Advancement of membrane separation technology for organic pollutant removal.

In the face of growing global freshwater scarcity, the imperative to recycle and reuse water becomes increasingly apparent across industrial, agricultural, and domestic sectors. Eliminating a range of organic pollutants in wastewater, from pesticides to industrial byproducts, presents a formidable challenge. Among the potential solutions, membrane technologies emerge as promising contenders for treating diverse organic contaminants from industrial, agricultural, and household origins. This paper explores cutting-edge membrane-based approaches, including reverse osmosis, nanofiltration, ultrafiltration, microfiltration, gas separation membranes, and pervaporation. Each technology's efficacy in removing distinct organic pollutants while producing purified water is scrutinized. This review delves into membrane fouling, discussing its influencing factors and preventative strategies. It sheds light on the merits, limitations, and prospects of these various membrane techniques, contributing to the advancement of wastewater treatment. It advocates for future research in membrane technology with a focus on fouling control and the development of energy-efficient devices. Interdisciplinary collaboration among researchers, engineers, policymakers, and industry players is vital for shaping water purification innovation. Ongoing research and collaboration position us to fulfill the promise of accessible, clean water for all.

Standard addition method for rapid, cultivation-independent quantification of Legionella pneumophila cells by qPCR in biotrickling filters.

Cultivation-independent molecular biological methods are essential to rapidly quantify pathogens like Legionella pneumophila (L. pneumophila) which is important to control aerosol-generating engineered water systems. A standard addition method was established to quantify L. pneumophila in the very complex matrix of process water and air of exhaust air purification systems in animal husbandry. Therefore, cryopreserved standards of viable L. pneumophila were spiked in air and water samples to calibrate the total bioanalytical process which includes cell lysis, DNA extraction, and qPCR. A standard addition algorithm was employed for qPCR to determine the initial concentration of L. pneumophila. In mineral water, the recovery rate of this approach (73%-134% within the concentration range of 100-5000 Legionella per mL) was in good agreement with numbers obtained from conventional genomic unit (GU) calibration with DNA standards. In air samples of biotrickling filters, in contrast, the conventional DNA standard approach resulted in a significant overestimation of up to 729%, whereas our standard addition gave a more realistic recovery of 131%. With this proof-of-principle study, we were able to show that the molecular biology-based standard addition approach is a suitable method to determine realistic concentrations of L. pneumophila in air and process water samples of biotrickling filter systems. Moreover, this quantification strategy is generally a promising method to quantify pathogens in challenging samples containing a complex microbiota and the classical GU approach used for qPCR leads to unreliable results.

An 18-µm microaggregate blood filter does not cause hemolysis during in vitro whole blood transfusions in sea turtles.

OBJECTIVE: Determine the hemolytic effect of an 18-µm microaggregate blood filter during in vitro sea turtle whole blood transfusions as well as describe the average diameter of leatherback (Dermochelys coriacea) and Kemp's ridley sea turtle (Lepidochelys kempii) RBCs. ANIMALS: 5 green (Chelonia mydas), 5 loggerhead (Caretta caretta), and 5 Kemp's ridley sea turtles (total n = 15). METHODS: Heparinized sea turtle blood was infused at 60 mL/h through a microbore extension set without and then with a postsyringe, inline 18-µm microaggregate blood filter. Pre- and postfiltration PCV, Hct, total solids, sodium, chloride, potassium, glucose, and free plasma hemoglobin concentrations were measured. With the use of light microscopy and archived blood smears, the maximum and minimum diameter of 20 RBCs from each of the 5 leatherback and 5 Kemp's ridley sea turtles were measured with a calibrated ocular micrometer using 400X magnification. RESULTS: There were no significant differences between pre- and postfiltration samples for Hct, total solids, sodium, chloride, potassium, glucose, and free plasma hemoglobin concentrations; however, there was a significant median postfiltration decrease in PCV of approximately 4%, representing a 13% decrease of the total RBCs transfused. Average maximum diameters for leatherback and Kemp's ridley sea turtle RBCs were 19.7 and 16.1 µm, respectively. CLINICAL RELEVANCE: Although the 18-µm microaggregate blood filter does not hemolyze transfused sea turtle RBCs and is likely safe for in vivo blood transfusions, the filter's pores may retain a small proportion of infused RBCs given their diameter.

Re-inventing protection in a post-pandemic world: A new aerodynamic endonasal filtration technology.

