Sensors International最新文献

Exploration of entire human body is now possible with the advancement in the field of biotechnology, biosensors and bio-inspired modeling. We model the flow of a fluid between parallel plates for a couple stress fluid in order to incorporate polar effects on the flow. The stream function is used to transform the governing equations to system of ordinary differential equations. The analytical solutions are found for velocity components, pressure distribution, the axial flow rate, the mean pressure drop and the shear stress. The effect of couple stress parameter on the velocity, pressure and the shear stress has been investigated through graphs. We have also used the data from the renal tubule of a rat kidney in our analytical results to study the effect of the couple stress parameter on the mean pressure drop across the slit of the rat’s renal tubule.

A simple, sensitive, and highly selective detection method was developed for creatinine using citrate-capped gold nanoparticles (C-AuNPs). TEM analysis confirmed the synthesis of the C-AuNPs and they were mostly spherical in shape. FTIR data showed peaks at 3302 cm⁻¹, 1635 cm⁻¹, 1219 cm⁻¹ and 771 cm⁻¹ indicating the presence of O–H, C=C, C–O, C–C groups on the surface of the synthesized C-AuNPs. XRD analysis revealed peaks at 33.8, 44.4, 64.6, 77.5, and 81.6° confirming the crystalline nature of the C-AuNPs. The principle of this method is based on the aggregation of C-AuNPs induced by the creatinine molecules which has been successfully employed for the colorimetric detection of creatinine ranging from 0.3 to 0.8 μg/100 μl (3–8 ppm). The degree of aggregation of C-AuNPs was found to have a linear relationship with the concentration of creatinine which allows the development of a colour gradient based on the varying creatinine concentrations. UV–Vis spectrophotometric analysis further confirmed the selectivity of the method among different analytes such as ascorbic acid, nicotinic acid, polyvinyl pyrrolidone, glucose, uric acid, and bovine serum albumin. It has also been successfully applied for the detection of creatinine in urine mimic samples with good recovery rates. Therefore, this method can be successfully employed for both qualitative and quantitative analysis of creatinine.

Different nanomaterials in single (CeO₂), binary (CdS/CeO₂ and Ag₃PO₄/CeO₂), ternary CdS/CeO₂/Ag₃PO₄ (4:1 molar ratio) and conductive polymer supported (PANI-CdS/CeO₂/Ag₃PO₄) were synthesized by co-precipitation method. Elemental analysis, crystal structure, surface area, morphology and optical properties of the as-synthesized nanoparticles were characterized. Electrochemical behavior of glassy carbon electrode modified by polyaniline supported CdS/CeO₂/Ag₃PO₄ nanocomposite were also characterized by electrochemical impedance spectroscopy and cyclic voltammetry in 0.1 M of K₃[Fe(CN)₆] containing 0.1 M KCl at pH 7 with a frequency range of 0.1 to 1000 Hz, with an amplitude of 50 mV. The voltammogramm shows that the process of all as synthesized nanocomposites modified glassy carbon electrode is diffusion controlled. Under optimum conditions, the electrochemical sensor showed Malathion concentrations in linear range of 1-13 $\times$ 10⁻⁷ M, good reproducibility, and no interference by other pesticides and high recovery values around 98.90%. As-synthesized nanocomposite modified glassy carbon electrode exhibits the lowest detection limit of 3.0 $\times$ 10⁻⁹ M for Malathion detection. The simplicity of preparation, high sensitivity, good stability and reproducibility of this nanostructured polyaniline supported CdS/CeO₂/Ag₃PO₄ electrode can be a potential candidate for application in the detection of Malathion.

An electrochemical biosensor for H₂O₂ detection was developed by using soybean peroxidase-copper phosphate mediated organic inorganic hybrid (OIH). The characterization of OIH was carried out by FESEM and FTIR. FESEM analysis showed a flower-like porous morphology of the OIH and FTIR confirmed the presence of soybean peroxidase and copper phosphate in the OIH. For sensor development, the paste of OIH was formulated in the presence of phosphate buffered saline (PBS) and was screen printed on indium tin oxide (ITO) coated glass substrate. Cyclic voltammetry analysis showed that the developed biosensor could detect H₂O₂ in the linear range of 20–100 ​μM with R² value of 0.963. The limit of detection (LOD) and sensitivity values calculated for H₂O₂ are 0.19 ​μM and 27.44 μA/(μM.cm2) respectively. Along with cyclic voltammetry experiments, electrochemical impedance spectroscopy (EIS) analysis was also carried out to study the sensing mechanism. The developed biosensor showed better selectivity towards H₂O₂ when tested against d-glucose, l-tyrosine, l-lysine, and l-ascorbic acid.

This work has been focused on developing a novel biosensor assisted by multivariate calibration methods to determine triglycerides (TGs, triacetin, tributyrin, tricaproin, tricaprylin, and tricaprin) in lyophilized serum samples. To achieve this goal, a bare glassy carbon electrode (GCE) was modified and used as the biosensing platform. To increase the sensitivity of the developed method, hydrodynamic methods were used to calibrate the biosensor response. To increase the selectivity of the developed biosensor, it was assisted by partial least squares-1 (PLS-1), radial basis function-PLS (RBF-PLS), and RBF-artificial neural network (RBF-ANN) for exploiting first-order advantage. After characterization of the modifications, the first-order advantage was exploited to increase the selectivity of the method by building a multivariate calibration set in a pre-analyzed lyophilized serum with different TGs concentrations, which were chosen according to the individual calibration curve. Calibration models were then built in the same pre-analyzed lyophilized serum and analyzed by PLS-1, RBF-PLS, and RBF-ANN. Therefore, their performances were examined to predict concentrations of a validation set. The results confirmed the successfulness of the calibration model developed by RBF-ANN. Finally, it was used to analyze two serum samples, and the results demonstrated that the method was successful because its results were compared with a reference method.

