U-shaped Probe Research Articles

[formula omitted] modified U-shaped fiber surface plasmon resonance sensor with high sensitivity

Design of optical fiber structure and sensitive material coating are two effective performance improvement approaches for fiber optic surface plasmon resonance (SPR) sensors. Here, a tungsten diselenide (WSe2) modified U-shaped fiber optic SPR sensor is proposed. It is found that the sensing performances of the proposed U-shaped probe can be controlled with the thickness of gold film, WSe2 layers, and bending radius of the U-shaped fiber. A sensitivity of 27520 nm/RIU (RIU: refractive index unit) is obtained with the optimized U-shaped probe, which is about 11.56-fold and 12.29-fold improvements over the traditional in-line transmission fiber optic SPR sensors without WSe2 coating and with monolayer WSe2, respectively. These results demonstrate a promising approach for sensitivity improvement of fiber optic SPR sensors, and the proposed WSe2 modified U-shaped fiber optic SPR sensor may have prospective potential applications in biological sensing, chemical sensing, and environmental monitoring.

High performance of straight and U-shaped probe microfiber sensors for sucrose solution detection applications

A low cost, highly sensitive sensor with easy fabrication has been successfully developed to detect variations in the concentration of sucrose solutions using a microfiber probe sensor. The microfiber probe was fabricated using a flame brushing mixture of butane and oxygen with single-mode optical fiber material and pulled on both sides to achieve a size of 16.48 µm. These microfiber probes were characterized into two sensor probe shapes: straight and u-shaped, to measure variations in the sucrose solution concentration. The results for both probe shapes showed a decrease in peak output intensity and a shift in peak wavelength as the sucrose concentration increased from 0.5% to 3%. The straight shape exhibited a sensitivity of 0.241 dBm/% with a slope linearity of 99.5% and a resolution of 0.0415%, while the U-shape had a sensitivity of 2.692 dBm/% with a slope linearity of 90.6% and a resolution of 0.0030%. The measurement spectra results indicated significant differences in u-shape at each concentration. In conclusion, both microfiber sensor probe shapes exhibited excellent performance and are suitable for use as chemical sensors to measure variations in solutions.

Development of an Immunocapture-Based Polymeric Optical Fiber Sensor for Bacterial Detection in Water.

Conventional methods for pathogen detection in water rely on time-consuming enrichment steps followed by biochemical identification strategies, which require assay times ranging from 24 hours to a week. However, in recent years, significant efforts have been made to develop biosensing technologies enabling rapid and close-to-real-time detection of waterborne pathogens. In previous studies, we developed a plastic optical fiber (POF) immunosensor using an optoelectronic configuration consisting of a U-Shape probe connected to an LED and a photodetector. Bacterial detection was evaluated with the immunosensor immersed in a bacterial suspension in water with a known concentration. Here, we report on the sensitivity of a new optoelectronic configuration consisting of two POF U-shaped probes, one as the reference and the other as the immunosensor, for the detection of Escherichia coli. In addition, another methos of detection was tested where the sensors were calibrated in the air, before being immersed in a bacterial suspension and then read in the air. This modification improved sensor sensitivity and resulted in a faster detection time. After the immunocapture, the sensors were DAPI-stained and submitted to confocal microscopy. The histograms obtained confirmed that the responses of the immunosensors were due to the bacteria. This new sensor detected the presence of E. coli at 104 CFU/mL in less than 20 min. Currently, sub-20 min is faster than previous studies using fiber-optic based biosensors. We report on an inexpensive and faster detection technology when compared with conventional methods.

Smallest form-factor multi-stacked ceramic patch antenna on package for 5G millimeter-wave mobile applications

A new design for a 5G millimeter-wave array antenna that is only 2.8 mm wide, using multi-stacked high-temperature ceramic substrates, is proposed in this paper. The antenna is designed to meet the requirements for esthetically pleasing and ergonomic smartphone designs and efficient component installations. To overcome challenges posed by the high relative permittivity and dielectric loss tangent of the ceramic substrates, the authors use a polymer adhesion layer with an air cavity and U-shaped probe feeding structures. The resulting 1 × 5 ceramic array antenna has a −10 dB impedance bandwidth in the low-band range of 24.25–28.35 GHz and the high-band range of 37–40 GHz, which covers the 5G New Radio frequency ranges n258, n260, and n261.

