Illumination Power Research Articles

Spatially Precise Light-Activated Dedoping in Wafer-Scale MoS2 Films.

2D materials, particularly transition metal dichalcogenides (TMDCs), have shown great potential for microelectronics and optoelectronics. However, a major challenge in commercializing these materials is the inability to control their dopingat a wafer scale with high spatial fidelity. Interface chemistry is used with the underlying substrate oxide and concomitant exposure to visible light in ambient conditions for photo-dedoping wafer scale MoS2. It is hypothesized that the oxide layer traps photoexcited holes, leaving behind long-lived electrons that become available for surface reactions with ambient air at sulfur vacancies (defect sites) resulting in dedoping. Additionally, high fidelity spatial control is showcased over the dedoping process, by laser writing, and fine control achieved over the degree of doping by modulating the illumination time and power density. This localized change in MoS2 doping density is very stable (at least 7 days) and robust to processing conditions like high temperature and vacuum. The scalability and ease of implementation of this approach can address one of the major issues preventing the "Lab to Fab" transition of 2D materials and facilitate its seamless integration for commercial applications in multi-logic devices, inverters, and other optoelectronic devices.

Dual color optogenetic tool enables heart arrest, bradycardic, and tachycardic pacing in Drosophila melanogaster

In order to facilitate cardiovascular research to develop non-invasive optical heart pacing methods, we have generated a double-transgenic Drosophila melanogaster (fruit fly) model suitable for optogenetic pacing. We created a fly stock with both excitatory H134R-ChR2 and inhibitory eNpHR2.0 opsin transgenes. Opsins were expressed in the fly heart using the Hand-GAL4 driver. Here we describe Hand > H134R-ChR2; eNpHR2.0 model characterization including bi-directional heart control (activation and inhibition) upon illumination of light with distinct wavelengths. Optical control and real-time visualization of the heart function were achieved non-invasively using an integrated light stimulation and optical coherence microscopy (OCM) system. OCM produced high-speed and high-resolution imaging; simultaneously, the heart function was modulated by blue (470 nm) or red (617 nm) light pulses causing tachycardia, bradycardia and restorable cardiac arrest episodes in the same animal. The irradiance power levels and illumination schedules were optimized to achieve successful non-invasive bi-directional heart pacing in Drosophila larvae and pupae.

Study on the Preparation and PEC-Type Photodetection Performance of β-Bi2O3 Thin Films.

Bismuth-based compounds have been regarded as a kind of promising material due to their narrow bandgap, high carrier mobility, low toxicity, and strong oxidation ability, showing potential applications in the field of photoelectrochemical (PEC) activities. They can be applied in sustainable energy production, seawater desalination and treatment, optical detection and communication, and other fields. As a member of the broader family of bismuth-based materials, β-Bi2O3 exhibits significant advantages for applications in engineering, including high photoelectric response, stability in harsh environments, and excellent corrosion resistance. This paper presents the synthesis of β-Bi2O3 thin films utilizing the mist chemical vapor deposition (CVD) method at the optimal temperature of 400 °C. Based on the β-Bi2O3 thin film synthesized at optimal temperature, a PEC-type photodetector was constructed with the highest responsivity R of 2.84 mA/W and detectivity D of 6.01 × 1010 Jones, respectively. The photodetection performance was investigated from various points like illumination light wavelength, power density, and long-term stability. This study would broaden the horizontal and practical applications of β-Bi2O3.

High-Performance Broadband Self-Driven Photodetector Based on MoS2/Cs2CuBr4 Heterojunction.

Few-layer transition metal dichalcogenides and perovskites are both promising materials in high-performance optoelectronic devices. Here, we developed a self-driven photodetector by creating a heterojunction between few-layer MoS2 and lead-free perovskite Cs2CuBr4. The detector shows a unique property of very high sensitivity in a broad spectral range of 400 to 800 nm with response speed in a millisecond order. Current-voltage characteristics of the heterojunction device show rectifying behavior, in contrast to the ohmic behavior of the MoS2-based device. The rectifying behavior is attributed to the type II band alignment of the MoS2/Cs2CuBr4 heterojunction. The device shows a broadband (400 to 800 nm) photodetection with very high responsivity reaching up to 2.8 × 104 A/W and detectivity of 1.6 × 1011 Jones at a bias voltage of 3 V. The detector can also operate in self-bias mode with sufficient response. The photocurrent, photoresponsivity, detectivity, and external quantum efficiency of the device are found to be dependent on the illumination power density. The response time of the device is found to be ∼32 and ∼79 ms during the rise and fall of the photocurrent. The work proposes a MoS2/Cs2CuBr4 heterostructure to be a promising candidate for cost-effective, high-performance photodetector.

