Bias Light Research Articles

Determining The Lens Aberations on Positive Lenses Through Science Process Skill

Abstract This research aims to determine aberrations or image distortions in a positive lens using an optics experiment kit for image distortions. The experimental tool consists of a diaphragm, a positive lens, a light source, lens path, an image capture screen, and a flint glass used to reduce lens distortions. The main tool is made of acrylic, which is durable and easy to use. The lens used is a strong positive lens (+100). The diaphragms used vary, including a slit diaphragm with five slits and a four-ring diaphragm. These diaphragms are used to produce image shapes and observe the distortions that occur. The work process refers to the skills of scientific processes such as observation, classification, measurement, prediction, communication, and conclusion, which are implemented in the work instructions for creating aberrations or image distortions by placing the positive lens parallel to the light source and the image capture screen. Then, the distortions that occur are observed, and a flint glass is placed in front of the light source to reduce the distortions that are formed. By observing the resulting image, it can be seen that the distortions that occur on the positive lens and how the flint glass works to reduce these aberrations. This is in line with the theory that aberrations on a positive lens occur due to imperfect light bias, either because of the different refractive index biases from different media in the lens, or because of the lens shape not being ideal. Flint glass is one of the methods used to reduce these aberrations.

Exploring the complementary potential of DVT-Grown InxMo1-xS2 (x = 0.05 & 0.1) for enhanced photoelectrochemical photodetectors and dye degradation

The platform used in this work, InxMo1-xS2 (x = 0.05 & 0.1) nanosheets, allows for exploration of two crucial areas: remediation of the environment and optoelectronic applications. The sonochemical exfoliation approach generated the MoS2 nanosheets. The exfoliated MoS2 has a 2H-hexagonal lattice structure and a P63/mmc space group. The MoS2 nanosheets' lateral shape was observed using transmission electron microscopy (TEM), and their extremely crystalline nature was verified by selected area electron diffraction (SAED). The absorption spectra of MoS₂ nanosheets show unique A and B excitonic resonances. It investigates pulse photo-response characteristics associated with dye degradation methods, emphasizing InxMo1-xS2 (x = 0.05 & 0.1) efficiency in destroying dyes and enabling photocatalytic degradation, particularly with methylene blue (MB) solutions. After 120 min of exposure to light, these nanosheets are effective, breaking down organic pigments. The work also indicates a distinct pulse photoresponse in InxMo1-xS2 (x = 0.05 & 0.1) Nanosheets, increasing their potential as ultrafast photodetectors for optoelectronics. Built-in electrodes produce noticeable photocurrents under 8 mV bias and polychromatic light, demonstrating a strong photovoltaic effect. The In0.05Mo0.95S2 nanosheet-based working electrodes are significantly photovoltaic, with a photocurrent of 3.427 mA under an 8 mV bias and 100 mW/cm2 of polychromatic light. These electrodes have a remarkable peak photoresponsivity of 2.715 A/W under optimum conditions. In the end, this work demonstrates the potential of InxMo1-xS2 (x = 0.05 & 0.1) nanosheets in improving optoelectronic devices and environmentally friendly solutions by revealing when dye degradation and pulse photo-response interact with one another.

Lateralization of Feeding Behaviour in White-Fronted Lemur (Eulemur albifrons) and Ring-Tailed Lemur (Lemur catta) in Captivity

Introduction: Functional cerebral asymmetry is reflected in the lateralization of some behavioural patterns in many vertebrate species. In primates, behavioural lateralization has been related to both life style and age and sex, and it affects behaviours such as feeding and other tasks that require precision movements. Methods: We have studied feeding lateralization concerning the use of right and left hand to take the food in two species of lemurs in captivity, the mainly arboreal white-fronted lemur and the more terrestrial ring-tailed lemur, taking also account the age and the sex of the individuals. We calculated for each individual the hand preference (if it was the case) by means of z scores, and the strength of such preference using the handedness index (HI). Finally, we determined for each species the existence of right/left bias at the group level with the t Student test. Results: Half of the white-fronted lemurs (7 of 14) showed lateralization in feeding, while only a few ring-tailed lemurs (3 of 19) showed it. In the first species, a light bias seems to emerge (5 individuals used mostly the right hand for taking the food, while only 2 used mainly the left hand), while in the second species no bias could really be appreciated. Conclusion: Feeding lateralization was more accentuated in white-fronted lemur, in which a light bias towards the use of the right hand seems to be evidenced. No clear effect of age and sex on the presence and direction of lateralization could be evidenced. The results somehow contrast with what the postural theory of lateralization postulates about the preferential use of the right hand in terrestrial species.