A C-band folded planar low-pass filter utilizing U-shaped probe for high power TR module

In this paper, a C-band folded low-pass filter is realized in the planar circuit by utilizing a U-shaped probe. The proposed filter consists of four microstrip patches and a U-shaped probe. The configuration, equivalent circuit and design method of the proposed filter are demonstrated. A prototype of the low-pass filter operating in C-band has been designed, fabricated and measured. The maximum insertion loss of the fabricated filter is about 0.8 dB from 5 GHz to 6 GHz, while the maximum return loss is -11 dB. The out of band rejection is over 30 dB at 12 GHz. The measured results show reasonable correlation with the ideal circuit and the simulated results. The proposed low-pass filter can be used for the high power transmit/receive (TR) module in active electronically scanned array (AESA).

Design and development of cost-effective fiber Bragg grating temperature sensor package

A cost-effective fiber Bragg grating (FBG) temperature sensor package was designed and developed with two distinct sensing probes and demodulation schemes. U-shaped and capillary shape probes were designed and tested using an optical spectrum analyzer and two different indiginously developed intensity demodulation schemes. The temperature sensitivities were measured as 12.94 ± 0.15 pm °C−1, 11.57 ± 0.12 pm °C−1, and 12.03 ± 0.14 pm °C−1 for a bare FBG and for FBGs encapsulated in the U-shaped and capillary probes, respectively, with negligible hysteresis and a repeatability of 1 °C–3 °C. The performance of the probes was demonstrated by twin-FBG intensity demodulation schemes, the range of which was increased up to 181.50 °C with a resolution of 0.120 °C by the development of a CFBG-FBG intensity demodulation scheme.

Взаимодействие температурных полей в массиве грунта при отборе низкопотенциальной теплоты U-образными зондами геотермальной теплонасосной установки

Research in the field of alternative energy sources use is of relevance due to the limited reserves of fossil fuels, the constant cost increase and flue gas emissions generated by power plants along with fuel combustion. The use of low-grade ground energy with the help of geothermal heat pump stations makes it possible to save fossil fuel and reduce environmental pollution. Since about 50 % of the one-time capital investment is spent on the construction of ground loop, the issues on improving the efficiency of ground heat abstraction are of particular relevance. However, until now there is no unified normative technique to calculate ground probes and to create ground loops of optimal constructions. The absence of calculation methods and intelligible practical dependencies does not allow one to quantify the influence of various factors on the heat extraction process, the intensity of which varies significantly over time. The authors have applied two analytical methods in the developed mathematical model. The first one is a source-sink method adapted to the non-stationary process of heat abstraction away from the soil mass. And the second one is the superposition method which made it possible to quantify the effect of the interaction of temperature fields in the well. The mathematical model has been developed, and calculated dependences have been obtained. The authors have presented a calculation method and the results of mathematical modeling of the non-stationary process of soil heat abstraction by a vertical U-shaped geothermal probe and the internal interaction of the temperature fields of the downcomer and riser pipes. The results of the computational experiment are presented in the form of graphs. The authors have determined three key particular cases of the operation of a ground probe and formulas to define the maximum allowable increment of the temperature of the heated coolant under the condition of maximum efficient use of the heat-receiving surface applicable to various types of soil. The analysis of the obtained results makes it possible to identify the main factors affecting the heat-absorption efficiency (actual heat transfer coefficients and specific heat inflows) for each of the pipes and for the entire probe, considering the interaction of temperature fields around the downcomer and riser pipes during the heating period.

Evaluation of vertical closed loop system performance by modeling heat transfer in geothermal probes

This study aims to develop and validate the heat transfer models for evaluating the performance parameters of closed loop geothermal systems, considering in detail probe internal geometry, heat exchange between the tubes, surrounding medium, and its depth-dependent temperature. The developed models are based on numerical solutions of differential equations that govern heat transfer in tubes, with refining the thermal resistance coefficients of probe elements. The models allow to calculate performance parameters, first of all, the fluid output temperature and system thermal capacity, for vertical single, double U-shaped and coaxial probes contacting either soil or mine water. We validated the models using the experiments performed in-situ at three sites in Germany and Turkey demonstrating high agreement between calculated and measured parameters. In addition, we proposed and tested the criterion to optimize the geothermal system operation regarding the technology features.

