Sensors and Actuators Reports最新文献

The research proposes and investigates an extraordinarily sensitive, label-free WaveFlex biosensor utilizing optical fiber technology for the detection of Staphylococcus aureus (S. aureus), a common foodborne bacterium. The WaveFlex biosensor (plasmon Wave based Flexible optical fiber Biosensor) is based on a novel flexible tapered single-mode fiber structure, utilizing gold nanoparticles (AuNPs) to trigger the phenomenon of localized surface plasmon resonance (LSPR). Additionally, the sensitivity is further enhanced using chitosan-coated iron(III) oxide nanoparticles (Fe₃O₄–CS NPs) and tungsten disulfide quantum dots (WS₂-QDs). The optical fiber surface is functionalized with antibodies to achieve specific detection of S. aureus. For S. aureus concentrations at 1 × 10⁸ CFU/mL (colony-forming units per milliliter), the sensor's maximum sensitivity of 2.74 nm/lg (CFU/mL), and a detection limit (LOD) of 6.67 CFU/mL. This ultra-sensitive biosensor holds great potential for widespread applications in various fields, including disease detection, medical diagnostics, and food safety inspection.

Understanding the molecular redox state is crucial for investigating chemical activities involving electron exchange, particularly in optical electrochemistry. Methyl viologen (MV) is commonly employed as a redox mediator and electron acceptor, exhibiting three distinct redox states (MV⁰, MV⁺, and MV²⁺), each characterized by a unique molecular structure and Raman spectrum. Utilizing surface-enhanced Raman spectroscopy (SERS), we explore the discrete molecular redox states of MV on shell-isolated nanoparticles (SHINs), which are gold nanoparticles (AuNPs) coated with silica shells of varying thicknesses, ranging from 1 to 10 nm. Our study, employing 532 nm excitation, reveals that all three redox forms of MV are sporadically observed on the metallic surfaces of AuNPs. However, the radical cation (MV⁺) state is predominantly detected on the silica surfaces of the SHINs, irrespective of the shell thickness. This consistency across different shell thicknesses suggests that electromagnetic (EM) effect predominantly contributes to the Raman enhancement in shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), rather than enhancement via electron transfer. If electron transfer were induced by laser excitation, varying redox species would likely appear dependent on shell thickness. Given the absence of external perturbation such as applied potential or reducing agents, we believe our findings can provide a crucial reference for future studies using MV as a redox state-sensing probe. Furthermore, our results demonstrate the efficacy of SHINs as a robust nano-sensing platform that efficiently prevents direct contact with the metallic surface and unwanted reactions.

Background

Multiple fluorescence PCR was used to facilitate the low cost detection of such infectious pathogens. The melting curve combined with the fluorescence PCR method was used to detect more targets. The characteristic melting peaks of the melting curve formed by the melting probe were complementary to the fluorescent probes and more targets could be identified by the different melting peaks in one fluorescence channel.

Results

The most optimal conditions were confirmed by optimizing the experimental conditions, such as the concentration of fluorescent probes and the melting probe, which is crucial for forming the characteristic melting peaks. LOD, multiplex performance and sample detection performance were evaluated separately. According to the results, the LOD of all targets was as low as five or ten copies/tube, excepting for Zaire type Ebola virus, whose LOD is 25 copies/tube. The method could simultaneously detected more targets, even up to eight bacteria or nine viruses and the result was accurate. In 173 clinical or real-world samples, the result was in keeping with the expected or clinical results, excepting for one case of the soil sample, and the consistency rate of the detection results reached 99.42%.

Significance

We achieved a novel method for multiple detection of up to 17 highly infectious pathogenic microorganisms and performed well in real sample detection, and the results were consistent with the expected or clinical results. We provided a new detection tool for disease prevention, control centers and clinical practice.