Optically Mediated Hydrogel-Based Ionic Diode.

Ionic diodes with environmentally modulated ion-rectifying characteristics have attracted much attention and show great promise in the construction of smart devices with environmental adaptability. One immediate challenge is to integrate stimuli responsiveness and ion rectification into one single ionic diode, which requires a close cooperation of chemical principles and device technologies. Herein, an ionic diode based on a photoresponsive hydrogel with optically mediated ion-rectifying performances is introduced. Relying on the photoresponsive concentration of proton in the hydrogel, the ionic current rectification can be prominently enhanced upon ultraviolet (UV) irradiation. A maximum ionic current rectification ratio of the optically mediated ionic diode about 4× 105 is achieved. Furthermore, the hydrogel-based diode can serve as an AND logic gate operated by UV light and voltage bias as two independent inputs. As a proof of concept, to use the optically mediated diode is achieved to modulate the feedback of a robot with logic behaviors. This work provides a novel and valuable strategy for designing functional hydrogel-based devices with the integration of stimuli-responsiveness and logic signal processing through chemical approaches.

Sub-bandgap Photocurrent Spectra of p-i-n Perovskite Solar Cells with n-Doped Fullerene Electron Transport Layers and Bias Illumination.

In p-i-n perovskite solar cells optical excitation of defect states at the interface between the perovskite and fullerene electron transport layer (ETL) creates a photocurrent responsible for a distinct sub-bandgap external quantum efficiency (EQE). The precise nature of these signals and their impact on cell performance are largely unknown. Here, the effect of n-doping the fullerene on the EQE spectra is studied. The n-doped fullerene is either deposited from solution or by coevaporation. The latter method is used to create undoped-doped fullerene bilayers and investigate the effect of the proximity of the doped region on the EQE spectra. The intensity of the sub-bandgap EQE increases when the ETL is n-doped and also when the device is biased with green light. Using these results, the sub-bandgap EQE signal is attributed to originate from electron trap states in the perovskite with an energy below the conduction band that are filled by excitation with low-energy photons. The trapped electrons give rise to photocurrent when they are collected at a nearby electrode. The enhanced sub-bandgap EQE observed when the ETL is n-doped or bias light is applied, is related to a higher probability to extract trapped electrons under these conditions.

Dual-Band Photomultiplication-Type Organic Photodetectors with Ultrahigh Signal-to-Noise Ratios.

A series of dual-band photomultiplication (PM)-type organic photodetectors (OPDs) were fabricated by employing a donor(s)/acceptor (100:1, wt/wt) mixed layer and an ultrathin Y6 layer as the active layers, as well as by using PNDIT-F3N as an interfacial layer near the indium tin oxide (ITO) electrode. The dual-band PM-type OPDs exhibit the response range of 330-650 nm under forward bias and the response range of 650-850 nm under reverse bias. The tunable spectral response range of dual-band PM-type OPDs under forward or reverse bias can be explained well from the trapped electron distribution near the electrodes. The dark current density (JD) of the dual-band PM-type OPDs can be efficiently suppressed by employing PNDIT-F3N as the anode interfacial layer and the special active layers with hole-only transport characteristics. The light current density (JL) of the dual-band PM-type OPDs can be slightly increased by incorporating wide-bandgap polymer P-TPDs with relatively large hole mobility (μh) in the active layers. The signal-to-noise ratios of the optimized dual-band PM-type OPDs reach 100,980 under -50 V bias and white light illumination with an intensity of 1.0 mW·cm-2, benefiting from the ultralow JD by employing wide-bandgap PNDIT-F3N as the anode interfacial buffer layer and the increased JL by incorporating appropriate P-TPD in the active layers.