Open string probe in soft hair BTZ

We study the boundary CFT under supertranslation in terms of the AdS/CFT correspondence. In particular, we probe the soft hair BTZ background by several open string configurations as follows. The Ryu–Takayanaki formula of holographic entanglement remains intact under supertranslation. The U-shape string probe indicates that the flat part of meson potential is altered by the soft charge. The trailing string solution shows that the hair parameter plays the role of external field in the drag force. The study of hanging string in the Brownian motion suggests the transport variables, such as friction coefficient are likely affected by supertranslation.

Comparison of different types of focusing probes in pulsed eddy current testing

Pulsed eddy current (PEC) testing has attracted widespread attention because of its unique advantages in detecting local defects in insulated pipes. In this paper, rectangular, U-shaped, and semicircular PEC focusing probes are designed, the magnetic energy utilization efficiency and focusing properties of the developed probes are simulated and compared, and their detection sensitivities are experimentally compared. The magnetic flux through specific surfaces is calculated to find the utilization of magnetic energy by the different probes, and the eddy current dissipation power is used to quantitatively describe the eddy current field focusing properties of various types of probes. The simulation results show that the magnetic field energy utilization efficiency of the semicircular focusing probe is significantly higher than that of the other two probes, but the eddy current field distributions of the three probes are similar, and the focusing properties are not significantly different. The experimental results show that the three types of PEC probes can effectively detect local defects under a certain lift-off. By calculating the detection sensitivity of different probes to defects under different lift-off conditions, it is determined that the detection sensitivity of the semicircular probe is significantly higher than that of the U-shaped probe and rectangular probe. The experimental results are consistent with the numerical simulation results. The research results are conducive to the optimal design of PEC focusing probes for insulated pipes.

SARS-CoV-2 Detection Using Optical Fiber Based Sensor Method.

The SARS-CoV-2 Coronavirus disease, also known as the COVID-19 pandemic, has engendered the biggest challenge to human life for the last two years. With a rapid increase in the spread of the Omicron variant across the world, and to contain the spread of COVID-19 in general, it is crucial to rapidly identify this viral infection with minimal logistics. To achieve this, a novel plastic optical fiber (POF) U-shaped probe sensing method is presented for accurate detection of SARS-CoV-2, commonly known as the COVID-19 virus, which has the capability to detect new variants such as Omicron. The sample under test can be taken from oropharyngeal or nasopharyngeal via specific POF U-shaped probe with one end that is fed with a laser source while the other end is connected to a photodetector to receive the response and postprocess for decision-making. The study includes detection comparison with two types of POF with diameters of 200 and 500 µm. Results show that detection is better when a smaller-diameter POF is used. It is also seen that the proposed test bed and its envisaged prototype can detect the COVID-19 variants within 15 min of the test. The proposed approach will make the clinical diagnosis faster, cheaper and applicable to patients in remote areas where there are no hospitals or clinical laboratories due to poverty, geographic obstacles, or other factors.

Investigation of U-shape tapered plastic optical fibers based surface plasmon resonance sensor for RI sensing

In this paper, a U-shape tapered plastic optical fibers (TPOFs) based surface plasmon resonance (SPR) sensors are fabricated and proposed for refractive index (RI) sensing. The RI sensing performances for the straight and U-shape TPOFs probes are compared, and the influences of the taper ratios and Au-film coating methods, horizontal and vertical coating, on the RI sensing performance for the U-shape probes are investigated experimentally. The experimental results show that the proposed sensor has a good linearity, and a sensitivity of 1534.53 nm/RIU in the RI sensing range of 1.335–1.41 can be obtained for the U-shape probe with taper ratio of 6.7 and vertical coating of Au film. The proposed probe has the advantages of easy fabrication and simple structure, which has potential applications in fields of biochemical sensing.

