Sensitive Applications Research Articles

High sensitivity and high figure of merit graphene mid-infrared multi-band tunable metamaterial perfect absorber

In the research of this paper, we have devised a mid-infrared band metamaterial perfect absorber made of graphene material. The absorber is composed of a traditional three-layer structure of MPA. The top layer is a graphene layer with a specific structure, with SiO2 as the dielectric layer and the gold film as the substrate. In the wavelength range of 5500 – 13000 nm, the graphene layer generates seven absorption peaks and shows ultra-high absorption efficiency. The respective absorption rates are 91.17%, 99.41%, 99.01%, 95.69%, 94.16%, 96.89%, and 95.01%. By verifying the absorption spectra and the principle of effective impedance matching, analyze the electric field distribution image of the xoy plane based on the principle of surface plasmon resonance, we have proved that it conforms to the classical physical theory and expounded the reason why the absorption peaks were formed. The comparison of different graphene patterns has confirmed the superiority of this structure. By changing the relaxation time and Fermi level of graphene, the tunability of the absorber structure has been verified. Changing the incident angle has proved its insensitivity to the polarization angle (0° - 50°). Finally, by calculating and comparing the figure of merit (FOM) and the sensitivity (S), it is shown that this structure has significant sensitivity and excellent application ability and value. We firmly believe that our absorber can be well applied in high-sensitivity sensors, filters and detectors, and can contribute to fields such as photoelectric detection, optical communication and photoelectric sensing.

3D Printed Metallic Pillar Nanomechanical Resonators Decorated with TiO2 Nanotubes for Highly Sensitive Environmental Applications

AbstractMicro and nanomechanical devices offer enhanced sensing capabilities for detecting biological and chemical small molecules. However, miniaturization necessitates advanced fabrication processes and complex measurement systems, hindering routine sensor analysis. While alternative methods like 3D printing show promise, challenges such as low device resolution persist due to intrinsic damping of polymer inks. In this study, an array of micrometric pillar resonators is fabricated in Ti6Al4 V alloy using additive manufacturing based on laser powder bed fusion technology. These metallic nanomechanical resonators exhibit a very high quality factor with minimal difference between air and vacuum measurements due to low intrinsic damping. Furthermore, titania nanotubes grown on the pillars via anodic oxidation heighten sensitivity for molecular dye degradation evaluation. Leveraging the weak coupling phenomenon among the pillars in the array, these devices facilitate large‐scale parallelized measurements, here demonstrated with real‐time analysis of dye degradation process. This approach to creating mass sensing devices via metallic additive manufacturing can usher in a new generation of highly performing resonating sensor arrays, offering a cost‐effective and efficient alternative to traditional silicon microfabrication methods.

Enhancing Reliability in Multilevel Inverter: A Fault‐Tolerant Approach With Reduced Switch Count

ABSTRACTReliability is a major concern in multilevel inverters (MLI) due to the increased number of power switches and diodes, which increases the chance of switch failures and complicates the inverter design. The primary challenges faced by the current MLI design include higher control complexity, increased parasitic elements, more extensive protection, and lack of multiple fault tolerance. Therefore, developing reduced switch MLI with fault‐tolerant ability is crucial to ensure system availability and prevent adverse outcomes. To address these challenges, this article introduces a highly resilient fault‐tolerant reduced switch count (FTRSC) MLI topology offering fault tolerance with minimal switch count. The proposed topology provides fault tolerance in case of single‐ and multiple‐switch open‐circuit (OC) failures. The inherent fault‐tolerant operation is analyzed for the proposed topology's symmetric and asymmetric configurations. The simulation and experimental results validate the effectiveness of the proposed topology considering normal, faulty, and postfault conditions. Furthermore, the reliability evaluation of the proposed work is carried out using the Markov chain model, resulting in a high total mean time to failure of approximately 117,550 h/failures, along with an efficiency of 96.3%. These findings demonstrate that the proposed circuit has enhanced reliability and extended mean time to failure, affirming its suitability for sensitive industrial applications. Finally, a thorough comparison with recent studies highlights the superiority of the proposed system.