Cu2O photocathodes prepared by thermal reduction of CuO: Influence of O2 concentration on photocurrent stability

Copper oxide (CuO and Cu2O) p-type semiconducting photocathodes have gained attention for hydrogen production (proton reduction), due to their appropriate conduction band potentials and light sensitivity in the visible. However, photocorrosion is the main handicap for both compounds. In this work, the transformation of CuO layers deposited via spray pyrolysis on conductive FTO (fluorine doped tin oxide on glass) into Cu2O via thermal reduction was studied. Optimal conditions for obtaining Cu2O were found by in situ temperature-controlled XRD. Synthesis of Cu2O films was finally carried out under moderate temperature and vacuum conditions (380 °C, 1·10−2 mbar). The influence of 3 different oxygen concentration in the electrolyte on the stability of the Cu2O electrodes under light and electrical bias was studied, and it was found that the O2 content had a high impact on the photoelectrochemical performance of Cu2O electrodes. The stability of the electrodes against self-reduction was demonstrated.

Self‐Powered Broadband Photodetectors Based on Si/SnS2 and Si/SnSe2 p–n Heterostructures

AbstractThe escalating interest in 2D nanoflakes‐based group‐IVA metal chalcogenides is attributed to their noteworthy properties, such as high electron mobility, exceptional chemical stability, and applicability across diverse scientific disciplines such as sensing, energy storage applications, supercapacitors, and lithium‐ion batteries. This study introduces an innovative self‐powered photodetector based on 2D metal chalcogenide nanoflakes (SnS2 and SnSe2) formed into nanoflowers on a silicon substrate through the hydrothermal method. The amalgamation of the light‐induced pyroelectric effect into the SnS2 photodetector achieves impressive enhancement ratios of 353%, 425%, 351%, 662%, and 153% in photoresponsivity and detectivity compared to the photovoltaic effect at 365, 456, 532, 632, and 850 nm, respectively, at zero bias. The SnSe2 photodetector achieved responsivity values of 14, 82, 36, 4, and 28 mA W−1 at the corresponding wavelengths in self‐powered mode. The SnSe2 device exhibits superior photosensitivity of 30792%, 55692%, 28803%, 9678%, and 68587% at the corresponding wavelengths, under zero bias. In addition, the photocurrent response caused by the photovoltaic‐pyroelectric effect is thoroughly defined, and the impacts of light wavelength, power intensity, and bias voltage are studied. This study presents a cutting‐edge self‐powered broadband photodetector utilizing pyroelectric materials and opens possibilities for designing high‐performance, fast photodetectors based on the pyro‐phototronic effect.

Band Alignment Transition and Enhanced Performance in Vertical SnS2/MoS2 van der Waals Photodetectors.

The strong light-matter interaction and naturally passivated surfaces of van der Waals materials make heterojunctions of such materials ideal candidates for high-performance photodetectors. In this study, we fabricated SnS2/MoS2 van der Waals heterojunctions and investigated their photoelectric properties. Using an applied gate voltage, we can effectively alter the band arrangement and achieve a transition in type II and type I junctions. It is found that the SnS2/MoS2 van der Waals heterostructures are type II heterojunctions when the gate voltage is above -25 V. Below this gate voltage, the heterojunctions become type I. Photoelectric measurements under various wavelengths of incident light reveal enhanced sensitivity in the ultraviolet region and a broadband sensing range from 400 to 800 nm. Moreover, due to the transition from type II to type I band alignment, the measured photocurrent saturates at a specific gate voltage, and this value depends crucially on the bias voltage and light wavelength, providing a potential avenue for designing compact spectrometers.

Light and voltage dual-modulated volatile resistive switching in single ZnO nanowires.

