recent years. The formation of active substances in water is closely related to the formation characteristics of discharge channels in the process of pulse discharge, as a result of which it is of great importance to study the characteristics of discharge channels in water for further development of high voltage pulse discharge technology. In this study, pulsed voltage produced by Marx pulse generator with frequency set to be 1Hz is applied for analyze characteristics of discharge channels induced by pulsed discharge in water. With the increase of voltage amplitude, transition of discharge mode from streamer discharge to spark breakdown is realized. Based on the fundamental results of discharge channels, preliminary experiments of its application in solar panel recycling are performed, which show that high voltage fragmentation is an effective method to deal with solar panels and the optimal parameter is 193J/g imported in this research. Circular holes and dendritic discharge channels are formed on the surface of the back sheets, and the ablation on the surface of the back plates shows a rugged pore structure on the micro level. Main metals in the broken products are concentrated in specific size fractions, which is convenient for resource recovery.

In this paper, we experimentally demonstrate that molecules with maximum absorption wavelength corresponding to the first excitation energy of base liquid molecules are able to significantly improve the electrical performances of natural ester oils. The positive lightning impulse breakdown and acceleration characteristics, ac breakdown characteristics, and streamer structure of the natural ester oils, as well as the electronic properties of the molecules, are presented. The molecules with different absorptions in ultraviolet lights were doped into the natural ester oil. The positive lightning impulse breakdown characteristics of natural ester oil with different doped molecules indicated that the doped molecule with great absorption in the medium wavelength ultraviolet irradiation was able to significantly enhance the positive lightning impulse breakdown and acceleration voltages of natural ester oil by 15% and 60%, respectively. In addition, it also enhanced the ac breakdown voltage by 17%. The base liquid molecules exhibited first excitation energy of 4 eV, which corresponds to the maximum absorption wavelength of such molecules, indicating that the improved electric breakdown strength was a result of the reduced the number of excited molecules and weakened ionization of molecules during the streamer propagation.

Although there are plenty of commercial systems dedicated to measuring environmental parameters, because of need for specific parameters of interest (temperature, relative humidity, atmospheric pressure, ultraviolet light level, infrared light level and visible light level, micro-sized particles concentrations, magnetic flux density, and wind speed) we proposed a multi-sensors and low-cost platform designed for remote monitoring of environmental conditions on a bee yard. The proposed system has specific features such as portability, battery-power supply, and unit for transmitting data to the remote server. Initial testing showed ability of the system to process all data on time and to perform reliable acquisition.

Stereolithography - also known as SLA 3D printing is one of the most popular, emerging and widespread technology in the world of additive manufacturing. This technique basically works with the help of a high powered ultraviolet laser, which is used to harden the liquid resin by adding progressive layers on the base of built-in platform present in the tank to create the desired 3D shape. Our SLA 3D printer is generally composed of five main sections which involves a tank filled with photopolymer resin, a built-in platform, ultraviolet LEDs, Raspberry Pi and Arduino Uno. Our printer employs a hybrid approach of 3D-printing in which a modified LCD is used as a barrier between the UV LED and resin tank as well as the whole idea focuses on creating an cost effective printer. The LCD screen acts as a stencil for shaping the layers of the 3D model. The ultraviolet light from light source shines directly, in a parallel fashion, onto the build area in order to create the desired 3D model in a layer-by-layer fashion.