Is there a "missing device" for respiratory personal protection? Does it exist an easy-to-use device, allowing extensive use in everyday settings by the population, maximizing tolerability and low visual and physical invasiveness protecting from a wide range of threats including airborne pathogens, hence including the particle range of fine and ultrafine particles? Looking at the recent past, in the urgency of finding ready-to-use solutions for the respiratory protection of the population during the outbreak of the SARS-CoV-2 pandemic, devices for occupational safety have been used, such as filtering face masks. These are devices intended for workers operating during work shifts in environments characterized by potential high risk, known a priori, often directly sensible; this makes wearers motivated to tolerate discomfort for a given period to face a localized risk, and safety managers determined to supervise compliance with usage specifications. Their use by general population has implied known shortcomings, such as weak compatibility with relational work and activities, low tolerability during prolonged use, low compliance with the proper use of the device, all of this lessening actual protection. The need for a new perspective has emerged, targeting effectiveness in whole daily life, rather than punctual efficacy. Nasal filters are promising candidates to protect individuals throughout the day during the most varied activities, but they lack a systematic definition as a device and as a product; it follows that the high complexity needed to reach an effective performance envelop is generally underestimated. By reviewing available literature, the present paper draws on the experience from the pandemic and infers systematic product specifications and characterization methods for a new, effective personal respiratory protection device; these specifications are compared with the stringent constraints associated with the endonasal applications and, based on air filtration state of the art, quantifies the need for technology disruption and outlining possible new development paths.

Continuous air purification by aqueous interface filtration and absorption.

The adverse impact of particulate air pollution on human health1,2 has prompted the development of purification systems that filter particulates out of air3-5. To maintain performance, the filter units must inevitably be replaced at some point, which requires maintenance, involves costs and generates solid waste6,7. Here we show that an ion-doped conjugated polymer-coated matrix infiltrated with a selected functional liquid enables efficient, continuous and maintenance-free air purification. As the air to be purified moves through the system in the form of bubbles, the functional fluid provides interfaces for filtration and for removal of particulate matter and pollutant molecules from air. Theoretical modelling and experimental results demonstrate that the system exhibits high efficiency and robustness: its one-time air purification efficiency can reach 99.6%, and its dust-holding capacity can reach 950 g m-2. The system is durable and resistant to fouling and corrosion, and the liquid acting as filter can be reused and adjusted to also enable removal of bacteria or odours. We anticipate that our purification approach will be useful for the development of specialist air purifiers that might prove useful in a settings such as hospitals, factories and mines.

A facile technique to develop conductive paper based bioelectrodes for microbial fuel cell applications.

Electronic devices with multifunctional capabilities is forever an attractive area with diverse scope including towards developing solutions to sustainable energy technology. Microbial biofuel cells (MiBFCs) are one such sustainable energy technology based electronic device which can not only harvest energy, but can perform biosensing leading to bioremediation. However, low energy yield, costly fabrication procedures and bulky devices are some of the limitations of such MiBFCs. In this work, for the first time a simple vacuum filtration fabrication technique is used for making thin and conductive electrodes with homogeneous CNT solution for MiBFC application. The fully paper-based MiBFC is integrated into a compact micro device with 3D printed components which adds novelty to the work. The MiBFC is capable of maintaining a stable open circuit voltage of 410 mV for more than 1 h and can deliver a maximum power density of 192 µW/cm2 which is reasonably high for such paper-based MiBFCs operating with micro-volume of substrate. This device will help in developing more freestanding power sources for instant diagnostics and data transfer.

Regenerated Silk Nanofibers for Robust and Cyclic Adsorption-Desorption on Anionic Dyes.

In recent years, adsorption-based membranes have been widely investigated to remove and separate textile pollutants. However, cyclic adsorption-desorption to reuse a single adsorbent and clear scientific evidence for the adsorption-desorption mechanism remains challenging. Herein, silk nanofibers were used to assess the adsorption potential for the typical anionic dyes from an aqueous medium, and they show great potential toward the removal of acid dyes from the aqueous solution with an adsorption rate of ∼98% in a 1 min interaction. Further, we measured the filtration proficiency of a silk nanofiber membrane in order to propose a continuous mechanism for the removal of acid blue dye, and a complete rejection was observed with a maximum permeability rate of ∼360 ± 5 L·m-2·h-1. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy studies demonstrate that this fast adsorption occurs due to multiple interactions between the dye molecule and the adsorbent substrate. The as-prepared material also shows remarkable results in desorption. A 50-time cycle exhibits complete adsorption and desorption ability, which not only facilitates high removal aptitude but also produces less solid waste than other conventional adsorbents. Additionally, fluorescent 2-bromo-2-methyl-propionic acid (abbreviated as EtOxPY)-silk nanofibers can facilitate to illustrate a clear adsorption and desorption mechanism. Therefore, the above-prescribed results make electrospun silk nanofibers a suitable choice for removing anionic dyes in real-time applications.