Investigation of Focusing Properties of Probes for Pulsed Eddy Current Testing

Pulsed eddy current testing (PECT) for detecting localized corrosion and wall thinning in the pipeline under insulation has attracted much attention. In this paper, cylindrical and U-shaped PECT probes are used and their focusing properties are studied by simulations and experiments. In the simulations, the focusing properties of these two types of probes are compared by analyzing the gathering degree of the eddy currents, which is closely related to the detection sensitivity of a probe to localized defects. The focusing region of eddy currents of a cylindrical probe is not under the center of the probe while that of a U-shaped probe is. The power dissipated by the eddy currents is introduced to quantitatively characterize the focusing performance of the probe. The simulation results indicate that the U-shaped probe achieves a much better focusing performance of eddy currents than the cylindrical probe. The experimental results show that the two probes designed can effectively detect the localized corrosion of non-magnetic stainless-steel plates under certain lift-off distances and the U-shaped probe has higher detection sensitivity than the cylindrical probe. The research results are helpful for the optimization of the PECT probe to detect localized corrosion.

U-Shaped Optical Fiber Probes Coated with Electrically Doped GQDs for Humidity Measurements.

The influence of the bending radius on the sensitivity of the graphene quantum dots (GQDs)-coated probe is experimentally investigated for a U-shaped probe. The fiber is bent into a U shape using the optic fiber flame heating method, and the optic fiber is enclosed in a glass tube to increase the stability of the probe. The surface of the U-shaped optical fiber was coated with electrospun fibers formed via electrospinning. Polymer materials doped with GQDs are applied to U-shaped optical fiber as humidity sensors. Graphene quantum dot nanofibers on the U-shaped optical fiber sensor to form a network structure of graphene quantum dots U-shape fiber sensor (GQDUS). The polymer network structure absorbs water molecules, which in turn affects the bending radius of the optical fiber, and changes the optical fiber spectrum. Graphene quantum dots provide optical enhancement benefits, which in turn increase the sensitivity of fiber optic sensors. The spectra monitoring system consists of an optical spectrum analyzer (OSA) and an amplified spontaneous emission (ASE). This system can be used to detect humidity changes between 20% RH and 80% RH in the chamber. Our results indicate promising applications for quantum dots probe sensors from electrospun nanofibers increasing sensitive environmental monitoring. As such, it could be of substantial value in optical sensors detection.

Direct contact evanescent wave absorption enabled fiber optic refractive index sensor operating in the dynamic range of 20 °C to 60 °C

The study of refractive index provides the complete picture of material bodies with reference to their major properties like physical, chemical, optical, etc., and hence decides the behavior of the material body at macro level. Measurement of refractive index in small volume samples using a U-shaped extrinsic fiber optic sensor based on the principle of direct contact evanescent wave absorption can be employed to detect such information. In order to obtain such measurements, a U-shaped glass probe connected between a light transmitter and an optical detector using two PCS multimode optical fibers of the same diameters (200/230 μm) was developed and investigated in the present study. Liquid mixtures prepared using Toluene and Acetic acid taking at different proportions making total volume equivalent to 20 ml employing a two burette system. When the liquid mixtures are applied on the U-shaped probe the light reaching the detector from the source was shown varying depending upon the refractive index of the mixture. The changes in the transmitted power spectra were measured as a function of absorption of higher order evanescent wave modes at various refractive index values at different temperature levels ranging from 20 °C to 60 °C of the mixture and by repeating the experiment with various operating wavelengths (630 nm, 660 nm, 820 nm & 850 nm). The calibrated curves were plotted, which can be used to determine the refractive index of liquids at various temperatures with high degree of accuracy, precision and sensitivity measurements, exploiting all the benefits offered by the optical fiber communication systems.

Comprehensive Study and Experimental Validation of U-shaped Probe Extrinsic Fiber Optic Sensor for the Measurement of Refractive Index at Various Temperatures using a Tunable Light Source

Extensive detection performances due to sensitivity to external and internal perturbations in the fiber structure makes the optical fiber sensors highly superior over the conventional sensors. The fiber optic sensors with clad removed fibers at some portion along its length play a vital role in the determination of refractive index of various liquids at several wavelengths and at several temperatures. In the present paper a refractive index sensor has been developed to investigate the performance and experimental validation in the measurement of R.I. values of liquids at various temperatures using a tunable light source capable of emitting light at the wavelengths of 630nm, 660nm, 820nm and 850nm. The U-shaped glass probe connected between the tunable light source and an optical detector using two multimode PCS fibers of 200/230μm, acts as a clad removed portion of the sensor which is called as sensing zone or sensing region. In the working principle of the sensor, the U-shaped glass rod immersed into each mixture prepared with the combination of Toluene and Acetonitrile, the light launched from the source reaching the detector was noted at various temperatures and by tuning the wavelength of the source to 630nm, 660nm, 820nm and 850nm. From the data obtained, the sensor was calibrated to measure the refractive index of various liquids at different temperatures and wavelengths. Exploiting all the advantages offered by the fiber optic communication systems, the sensor was expected to be rugged, robust, reliable, and durable offering the sensitivity in the range of the order of 10-5.