A single ZnO nanowire device with volatile resistive switching behavior has been prepared. Different from traditional resistive switching devices, such ZnO nanowire devices do not exhibit resistive switching behaviors under a single bias voltage, and appear resistive switching behavior under the combined action of light stimuli and bias voltage. Through the demonstration of the time-dependent hysteresis curve and atmosphere-dependent hysteresis loop of the resistive switching devices, it is believed that under the resistive switching process, ultraviolet illumination can increase the carrier concentration and modulate the barrier depletion structure, and external bias voltage can ionize the surface state. They work together to modulate the switching process of the devices. Such light stimuli and bias voltage dual-modulated resistive switching device enables optical control and may thus be considered for sensory applications or optically tunable memories.

Light Effect on Amorphous Tin Oxide Thin‐Film Transistors

Amorphous tin oxide (a‐SnOx) is a potential transparent oxide semiconductor candidate for future large‐area electronic applications. The thin‐film transistor (TFT) mobilities reach ≈100 cm2 Vs−1, a mobility higher than other multiple cation‐based oxide semiconductor TFTs. Few optical properties have been reported so far and therefore both the effect of visible light and negative bias illumination stress (NBIS) on a‐SnOx TFT performances, known to dramatically impact oxide semiconductor‐based TFTs, have been investigated. The variation of density of states (DOS) due to NBIS by device simulation is analyzed, and a fourfold increase of the donor‐like states and a decrease in the band edge DOS from 2.3 to 2.0 × 1019 cm−3 eV−1 are showed. The evaluation of the effect of neutral, singly, and doubly ionized oxygen vacancies by density functional theory using 95 atoms reveals not only states in the gap of SnO2, but also variations in the electron density, and modifications in the crystal parameters compared to a structure without an oxygen vacancy. Material and device simulation analysis reveal that the oxygen vacancies have a dramatical impact on the DOS in the gap of SnO2 and can explain the NBIS phenomenon observed in a‐SnOx TFT.

Motion-resistant three-wavelength spatial frequency domain imaging system with ambient light suppression using an 8-tap CMOS image sensor.

We present a motion-resistant three-wavelength spatial frequency domain imaging (SFDI) system with ambient light suppression using an 8-tap complementary metal-oxide semiconductor (CMOS) image sensor (CIS) developed at Shizuoka University. The system addresses limitations in conventional SFDI systems, enabling reliable measurements in challenging imaging scenarios that are closer to real-world conditions. Our study demonstrates a three-wavelength SFDI system based on an 8-tap CIS. We demonstrate and evaluate the system's capability of mitigating motion artifacts and ambient light bias through tissue phantom reflectance experiments and in vivo volar forearm experiments. We incorporated the Hilbert transform to reduce the required number of projected patterns per wavelength from three to two per spatial frequency. The 8-tap image sensor has eight charge storage diodes per pixel; therefore, simultaneous image acquisition of eight images based on multi-exposure is possible. Taking advantage of this feature, the sensor simultaneously acquires images for planar illumination, sinusoidal pattern projection at three wavelengths, and ambient light. The ambient light bias is eliminated by subtracting the ambient light image from the others. Motion artifacts are suppressed by reducing the exposure and projection time for each pattern while maintaining sufficient signal levels by repeating the exposure. The system is compared to a conventional SFDI system in tissue phantom experiments and then in vivo measurements of human volar forearms. The 8-tap image sensor-based SFDI system achieved an acquisition rate of 9.4 frame sets per second, with three repeated exposures during each accumulation period. The diffuse reflectance maps of three different tissue phantoms using the conventional SFDI system and the 8-tap image sensor-based SFDI system showed good agreement except for high scattering phantoms. For the in vivo volar forearm measurements, our system successfully measured total hemoglobin concentration, tissue oxygen saturation, and reduced scattering coefficient maps of the subject during motion (16.5cm/s) and under ambient light (28.9lx), exhibiting fewer motion artifacts compared with the conventional SFDI. We demonstrated the potential for motion-resistant three-wavelength SFDI system with ambient light suppression using an 8-tap CIS.

Intensity-Modulated Photocurrent Spectroscopy Measurements of High-Efficiency Perovskite Solar Cells.