Printed Electronics creates new areas of applications with a new manner of manufacturing electronics. Due to its technical and 3D design freedom, new markets and innovative products arise that were initially unthinkable. However, the focus of research is currently on mastering and improving the printing process. The subsequent process step of drying and densifying the printed structures to achieve high conductivities in the shortest possible time is up to now hardly considered. This paper treats the inquiry of fitted and optimized parameters of alternative promising photonic sintering methods for printed electronics compared to the much more time-intensive state of the art sintering process in a furnace. These photonic sintering methods comprise the near infrared, ultraviolet light as well as laser irradiation of the printed structures. Photonic sintering promises faster and more efficient curing and sintering due to the direct and selective application of energy to the printing structures without damaging the temperature-sensitive substrates. As substrate materials ABS and PC-ABS, as well as a glass material were used. Both polymer materials are standard and technical thermoplastics which are available at the market in huge quantities at low price. For the manufacture of printed circuits, a dispense printer was used, in order to process a low-cost silver-based micro particle paste. The evaluation of the sintering result was carried out based on the electrical conductivity of the printed conductor path and the adhesion strength on the substrate. In addition, the sintering time required for the curing of the structures as well as impacts on the substrate or the printed tracks due to photonic treatment were taken into account. To perform the experiments, two different print layouts were set up in order to be able to assess the electrical properties on the first layout and the adhesion on the second layout. To obtain a detailed statement on the exploration on the photonic sintering methods, a fully factorial design plan was conducted. For the near-infrared irradiation, the important parameters were the irradiation duration and the irradiation power. While sintered by ultraviolet light, the parameters were irradiation time, as well as the distance between the sample surface and the UV emitter. In the treatment by means of laser radiation, laser power and the motion speed were identified as the relevant parameters. In order to be able to draw a comparison to the mainly used sintering method, samples were also sintered in a furnace. The results show a significant reduction of the sintering time to a few seconds with comparable and even significantly better electrical and mechanical properties.

In order to solve the problem of low time catalytic efficiency of photocatalytic hydrogen production in the field of photocatalysis, this paper proposes to improve the photocatalytic efficiency from the aspects of preparation technology of catalysts and modification by doping of other elements. First, titanium dioxide nanotube arrays were prepared by anodic oxidation. Then, by changing the process parameters, such as oxidation voltage, titanium wire diameter, water content in electrolyte and oxidation time, different morphology of titanium dioxide nanotubes were obtained. At the same time, the catalyst was doped with Fe by soaking the catalyst in iron nitrate solution, and the modification of Tio2 nanotubes was achieved, and their photocatalytic efficiency was studied. The results showed that the photocatalytic performance of the catalyst was better under the following conditions: the ratio of water to ethanol was 8:1, the diameter of the titanium filament was larger, the oxidation time was 4h, the oxidation voltage was 60V, and the iron doping concentration was 0.02mol/L. In conclusion, the above items have a significant impact on the photocatalytic efficiency. Especially, the Fe-doped catalyst showed better catalytic activity, and its hydrogen production efficiency was greatly improved when irradiated with ultraviolet light than that of the undoped catalyst.

Ultraviolet light emitting diode (UVLED) is a new curing method that can be applied to the printing industry. It can save more than 80% energy compared with the traditional curing method. The traditional Proportion Integration Differentiation. (PID) control method is generally adopted for the control method of UVLED. However, compared with the actual production demand, the intelligent control method is becoming more and more popular. This paper designs the UVLED control system, which is mixed in series and parallel, and uses the single-pole active power factor correction (APFC) converter to design the online adjustment in the discontinuous mode. Flyback constant current drive power supply. Through comparison and analysis of different heat dissipation methods, the Light Emitting Diode (LED) chip adopts a flip-chip structure, and the outer surface is encapsulated by a hemispherical epoxy resin, and the maximum exiting light angle is 45 degrees, and a baffled parallel flow path is adopted. Finally, the control method is upgraded by particle swarm optimization (PSO), and the simulation results can reach the ideal control condition.

In order to solve the printing failure caused by the projection part of the light source in the 3D printing process, this paper proposes a system adjustment scheme. By analyzing the polymerization state of the photosensitive resin, detecting the intensity of ultraviolet light, extracting the outline of the picture, and comparing the similarity of the picture, the optical detection system can find out the cause of the printing failure and provide us with advice on how to adjust the system to ensure that the system can continue to be normal. In the following, the authors proposed the detection process of the system, and simulated the experiment to confirm whether the ultraviolet light irradiated on the photosensitive resin is the same as the image in the slice file.