In Situ Crystal Growth and Fusing-Confined Engineering of Quasi-Monocrystalline Perovskite Thick Junctions for X-ray Detection and Imaging.

Metal halide perovskites exhibit great promise for utilization in X-ray detection owing to their excellent optoelectronic properties and high X-ray attenuation capabilities. However, fabricating large-area thick films for high-performance perovskite X-ray detection remains challenging. This study develops an in situ crystal growth and fusing-confined approach to prepare high-quality, large-scale perovskite quasi-monocrystalline thick junctions. The perovskite crystals are grown in situ using a highly concentrated perovskite colloidal solution in 2-methoxyethanol. Introducing methylammonium chloride enhances grain reorganization during in situ growth and fusing-confined processes, effectively reducing grain boundaries and surface defects. This allows for the preparation of quasi-monocrystalline thick junctions of large grains (>100 μm) with high crystallinity, uniform orientation, and vertical penetration across the film thickness. Additionally, the carrier mobility and lifetime of the thick junctions are significantly enhanced. The optimized MAPbI3 detectors demonstrate an X-ray sensitivity of 2.6 × 104 μC Gyair-1 cm-2 and an exceptionally low detection limit of 1 nGyair s-1. Furthermore, inspired by a honeycomb structure, these detectors realize X-ray imaging in 64 × 64 pixels through a pixelated separation design, effectively reducing the charge-sharing effect. This study offers valuable insights into the preparation of large-scale perovskite quasi-monocrystalline thick junctions for highly sensitive X-ray detection and imaging applications.

GC/MS Screening of Substances Released from Post-Consumer Recycled HDPE Pellets into 95% Ethanol: Reproducibility and Variation between Production Batches

The use of post-consumer recycled (PCR) plastic materials in sensitive packaging applications, such as for cosmetic products and detergents, requires a clear understanding of the identities and quantities of chemical substances, which they may release into packed products. With many potential sources of and thus different types of potentially releasable substances, a reliable non-targeted screening method is required to assess these materials. Such a method should be readily applicable in industrial practice and provide a realistic estimation of substance release. This investigation focused on the use of gas chromatography/coupled mass spectrometry (GC/MS) to analyze substances, which recycled HDPE (rHDPE) plastic pellets release into 95% ethanol under accelerated testing conditions. The results of the repeated testing of reference samples clearly demonstrated the good reproducibility of the described methodology, with standard deviations of repeated determinations of the total released substance amounts of 6.8–8.1%. The application to several production batches of three commercial rHDPE grades additionally demonstrated that the batch-to-batch variation of substances which rHDPE materials release can be confined to less than 10% of variation of the total detectable substance amount. The described methodology is therefore seen as a pragmatic, repeatable assessment of recycled HDPE plastic batches with a view to substance release.

From materials to structures: A holistic examination of achieving linearity in flexible pressure sensors.

As a pivotal category in the realm of wearable electronics, flexible pressure sensors have become a focal point due to their diverse applications such as human-machine interfaces and health monitoring. To cater for these applications, novel material design and fabrication strategies have been devised as to enhance the device performance by manipulating mechanical and electrical properties. This work primarily reviews the development of flexible pressure sensors during recent years with a focus on sensitive materials and related applications. First, an overview of the fundamental working mechanisms for various sensors was elucidated. Then, the influence of distinct surface microstructures or internal microstructures on the linearity of flexible sensors was explored. Following this, we delve into diverse applications of linear flexible pressure sensors, spanning from robotics, safety, electronic skin, to health monitoring. Finally, the existing constraints and future research prospects are outlined to pave the way for the further development of high-performance flexible pressure sensors.&#xD.