Frequency domain characterization has long served as an important method for the examination of diverse kinetic processes that occur in solar cells. In this study, we investigated the dynamic response of high-efficiency perovskite solar cells utilizing ultra-low-intensity-modulated photocurrent spectroscopy. Distinctive intensity-modulated photocurrent spectroscopy (IMPS) attributes were detected only as a result of this low-intensity modulation, and their evolution under light and voltage bias was investigated in detail. We generally observed only two arcs in the Q-plane plots and attributed the smaller, low-frequency arc to trap-dominated charge transport in the device. Light and voltage bias-dependent measurements confirm this attribution. An equivalent circuit model was used to better understand the features and trends of these measurements and to validate our physical interpretation of the results. Additionally, we tracked the IMPS response of one of the cells over time and showed that slow degradation impacts the size and attributes of the low-frequency arc. Finally, we found that changes in the IMPS response correlate closely with the current versus voltage characteristics of the devices.

LIBERO: LIght Bias as effective countermeasure against EavesdROpper attacks

LIBERO: LIght Bias as effective countermeasure against EavesdROpper attacks

Synergetic interfacial conductivity modulation dictating hysteresis evolution in perovskite solar cells under operation.

In this work, the configuration of compact TiO2 coating (c-TiO2) interface as electron transport layer (ETL) in giving rise to loss and gain of fill factor (FF) and therefore modulation of hysteresis behavior in perovskite solar cells (PSCs) is investigated. For this purpose, PSCs based on planar compact TiO2 (c-TiO2) as well as a scaffold-based architecture are studied. In the latter case c-TiO2 coats a hydrothermally grown titania nanorod scaffold. The results demonstrate that when c-TiO2 is used in planar configuration, FF considerably improves with prolonged light soaking which is in sharp contrast to what is observed for scaffold-based PSCs. Moreover, higher thickness of planar c-TiO2 is shown to be beneficial for sustaining FF in forward scan. Finally, through studying the intricate interfacial dynamics utilizing electrochemical impedance spectroscopy (EIS), it was concluded that for a PSC under operation, the cumulative effect of conductivity modulation at the perovskite with transport layer interfaces, for their respective charge carriers, determines the loss and gain in performance depending on scan rate, applied bias and prolonged light soaking. This work points towards multiple factors affecting PSC output, which could work either in confluence or against one another depending on the interfacial configuration of transport layers.

A novel method of determining bias lights for spectral response measurement of GaAs multi-junction laser power converters and its applications

Quantitative electrical analysis of sub-cells is crucial for the designing of high-efficiency GaAs multi-junction laser power converters (MJLPCs). However, finding suitable bias lights to separate the electrical performance of sub-cells is an enormous challenge, due to GaAs MJLPCs being assembled by GaAs p-n junctions. Therefore, this study proposes a novel and general method of determining bias lights for the SR measurement of GaAs MJLPCs based on the variation rules of simulated short-circuit current densities with wavelengths in the sub-cells of GaAs MJLPCs. By the method of determining bias lights, the external quantum efficiency (EQE) curves of a GaAs four-junction LPC have been successfully measured for the first time, which confirms the validity of the method.

Photonic Spin Hall Effect as a Highly Sensitive Refractive Index Sensing Platform for Glucose

AbstractThis study presents an innovative refractive index (RI) sensor that measures glucose concentration by utilizing the photonic spin Hall effect (SHE) in a resonant optical tunneling effect (ROTE) structure. The ROTE structure consists of three InP layers with the high RI and two analyte layers (with a high‐low‐high‐low‐high RI distribution), in which glucose solution samples with the low RI are injected. By subjecting the InP layers to external bias‐assisted light, the photonic SHE can be flexibly manipulated, enabling the modulation of the sensing performance accordingly. It is found that the transverse shift of photonic SHE presents a large variation in response to the tiny change in glucose concentrations. By optimizing the parameters (i.e., intensity or wavelength) of bias light, the sensitivity of this sensor can reach as high as 735.7 µm RIU−1. Compared to traditional glucose sensors, this original work implements the novel photonic SHE with the superior sensing performance. Therefore, the proposed design shows promising potential for biomedical applications, such as medical diagnoses and drug discovery.