Improvement of DBR routing protocol in underwater wireless sensor networks using fuzzy logic and bloom filter.

Routing protocols for underwater wireless sensor networks (UWSN) and underwater Internet of Things (IoT_UWSN) networks have expanded significantly. DBR routing protocol is one of the most critical routing protocols in UWSNs. In this routing protocol, the energy consumption of the nodes, the rate of loss of sent packets, and the rate of drop of routing packets due to node shutdown have created significant challenges. For this purpose, in a new scenario called FB-DBR, clustering is performed, and fuzzy logic and bloom filter are used in each cluster's new routing protocol in underwater wireless sensor networks. Due to the fuzzy nature of the parameters used in DBR, better results are obtained and bloom filters are used in routing tables to compensate for the deceleration. as the average number of accesses to routing table entries, dead nodes, Number of Packets Sent to Base Station (BS), Number of Packets Received at BS, Packet Dropped, and Remaining Energy has improved significantly.

Airborne pathogenic microorganisms and air cleaning technology development: A review.

Transmission of pathogens through air is a critical pathway for the spread of airborne diseases, as airborne pathogenic microorganisms cause several harmful infections. This review summarizes the occurrence, transmission, and adverse impacts of airborne pathogenic microorganisms that spread over large distances via bioaerosols. Air cleaning technologies have demonstrated great potential to prevent and reduce the spread of airborne diseases. The recent advances in air cleaning technologies are summarized on the basis of their advantages, disadvantages, and adverse health effects with regard to the inactivation mechanisms. The application scope and energy consumption of different technologies are compared, and the characteristics of air cleaners in the market are discussed. The development of high-efficiency, low-cost, dynamic air cleaning technology is identified as the leading research direction of air cleaning. Furthermore, future research perspectives are discussed and further development of current air cleaning technologies is proposed.

A First Assessment of an Aerodynamic Barrier Layer for Filtering Airborne Hygroscopic Particles.

In this work, consideration is given to an aerodynamic concept to boost the filtration in face masks of airborne hygroscopic particles such as those caused by an infected person when coughs or sneezes. Nowadays, increasing the filtration efficiency of face masks implies either increasing the number of crisscrossing fiber layers or decreasing the equivalent hydraulic diameter of the pore, however, both measures are in clear detriment of its breathability. Here, a novel strategy is proposed in which the filtration of an airborne particle is boosted by increasing its diameter. We called properly this concept as the aerodynamic barrier layer. In this concept, a traditional crisscrossing fiber layer is replaced by a parallel rearranged of the fibers in the direction of the flow. This rearrangement will promote central lift forces which will push the particles toward the center of the channel where after clustering they will coalesce resulting in a bigger particle that can be now easily captured by a conventional fiber crisscrossing layer. Utilizing a simplified geometrical model, an expression for the required length of the aerodynamic barrier layer was derived. It is shown that an aerodynamic barrier layer with a length of only a few millimeters can aerodynamically focus water droplets around 1 µm-diameter and the penetration of airborne particles can be reduced up to 55%.

Neonatal digital chest radiography- should we be using additional copper filtration?

OBJECTIVES: Copper filtration removes lower energy X-ray photons, which do not enhance image quality but would otherwise contribute to patient radiation dose. This study explores the use of additional copper filtration for neonatal mobile chest imaging. METHODS: A controlled factorial-designed experiment was used to determine the effect of independent variables on image quality and radiation dose. These variables included: copper filtration (0 Cu, 0.1 Cu and 0.2 Cu), exposure factors, source-to-image distance and image receptor position (direct / tray). Image quality was evaluated using absolute visual grading analysis (VGA) and contrast-to-noise ratio (CNR) and entrance surface dose (ESD) was derived using an ionising chamber within the central X-ray beam. RESULTS: VGA, CNR and ESD significantly reduced (p < 0.01) when using added copper filtration. For 0.1 Cu, the percentage reduction was much greater for ESD (60%) than for VGA (14%) and CNR (20%), respectively. When compared to the optimal combinations of parameters for incubator imaging using no copper filtration, an increase in kV and mAs when using 0.1-mm Cu resulted in better image quality at the same radiation dose (direct) or, equal image quality at reduced dose (in-tray). The use of 0.1-mm Cu for neonatal chest imaging with a corresponding increase in kV and mAs is therefore recommended. CONCLUSION: Using additional copper filtration significantly reduces radiation dose (at increased mAs) without a detrimental effect on image quality. ADVANCES IN KNOWLEDGE: This is the first study, using an anthropomorphic phantom, to explore the use of additional Cu for digital radiography neonatal chest imaging and therefore helps inform practice to standardise and optimise this imaging examination.