Application of high-throughput drug sensitivity testing in children with relapsed and refractory acute leukemia

To explore the current application of high-throughput drug sensitivity (HDS) testing in children with relapsed and refractory acute leukemia (RR-AL) and analyze the feasibility of salvage treatment plans. A retrospective collection of clinical data from children with RR-AL who underwent HDS testing at the Department of Children's Hematology and Oncology of the First Affiliated Hospital of Zhengzhou University from November 2021 to October 2023 was conducted, followed by an analysis of drug sensitivity results and treatment outcomes. A total of 17 children with RR-AL underwent HDS testing, including 7 cases of relapsed refractory acute myeloid leukemia and 10 cases of relapsed refractory acute lymphoblastic leukemia. The detection rate of highly sensitive chemotherapy drugs/regimens was 53% (9/17), while the detection rate of moderately sensitive chemotherapy drugs/regimens was 100% (17/17). Among the 17 RR-AL patients with highly and moderately sensitive chemotherapy drugs and regimens, the MOACD regimen (mitoxantrone + vincristine + cytarabine + cyclophosphamide + dexamethasone) accounted for 100%, with the highest inhibition rate for single-agent mitoxantrone (94%, 16/17), and the highest inhibition rate for targeted therapy being bortezomib (94%, 16/17). Nine patients adjusted their chemotherapy based on HDS testing results, with 4 undergoing hematopoietic stem cell transplantation. Four patients achieved disease-free survival, while 5 died. Eight patients received empirical chemotherapy, with 2 undergoing hematopoietic stem cell transplantation; 4 achieved disease-free survival, while 4 died. HDS testing can identify highly sensitive drugs/regimens for children with RR-AL, improving the rate of re-remission and creating conditions for subsequent hematopoietic stem cell transplantation.

PPDNN-CRP: privacy-preserving deep neural network processing for credit risk prediction in cloud: a homomorphic encryption-based approach

This study proposes a Privacy-Preserving Deep Neural Network for Credit Risk Prediction (PPDNN-CRP) framework that leverages homomorphic encryption (HE) to ensure data privacy throughout the credit risk prediction process. The PPDNN-CRP framework employs the Paillier homomorphic encryption scheme to secure sensitive loan application data during both the training and inference phases. Implemented using TensorFlow for deep neural network operations and TenSEAL for HE, the framework uses the Kaggle loan dataset to evaluate its performance. The results show that PPDNN-CRP achieved an accuracy of 80.48%, demonstrating competitive performance compared to Privacy-Preserving Logistic Regression (PPLR) at 77.23% and a slight decrease from the non-private DNN-CRP model at 86.18%. The model exhibited strong metrics with a precision of 0.84, recall of 0.91, F1-score of 0.87, and an AUC of 0.74. Security analysis confirms that PPDNN-CRP effectively defends against various privacy attacks, including poisoning, evasion, membership inference, model inversion, and model extraction, through robust encryption techniques and privacy measures. This framework offers a promising approach for achieving high-quality credit risk prediction while maintaining data privacy and complying with legal and ethical standards.

Surface Defects‐Induced Photoactivation of Carbon Dots‐NiFe2O4 Nanocomposite: Synthesis, Mechanism and Applications

AbstractThe optical properties of quantum dots are significantly influenced by photoactivation. However, the progress in the development of photoactivation carbon dot (CDs) is still stagnant. Herein, a method for preparing photoactivated CDs/NiFe2O4 by introducing affluent defects onto the surface of CDs through modification with NiFe2O4, extremely filling the gap of photoactivated CDs is proposed. Interestingly, a fantastic fluorescence detection strategy in a unique “OFF‐ON‐OFF” mode, combined with Ag+‐assisted fluorescence enhancement, to establish a dual‐channel regulation mechanism for ultra‐sensitive detection of Hg2+ is first proposed. By increasing surface traps and non‐radiative recombination, defect‐induced manipulation on the surface of CDs creates favorable conditions for enhancing photoactivation capacity. Unexpectedly, the CDs/NiFe2O4 shows a 25‐fold enhancement in fluorescence intensity after exposure to UV‐lamp. Compared to CDs/NiFe2O4, Ag+‐assisted photoactivation CDs/NiFe2O4 exhibits superior selectivity and sensitivity for Hg2+ detection, with low detection limits of 0.7 nM. Moreover, TiO2@CDs/NiFe2O4 catalyst is successfully prepared by anchoring CDs/NiFe2O4 onto the surface of TiO2, which demonstrates efficient degradation of tetracycline within 90 min under visible light irradiation, with a degradation rate of 98.3%. This work first provides a novel defects modification strategy for developing highly active photoactivated CDs technology that is significant for future environmentally sensitive applications.