White-light activatable organic NIR-II luminescence nanomaterials for imaging-guided surgery

While second near-infrared (NIR-II) fluorescence imaging is a promising tool for real-time surveillance of surgical operations, the previously reported organic NIR-II luminescent materials for in vivo imaging are predominantly activated by expensive lasers or X-ray with high power and poor illumination homogeneity, which significantly limits their clinical applications. Here we report a white-light activatable NIR-II organic imaging agent by taking advantages of the strong intramolecular/intermolecular D-A interactions of conjugated Y6CT molecules in nanoparticles (Y6CT-NPs), with the brightness of as high as 13315.1, which is over two times that of the brightest laser-activated NIR-II organic contrast agents reported thus far. Upon white-light activation, Y6CT-NPs can achieve not only in vivo imaging of hepatic ischemia reperfusion, but also real-time monitoring of kidney transplantation surgery. During the surgery, identification of the renal vasculature, post-reconstruction assessment of renal allograft vascular integrity, and blood supply analysis of the ureter can be vividly depicted by using Y6CT-NPs with high signal-to-noise ratios upon clinical laparoscopic LED white-light activation. Our work provides efficient molecular design guidelines towards white-light activatable imaging agent and highlights an opportunity for precision imaging theranostics.

Preparation and characterization of silicon nanoparticles (core) with gold nanoparticles (shell) configuration

Herein, we used a simple yet novel approach to create and characterize silicon nanoparticles Si NPs/core, gold nanoparticles AuNps/shell hybrid structure. The meso porous silicon layer was synthesized using a laser-supporting etching process with 50 mW/cm2 and 405 nm laser power density and illumination wavelength in a Teflon cell comprising a 1:3 volumetric ratio of 40 % HF in ethanol with etching current density of 25 mA/cm2 for 15 min. The SiNps/AuNps hybrid structure was synthesized by a simple ion reduction process of gold ions via dangling bonds of SiNps in an aqueous solution of HaUcl4 of 0.001 M for 5 min. The characterization of SiNps and SiNps/AuNps hybrid structure were investigated using FE-SEM, TEM, XRD and PL measurements. The results showed that the pores diameter ranged from 5 nm to 50 nm, while the average diameter of the SiNps core layer and AuNps shell layer are about 59.5 nm and 38 nm respectively. The surface morphology of the SiNps characterizes the synthesized hybrid structure; the PL emission of hybrid structure has a high intensity with blue shifting towards short wavelength compared with SiNps. Deposition of AuNps on SiNps led to synthesis more chemical stable hybrid structure with specific increase in the surface area.This resulting hybrid structure can be adoptedin various types of plasmonics and gas sensors in addition to optoelectronics devices.

Field Assessment for Initial Preparation of Net Zero Building Certification for The Universitas Multimedia Nusantara (UMN) Building: A Case Study On Visual Comfort in C and D Tower

Ensuring optimal physical comfort, the need for a comprehensive evaluation of the performance of building systems was established. This investigation endeavors to meticulously scrutinize illuminance and light power density metrics across distinct temporal segments (morning, noon, afternoon, and night), as well as the dynamism of daylighting and artificial lighting presence within Tower C and D of Universitas Multimedia Nusantara (UMN). Noteworthy for their incorporation of double skin façades, these edifices serve as focal points of inquiry. The empirical findings reveal that illuminance levels within classrooms and offices, irrespective of natural or artificial lighting, consistently fall short of the prescribed 350 lux threshold based on SNI across most floor levels. The efficacy of the double skin façade manifests in a discernible attenuation, diminishing illuminance ingress to the building by approximately 50%, and precipitously by up to 90% about window fixtures. Furthermore, the analysis of light power density underscores an energy efficiency quotient hovering around 60%. These empirical insights are intended to serve as a foundational resource for guiding the initiation of Net Zero Healthy Greenship certification endeavors.