The detection of the typhoid pathogen, Salmonella enterica serotype Typhi (S. Typhi), holds massive clinical, public health, and epidemiological significance around the globe. Conventional diagnosis relies on bacterial isolation having a set of challenges when it comes to accurate detection, therapeutic intervention and disease management. Substantial reviews and reports exist on the advantages of bacteriophage-based biosensors (phagosensors) concerning Salmonella. However, phagosensor for Salmonella Typhi point of care detection at a lower limit of detection (LOD) has yet to be reported. This study is the earliest endeavor to develop a multi-wall carbon nanotubes (MWCNTs) based electrochemical phagosensor utilizing a unique bacteriophage SAL_R1S as a biomolecular recognition element, selectively binding S. Typhi DMS_A1 at LOD of 1 CFU/ml. S. Typhi DMS_A1, retrieved from patient's blood, consists of 10 pathogenicity islands and a wide range of efflux pump genes in its whole genome, which has not yet been documented for Salmonella. Subsequent screening for its specific bacteriophage from a sewage sample pinpointed the phage SAL_R1S of class Caudoviricetes, family Autographiviridae and genus Teseptimavirus. The whole genome- and tail-fiber protein- based alignment was close to Salmonella phage Vi06 covering 88.8 % and 90 % similarity, respectively. SAL_R1S exclusively binds S. Typhi in a specific manner and also possess excellent genetic feature as a candidate for developing a highly sensitive electrochemical phagosensor. Therefore, it was covalently immobilized onto a modified SPE/MWCNT/PANI-based electrode surface, allowing charge-directed, oriented immobilization which then confirmed through scanning electron microscopy. The electrode surface was featured via field emission scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The pathogen detection process of the phagosensor is quick (∼ 20 min). It has exceptional selectivity for typhoid pathogens from blood, wastewater or within mixed populations, indicating the application of this proposed phagosensor in clinical settings as a rapid, alternative to available conventional detection techniques, and low-cost surveillance tool.

Terfenol-D, a rare earth substance renowned for its remarkable magnetostrictive capabilities, is used in the field of actuators and sensors. The objective of this study is to demonstrate the most recent developments in Terfenol-D actuator technology and its use in many fields such as motors, fuel injectors, inkjet printing heads, servovalves, pumps, and active vibration controllers. The emphasis will be on showcasing the latest accomplishments in this domain. This study offers comprehensive insights into the design, operational features, and performance metrics of several Terfenol-D actuators, accompanied by pertinent schematic illustrations and quantitative measurements. This paper provides an overview of the fundamental structures, consistency of the magnetic field along the Terfenol-D rod, displacement amplification process, and several applications. The focus of the argument has been on the ongoing scientific studies about the actuation capabilities of Terfenol-D actuators. This review paper aims to appeal to the interests and passion of academics, researchers, and engineers involved in the manufacturing, design, analysis, and control of Terfenol-D actuators.

In this study, we synthesized Co₂P nanoparticles using a solid-state phosphorization method and evaluated the electrocatalytic response to glucose oxidation reaction (GORs). The influence of synthesis conditions on the particle size, morphology of Co₂P species and formation of byproducts is discussed. A lower molar ratio of the phosphorus precursor leads to a decrease in the generation of byproducts. In addition, the calcination temperature and time greatly influence the purity level of the Co₂P species and its particle size. Thus, we obtained three pure Co₂P nanoparticles with different sizes and morphologies. Significant differences in their electrocatalytic activity against the GOR are observed depending on the size of the particles, being the smaller ones the most efficient. Based on Tafel analysis, a higher catalytic activity was observed for the carbon fibre (CF)/Co₂P composite compared to Co₂P, which presented a greater onset potential and low response in current density. Tafel slopes close to 120 mV/dec were obtained for both materials, indicating that the mechanism is independent of the type of Co₂P-based material used. Finally, the performance of the GCE/CF/Co₂P sensor was demonstrated by amperometric measurements, with a sensitivity of 409 µAmM^-1cm^-2, a linear range between 39.4 µM and 150 µM, and a detection limit of 0.97 µM, analytical characteristics better than those obtained for other cobalt phosphide-based sensors reported in the literature. In addition, the GCE/CF/Co₂P sensor shows excellent selectivity and demonstrated to be competitive compared to other Co-based non-enzymatic glucose sensors.

