Light Requirements Research Articles

A synthetic switch based on orange carotenoid protein to control blue-green light responses in chloroplasts.

Synthetic biology approaches to engineer light-responsive systems are widely used, but their applications in plants are still limited due to the interference with endogenous photoreceptors and the intrinsic requirement of light for photosynthesis. Cyanobacteria possess a family of soluble carotenoid-associated proteins named orange carotenoid proteins (OCPs) that, when activated by blue–green light, undergo a reversible conformational change that enables the photoprotection mechanism that occurs on the phycobilisome. Exploiting this system, we developed a chloroplast-localized synthetic photoswitch based on a protein complementation assay where two nanoluciferase fragments were fused to separate polypeptides corresponding to the OCP2 domains. Since Arabidopsis (Arabidopsis thaliana) does not possess the prosthetic group needed for the assembly of the OCP2 complex, we first implemented the carotenoid biosynthetic pathway with a bacterial β-carotene ketolase enzyme (crtW) to generate keto-carotenoid-producing plants. The photoswitch was tested and characterized in Arabidopsis protoplasts and stably transformed plants with experiments aimed to uncover its regulation by a range of light intensities, wavelengths, and its conversion dynamics. Finally, we applied the OCP-based photoswitch to control transcriptional responses in chloroplasts in response to green light illumination by fusing the two OCP fragments with the plastidial SIGMA FACTOR 2 and bacteriophage T4 anti-sigma factor AsiA. This pioneering study establishes the basis for future implementation of plastid optogenetics to regulate organelle responses upon exposure to specific light spectra.

The operation characteristics analysis of a novel glass curtain wall system by using simulation and test

New type of glass curtain wall system was designed with the flexible PV batteries as receiver, it can make the best use of the excess solar radiation at noon to generate electricity and ensuring to meet the requirements of indoor lighting in the morning and evening. Water and air circulation systems were used to reduce the indoor heat load. In this paper, the operation characteristics of new glass curtain wall in different seasons are studied by numerical calculation and experimental test. The simulation results show that energy flux density of the receiver decreases gradually with the increase of the incident angle and when it is greater than 65°, energy flux density is close to zero. The thermal characteristics were simulated to evaluate the performance of system. To verify the accuracy of the numerical calculation results, a test bench was built to carry out the experiments. The test results are in good agreement with simulation results. The heat receiving rate reaches the maximum value throughout the day at noon, and the air heating efficiency ranges from 13% to 18%. Combined with the indoor and outdoor temperature characteristics and indoor fresh air demand in different seasons, three working conditions were selected for each season. The heat transfer characteristics were simulated by CFD under each working condition. The purpose is to study the operation characteristics of the new glass curtain wall system in actual weather, and provide theory basis for the operation strategy in the practical application in the future.

An Investigation of the Implications of Visual Impairment for Illumination Requirements

Introduction The present contribution mainly focuses on the evaluation of the visual performance of people with impaired vision and, for comparison purposes, individuals with typical vision under different lighting conditions. Methods: A monitor with adjustable brightness facilitated various test runs to determine the visual performance as a function of the adaptation luminance and glare. In addition, the subjective impressions of the participants with impaired vision were queried via interviews. The study included 98 people with impaired vision and 38 people without visual impairments. Results: The interview results suggest that most people with visual impairments require special lighting conditions. An increased lighting requirement is observed amongst 50% of this group. Moreover, 75% of this group display increased glare sensitivity. Likewise, adaptation problems and critical issues related to nonuniform lighting are manifest. Individuals with impaired vision included in this study display a greatly reduced contrast threshold and a higher subjective level of discomfort compared to individuals with typical vision.Discussion: Most visually impaired participants state that they require a higher degree of brightness to achieve their maximum personal visual performance. However, about a quarter of the participants reported that they achieve a better visual performance at lower brightness, while displaying an increased sensitivity to glare. In general, glare has a decisive influence on the visual performance of the participants with impaired vision in our study. Implications for Practitioners: The study reconfirms the essential importance of glare-free and uniform general lighting strategies (e.g., via predominantly indirect lighting) as well as avoiding abrupt spatiotemporal luminance changes (e.g., via provision of a transition zone between locations with very different luminance levels).

