Probe Measurements Research Articles

Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

COMPARISON OF CONFOCAL SENSOR FOR DIAMETER MEASUREMENT WITH MEASURING PROBE

The measurement and inspection of products and their dimensions in industry plays an important role in determining the quality of a product. Correct measurement is a key factor in production. Many companies are subject to stringent safety standards and specific product requirements. Accurate measurement ensures compliance with these guidelines, avoiding fines, penalties and legal complications. Effective measurement processes can identify inefficiencies, defects and areas for improvement, leading to cost savings. By detecting defects early in the production cycle, manufacturers can reduce waste and optimize resource utilization thereby reducing overall production costs. A fundamental principle of good measurement is to ensure that the measuring instruments are suitable for the specific application and that they meet the measurement requirements for the measurement parameter. The objective of the experiment is to verify and compare the measurement capability of a confocal chromatic sensor against a measurement probe used in production. The parameter to be measured is the diameter, since the correct diameter plays an essential role in the production of shafts or other cylindrical products. The results contained in the thesis highlight the importance and differences between the different measuring devices and the qualification to use the measurement of a given parameter.

Impact of metal deposition on the optical and interface properties of NiO: growth and characterization of NiO/metal thin bilayer films

Abstract Since transparent conductive oxides (TCOs) provide electrical conductivity together with optical transparency, they have found wide applications in optoelectronic devices and photovoltaics. Among the TCOs, nickel oxide (NiO) is challenging due to its inherent trade-off between transparency and electrical conductivity. To address this challenge, one effective approach is to deposit a metal layer onto NiO thin films. In this work, NiO, NiO/Au, NiO/Ag, and NiO/Cu thin films are prepared by sputtering and thermal evaporation techniques on glass substrates and fully characterized finding the proper film for optoelectronic applications. The electrical and optical properties of the fabricated films are examined by four-point probe measurements and optical spectrometry. According to the obtained results, the NiO/Au, NiO/Ag, and NiO/Cu bilayers show sheet resistance of 200, 338, and 925 Ω sq−1 respectively while their optical bandgaps vary from 3.2 to 3.76 eV. These findings provide valuable insights into the performance of these films, making them potentially viable choices for various optoelectronic applications.

Enhanced Catalytic Probe Design for Mapping Radical Density in the Plasma Afterglow.

The electrification of chemical processes using plasma generates an increasing demand for sensors, monitoring concentrations of plasma-activated species such as radicals. Radical probes are a low-cost in situ method for spatially resolved quantification of the radical density in a plasma afterglow using the heat from the exothermal recombination of radicals on a catalytic surface. However, distinguishing recombination heating from other heat fluxes in the system is challenging. In this study, we present a heat flux analysis based on probe measurements inside the reactor, with simultaneous IR imaging monitoring of the temperature of the reactor wall. The impact of radiation heat on a single thermocouple as well as the advantage of a dual thermocouple setup (using a catalytic unit together with a reference thermocouple) is shown. We add a heat sink with a monitored temperature to the dual thermocouple setup, allowing the determination of conductive and radiative heat fluxes. The heat sink gives more information on the measurement and reduces ambiguities in the evaluation used by others. The probe was tested by mapping N atom densities throughout the plasma afterglow of our reactor, enabling evaluation of the recombination kinetics of the radicals in the gas phase. Three-body recombination was shown to be the main pathway of recombination, with a recombination rate of krec = (2.0 ± 0.9)·10-44 m6/s, which is in line with the known literature findings, demonstrating that the measured species are N radicals and the probe did not influence the plasma or recombination reactions in the afterglow.