Digital asthenopia: blue-blocking lenses and + 0,40D additional power in the near zone, for eye strain, accommodation and convergence functions / Astenopia digital: avaliação de lentes com filtro de luz azul e poder adicional de +0,40D na zona de perto, para fadiga visual e nas funções de convergência e acomodação

ABSTRACT Purpose Evaluate blue-violet light filter and additional power of +0.40 D in the near zone ophthalmic lenses, on convergence, accommodative functions, and symptoms of digital asthenopia (DA). Methods Randomized study in cross-over design conducted on 49 volunteers (age, 29 ± 5.5 years; male: female, 18:31). Each subject wore test (+0.40 D in the near zone) and control lenses (regular single vision) for 4 weeks in randomized order. Both lenses had a selective blue-violet light filter. A baseline measurement was taken with the subjects' current updated glasses. Accommodation amplitude (AA) and near point of convergence (NPC) were measured binocularly with the RAF ruler. DA was evaluated by a questionnaire. Results No significant difference (p=.52) was found for AA comparing baseline (11.50±1.88 D), test (11.61± 1.62 D), and control SV lenses (11.88±1.50 D). No significant difference was found for NPC (p=.94), between baseline (6.50 ± 2.89cm), test (6.71± 3.49) and control SV lenses (6.82± 3.50 cm). No significant difference was found comparing test and control SV lenses in symptoms of DA (p=0.20). Conclusions The +0.40 D lenses have no negative impact on convergence or loss of accommodation power. The +0.40 D and control SV lenses had a similar impact on attenuating symptoms of DA.

RESUMO Objetivo Avaliar os efeitos do uso de lentes oftálmicas com filtro seletivo de luz azul-violeta, sem e com poder adicional de + 0,4D na zona de perto nas funções de acomodação e convergência e para sintomas de astenopia digital (AD). Métodos Ensaio clínico controlado, randomizado e mascarado, com 49 voluntários (idade, 29 ± 5,5 anos; masculino: feminino, 18: 31). Cada participante usou lentes de teste (+0,40 D na zona de perto) e controle (visão simples), por 4 semanas de forma randomizada. Ambas as lentes tinham filtro seletivo de luz azul-violeta. A medição inicial (baseline) foi feita com os óculos atualizados de cada participante. A amplitude de acomodação (AA) e o ponto de convergência próximo (PPC) foram medidos binocularmente com a régua RAF. A AD foi avaliada por um questionário. Resultados Não houve diferença estatisticamente significante (p=0,52) para as medidas de AA comparando as lentes baseline (11,50±1,88 D), teste (11,61±1,62 D) e controle VS (11,88±1,50 D). Nenhuma diferença significativa foi encontrada para a medida do PPC (p=0,94), entre as lentes baseline (6,50 ± 2,89cm), teste (6,71±3,49) e controle VS (6,82±3,50 cm). Nenhuma diferença significativa foi encontrada comparando lentes teste de VS e controle nos sintomas de AD (p=0,20). Conclusões As lentes com +0,40 D não têm impacto negativo na convergência ou na perda de acomodação. As lentes +0,40 D e controle VS, tiveram impacto semelhante na redução dos sintomas de AD.

Discrepancy of particle passage in 101 mask batches during the first year of the Covid-19 pandemic in Germany.

During the first wave of Covid-19 infections in Germany in April 2020, clinics reported a shortage of filtering face masks with aerosol retention> 94% (FFP2 & 3, KN95, N95). Companies all over the world increased their production capacities, but quality control of once-certified materials and masks came up short. To help identify falsely labeled masks and ensure safe protection equipment, we tested 101 different batches of masks in 993 measurements with a self-made setup based on DIN standards. An aerosol generator provided a NaCl test aerosol which was applied to the mask. A laser aerosol spectrometer measured the aerosol concentration in a range from 90 to 500 nm to quantify the masks' retention. Of 101 tested mask batches, only 31 batches kept what their label promised. Especially in the initial phase of the pandemic in Germany, we observed fluctuating mask qualities. Many batches show very high variability in aerosol retention. In addition, by measuring with a laser aerosol spectrometer, we were able to show that not all masks filter small and large particles equally well. In this study we demonstrate how important internal and independent quality controls are, especially in times of need and shortage of personal protection equipment.