Freestanding Germanium Photonic Crystal Waveguide for a Highly Sensitive and Compact Mid-Infrared On-Chip Gas Sensor.

The performance of mid-infrared (MIR) on-chip gas sensors, operating via laser absorption spectroscopy, hinges critically on light-matter interaction dynamics, significantly influenced by external confinement and the effective light path length. Conventional on-chip sensors, however, face challenges in achieving the required limit of detection for highly sensitive applications, primarily due to their intrinsically short effective light path. Furthermore, these sensors are limited in their spectral range coverage within the MIR spectrum by the constraints of standard silicon-based platforms. To overcome these limitations, our research presents a novel approach to fabricate a freestanding germanium (Ge) photonic crystal waveguide (PCW) on a germanium-on-insulator (Ge-OI) platform, utilizing yttrium oxide (Y2O3) as the buried oxide layer. This device leverages the broad transparent windows of Ge and Y2O3, broadening the spectral coverage across the MIR range. The introduction of the PCW and its slow light effect significantly elevate external confinement and light-matter interactions, enabling a notable reduction in waveguide length, which traditionally limits on-chip configurations. The freestanding structure not only expands the sensing region and enhances external confinement but also prevents the emergence of leaky modes within the PCW. As a result, our compact sensor achieves an exceptionally low LoD of 7.56 ppm for carbon dioxide (CO2) sensing at the operational wavelength of 4.23 μm, with a compact waveguide length of only 800 μm.

Application and Challenge of Metalloporphyrin Sensitizers in Noninvasive Dynamic Tumor Therapy

Dynamic tumor therapies (mainly including photodynamic therapy (PDT) and sonodynamic therapy (SDT)) offer new approaches to cancer treatment. They are often characterized by their noninvasive nature, high selectivity, and low toxicity. Sensitizers are crucial for dynamic therapy. Developing efficient sensitizers with good biocompatibility and controllability is an important aim in dynamic therapy. Porphyrins and metalloporphyrins attract great attention due to their excellent photophysical properties and low cytotoxicity under non-light. Compared to porphyrins, metalloporphyrins show greater potential for dynamic therapy due to their enhanced photochemical and photophysical properties after metal ions coordinate with porphyrin rings. This paper reviews some metalloporphyrin-based sensitizers used in photo/sonodynamic therapy and combined therapy. In addition, the probable challenges and bottlenecks in clinical translation are also discussed.

Sulfur dioxide gas sensor based on vanadium oxide doped TiO2 nanopaper

Abstract The gas sensor based on TiO2 nanomaterials is promising for both industry and daily life because of its simple fabrication, low cost, high sensitivity, and easy application to micro-devices. However, its selectivity is relatively low and strongly influenced by the environment, thus limiting its practical application. In this work, we prepared TiO2 nanopaper by methods of hydrothermal synthesis and conventional paper preparation. To improve the selectivity, we added V2O5 by immersing the as-prepared nanopaper in an ammonium metavanadate (NH4VO3) solution evenly dispersed in ethanol. Nanopaper is a random array of long nanowires and nanofibers, which retains its shape and structure at high temperature, unlike pure nanowires, due to its high porosity and mechanical stability. V2O5 leads to a selective sensing performance with high catalytic activity for SO2 gas. The surface structure of the sensing material and its porosity were characterized by SEM, XRD, XPS. The improved sensing material exhibited a high response of about 22.6 for 100 ppm SO2 and a fast response and recovery of 9 s and 14 s, respectively. It also exhibited good reproducibility and selectivity in other interfering gases. Furthermore, the long-term sensing performance in the atmospheric environment was maintained for about 50 days.

A Photovoltaic Self-Powered Volatile Organic Compounds Sensor Based on Asymmetric Geometry 2D MoS2 Diodes

Transition metal dichalcogenides have gained considerable interest for vapour sensing applications due to their large surface-to-volume ratio and high sensitivity. Herein, we demonstrate a new self-powered volatile organic compounds (VOC) sensor based on asymmetric geometry multi-layer molybdenum disulfide (MoS2) diode. The asymmetric contact geometry of the MoS2 diode induces an internal built-in electric field resulting in self-powering via a photovoltaic response. While illuminated by UV-light, the sensor exhibited a high responsivity of ∼60% with a relatively fast response time of ∼10 sec to 200 ppm of acetone, without an external bias voltage. The MoS2 VOC diode sensor is a promising candidate for self-powered, fast, portable, and highly sensitive VOC sensor applications.