Detection performance of flower-like hydrothermally synthesized ZnO in silicon-type photodetector

Zinc oxide (ZnO) is a versatile compound or metal oxide with a wide range of applications across various industries such as electronics, optoelectronics, and gas sensors, etc. A simple hydrothermal method was used to synthesize ZnO flower-like structures in this study. The synthesized ZnO structures were analyzed by x-ray diffractometer (XRD) and scanning electron microscope (SEM). We used ZnO structures as an interfacial layer for a Schottky-type silicon-based photodetector. While Au and Al metals were employed as metallic and ohmic contacts, respectively, p-Si was utilized as a semiconductor and substrate. Thus, Au/ZnO/p-Si sandwich was successfully fabricated and tested by current–voltage (I–V) measurements under dark and various light power illumination densities from 10 mW cm−2 to 150 mW cm−2 as well as the various wavelengths in the case of same power. The I–V characteristics were used to determine the diode and photodetection parameters. The fabricated heterostructure exhibited 77.51 mA W−1 responsivity, 1.30 × 1010 Jones specific detectivity, and 26.33% external quantum efficiency (EQE) values.

High power illumination system for uniform, isotropic and real time controlled irradiance in photoactivated processes research

In the study of photocatalytic and photoactivated processes and devices a tight control on the illumination conditions is mandatory. The practical challenges in the determination of the necessary photonic quantities pose serious difficulties in the characterization of catalytic performance and reactor designs and configurations, compromising an effective comparison between different experiments.To overcome these limitations, we have designed and constructed a new illumination system based in the concept of the integrating sphere (IS). The system provides uniform and isotropic illumination on the sample, either in batch or continuous flow modes, being these characteristics independent of the sample geometry. It allows direct, non-contact and real time determination of the photonic quantities as well as versatile control on the irradiance values and its spectral characteristics. It can be also scaled up to admit samples of different sizes without affecting its operational behaviour.The performance of the IS system has been determined in comparison with a second illumination system, mounted on an optical bench, that provides quasi-parallel beam (QPB) nearly uniform illumination in tightly controlled conditions. System performance is studied using three sample geometries: a standard quartz cuvette, a thin straight tube and a microreactor by means of potassium ferrioxalate actinometry. Results indicate that the illumination geometry and the angular distribution of the incoming light greatly affect the absorption at the sample. The sample light absorption efficiency can be obtained with statistical uncertainties of about 3% and in very good agreement with theoretical estimations.

Intelligent Lighting System Using Color-Based Image Processing for Object Detection in Robotic Handling Applications

In applications reliant on image processing, the management of lighting holds significance for both precise object detection and efficient energy utilization. Conventionally, lighting control involves manual switching, timed activation or automated adjustment based on illuminance sensor readings. This research introduces an embedded system employing image processing methodologies for intelligent ambient lighting, focusing specifically on reference-color-based illumination for object detection and positioning within robotic handling scenarios. Evaluating the system’s efficacy entails analyzing the illuminance levels and power consumption through a tailored experimental setup. To minimize illuminance, the LED-based lighting system, controlled via pulse-width modulation (PWM), is calibrated using predetermined red, green, blue and yellow (RGBY) reference objects, obviating the need for external sensors. Experimental findings underscore the significance of color choice in detection accuracy, highlighting yellow as the optimal color requiring minimal illumination. Successful object detection based on color is demonstrated at an illuminance level of approximately 50 lx, accompanied by energy savings contingent upon ambient lighting conditions.