Improving spatial resolution with an edge-enhancement model for low-dose propagation-based X-ray phase-contrast computed tomography.

Propagation-based X-ray phase-contrast computed tomography (PB-PCCT) has been increasingly popular for distinguishing low contrast tissues. Phase retrieval is an important step to quantitatively obtain the phase information before the tomographic reconstructions, while typical phase retrieval methods in PB-PCCT, such as homogenous transport of intensity equation (TIE-Hom), are essentially low-pass filters and thus improve the signal to noise ratio at the expense of the reduced spatial resolution of the reconstructed image. To improve the reconstructed spatial resolution, measured phase contrast projections with high edge enhancement and the phase projections retrieved by TIE-Hom were weighted summed and fed into an iterative tomographic algorithm within the framework of the adaptive steepest descent projections onto convex sets (ASD-POCS), which was employed for suppressing the image noise in low dose reconstructions because of the sparse-view scanning strategy or low exposure time for single phase contrast projection. The merging strategy decreases the accuracy of the linear model of PB-PCCT and would finally lead to the reconstruction failure in iterative reconstructions. Therefore, the additive median root prior is also introduced in the algorithm to partly increase the model accuracy. The reconstructed spatial resolution and noise performance can be flexibly balanced by a pair of antagonistic hyper-parameters. Validations were performed by the established phase-contrast Feldkamp-Davis-Kress, phase-retrieved Feldkamp-Davis-Kress, conventional ASD-POCS and the proposed enhanced ASD-POCS with a numerical phantom dataset and experimental biomaterial dataset. Simulation results show that the proposed algorithm outperforms the conventional ASD-POCS in spatial evaluation assessments such as root mean square error (a ratio of 9.78%), contrast to noise ratio (CNR) (a ratio of 7.46%), and also frequency evaluation assessments such as modulation transfer function (a ratio of 66.48% of MTF50% (50% MTF value)), noise power spectrum (a ratio of 35.25% of f50% (50% value of the Nyquist frequency)) and noise equivalent quanta (1-2 orders of magnitude at high frequencies). Experimental results again confirm the superiority of proposed strategy relative to the conventional one in terms of edge sharpness and CNR (an average increase of 67.35%).

An Application of the Integrated Behavioral Model for Water, Sanitation and Hygiene to Assess Perceived Community Acceptability and Feasibility of the Biosand Filter among Maasai Pastoralists in Rural Tanzania.

In addition to diarrheal disease risk, lack of access to safe water may have other indirect effects throughout one's life, such as school and workplace absenteeism, leading to less economic productivity. In contexts with scarce resources and unsafe drinking water, household water treatment and safe storage options such as the Biosand filter (BSF) allows households to directly reduce contamination and increase the quality of their drinking water. This study aimed to develop an understanding of perceived community acceptability and feasibility related to pre- and post-implementation of a BSF pilot project in rural Maasai households in the Ngorongoro Conservation Area (NCA), Tanzania. The study was guided by the Integrated Behavioral Model for Water Sanitation and Hygiene interventions (IBM-WASH) to understand the various factors influencing end-user perceptions of the BSF. In-depth interviews, group discussions and think tanks were conducted among a cross-section of community members, stakeholders, and other actors from May 2016 to September 2017. The data were analyzed using a thematic content analysis approach. A range of perceived contextual, technological, and psychosocial factors were found to potentially affect the acceptability and feasibility of BSF adoption in the NCA, highlighting the complex layers of influences in the setting. Whilst the BSF is seemingly an accepted option to treat water within the NCA, the community identified key barriers that may lower BSF adoption. The application of the IBM-WASH model served as a useful framework for evaluating the introduction of the BSF, identifying insights into contextual, technological, and psychosocial community factors.

Quantitative modeling of the impact of facemasks and associated leakage on the airborne transmission of SARS-CoV-2.