Comparing growth of titania and carbonaceous dusty nanoparticles in weakly magnetised capacitively coupled plasmas

Abstract This study compares the growth cycles and spatial distribution of dust cloud for titania and carbonaceous dusty nanoparticles in capacitively coupled radiofrequency plasmas, with and without the presence of a weak magnetic field of approximately 500 Gauss. Findings on cycle time, growth rate, and spatial distribution of dust cloud are discussed. The growth of nanoparticles in these plasmas is cyclic, with particles reaching their maximum size and subsequently moving out of the plasma, followed by the generation of a new particle growth cycle. The presence of the magnetic field speeds up the growth cycle in both plasma. The magnetic field also makes the spatial distribution of the two dust cloud different from each other. Langmuir probe measurement of the background plasma parameters such as electron temperature and floating potential reveal radial variations in floating potential but not electron temperature. Furthermore, the magnetic field changes the radial variation of floating potential. These measurements, however, are not sufficient to explain why the two dust clouds appear differently. It is possible that the differences occur due to a gradient in the radial distribution of the magnetic field.

Stellar Models are Reliable at Low Metallicity: An Asteroseismic Age for the Ancient Very Metal-poor Star KIC 8144907

Very-metal-poor stars ([Fe/H] < −2) are important laboratories for testing stellar models and reconstructing the formation history of our galaxy. Asteroseismology is a powerful tool to probe stellar interiors and measure ages, but few asteroseismic detections are known in very-metal-poor stars and none have allowed detailed modeling of oscillation frequencies. We report the discovery of a low-luminosity Kepler red giant (KIC 8144907) with high signal-to-noise ratio oscillations, [Fe/H] = −2.66 ± 0.08 and [α/Fe] = 0.38 ± 0.06, making it by far the most metal-poor star to date for which detailed asteroseismic modeling is possible. By combining the oscillation spectrum from Kepler with high-resolution spectroscopy, we measure an asteroseismic mass and age of 0.79 ± 0.02(ran) ± 0.01(sys) M ⊙ and 12.0 ± 0.6(ran) ± 0.4(sys) Gyr, with remarkable agreement across different codes and input physics, demonstrating that stellar models and asteroseismology are reliable for very-metal-poor stars when individual frequencies are used. The results also provide a direct age anchor for the early formation of the Milky Way, implying that substantial star formation did not commence until redshift z ≈ 3 (if the star formed in situ) or that the Milky Way has undergone merger events for at least ≈12 Gyr (if the star was accreted by a dwarf satellite merger such as Gaia-Enceladus).

Self-Assembly and Wound Healing Activity of Biomimetic Cycloalkane-Based Lipopeptides.

The self-assembly of lipopeptide (peptide amphiphile) molecules bearing single linear lipid chains has been widely studied, as has their diverse range of bioactivities. Here, we introduce lipopeptides bearing one or two cycloalkane chains (cycloheptadecyl or cyclododecyl) conjugated to the collagen-stimulating pentapeptide KTTKS used in Matrixyl formulations. The self-assembly of all four molecules is probed using fluorescence probe measurements to detect the critical aggregation concentration (CAC), and cryogenic-TEM and small-angle X-ray scattering (SAXS) to image the nanostructure. The peptide conformation is studied using circular dichroism (CD) and FTIR spectroscopies. All the cycloalkane lipopeptides show excellent compatibility with dermal fibroblasts. The compounds bearing one or two cyclododecyl chains (denoted as DKT and DDKT, respectively) show wound healing in diabetic rats, the improvement being markedly enhanced for DDKT. Interestingly, the revival of hair follicles and blood vessels in the dermis were observed, which are the critical markers of effective wound repair. Analysis of H&E-stained tissue images (from a rat model) shows that the rat groups treated with DDKT and DKT displayed a significantly increased amount of regenerated hair follicles, indicating a faster healing process for DDKT compared to the control group. Collagen deposition was also enhanced, especially for DDKT, and by day 20, the DDKT-treated groups had developed a dense collagen network accompanied by a regenerated epidermis. At the same time, the number of blood vessels in DDKT-treated diabetic wounds was significantly higher than in control groups and neovascularization was substantially enhanced, as assayed using α-SMA (a marker for vascular smooth muscle cells) and CD31 (a marker specific to vascular endothelial cells). These results suggest that the lead lipopeptide DDKT exhibits a remarkable pro-vascularization capability and shows great promise for future application as a wound-healing biomaterial.