The proposed refractive index-based biosensor made of cost-effective polymer material in Mach-Zehnder configuration with novel horizontal slot waveguide structure offers high sensitivity. Due to the recent demand for low-cost point-of-care biosensor, silicon wafer-based polymer material has the potential for developing new hybrid waveguides for sensors. Hence we designed BenzoCycloButene (BCB), SU8 material as the core, and polymethyl methacrylate (PMMA) clad on a silicon wafer. The novelty of proposed BCB and SU8 horizontal slot waveguide structure of 2.5 $\mu$ m wide and 1.$8\mu$ m thick with a slot height of 400 ​nm, which handles the analyte effectively without any external sample holder. In Mach-Zehnder Interferometer architecture, reference arm 1 ​cm and sensing arm at a length of 1.1 ​cm with analyte refractive index of cancer cell (RI ​= ​1.401) and Influenza A type virus (RI ​= ​1.48) are used. Effective mode index of BCB core and SU8 are investigated through Finite-difference time domain (FDTD) analysis, and sensitivity results are calculated. Detection of disease are plotted in the transmission spectrum with reference to normal human serum (RI ​= ​1.35). This horizontal slot waveguide of BCB core achieves a sensitivity of 19280 nm/RIU and SU8 horizontal slot core waveguide provides a sensitivity of 16500 nm/RIU, which is higher in this polymer based refractive index biosensing.

The most recurrent side effect of diabetes is diabetic foot ulcers and if unattended cause imputations. Diabetic feet affect 15% to 25% of diabetic people globally. Diabetes complications are due to less or no awareness of the consequences of diabetes among diabetic patients. Technology leveraging is an attempt to create distinct, affordable, and simple diabetic foot diagnostic strategies for patients and doctors. This work proposes early detection and prognosis of diabetic foot ulcers using the EfficientNet, a deep neural network model. EfficientNet is applied to an image set of 844-foot images, composed of healthy and diabetic ulcer feet. Better performance is obtained compared to earlier models using EfficientNet by carefully balancing network width, depth, and image resolution. The EfficientNet performed better compared to popular models like AlexNet, GoogleNet, VGG16, and VGG19. It gave maximum accuracy, f1-score, recall, and precision of 98.97%, 98%, 98%, and 99%, respectively.

Microwave sensors offer appealing features such as susceptibility, quick response, and non-invasiveness, making them valuable tools for highly accurate measurements of material characterisation. A wide range of techniques, including cavity waveguide, planar transmission line, cavity waveguide perturbation, open-ended coaxial probe, and free-space transmission, have been employed to characterise materials that are essential for their cost-effectiveness, ease of manufacturing, high sensitivity, good quality factor (Q-factor), and compact size, allowing them to be applied to different material types. Among the microwave sensor types, the substrate-integrated waveguide (SIW) has emerged as a promising technology in order to characterise materials in an efficient manner. This paper presents a review of the current state and potential opportunities of SIW microwave sensors in the characterisation of dielectric materials. It provides insights into various design principles, techniques, and applications of SIW microwave sensors across different sectors, highlighting their advantages and limitations compared to conventional waveguide-based sensors. Furthermore, the paper summarises several fabrication methods that can be implemented for SIW microwave sensors to enable the production of efficient and reliable sensors. Additionally, the future directions provided in this paper aim to contribute to the ongoing development and optimisation of SIW-based microwave sensors for accurate and efficient dielectric material characterisation. Overall, this review article serves as a beneficial resource for new researchers seeking to understand the role of SIW microwave sensors in material characterisation. It outlines the current status, opportunities, and potential advancements of SIW sensors, shedding light on their significance and potential impact in the field of material characterisation.

In this research, the conductive polymers including polypyrrole (PPy), polyaniline (PANI), and polythiophene (PTh) and their hybrids in the role of sensors were studied for the detection of the gas molecules. The synthesis principles, sensing performance, sensing mechanism, characterization of the conductive polymers, and scale-up discussion have been investigated. In addition, the impact of the operating conditions including temperature, humidity, gas concentration, time, recovery, and common additives like tin oxide, iron chloride, and Pd were analyzed. Sensitivity, conductivity, and response were discussed as criteria to evaluate the efficiency of the sensors. The difference of conductive polymers in the gas sensing returns to the level of porosity and morphology in the different conductive polymers. The results reveal that PANI and its composites are the desired choice for sensing toxic gases even in industrial centers or commercial scales.

This paper shows how a single parallel plate capacitor can be used to sense volumetric flow rate in micro/nano and smaller scale fluidic conduits and how a double parallel plate capacitor can be used to sense both volumetric flow rate and direction of flow. The concept was developed based on the principles of conservation of energy with some fundamentals of electricity and electromagnetics. Furthermore, the concept was validated experimentally to be accurate. Upon validation the measurement of the sensor was found to be in good agreement with experimental measurement with more accuracy obtained as the supplied voltage for the sensor is increased. Also, the accuracy of the developed concept increases as the characteristic length of the conduit decreases which makes the developed concept even more suitable for smaller scales applications. The concept consumes extremely low power and can be used directly without calibration provided that accurate value for magnetic permittivity of fluid is available. Moreover, the concept can be used for any type of fluid of any conduit shape with easy incorporation onto lab-on-a-chip or MEMS technology. The sensitivity of the sensor is approximately 0.03 A/(m³/s) which is good compared to other sensors.