Competitive Hierarchy Processes Support Mixed Species Regeneration in Strip-Cuts in the British Columbia Interior

Competitive exclusion can lead to a loss of species diversity within small forest gaps. Thus, it poses a potential concern for mixed species regeneration following strip-cut harvesting in the species rich interior moist forests of British Columbia. In this study, we compare nine tree species widely used in reforestation for their growth rates along a light/gap-position gradient in 50 m wide east-west oriented strip-cuts. Data after 15 growing seasons reveal that a crossover of species’ growth patterns along the light gradient can be linked to their shade tolerance ranking, and competitive hierarchy processes can be observed between species. The growth of two shade-intolerant (lodgepole pine and ponderosa pine), and two moderately tolerant (Douglas fir and white pine) species did surpass the growth of other more tolerant species under high light conditions in this study. Thus, we conclude that maintaining shade-intolerant species within 50 m wide strip-cuts is feasible, but species need to be planted in locations that suit their light requirements.

Effects of Epiphytes on the Seagrass Phyllosphere

The seagrass phyllosphere consists of a dynamic mosaic of physico-chemical microgradients that modulate light harvesting, gas and nutrient exchange between the photosynthetic leaves and the surrounding water-column. The phyllosphere is thus of vital importance for seagrass growth and fitness. However, unfavorable environmental conditions such as water-column hypoxia, increasing temperature and high nutrient inputs that are predicted to increase in frequency and severity in the Anthropocene, can render the leaf microenvironment into a hostile microhabitat that is challenging or even harmful for the plants—especially if leaves are covered by epiphytic biofilms. Here we summarize effects of epiphytic biofilms on seagrass leaves and discuss how they change and affect the biogeochemical processes and chemical conditions in the seagrass phyllosphere. During night-time, water-column hypoxia can lead to anoxic conditions at the leaf/epiphyte interface, reducing diffusive O2supply and thus O2availability for plant respiration and transport to below-ground tissues. Furthermore, anoxia in epiphytic biofilms can also enable anaerobic microbial processes that can lead to harmful nitric oxide productionviadenitrification. Such microenvironmental stress conditions at night-time are exacerbated by increasing temperatures. In the light, the leaf epiphytic biofilm community often results in lower leaf photosynthetic activity and efficiency due to epiphyte-induced shading and a combination of O2build-up and CO2reduction in the phyllosphere owing to thicker total diffusional pathways, phyllosphere basification and epiphytic carbon fixation. Furthermore, absorbed light energy in the epiphytic biofilm can also drive an increase in the leaf surface temperature relative to the surrounding seawater potentially aggravating heating events in the surrounding seawater. In combination, all these above-mentioned diurnal effects of epiphytes result in higher compensation photon irradiance of epiphyte-covered leaves and thus higher light requirements of seagrasses.

Soil Seed Bank Persistence Across Time and Burial Depth in Calcareous Grassland Habitats.

Seed persistence in the soil is crucial for population dynamics. Interspecific differences in soil seed mortality could be a mechanism that may stimulate species coexistence in herbaceous plant communities. Therefore, understanding the levels and causes of seed persistence is vital for understanding community composition and population dynamics. In this study, we evaluated the burial depth as a significant predictor of the temporal dynamics of soil seed persistence. We suppose that species differ in this temporal dynamics of soil seed persistence according to burial depth. Furthermore, we expected that burial depth would affect soil seed persistence differently concerning the species-specific type of dormancy, light, and fluctuating temperature requirements for germination. Seeds of 28 herbaceous species of calcareous grasslands were buried in the field into depths of 1, 5, and 10 cm under the soil surface. Seed viability was tested by germination and tetrazolium tests several times for three years. Species-specific seed traits—a type of dormancy, light requirements and alternating temperature requirements for germination, and longevity index—were used for disentangling the links behind species-specific differences in soil seed persistence. Our study showed differences in soil seed persistence according to the burial depth at the interspecific level. Generally, the deeper the buried seeds, the longer they stayed viable, but huge differences were found between individual species. Species-specific seed traits seem to be an essential determinant of seed persistence in the soil. Seeds of dormant species survived less and only dormant seeds stayed viable in the soil. Similarly, seeds of species without light or alternating temperature requirements for germination generally remained viable in the soil in smaller numbers. Moreover, seeds of species that require light for germination stayed viable longer in the deeper soil layers. Our results help understand the ecosystem dynamics caused by seed reproduction and highlight the importance of a detailed long-term investigation of soil seed persistence. That is essential for understanding the fundamental ecological processes and could help restore valuable calcareous grassland habitats.

Multi-objective optimization method for reducing mutual interference in cockpit illumination.