Technoeconomic analysis of rooftop PV system in elevated metro station for cost-effective operation and clean electrification

Metro system constitutes an essential component of urban transportation infrastructure, simultaneously serving as a significant energy consumer and carbon emitter. Integration of rooftop PV systems in elevated stations can effectively mitigate carbon emissions and enhance the utilization rate of clean energy. Nevertheless, current research rarely explores the application and feasibility analysis of rooftop PV systems in elevated metro stations. To address this research gap, the study investigates potential of rooftop PV systems applied in the elevated stations, and optimizes the PV scale and battery capacity for achieving the maximum net present value. The results show that the optimized photovoltaic-battery (PVB) system can bring about a PV self-sufficiency (SS) of 0.54, in the baseline scenario. For the entire line, SS can achieve 0.26–0.59 with the integration of PVB systems. Furthermore, the impact of skylights on energy consumption for illumination and PV power generation is discussed, and the PV potential of skylights is investigated. The results show that PV skylights lead to an increase a rise in the SS of 8.6%–15.3%. This study contributes reference for the potential of PV systems on elevated stations and for cost-effective operation and clean electrification of the urban rail transit sector.

Phase-shifting optothermal microscopy enables live-cell mid-infrared hyperspectral imaging of large cell populations at high confluency.

Rapid live-cell hyperspectral imaging at large fields of view (FOVs) and high cell confluency remains challenging for conventional vibrational spectroscopy-based microscopy technologies. At the same time, imaging at high cell confluency and large FOVs is important for proper cell function and statistical significance of measurements, respectively. Here, we introduce phase-shifting mid-infrared optothermal microscopy (PSOM), which interprets molecular-vibrational information as the optical path difference induced by mid-infrared absorption and can take snapshot vibrational images over broad excitation areas at high live-cell confluency. By means of phase-shifting, PSOM suppresses noise to a quarter of current optothermal microscopy modalities to allow capturing live-cell vibrational images at FOVs up to 50 times larger than state of the art. PSOM also reduces illumination power flux density (PFD) down to four orders of magnitude lower than other conventional vibrational microscopy methods, such as coherent anti-Stokes Raman scattering (CARS), thus considerably decreasing the risk of cell photodamage.

Nanographene-Au fine-tuning to intensify plasmonic-resonance of polymeric hybrid bionanosystem for synergistic phototherapy and nerve photobiomodulation

Here, we report the multi-photo-bioactivity of the plasmonic-nano graphitic coordinated polycaprolactone-based aligned nanofibrous scaffolds-based bionanosystem for photothermal breast and colon cancer therapies and peripheral nerve photobiomodulation. The size-optimized colloidal reduced graphene oxide (nRGO, 180 nm) nanosheets, for enhanced photothermal impact, were surface-functionalized with gold nanospheres (AuNPs) to prepare the nRGO@AuNP monodispersed nano-composite and then doped 2.0 mg of nRGO@AuNP in biocompatible and biodegradable polymer polycaprolactone (PCL) to fabricate the nRGO@AuNP-PCL (2.0 mg) plasmonic aligned nanofibrous scaffolds. More than 90% of cancer cells, breast cancer (MCF-7) as well as colon cancer (CT-26), ablated after 5 min of low NIR (808 nm) laser power (0.72 W/cm2) illumination with nRGO@AuNP-PCL (2.0 mg) aligned nanofibrous scaffolds. Besides, the nRGO@AuNP-PCL (2.0 mg) provided an extraordinary microenvironment for adhesion, nerve growth, proliferation, and differentiation of PC12 and S42 cells which mimics the natural extracellular matrix. The 2.5-fold increase in neurite length was observed with NIR illumination after 3 days whereas 1.7-fold was found without NIR illumination after 7 days in comparison to PCL (pure). The current findings will be useful to provide a new crucial approach for preparing biocompatible multifunctional composite plasmonic nanofibers as a highly efficient distinct platform for photothermal therapies and promising bioimplants to overcome the loss of sensation after cancer surgery through nerve photobiomodulation.