Investigating Gold Deposition with High-Power Impulse Magnetron Sputtering and Direct-Current Magnetron Sputtering on Polystyrene, Poly-4-vinylpyridine, and Polystyrene Sulfonic Acid.

Fabricating thin metal layers and particularly observing their formation process in situ is of fundamental interest to tailor the quality of such a layer on polymers for organic electronics. In particular, the process of high power impulse magnetron sputtering (HiPIMS) for establishing thin metal layers has sparsely been explored in situ. Hence, in this study, we investigate the growth of thin gold (Au) layers with HiPIMS and compare their growth with thin Au layers prepared by conventional direct current magnetron sputtering (dcMS). Au was chosen because it is an inert noble metal and has a high scattering length density. This allows us to track the growing nanostructures via grazing incidence scattering. In particular, Au deposition on the polymer polystyrene (PS) with the respective structural analogues poly-4-vinlypyridine (P4VP) and polystyrene sulfonic acid (PSS) is studied. Additionally, the nanostructured layers on these different polymer films are further probed by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray reflectometry (XRR), and four-point probe measurements. We report that HiPIMS leads to smaller island-to-island distances throughout the whole sputter process. Moreover, an increased cluster density and an earlier percolation threshold are achieved compared to dcMS. Additionally, in the early stage, we observe a significant increase in coverage by HiPIMS, which is favorable for the improvement of the polymer-metal interface.

On the рossibility of multichannel optical backscattering sondes for joint balloon and lidar studies of the aerosol composition of the middle atmosphere

Aerosol backscattering sondes in the practice of aerological sounding, along with lidar observations, are used at night to study and monitor polar stratospheric clouds, tropospheric and stratospheric aerosol, cirrus clouds, pyroconvection, volcanic aerosol, as well as to verify remote methods and means of ground-based and satellite-based aerosol observations. For aerosol sondes, a simple two-wave measurement technique is used, which makes it possible to diagnose changes in aerosol composition by color index. The possibilities of the two-wave technique have limitations, which are discussed in this article. Aerological sounding combined with lidar observations expands the wavelength range for multi-wavelength studies, and direct measurements of atmospheric temperature increase the accuracy of aerosol sensing. The paper considers the application of 3 or more wavelenght techniques. Data from probe measurements using wavelengths of 470, 528, 850 and 940 nm and lidar sensing at wavelengths of 355 and 532 nm are presented.

Uncertainty study of two-phase flow distribution characteristics measurement based on bubble trajectory tracking method

Bubbles undergo complex motions such as nonlinear trajectories in two-phase flow, where the position, velocity magnitude, and direction of bubble centers continuously change as they evolve under the influence of forces. The complexity of bubble trajectory increases the difficulty in measuring the flow field distribution characteristics, which has been understudied in the previous. The bubble trajectory tracking model based on the Monte Carlo method is constructed to study the uncertainty of two-phase flow distribution characteristics measurement by the conductivity probe. The Monte Carlo method is adopted to randomly generate the bubble velocity at the initial moment and the bubble force characteristics are embedded to simulate the three-dimensional motion of the bubble. The influence of various factors on the distribution of effective bubble numbers and velocity relative error at the local point is quantitatively analyzed. It is found that the lateral spacing of the sensors has the greatest influence on the measurement results of small-sized bubbles, the accuracy is greatly reduced when the space is larger than the radius of the measured bubbles. Moreover, the measurement accuracy of the probe for medium-sized bubbles is high, and the effect of bubble lateral velocity and aspect ratio on the effective bubble ratio and velocity relative error is negligible. In addition, the maximum measurement range of the probe at local points is investigated which is found to be 4 mm in the lateral direction and 2 mm in the longitudinal direction. Finally, uniformly distributed bubbles are generated in a 20 mm × 10 mm transverse plane and the distribution of the effective bubble ratio of the probe is found to be consistent at different measurement points, which verifies the reliability of the probe measurement.