The ongoing worldwide outbreak of COVID-19 has set personal protective equipment in the spotlight. A significant number of countries impose the use of facemasks in public spaces and encourage it in the private sphere. Even in countries where relatively high vaccination rates are achieved at present, breakthrough infections have been frequently reported and usage of facemasks in certain settings has been recommended again. Alternative solutions, including community masks fabricated using various materials, such as cotton or jersey, have emerged alongside facemasks following long-established standards (e.g., EN 149, EN 14683). In the present work, we present a computational model to calculate the ability of different types of facemasks to reduce the exposure to virus-laden respiratory particles, with a focus on the relative importance of the filtration properties and the fitting on the wearer's face. The model considers the facemask and the associated leakage, the transport of respiratory particles and their accumulation around the emitter, as well as the fraction of the inhaled particles deposited in the respiratory system. Different levels of leakages are considered to represent the diversity of fittings likely to be found among a population of non-trained users. The leakage prevails over the filtration performance of a facemask in determining the exposure level, and the ability of a face protection to limit leakages needs to be taken into account to accurately estimate the provided protection. Filtering facepieces (FFP) provide a better protection efficiency than surgical and community masks due to their higher filtration efficiency and their ability to provide a better fit and thus reduce the leakages. However, an improperly-fitted FFP mask loses a critical fraction of its protection efficiency, which may drop below the protection level provided by properly-worn surgical and community masks.

A smart mask for active defense against airborne pathogens.

Face masks are a primary preventive measure against airborne pathogens. Thus, they have become one of the keys to controlling the spread of the COVID-19 virus. Common examples, including N95 masks, surgical masks, and face coverings, are passive devices that minimize the spread of suspended pathogens by inserting an aerosol-filtering barrier between the user's nasal and oral cavities and the environment. However, the filtering process does not adapt to changing pathogen levels or other environmental factors, which reduces its effectiveness in real-world scenarios. This paper addresses the limitations of passive masks by proposing ADAPT, a smart IoT-enabled "active mask". This wearable device contains a real-time closed-loop control system that senses airborne particles of different sizes near the mask by using an on-board particulate matter (PM) sensor. It then intelligently mitigates the threat by using mist spray, generated by a piezoelectric actuator, to load nearby aerosol particles such that they rapidly fall to the ground. The system is controlled by an on-board micro-controller unit that collects sensor data, analyzes it, and activates the mist generator as necessary. A custom smartphone application enables the user to remotely control the device and also receive real-time alerts related to recharging, refilling, and/or decontamination of the mask before reuse. Experimental results on a working prototype confirm that aerosol clouds rapidly fall to the ground when the mask is activated, thus significantly reducing PM counts near the user. Also, usage of the mask significantly increases local relative humidity levels.

Design of a confocal micro-Raman spectroscopy system and research on microplastics detection.

Traditional micro-Raman spectroscopy technology has the disadvantages of a weak signal and low signal-to-noise ratio. To fix these issues, a cost-effective and rigorous design method is proposed in this paper, whereby a confocal micro-Raman spectroscopy system is designed and built, and a low-cost reflector and high-pass filter are introduced into the Raman signal-receiving module. The Raman light incident is fully perpendicular to the coupling lens by adjusting the reflection angle of the mirror, making the focus of the coupling lens highly conjugate with the focus of the microscope objective, to enhance the intensity of the Raman signal and improve the signal-to-noise ratio. In order to better apply this technology to the detection and study of microplastics in offshore sediments, a reflective illumination light path is used to avoid the visual interference caused by the capillary structure and opacity of the glass cellulose filter membrane. The detection and analysis of the microplastics on the glass cellulose filter membrane have been carried out by the confocal micro-Raman system designed, which is low cost and capable of obtaining good detection results and meeting the requirements of microplastics detection. The system designed in this paper is expected to be applied to the research and development of Raman detection equipment for microplastics in marine sediments, which is beneficial to promote the development of marine microplastic monitoring technology in the world.

Hybrid plasmonic slot waveguide with a metallic grating for on-chip biosensing applications.

Designing reliable and compact integrated biosensors with high sensitivity is crucial for lab-on-a-chip applications. We present a bandpass optical filter, as a label-free biosensor, based on a hybrid slot waveguide on the silicon-on-insulator platform. The designed hybrid waveguide consists of a narrow silicon strip, a gap, and a metallic Bragg grating with a phase-shifted cavity. The hybrid waveguide is coupled to a conventional silicon strip waveguide with a taper. The effect of geometrical parameters on the performance of the filter is investigated by 3D finite-difference time-domain simulations. The proposed hybrid waveguide has potential for sensing applications since the optical field is pulled into the gap and outside of the silicon core, thus increasing the modal overlap with the sensing region. This biosensor offers a sensitivity of 270 nm/RIU, while it only occupies a compact footprint of 1.03µm×17.6µm.