This paper presents a simple and low-cost ultraviolet (UV) Light Emitting Diode (LED)-based light source with uniform and controllable light intensity for portable exposure photolithography process. The system can receive user-defined parameter values for exposure dose and duration time, controlled by the microcontroller through a LED driver circuit. The measurement results show that LED has a peak wavelength of 394 nm and very narrow full-width at half maximum (FWHM) of 12.59 nm. By rotating LED array, the UV light source can produce uniform irradiance at the average 82 mW/cm2 at near-zero contact, 51 mW/cm2 at 1 cm, and 8 mW/cm2 at 5 cm. We also found that exposure time and distance of the light source to the pattern greatly affect the results of the pattern transfer on the substrate. The smallest resolution that can be exposed in this study on the Printed Circuit Board (PCB) substrate with dimension 2 × 2cm2 is 100 microns. Using the developed UV-LED light source, it shows great potential as a low-cost light source and feasible applications for microfabrication.

Ultraviolet light in the wavelength range between 200 nm and 240 nm is of great interest for spectroscopic gas analytics. Particularly, for industrial applications, optical gas analyzers based on this spectral range are promising for combustion gas and natural gas analytics but require availability of suitable robust, compact and low-cost light sources. We have demonstrated a gas analyzer using a compact solid-state laser module which emits wavelengths near 219 nm and which offers significant advantages compared with conventional light sources. The key characteristics of the laser module are outlined in the paper and the integration of the laser into a gas analyzer prototype is described. In a simple absorption setup, using the example of hydrogen sulfide as analyte, we demonstrate a detection limit of 0.02 ppm•m (3 σ, 50 s average, 1 Hz sampling rate). The properties of the laser having a small footprint, low supply voltage, and low power consumption are key advantages for the integration into future robust, low-cost, industrial products.

The main purpose of this study is to establish an intelligent environmental monitoring system based on Long Range (LoRa) transmission technology with low power consumption to be installed in large-scaled campus with high population density. First of all, sensors at different locations will be configured to provide statistics such as temperature, humidity, suspended particles, carbon monoxide, and carbon dioxide in indoor environment, and temperature, humidity, wind speed, apparent temperature, suspended particles, and ultraviolet light in outdoor environment to serve as the basis for analysis. LoRa 915 MHz serves as the communication protocol of the transmission technology of this system via the transmission module LRM001 developed by Liyatech. An industrial computer is used as the Gateway, and C# Windows Forms is installed for analyzing data from various detection points. The data will be uploaded to Microsoft Azure SQL Server by the unit of hour. In the end the Server end will publish the website via ASP.NET technology and position different detection stations via Google Map API such that users can use the webpage to inquire the trend of environmental quality and the further Big Data analysis.

This work describes simple method for sensing bacteria, Legionella by using a photogate-type optical sensor (PG-sensor) and MEMS chip. We observed the behavior of fluorescence from Legionella dumoffii (L. dumoffii) and Legionella erythra (L. erythra) when they are exposed to ultraviolet light. The time dependence of the fluorescence intensity of L. dumoffii and L. erythra obtained with PG-sensor agreed well with that of fluorescence intensity obtained with spectrometer, showing that each Legionella is able to be detected by PG-sensor. Using the difference of their behavior, the identification of each bacterium was successfully performed for a mixed bacterial system of L. dumoffii and L. erythra by using the combination of PG-sensor and optical filters.

In this work, we have explored the effect of TIPSpentacene: polystyrene (PS) blend on electrical performance and photo-response of solution processed organic field-effect transistors (OFETs). It was observed that though the blend OFETs show better electrical performance, the photo-responsivity (R) of neat TIPS-pentacene OFETs was significantly better. This study was performed for different color lights such as blue, red, and green, as well as for ultraviolet light (UV). R was highest for blue color (~2600 mA/W for neat, ~230 mA/W for blend), and smaller for other cases. Low R value in blend devices is attributed to less trapping of photo-generated charge carriers during photo-illumination compared to their neat counterparts.