Effects of bird feather-like convergent–divergent-riblet surfaces on the total pressure loss and wake turbulence of a transonic compressor cascade

The flow loss caused by the fan blades in a turbofan engine with a large bypass ratio is significant, and the wake considerably affects the inlet flow of downstream components. Surfaces with bird feather-like convergent–divergent (C–D) riblets have been proven to modulate the boundary layer flow by inducing counter-rotating rolling modes; however, the effects of these surfaces on the total pressure loss and wake turbulence of transonic compressor cascades remain unexplored. In this study, the effects of C–D-riblet surfaces on the total pressure loss and wake turbulence of a transonic compressor cascade were experimentally investigated using a five-hole probe and hot-wire measurements. The flow-loss-control effects of C–D-riblet surfaces with different characteristic lengths were also analyzed. The most significant reduction in the area-averaged total pressure loss (11.23%) was achieved using a C–D-riblet surface with a characteristic length of 30 μm at a Mach number of 0.94; this total pressure loss reduction corresponded to an increase in the mean velocity and a decrease in the turbulence intensity of the wake profile. Furthermore, the effectiveness of the loss control varied significantly with the spreading position of the C–D riblets. The optimal control effect was observed in the divergence-line region, and the control was slightly less effective as the measurement position neared the convergence line. This paper demonstrates the promising potential of using C–D riblets to achieve flow loss control in transonic compressor cascades.

Vacuum entanglement probes for ultra-cold atom systems

Abstract This study explores the transfer of nonclassical correlations from an ultra-cold atom system to a pair of pulsed laser beams. Through nondestructive local probe measurements, we introduce an alternative to destructive techniques for mapping Bose–Einstein Condensate (BEC) entanglement. Operating at ultra-low temperatures, BEC density fluctuations emulate a relativistic vacuum field. We show that lasers can serve as Unruh–DeWitt detectors for vacuum BEC phonons. A quantum vacuum holds intrinsic entanglement, transferable to distant probes briefly interacting with it—a phenomenon termed ‘entanglement harvesting’. Our study accomplishes two primary objectives: first, establishing a mathematical connection between a pair of pulsed laser probes interacting with an effective relativistic field and the entanglement harvesting protocol; and second, to closely examine the potential and persisting obstacles for realising this protocol in an ultra-cold atom experiment.

Clinical knowledge-guided hybrid classification network for automatic periodontal disease diagnosis in X-ray image

Accurate classification of periodontal disease through panoramic X-ray images carries immense clinical importance for effective diagnosis and treatment. Recent methodologies attempt to classify periodontal diseases from X-ray images by estimating bone loss within these images, supervised by manual radiographic annotations for segmentation or keypoint detection. However, these annotations often lack consistency with the clinical gold standard of probing measurements, potentially causing measurement inaccuracy and leading to unstable classifications. Additionally, the diagnosis of periodontal disease necessitates exceptional sensitivity. To address these challenges, we introduce HC-Net, an innovative hybrid classification framework devised for accurately classifying periodontal disease from X-ray images. This framework comprises three main components: tooth-level classification, patient-level classification, and a learnable adaptive noisy-OR gate. In the tooth-level classification, we initially employ instance segmentation to individually identify each tooth, followed by tooth-level periodontal disease classification. For patient-level classification, we utilize a multi-task strategy to concurrently learn patient-level classification and a Classification Activation Map (CAM) that signifies the confidence of local lesion areas within the panoramic X-ray image. Eventually, our adaptive noisy-OR gate acquires a hybrid classification by amalgamating predictions from both levels. In particular, we incorporate clinical knowledge into the workflows used by professional dentists, targeting the enhanced handling of sensitivity of periodontal disease diagnosis. Extensive empirical testing on a dataset amassed from real-world clinics demonstrates that our proposed HC-Net achieves unparalleled performance in periodontal disease classification, exhibiting substantial potential for practical application.