Multiple levels of crypto-fiduciary security unforgeable stamp

The paper introduces the concept of a multi-level crypto-fiduciary security system, focusing on the development and implementation of an unforgeable stamp mechanism. This security architecture integrates cryptographic techniques with fiduciary principles to create a robust authentication framework that ensures data integrity, confidentiality, and trust in transactions. The unforgeable stamp serves as a cryptographic seal that is tamper-proof, traceable, and resistant to counterfeiting or duplication, providing enhanced protection against fraud and unauthorized access. The proposed system leverages multiple layers of encryption, key management, and blockchain technology to achieve a secure and verifiable method of transaction validation. This work aims to address critical security challenges in financial, governmental, and other sensitive applications, where trust and data authenticity are paramount.

Fabrication of Core-Shell Quantum Dots Microbeads with high stability, enhanced sensitivity and potential application in C-Reactive Protein (CRP) and Procalcitonin (PCT) Immunochromatography in Vitro Diagnostic Reagents

Cardiovascular and cerebrovascular diseases represent the leading causes of mortality among middle-aged and elderly populations in China, with inflammation identified as a significant contributing factor. Consequently, the early diagnosis and management of inflammation are of paramount importance. C-reactive protein (CRP) and procalcitonin (PCT) serve as biomarkers for myocardial inflammation. In this study, we developed a quantum dot immunochromatographic strip that was capable of simultaneously detecting these two biomarkers with enhanced sensitivity and specificity. The comb amphiphilic poly (octadecyl-alt-polyethylene glycol) was synthesized through an amide reaction, which was employed to coat oil-soluble quantum dots, thereby transforming them into water-soluble quantum dots microbeads suitable for the coupling with biological macromolecules. These quantum dots microbeads were utilized as luminescent materials in the immunochromatographic strip for the concurrent detection of CRP and PCT. The assay required only 100 μL of sample and provided results within 10 minutes, demonstrating commendable precision, stability, sensitivity, and accuracy. Clinical evaluations had confirmed that the developed CRP and PCT quantum dots immunochromatographic test strips were accurate reliable, underscoring their significant potential for practical routine clinical application in the early accurate diagnosis of myocardial inflammation.

A rapid, sensitive, and high-throughput pathogen detection method and application of identifying pathogens based on multiplex PCR technology combined with capillary electrophoresis

Respiratory infections are one of the leading causes of death worldwide. Rapid and accurate detection of pathogens is crucial for timely treatment. This study established a detection method based on multiplex PCR combined with capillary electrophoresis, capable of simultaneously detecting 28 common respiratory pathogens. We used specially designed homo-tag primers, significantly reducing the formation of primer dimers and improving the specificity and sensitivity of amplification. After two rounds of PCR amplification, the products were subjected to fragment analysis using the ABI 3500XL Genetic Analyzer, enabling automated result interpretation. The detection limit of this method reaches 2.77 × 102 copies/ml, with some pathogens reaching as low as 2.77 × 10 copies/ml. The detection of 147 clinical specimens showed that the overall consistency of this method with culture, colloidal gold, fluorescent quantitative PCR, and NGS was 75.5%. The multiplex PCR detection method established in this study is rapid, sensitive, and high-throughput, can be used for routine screening of common pathogens in respiratory infections, providing an important basis for clinical diagnosis and treatment.