The cockpit is a compact space comprised of various light-emitting devices. The light from different devices interferes and overlaps on the target surface. The light distribution requirements of different target surfaces are different. A suitable decision-making process is required to simultaneously meet the requirements of multiple target surfaces. A GPR-NSGA-II framework was proposed in the present study and a corresponding Gaussian process regression prediction model was established to predict and optimize multiple optical quality parameters in the cockpit. The luminous flux and beam angle of the typical luminaires were selected as controlled input parameters in a model case. The average illumination of targets that need lighting were set as constraints, and uniformity of illuminance of these surfaces and vertical illumination (direct light) of the eye position were set as the variables. An orthogonal experiment was conducted using the lighting model and a dataset was generated to validate the proposed framework. The results demonstrate that the solution set of luminescence parameters in cockpit illumination can be specified by GPR-NSGA-II framework.

Functional Traits Drive Dispersal Interactions Between European Waterfowl and Seeds.

Endozoochory by waterfowl is important for a broad range of angiosperms, most of which lack a fleshy fruit. This dispersal function contributes to the formation and maintenance of plant communities and may allow range shifts for plant species under global change. However, our current understanding of what seed or plant traits are important for this dispersal mechanism, and how they relate to variation in waterbird traits, is extremely limited. We addressed this question using a unique dataset identifying the plant species whose seeds are ingested by 31 different waterfowl species in Europe. We used RLQ and fourth-corner analyses to explore relationships between (1) bird morphological and foraging strategy traits, and (2) plant traits related to seed morphology, environmental preferences, and growth form. We then used Generalized Additive Models to identify relationships between plant/seed traits and the number of waterfowl species that disperse them. Although many waterfowl feed intentionally on seeds, available seed trait data provided little explanation for patterns compared to plant traits such as Ellenberg indicators of habitat preference and life form. Geese were associated with terrestrial plants, ingesting seeds as they graze on land. Diving ducks were associated with strictly aquatic plants, ingesting seeds as they feed at greater depths. Dabbling ducks ingest seeds from plants with high light and temperature requirements, especially shoreline and ruderal species growing in or around the dynamic and shallow microhabitats favored by these birds. Overall, the number of waterfowl vector species (up to 13 per plant species) increases for plants with greater soil moisture requirements and salinity tolerance, reflecting the inclination of most waterfowl species to feed in coastal wetlands. Our findings underline the importance of waterfowl dispersal for plants that are not strictly aquatic, as well as for plants associated with high salinities. Furthermore, our results reveal a soil moisture gradient that drives seed-bird interactions, in line with differences between waterfowl groups in their microhabitat preferences along the land-water continuum. This study provides an important advance in our understanding of the interactions that define plant dispersal in wetlands and their surroundings, and of what plants might be affected by ongoing changes in the distributions of waterfowl species.

Photocontrol of Axillary Bud Outgrowth by MicroRNAs: Current State-of-the-Art and Novel Perspectives Gained From the Rosebush Model.

Shoot branching is highly dependent on environmental factors. While many species show some light dependence for branching, the rosebush shows a strict requirement for light to allow branching, making this species an excellent model to further understand how light impinges on branching. Here, in the first part, we provide a review of the current understanding of how light may modulate the complex regulatory network of endogenous factors like hormones (SL, IAA, CK, GA, and ABA), nutrients (sugar and nitrogen), and ROS to control branching. We review the regulatory contribution of microRNAs (miRNAs) to branching in different species, highlighting the action of such evolutionarily conserved factors. We underline some possible pathways by which light may modulate miRNA-dependent regulation of branching. In the second part, we exploit the strict light dependence of rosebush for branching to identify putative miRNAs that could contribute to the photocontrol of branching. For this, we first performed a profiling of the miRNAs expressed in early light-induced rosebush buds and next tested whether they were predicted to target recognized regulators of branching. Thus, we identified seven miRNAs (miR156, miR159, miR164, miR166, miR399, miR477, and miR8175) that could target nine genes (CKX1/6, EXPA3, MAX4, CYCD3;1, SUSY, 6PFK, APX1, and RBOHB1). Because these genes are affecting branching through different hormonal or metabolic pathways and because expression of some of these genes is photoregulated, our bioinformatic analysis suggests that miRNAs may trigger a rearrangement of the regulatory network to modulate branching in response to light environment.