Implementation of U-Shaped Probe in the Construction of a Fiber Optic Sensor to Determine the Refractive Index of Liquids in the dynamic Range of 300C to 600C

Implementation of U-Shaped Probe in the Construction of a Fiber Optic Sensor to Determine the Refractive Index of Liquids in the dynamic Range of 300C to 600C

Light-sheet skew rays enhanced U-shaped fiber-optic fluorescent immunosensor for Microcystin-LR

A novel U-shaped fiber-optic evanescent-wave fluorescent immunosensor was designed that exploits light-sheet excitation of skew rays in a passive fiber for sensitive microcystin-LR (MC-LR) detection in real-time. In particular, a light sheet comprising a thin plane of light can be concentrated into exciting the optimum ray group, resulting in enhanced interaction between light and fluorophores. Meanwhile, skew rays excited by transmitting light into an optical fiber with an angle offset allow a much higher number of total-internal-reflections with increased interaction length along the fiber interface, which strengthens the light-matter interactions. Under the optimal angle offset, the proposed evanescent wave fluorescent immunosensor is the first demonstration of integrating light-sheet skew rays and a U-shaped fiber-optic probe for enhanced sensitivity. The results show that fluorescence sensitivity of the U-shaped fiber-optic probe with light-sheet skew rays excitation is 16 times higher than that of collimated skew rays excitation. Combined with this newly designed light-sheet skew rays enhanced U-shaped fiber-optic fluorescent immunosensor, a sensitive and real-time MC-LR detection method was established based on the indirect competitive immunoassay principle. Real environmental water samples spiked with MC-LR were determined by the immunosensor with recovery rates between 85% and 112%. The present system could be an alternative tool for the on-site environmental monitoring, in-field food safety assurance and clinical diagnostics. It also advances the fiber-optic sensors field in terms of experimental design.

Interaction of temperature fields in an unlimited array of soil during the selection of low-grade heat by U-shaped probes of a geothermal heat pump units

The methodology and results of mathematical modeling of the unsteady process of selecting low-grade soil heat with a vertical U-shaped geothermal probe placed in a well of heat pump units (HPU), the free space of which is filled with a heat-conducting filler, are presented. The developed mathematical model is based on the joint use of two classical analytical methods: a source-drain adapted to the unsteady process of heat extraction from an unlimited soil mass, and a superposition method that allows one to quantify the effect of the interaction of the temperature fields of the downpipe and the riser pipe laid at a small distance from each other in one well. As a result, the main calculated dependencies underlying the developed mathematical model on which the computational experiment was performed were obtained analytically. The results of a computational experiment, performed on the example of a well with a vertical U-shaped soil probe, designed to select low-grade heat from an unlimited array of dry sand, are presented in graphs. An analysis of the results made it possible to identify the main factors affecting the intensity of heat extraction, justify the conditions for the effective operation of U-shaped probes in the wells of the soil contour of heat pump units, and quantitatively determine the maximum allowable temperature increment of the heated coolant according to the condition of efficient use of the heat transfer surface.

The use of doped conductive bionic muscle nanofibers in a tennis racket–shaped optical fiber humidity sensor

This study introduces a unique method for the production of a highly sensitive tennis racket-shaped optical fiber humidity sensor consisting of a U-shaped probe and electrospun functional nanofibers. Functional nanofibers of the racket consist of conjugated polymers prepared through a mixture of two kinds of polymer molecules electrospun in an electric field of about 1.7 kV/cm. Interpenetrating polymer networks were fabricated through electrospinning, for which a polymer solution of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) doped in polyvinyl alcohol (PVA) was used. The hydrogen-bonding interaction of the interpenetrating polymer networks/H2O plays a major role in increasing the sensitivity of the humidity sensor. The sensitivity of the sensor was found to be −0.990 nm/%RH, which was 16.02 % greater than that of undoped PEDOT:PSS PVA nanofibers.