Experimental study of oil-water two-phase flow patterns in a vertical large diameter pipe

The flow structure and the phase inversion have great influence on the flow measurement in vertical upward oil-water two-phase flow. This paper attempts to investigate the flow patterns in oil-water flows through a vertical upward large pipe with the designed mini-conductance array probes measurement system and the vertical multi-electrode array (VMEA) measurement system. According to the output waveform of the mini-conductance array probes, the oil-in-water flow, transition flow and water-in-oil flow can be identified effectively. The fluctuating signals of the VMEA is processed by the recurrence plot and the time-frequency representation, the results show that the VMEA conductance signal with average measurement characteristics can realize an effective identification of the above three flow patterns, which has a good agreement with the results of the mini-conductance array probes. Finally, via comparing with previous published flow pattern transition boundary models in different pipe diameters, it is founded that the boundary line of the transition to oil-in-water based on the kinematic wave-based model and the observation-based model in the same diameter pipe are consistent with our experimental data. And the pipe diameter affects the flow pattern transition, compared with the boundary in small diameter pipe, the phase inversion requires a larger oil velocity, and the transition zone becomes narrower in large diameter pipe.

Navigation of superparamagnetic particles with a pre-magnetized high-temperature superconducting bulk in a weak background field

Abstract Recent research has shown significant progress towards a full body magnetic drug delivery (MDD) system for use in targeted cancer treatments. Although many different MDD systems have been proposed to generate strong remote forces capable of rapidly changing directions at distances greater than 10 cm, current state-of-the-art technologies lack in force strength and/or degrees of freedom. Knowing that high temperature superconducting (HTS) bulks can achieve trapped fields an order of magnitude larger than ferromagnets, this work aims at numerically and experimentally evaluating the forces that can be produced by HTS bulks in a uniform magnetic field. We first use Hall probe measurements and finite element simulations to determine the magnetic field generated by an HTS pellet and show that both results are in good agreement. Using a combination of simulations and experiments, we then show that for a 14 × 6 mm YBa2Cu3O 7 − x pellet magnetized at 2 T, remote forces on superparamagnetic microparticles are maximized at background fields of ∼50 mT. In addition, the direction of the magnetic forces can be flipped by changing the direction of the applied field relative to the HTS’s magnetization. The HTS bulk was successfully used to navigate magnetic microparticles in a glass bifurcation mimicking the hepatic artery of the human liver. Finally, we show by simulation that a large HTS pellet magnetized at 5 T in a field of ∼250 mT can generate stronger forces with more degrees of freedom than the strongest forces achievable in current MDD technologies.

Electron density measurement of an ionospheric-like plasma using an impedance probe.

In this work, an impedance probe was designed to measure ionospheric low-density plasma. The probe is made of short cylindrical dipoles with an antenna 20cm in length and 0.25cm in diameter, which can operate in the frequency range of 0-100 MHz. Combined with a vector network analyzer, the performance of the probe was tested in laboratory-created ionospheric-like plasma, and the results were compared with those of the Langmuir probe measurements. The densities measured by the two methods show a consistent trend, and the impedance probe data show much smaller uncertainties, which suggests that the impedance probe can achieve high-precision measurements. Furthermore, by fitting the antenna phase data, the electron-neutral collision frequency can also be obtained. Therefore, the impedance probe provides a feasible method for exploring low-density partially ionized plasma and can be expanded to actual ionospheric exploration in the future.