Urban surface-emitted longwave radiation estimation from high spatial resolution thermal infrared images using a hybrid method

Accurate estimation of the surface-emitted longwave radiation (SELR) has important scientific value in understanding its spatiotemporal dynamics and surface thermal environment. Thermal infrared (TIR) images with high spatial resolution offer enhanced data support for studying SELR of complex surfaces, such as urban surface. This study proposes a new urban-oriented hybrid (UoHy) method, which considers multiple scattering and adjacent effects of urban pixel using the term sky view factor, to estimate urban SELR from the top-of-atmosphere radiance of TIR images with high spatial resolution, and performs sensitivity analysis and application. The experimental results for the thermal images of GF-5/VIMS as an example showed that the UoHy method has relatively high accuracy, and obtains SELR errors of less than 12.0 W/m2 under low atmospheric water vapor conditions and less than 17.0 W/m2 under high atmospheric water vapor conditions. The application of the method during daytime and nighttime also demonstrated the method's validity and effectiveness. Compared with the natural surface-oriented hybrid method, the UoHy method obtains an improvement of about 7.0–10.0 W/m2 in SELR estimation, which indicates that it has the potential for practical SELR estimation over urban surface with TIR images of high spatial resolution.

Synthesis, characterization, and application of novel fluorescent sporopollenin for effective detection of mercury (II) ions from aqueous media.

In this investigation, a novel environmentally friendly functionalized fluorescent Sp-TAB hybrid material was advanced for the sensitive detection of environmentally polluting Hg(II). The characterization of the synthesized fluorescent Sp-TAB hybrid material using SEM and EDX provided insights into morphological and structural changes in the material's pore structure, while XRD and FT-IR analyses revealed the impact of the prepared material at each stage. Optimal parameters such as temperature, contact time, and pH influencing Hg(II) ion detection were determined. Application of the fluorescent Sp-TAB hybrid material was determined a detection limit (LOD) of 4.87μM for Hg(II) ions. This study shows the potential of the immobilization-enhanced fluorescent Sp-TAB hybrid material for sensitive Hg(II) ion detection in tap water. Additionally, this study is believed to serve as a model for sensitive and practical detection applications of heavy metals in the future.

Continuous GPS PPP-AR frequency transfer links

Abstract In this paper, we show that the SPARK software of the Natural Resources Canada (NRCan) with their DCR (Decoupled Clock Rapid) products can be used to generate the PPP-AR continuous batch clock solutions of multiple days, which we use to build frequency transfer links between two remotely located GPS receivers. The reliability and confidence in forming the long-term frequency transfer links have been improved compared to reference~\cite{jian2023gps}. We compare the SPARK PPP-AR links to an optical fiber and TWSTFT links for hundreds of days. The ∽500-day-long comparisons with TWSTFT show no frequency bias for continental and cross-continental links. Frequency transfer links formed using the SPARK solutions have uncertainty of 1×10-15/T, where T is in days, without reaching the noise floor, a critical requirement for comparing optical frequency standards and for the redefinition of the SI second. The short latency of the NRCan DCR products enables the quick availability of the PPP-AR links presented in this paper marking it particularly relevant for time sensitive applications.

Experimental Study of Fiber-Optic Temperature Sensor Based on Dual FSIs

To improve the sensitivity measurement of temperature sensors, a fiber optic temperature sensor structure based on the harmonic Vernier effect with two parallel fiber Sagnac interferometers (FSIs) is designed, and theoretical analysis and experimental testing are conducted. The FSI consisting of two polarization maintaining fibers (PMFs) with lengths of 13.62 m and 15.05 m respectively is used to achieve the basic Vernier effect. Then by changing the length of one PMF to approximately i times that of the others, the FSI composed of two PMFs of 7.1 m and 15.05 m is used to achieve the first-order harmonic Vernier effect. Afterward, temperature sensing tests are conducted to observe the wavelength drift during temperature changes and ultimately achieve high sensitivity. The experimental results show that the temperature sensitivity of the sensor based on the first-order harmonic Vernier effect is −28.89 nm/°C, which is 17.09 times that of a single FSI structure (−1.69 nm/°C) and 1.84 times that of the sensitivity generated by the structure based on the basic Vernier effect (−15.69 nm/°C). The experimental results are consistent with the theoretical analysis. The structure proposed in this paper achieves drift measurement of 0.1 °C variation based on 1 °C drift, making the fiber optic temperature sensor applicable to related fields that require high precision temperature. The proposed temperature sensor has the simple structure, low production cost, high sensitivity, and broad application prospects.