Ensuring the long-term stability of screen-printed (SP) reference electrodes (REs) is increasingly essential because a major technical challenge in fabricating electrochemical sensors using screen printing is preparing an RE with a stable potential as it scales down in size. In this study, we fabricated SP electrodes that exhibit long-term stability in voltammetric and potentiometric experiments. The SP electrodes consisted of carbon working electrodes, a carbon counter electrode, an Ag/AgCl RE, and an ion-selective electrode (ISE) for detecting nitrate ions. The Ag/AgCl RE featured an electrolyte layer, a hydrophobic junction layer, and a small hole, collectively contributing to its long-term stability. This design achieved potential stability with minimal drift over extended periods in both 0.01 M PBS (pH 7.4) and 0.1 M Bis-tris (pH 6.5) buffer solutions. Additionally, the SP Ag/AgCl RE exhibited relatively low potential drift in the presence of various chemicals and different pH solutions. We analyzed the electrochemical behavior of two redox species, Fe(CN)₆^3-/4− and Ru(NH₃)₆^2+/3+, using cyclic voltammetry and electrochemical impedance spectroscopy techniques at the SP electrodes. Potentiometric experiments confirmed the sensitivity, long-term stability, and selectivity of the SP ISE for nitrate ion detection, even in the presence of interfering ions.

The presence of nitrite, a prevalent contaminant in natural environments, presents a significant environmental and human health concern. Hence, it is imperative to develop a sensor with the ability to quantitatively detect nitrite. This study focuses on the design and development of i) probe 1: tilted fiber Bragg gratings (TFBGs) and ii) probe 2: fiber optic tip-based plasmonic sensors utilizing ion-imprinted polymers. The concentration of nitrite was assessed at various levels using both sensing configurations. The outcomes indicated that the TFBGs-based sensor exhibited a sensitivity and limit of detection (LOD) of 0.469 nm/ln(μg/mL) and 0.142 μg/mL in the linear detection range of 0.5–50 μg/mL. The fiber optic tip-based sensor exhibited a sensitivity and LOD of 1.16 nm/ln(μg/mL) and 0.176 μg/mL within the 1–50 μg/mL linear detection range. The obtained sensing results reveal that the sensors presented in this study are able to accurately detect nitrite at various concentrations in a quantitative manner. Moreover, an assessment was conducted to examine the selectivity and reusability of the sensor individually, yielding satisfactory results.

Diabetes disease caused by hyperglycemia has many complications, including cardiovascular disease, kidney disease and visual impairment. Effective and stable platform of enzyme-free glucose detection is significant important for the monitoring of diabetes disease. In this work, uniform single MXene layers were fabricated with large scale through HCl/LiF etching and tapered gold nanostructures (AuTNs) was electrodeposited on the MXene layers. The AuTNs with three-dimensional conical apex on the MXene layers can effectively increase the specific surface ratio and active sites. The composite materials of AuTNs and MXene layers assembled on the glassy carbon electrode (GCE) can significantly increase the electrochemical performance during glucose detection. The modified electrode of AuTNs/MXene/GCE shows good linearity from 0.1 nM to 10.0 mM, low limit of detection (LOD) of 1.43 nM and fast response time of 1.0 s, exhibiting high sensitivity, good stability and high selectivity for glucose during electrochemical detection. The high performance of the modified electrode provides promising potential application in enzyme-free sensor for the electrochemical detection of glucose.

In this study, cupric oxide nanowires (CuO NWs) on patterned interdigitated electrodes (PIEs) used as ozone (O₃) gas sensors, were successfully fabricated using thermal oxidation and the microelectromechanical systems (MEMS) technique. After the thermal oxidation process, CuO NWs with different heights and densities were fabricated using a pure copper seed layer with a thickness ranging from 0.5 μm to 2 μm. In this experiment, a low temperature, low concentration, and repeatable CuO NWs gas sensor was fabricated, which can detect O₃ gas at a low concentration of 50 ppb and low temperature of 100°C with a high sensor response (40%). The concentration response of this gas sensor shows an increasing linear trend, with an increase of O₃ concentration in the range of 50 ppb - 300 ppb. Additionally, the results indicated that this CuO NWs gas sensor is more selective for O₃ than CO, CO₂, C₂H₅OH, C₃H₆O, NO₂, or NH₃. While CuO has been less studied in O₃ detection compared with other semiconducting metal oxide materials, CuO NWs show potential applications in gas sensing devices for low-temperature and low-concentration O₃ environmental monitoring.