Effect of light bias on male mating signal and female mate choice in a sexually dimorphic Amazon fish

Colourful signals are usually honest indicators of mate quality since they are energetically costly. However, how colours are perceived by choosers is highly affected by the environmental light condition. Amazon black waters are strongly red-biased while clear waters show no apparent colour bias. The sailfin tetra Crenuchus spilurus is a sexually dimorphic Amazon fish species; males have hyperallometric dorsal and anal fins conspicuously ornamented with red and yellow markings. The species has two main lineages, which inhabit black and clear waters. A comparison of the red colouration of the ornaments of males from different lineages indicates that red bias increases the perceived intensity of red colouration but decreases the perceived among-individual variation in red colour. In mate choice experiments, females from all lineages preferred males with larger ornaments. Clear water lineage females were more likely to accept males under red-biased lighting, which increases the apparent red colouration, suggesting the importance of the red colouration in their mate choice. On the other hand, male acceptance by females from black waters did not change under different light conditions, suggesting that signals other than the red colouration (e.g. size of ornaments) were more important in their mate choice.

Photoelectro-Fenton microreactor integrated with MOF-derived porous α-Fe2O3 film for efficient nanoplastics degradation

The stubborn Nanoplastics (NPs) have provoked serious environment pollution globally and it is urgent to develop efficient technologies to decompose them efficiently. However, the degradation efficiency is still subject to various factors such as the reactor design, catalysts, and reaction pathways. In this work, a photoelectro-Fenton microfluidic reactor was designed to enable the fine-tuning of photoelectro-Fenton reactions by applying both light irradiation and bias potentials to the reaction chamber. To enhance its degradation efficiency and reusability, a MOF-derived porous Fe2O3 material was coated in the reaction chamber. In the experiment, the voltage, illumination, flow rate, and other factors were adjusted to investigate the reactor's properties and optimize the reaction conditions. The study showed α-Fe2O3 catalytic efficiency increased with bias, reaching maximum degradation rate of large than 0.438 %/s at the bias of 1.2 V under the solar light irradiation with the light intensity of 120 mW/cm2, and did not decrease significantly in 4 repeated experiments. Furthermore, the synergistic effect of various oxidation pathways was also revealed. The photoelectro-Fenton microreactor finally showed unprecedented degradability and excellent reusability. The proposed platform is adapted to guide the AOP degradation of NPs, and has potential to be scaled up for industrial NPs removal.

A scoping review exploring the confidence of healthcare professionals in assessing all skin tones.

Health inequalities and poorer outcomes have been identified for patients with dark skin tones. The reasons are multi-factorial, but may include delayed treatment due to a lack of recognition of early clinical signs of physiological deterioration. Within the medical literature there is a light skin tone bias, leading to healthcare professionals having insufficient knowledge regarding the assessment of patients with different skin tones, which may result in reduced confidence and create patient safety issues. The aim of this scoping review was to explore the confidence levels of healthcare professionals when assessing patients of different skin tones. The methodology followed scoping review frameworks set out by Arksey and O'Malley (2005), the Joanna Briggs Institute (Peters et al., 2020) and the PRISMA extension for Scoping Reviews (PRISMA-ScR) (Tricco et al., 2018). Searches for literature were performed between February and June 2022 using electronic databases EBSCO (Academic Search Complete, the Allied Complementary Medicine Database, e-journals, MEDLINE, CINAHL), British Nursing Index (ProQuest), Scopus, Web of Science, Zetoc, UpToDate, Google Scholar, NICE Evidence, ResearchGate, Opengrey and the British Association of Dermatologists. No date range was specified, expanders were left on and the findings were screened using inclusion and exclusion criteria. Included papers were synthesised using narrative synthesis. Thirteen papers were identified, and the extracted data charted by the paper's origin, sample size, profession and confidence levels. Our synthesis revealed reduced confidence in assessing, managing and diagnosing skin conditions in dark skin tones. A lack of training was cited by different health professionals, but undertaking tailored training and experiential learning increased confidence. There is a safety issue for patients with dark skin tones, as healthcare professionals lack clinical confidence in managing and treating all ethnicities equally. Tangible diversity within healthcare training is required, supported by inclusive skin tone imagery and appropriate terminology within medical literature.