On the scalability of helium-filled soap bubbles for volumetric PIV

The scalability of experiments using PIV relies upon several parameters, namely illumination power, camera sensor and primarily the tracers light scattering capability. Given their larger cross section, helium-filled soap bubbles (HFSB) allow measurements in air flows over a significantly large domain compared to traditional oil or fog droplets. Controlling their diameter translates into scalability of the experiment. This work presents a technique to extend the control of HFSB diameter by geometrical variations of the generator. The latter expands the more limited range allowed by varying the relative helium-air mass flow rates. A theoretical model predicts the bubble size and production rate, which is verified experimentally by high-speed shadow visualization. The overall range of HFSB produced in a stable (bubbling) regime varies from 0.16 to 2.7 mm. Imaging by light scattering of such tracers is also investigated, in view of controversies in the literature on whether diffraction or geometrical imaging dominate the imaging regime. The light scattered by scaled HFSB tracers is imaged with a high-speed camera orthogonal to the illumination. Both the total energy collected on the sensor for a single tracer, as well as its peak intensity, are found to preserve scaling with the square of the diameter at object magnification of 10–1 or below, typical of PIV experiments. For large-scale volumetric applications, it is shown that varying the bubble diameter allows increasing both the measurement domain as well as the working distance of the imagers at 10 m and beyond. A scaling rule is proposed for the latter.Graphical abstract

Photo-responsive analysis of branchy dendrites-like CuO/PS p-n junction visible light photodetector

A series of p-CuO/n-PS heterojunction self-powered visible light photodetector was fabricated as a function of CuO nanostructure deposition time through electrochemical process. Herein, X-ray diffraction confirmed the formation of crystalline layers, while field emission scanning electron microscopy evidenced the occurrence of nano-sized branchy dendrites-like morphology; the fabricated layers exhibited optical bandgap value of 2.07 eV. Simultaneously, the fabricated devices demonstrated a well-oriented figure of merits as a function of wavelength and illumination power at extremely low bias voltage (0.5 V). In detail, responsivity of 59 μA/W as well as detectivity of 23 ×1019Jones were obtained, respectively, for the optimum device at 635 nm; an external quantum efficiency of 115.2 at 100 mW/cm2 was attained whereas such an observation was found to be deteriorated at lower/higher wavelengths. The pronounced device exhibited response/recovery time of 0.33 and 0.83 sec. at zero bias voltage evidencing a self-powered feature of the proposed system.

“Be All That You Can Be”: The Role of Identity, Pro‐Social Labeling, and Narratives in Veterans Treatment Courts*

Veterans Treatment Courts (VTCs) are one of the ever‐developing brands of specialty or problem‐solving courts that have emerged in recent decades. These courts recognize that the criminal behavior stems from a variety of issues, and that punishment should represent a therapeutic jurisprudential approach in its strategies. As such, VTCs treat substance abuse and mental health issues and address criminality in a manner that recognizes a need for individualized treatment and accountability in structure. This research provides an in‐depth institutional ethnography of one Southern California VTC (SC VTC). To understand the powerful transformative tools of identity and narrative, this research utilized over 3 years of non‐participant observation at 117 court sessions in the SC VTC, and 23 in‐depth interviews with both current court participants and graduates and a judge, exploring participants' experiences with and perceptions of the SC VTC. This study demonstrates the utility of identity‐based narratives to navigate legal systems and potentially desist from crime. These mechanisms of narrative and identity provide a powerful illumination of these courts that have ramifications for successful reintegration into society post‐criminal justice interaction.

Sm, Pt asymmetric n- and p-type contacts in WSe2 phototransistor for high-performance broadband photodetection

The development of high-performance broadband photodetectors working at room temperature is still attractive. The Schottky barrier phototransistor based on asymmetric junction seems to be endowed with such potential—as photodetectors with low device power consumption and high photoresponse; however, it is rarely studied. Herein, a Sm–WSe2–Pt phototransistor with asymmetric metal contacts is constructed, and it is systematically investigated for their electronic and photoelectronic tunability via gate voltage, wavelength, and illumination power density. It was found that the tunable photogating process dominates the photoresponse mechanism, which allows for an excellent broadband photodetection from 300 to 1000 nm wavelength. In addition, the responsivity (R) and specific detectivity (D*) at 450 nm can reach 1723 A/W and 2.3 × 1013 Jones, respectively, while that of infrared illumination of 900 nm can reach 4.7 A/W and 3.1 × 1010 Jones, respectively. In addition, the device exhibits obvious photoresponse at zero bias, the R and D* can reach up to 27 mA/W and 8.5 × 1010 Jones, which realizes self-driven photodetection. This work provides an optimal option for realizing high-integrated, high-performance, low-power-consuming, and room-temperature-working broadband photodetectors.