Fixed Fiber Light Guide System with Concave Outlet Concentrators

Because a traditional optical fiber light guiding system includes a tracking device, it also inevitably has a complex structure, high construction and maintenance costs, short life span and low reliability. Although several types have been developed for decades, there are no successful products on the market. The biggest cause of the problem is that all traditional optical fiber light guiding systems must have a tracking device. This paper studies a solar fiber optic guide system without a tracking device, hoping to solve this problem. A fixed fiber light guide system using concave outlet concentrators as its receiving unit is proposed. The structure and working principle of the concave outlet concentrator, the receiving unit and the light guide system are introduced. With optical simulation software and the actual sunlight experimental method, this paper first discusses the conceptual design of the concentrator, then studies the transmission efficiency curve of the receiving unit with different angles of incident light, and finally tests the output illuminance of the whole system in actual sunlight. Field test results show that when the average sunshine intensity is about 800 W/m2, the system has an output of nearly 300 lux at 0.4 m in front of the outlet end of the fiber bundle with only 3.11×10−2 m2 receiving area. This illumination has been able to meet people’s daily lighting requirements. The results of computer simulation and actual sunlight experiments show that this fixed optical fiber light guide system with non-tracing structure is feasible. The absence of a tracking structure means that all moving parts of the system are completely discarded. This greatly improves the working reliability and operation life of the light guide system, and greatly reduces the maintenance and operating costs.

High‐Performance Indoor Organic Solar Cells Based on a Double‐Cable Conjugated Polymer

Indoor photovoltaic is one of the most important applications of organic solar cells (OSCs). As different from AM1.5G sunlight with broad spectra from the visible to near‐infrared region, the spectra of indoor light are usually located in the visible region. Therefore, a special material design for the photoactive layer to meet the requirement of indoor light is required for application in indoor photovoltaics. Herein, a wide‐bandgap double‐cable conjugated polymer is intentionally selected, which has the well‐matched absorption spectra with indoor light for use in indoor OSCs. This double‐cable polymer is used as a single photoactive layer in OSCs, providing a high power conversion efficiency of 19.44% under indoor light, which is comparable with the bulk‐heterojunction solar cells using near‐infrared electron acceptors. Moreover, the double‐cable polymer‐based indoor OSCs exhibit high storage stability. These results indicate that single‐component OSCs based on double‐cable polymers have promising applications in indoor OSCs.

Evaluation of growth period and water and light requirement for optimum production of hydroponic maize and horse gram fodder

Evaluation of growth period and water and light requirement for optimum production of hydroponic maize and horse gram fodder

Increasing the performance of cucumber (Cucumis sativus L.) seedlings by LED illumination

Light is one of the most important limiting factors for photosynthesis and the production of plants, especially in the regions where natural environmental conditions do not provide sufficient sunlight, and there is a great dependence on artificial lighting to grow plants and produce food. The influence of light intensity, quality, and photoperiod on photosynthetic pigments content and some biochemical and growth traits of cucumber seedlings grown under controlled conditions was investigated. An orthogonal design based on a combination of different light irradiances, ratio of LEDs and photoperiods was used. Treaments consisted of three light irradiance regimes (80, 100, and 150 µmol m−2 s−1) provided by light-emitting diodes (LEDs) of different ratios of red and blue (R:B) (30:70, 50:50, and 70:30) and three different photoperiods (10/14, 12/12, and 14/10 h). The white light was used as a control/reference. Plant height, hypocotyl length, stem diameter, leaf area, and soluble sugar content were highest when exposed to LM9 (150 µmol m−2 s−1; R70:B30; 12/12 h) light mode, while the lowest values for the above parameters were obtained under LM1 (80 µmol m−2 s−1; R30:B70; 10/14 h). Higher pigments contents (chlorophyll a, chlorophyll b, and carotenoid) were obtained when light regime LM9 (150 µmol m−2 s−1; R70:B30; 12/12 h) was applied. In general, cucumber seedlings grown under the LM9 regime showed a significant increase in growth as well as photosynthetic capacity. It seems that the content of photosynthetic pigments is the key factor responsible for the performance of cucumber seedlings grown under different lighting modes, compared to other traits studied. We recommend monitoring the content of chlorophyll a, b, and their ratio value when studying the light requirement of cucumber plants.