Origin of the type III radiation observed near the Sun

Aims. We investigate processes associated with the generation of type III radiation using Parker Solar Probe measurements. Methods. We measured the amplitudes and phase velocities of electric and magnetic fields and their associated plasma density fluctuations. Results. 1. There are slow electrostatic waves near the Langmuir frequency and at as many as six harmonics, the number of which increases with the amplitude of the Langmuir wave. Their electrostatic nature is shown by measurements of the plasma density fluctuations. From these density fluctuations and the electric field magnitude, the k-value of the Langmuir wave is estimated to be 0.14 and kλd = 0.4. Even with the large uncertainty in this quantity (more than a factor of two), the phase velocity of the Langmuir wave was &lt; 10 000 km/s. 2. The electromagnetic wave near the Langmuir frequency has a phase velocity lower than 50 000 km/s. 3. We cannot determine whether there are electromagnetic waves at the harmonics of the Langmuir frequency. If they existed, their magnetic field components would be below the noise level of the measurement. 4. The rapid (less than one millisecond) amplitude variations typical of the Langmuir wave and its harmonics are artifacts resulting from the addition of two waves, one of which has small frequency variations that arise because the wave travels through density irregularities. None of these results are expected in or consistent with the conventional model of the three-wave interaction of two counter-streaming Langmuir waves that coalesce to produce the type III wave. They are consistent with a new model in which electrostatic antenna waves are produced at the harmonics by radiation of the Langmuir wave, after which at least the first harmonic wave evolved through density irregularities such that its wave number decreased and it became the type III radiation.

Gate tunable edge magnetoplasmon resonators

AbstractQuantum Hall systems are platforms of choice to study topological properties of condensed matter systems and anyonic exchange statistics. In this work we have developed a tunable radiofrequency edge magnetoplasmonic resonator controlled by both the magnetic field and a set of electrostatic gates, meant to serve as a versatile platform for future interferometric devices designed to evidence non-abelian anyons. In our device, gates allow us to change both the size of the resonant cavity and the electronic density of the two-dimensional electron gas. We show that we can continuously control the frequency response of our resonator, making it possible to develop an edge magnetoplasmon interferometer. As we reach smaller sizes of our resonator, finite size effects caused by the measurement probes manifest. In the future, such device will be a valuable tool to investigate the properties of non-abelian anyons in the fractional quantum Hall regime.

Ultrasonic-aided preparation of poly(vanillin-co-thiophene)/green Fe₃O₄ nanocomposites via solution mixing for methyl orange adsorption and antibacterial applications

This work describes the preparation of novel nanocomposite materials comprising a newly synthesized semiconducting copolymer, poly(vanillin-co-thiophene) (PVTH), blended with different weight proportions (3 %, 6 %, and 9 % by weight) of greenly synthesized magnetite nanoparticles (GFe3O4 MNPs) via solution mixing, assisted by ultrasonic irradiation. PVTH copolymer was synthesized through the polycondensation of vanillin, a bioderived aldehyde, and thiophene, catalyzed by sulfuric acid. GFe3O4 MNPs were prepared via the coprecipitation method with mint extract as an environmentally friendly stabilizer. The physicochemical properties of the prepared samples were investigated by 1H NMR, 13C NMR, FTIR, XRD, UV–vis, TGA, FE-SEM/Eds, AFM, VSM, tauc plot method and the four-points probe measurement. The samples were evaluated for two applications: methyl orange (MO) adsorption from aqueous solutions and antibacterial activities against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus) bacterial strains. The results showed that ultrasound irradiation facilitated the easy preparation of well-dispersed and homogeneous nanocomposites with combined semiconducting and magnetic properties and improved thermal stability compared to the parent PVTH. The most effective nanocomposite for MO removal was the sample containing 9 % GFe3O4 MNPs, whose adsorption behavior followed pseudo-second-order kinetics and Freundlich isotherm. Its maximum adsorption capacity was 103.79 mg g−1. In addition, all samples showed antibacterial action against the tested bacterial strains, with PVTH showing the highest efficacy, followed by PVTH/GFe3O4 nanocomposites.

Terahertz conductivity mapping of thin films on smart textiles

Smart textiles that promise to become sensors and actuators for multiple applications are an active area of research. Conductive textiles formed by coating a fabric with a conductive film will play a key role in such applications. Here we present contactless mapping of the terahertz (THz) conductivity of thin conductive films deposited on textiles. These conductivity maps enable non-destructive assessment of the conductivity of such layers and therefore the identification and localization of non-uniformities in local conductivity. The THz measurements are quantitatively consistent with four-point probe measurements of the same areas.