Dual-propelled polydopamine@SiO2@Pt micromotor with asymmetrical yolk-mesoporous shell for the enhanced catalytic reduction

Micro/nanomotors exhibit unique self-propulsion capabilities at the micro/nanoscale, offering significant potential as nanocatalysts in the field of catalysis by enhancing the contact probability between catalytic active sites and reactant molecules. Herein, a dual-propelled polydopamine (PDA)@SiO2@Pt micromotor with asymmetric yolk-mesoporous shell nanostructure is developed to enhance the catalytic reduction performance. The synthesis of PDA@SiO2@Pt micromotor involves a two-step process. First, the mesoporous silica is grown on the surface of the thermally swelled PDA sphere through heterogeneous interface self-assembly. Subsequently, the Pt nanoparticles (Pt NPs) are selectively loaded onto the PDA yolk. The asymmetric PDA yolk demonstrates outstanding photothermal conversion abilities, generating local thermal gradients under near-infrared (NIR) light irradiation, which propels the micromotor through thermophoresis. Simultaneously, the Pt NPs on PDA yolk catalyze the decomposition of H2O2 decomposition, generating O2 gradient that drives the micromotor through self-diffusiophoresis. The motion behavior of PDA@SiO2@Pt micromotor can be controlled through adjusting the NIR light illumination power density or varying concentration of H2O2. Moreover, the mesostructured architecture of PDA@SiO2@Pt micromotor can be employed to achieve the efficient catalytic reduction, achieving up to 93 % conversion of methylene blue (MB) within 5 min due to the combined effects of photothermal and particle motion properties induced by NIR light. The PDA@SiO2@Pt micromotor exhibits immense potential for future applications in complex catalytic systems using multi-driven micro/nanomotors.

All-Optical Electrochemiluminescence at Metal-Insulator-Semiconductor Diodes.

Pt/InGa/n-Si/SiOx/Pt devices were prepared by using standard chemical and sputtering processes. These systems are diodes comprising a frontside photoactive metal-insulator-semiconductor (MIS) n-Si/SiOx/Pt junction and a backside Pt/InGa/n-Si Ohmic contact. Pt/InGa/n-Si/SiOx/Pt was first characterized by dark-solid-state electrical and impedance measurements. Then, each side of the device was investigated by electrochemical means in the dark and under near-IR illumination at 850 nm in the luminol-H2O2 electrochemiluminescence (ECL) electrolyte. The results suggested the possibility of triggering an all-optical ECL (AO-ECL) at Pt/InGa/n-Si/SiOx/Pt. This was confirmed by studying AO-ECL at the monolithic, all-integrated Pt/InGa/n-Si/SiOx/Pt device, immersed in the ECL electrolyte. The conversion process can occur with good stability and the intensity of the visible emission (440 nm) depends on tunable parameters such as the illumination power density, O2 concentration, or the concentration of added H2O2. These results are important for the next developments of AO-ECL in sensing and microscopy.

Design of a high-power collimating optical system based on Fresnel lenses.

In light-emitting diode (LED) illumination (e.g., LED maritime lighting for ships), creating a uniform light environment for optical systems is an important challenge. In this study, we present a high-power collimating system based on Fresnel lenses, which allows high-brightness LED illumination in the earlier-mentioned remote distance. The work presented in this article focuses on improving the power, compacting the optical structure, and promoting the brightness of the spot. To prove the claims, the system with a total power of 1 kW is designed. The system consists of a 27 W LED array, a freeform surface lens array, and a confocal Fresnel lens array. In comparison with the traditional optical system, the optical structure shortens from 390 to 120 mm, and the divergent angle decreases from 3° to 2 . Meanwhile, the illuminance of the system is obtained as high as 230 lx at the near field of 200 m and 3.0lx at the far field of 1.5 nautical miles. This new method provides a practical and effective way to solve the problem of low power, insufficient illuminance, and long optical structure for LED array illumination, which is suitable for remote illumination and guidance of ships.