Cantilever enhanced based photoacoustic detection of SF6 decomposition component SO2 using UV LED

PurposeThis paper aims to establish a photoacoustic detection system for SO2 using UV-LED and testify its feasibility for sensitive measurement. The work in this paper can avoid potential crossover interference in infrared (IR) range and also balance the capability and cost of feasible excitation for photoacoustic detection system.Design/methodology/approachIn this experimental work, a cantilever-enhanced–based photoacoustic SO2 detection system using an ultraviolet (UV) LED light source with a light power of 4 mW as the excitation was established.FindingsA feasible photoacoustic detection system for SO2 using UV-LED was established. Experimental results demonstrate that the detection limit of the system can reach the level of 0.667 ppm, which can serve as a reference for the application of PAS in insulation fault diagnosis.Originality/valueThis work investigated the potential of using ultraviolet photoacoustic spectroscopy to detect trace SO2, which provided an ideal replacement of infrared-laser-based detection system. In this paper, a photoacoustic detection system using LED with a low light power was established. Low light power requirement can expand the options of light sources accordingly. In this paper, the absorption characteristics of SO2 in the presented detection system and ultraviolet range were studied. And the detection limit of the presented system was given. Both of which can provide reference to SO2 detection in ambient SF6.

Regeneration from seed in herbaceous understorey of ancient woodlands of temperate Europe.

European ancient woodlands are subject to land use change, and the distribution of herbaceous understorey species may be threatened because of their poor ability to colonize isolated forest patches. The regeneration niche can determine the species assembly of a community, and seed germination traits may be important descriptors of this niche. We analysed ecological records for 208 herbaceous species regarded as indicators of ancient woodlands in Europe and, where possible, collated data on seed germination traits, reviewed plant regeneration strategies and measured seed internal morphology traits. The relationship between plant regeneration strategies and ecological requirements was explored for 57 species using ordination and classification analysis. Three regeneration strategies were identified. Species growing in closed-canopy areas tend to have morphological seed dormancy, often requiring darkness and low temperatures for germination, and their shoots emerge in early spring, thus avoiding the competition for light from canopy species. These species are separated into two groups: autumn and late winter germinators. The third strategy is defined by open-forest plants with a preference for gaps, forest edges and riparian forests. They tend to have physiological seed dormancy and germinate in light and at higher temperatures, so their seedlings emerge in spring or summer. Seed germination traits are fundamental to which species are good or poor colonizers of the temperate forest understorey and could provide a finer explanation than adult plant traits of species distribution patterns. Seed dormancy type, temperature stratification and light requirements for seed germination are important drivers of forest floor colonization patterns and should be taken in account when planning successful ecological recovery of temperate woodland understories.

Dormancy and viability ofFerocactus peninsulae(Cactaceae) seeds

AbstractKnowledge on seed dormancy is crucial for the understanding of plant population dynamics, as it controls seed germination and seed bank formation. Dormant seeds have high potential to establish in soil seed banks, but such information within Cactaceae is scarce, although it is essential for conservation programs. The aim of this study was to determine if seeds ofFerocactus peninsulaeshowed any kind of dormancy and to test their germination capacity after storage. This was assessed with 15 seed sowing experiments done over 4 years with seeds stored under room conditions (20 ± 2°C). We demonstrated the existence of physiological dormancy inF. peninsulaeseeds that is broken with an after‐ripening period. Germination was low during the first 3 months of storage (d = 0.206) but increased after 10 months of storage (d = 0.654), and seeds maintained their viability at 48 months (d = 0.707). Also, their speed of germination increased with storage time.Ferocactus peninsulaeseeds are positively photoblastic, and the requirement for light for germination persisted over all experiments. The results provide crucial information for propagation and conservation research and may allow us to infer thatF. peninsulaeseeds are able to form a persistent soil seed bank, as they maintained their viability after dormancy is released.

Variable seed bed microsite conditions and light influence germination in Australian winter annuals

Environmentally cued germination may play an important role in promoting coexistence in Mediterranean annual plant systems if it causes niche differentiation across heterogeneous microsite conditions. In this study, we tested how microsite conditions experienced by seeds in the field and light conditions in the laboratory influenced germination in 12 common annual plant species occurring in the understorey of the York gum-jam woodlands in southwest Western Australia. Specifically, we hypothesized that if germination promotes spatial niche differentiation, then we should observe species-specific germination responses to light. In addition, we hypothesized that species’ laboratory germination response may depend on the microsite conditions experienced by seeds while buried. We tested the laboratory germination response of seeds under diurnally fluctuating light and complete darkness, which were collected from microsites spanning local-scale environmental gradients known to influence community structure in this system. We found that seeds of 6 out of the 12 focal species exhibited significant positive germination responses to light, but that the magnitude of these responses varied greatly with the relative light requirement for germination ranging from 0.51 to 0.86 for these species. In addition, germination increased significantly across a gradient of canopy cover for two species, but we found little evidence to suggest that species’ relative light requirement for germination varied depending on seed bank microsite conditions. Our results suggest that variability in light availability may promote coexistence in this system and that the microsite conditions seeds experience in the intra-growing season period can further nuance species germination behaviour.

Study on the Strip Warpage Issues Encountered in the Flip-Chip Process.

This study successfully established a strip warpage simulation model of the flip-chip process and investigated the effects of structural design and process (molding, post-mold curing, pretreatment, and ball mounting) on strip warpage. The errors between simulated and experimental values were found to be less than 8%. Taguchi analysis was employed to identify the key factors affecting strip warpage, which were discovered to be die thickness and substrate thickness, followed by mold compound thickness and molding temperature. Although a greater die thickness and mold compound thickness reduce the strip warpage, they also substantially increase the overall strip thickness. To overcome this problem, design criteria are proposed, with the neutral axis of the strip structure located on the bump. The results obtained using the criteria revealed that the strip warpage and overall strip thickness are effectively reduced. In summary, the proposed model can be used to evaluate the effect of structural design and process parameters on strip warpage and can provide strip design guidelines for reducing the amount of strip warpage and meeting the requirements for light, thin, and short chips on the production line. In addition, the proposed guidelines can accelerate the product development cycle and improve product quality with reduced development costs.

Efficiency of LED lamps used in cereal crop breeding greenhouses

LED lamps, which are becoming prevalent in horticulture, are also being installed in greenhouses dedicated to cereal crop breeding. However, the issue arises with the real efficiency of LED lamps. Besides high-budget programs, the smaller breeding companies in Poland face problems concerning the plant growth under LED lamps and the real costs of their exploitation. The experiment was conducted to compare seven different LED lamps and a high-intensity discharge (HID) lamp with a high-pressure sodium lamp (HPS) used as a control. For studies, two varieties of wheat, barley, and oat species were used. The plants’ growth rate was assessed based on elongation growth and earing time. Plants’ physiological conditions were evaluated using chlorophyll a (Chl a) fluorescence measured on dark-adapted leaves. The light spectra and intensities of tested lamps in parallel with electricity consumption were also recorded. The results showed that 1) LEDs’ physical properties and luminaire construction influence the amount of electricity consumed; 2) the cereal crop species differ in lighting requirements. The less light-sensitive was oat opposite barley, with wheat of moderate sensitivity; 3) LED-6 lamp (PlantaLux S.A, Lublin, Poland) based on white diodes enriched by blue ones was the most cost-efficient and most optimal for studied species. Keywords: greenhouse, light-emitting diodes, cost-effectiveness, cereal, Triticum aestivum, Hordeum vulgare, Avena sativa DOI: 10.25165/j.ijabe.20221502.5775 Citation: Stefański P, Siedlarz-Slowacka P, Matysik P, Rybka K. Efficiency of LED Lamps used in cereal crop breeding greenhouse. Int J Agric & Biol Eng, 2022; 15(2): 75–83.

Smartphone surface plasmon resonance imaging for the simultaneous and sensitive detection of acute kidney injury biomarkers with noninvasive urinalysis.

A surface plasmon resonance imaging (SPRi) platform integrated with a smartphone was constructed for the simultaneous and sensitive detection of acute kidney injury (AKI) biomarkers. The smartphone SPRi platform was developed without the requirement of additional light and power sources. The LED flash of the smartphone was used as the light source for the excitation of surface plasmon resonance of a gold sensor chip based on the Kretschmann configuration, while the reflected light was collected by the camera of the smartphone. This smartphone SPRi system was conveniently fabricated by 3D printing and showed a sensitivity of 1.78 × 10-5 refractive index unit (RIU). In addition, based on a magnetic nanoparticle-enhanced sandwich immunoassay, the smartphone SPRi system with a gold array chip was employed for the detection of multiple AKI biomarkers, with a low limit of detection (LOD) of 0.19 ng ml-1, 0.51 ng ml-1 and 0.7 ng ml-1 for the simultaneous detection of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18) and retinol-binding protein (RBP) in urine, respectively. The biosensors demonstrated high specificity and sensitivity for the simultaneous detection of multiple AKI biomarkers in PBST and urine. The smartphone SPRi system provided a portable and cost-effective platform for point-of-care diagnosis, in-field healthcare and environmental monitoring.