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Electromagnetic tracking (EMT) can benefit image-guided interventions in cases where line of sight is unavailable. However, EMT can suffer from electromagnetic distortion in the presence of metal instruments. Metal instruments are widely used in laparoscopic surgery, ENT surgery, arthroscopy and many other clinical applications. In this work, we investigate the feasibility of tracking such metal instruments by placing the inductive sensor within the instrument shaft. We propose a magnetostatic model of the field within the instrument, and verify the results experimentally for frequencies from 6 kHz to 60 kHz. The impact of the instrument's dimensions, conductivity and transmitting field frequency is quantified for ranges representative of typical metal instruments used in image-guided interventions. We then performed tracking using the open-source Anser EMT system and quantify the error caused by the presence of the rod as a function of the frequency of the eight emitting coils for the system. The work clearly demonstrates why smaller tool diameters (less than 8 mm) are less susceptible to distortion, as well as identifying optimal frequencies (1 kHz to 2 kHz) for transmitter design to minimise for distortion in larger instruments. [ABSTRACT FROM AUTHOR]

Inductive contact force sensors, known for their high precision and anti-interference capabilities, hold significant potential applications in fields such as wearable and medical monitoring devices. Most of the current research on inductive contact force sensors employed novel nanomaterials as sensitive elements to enhance their sensitivity and other performance characteristics. However, sensors developed through such methods typically involve complex preparation processes, high costs, and difficulty in biodegradation, which limit their further development. This article introduces a new flexible inductive contact force sensor using paper as a sensitive element. Paper inherently possesses micro- and nanostructures on its surface and interior, enabling it to sensitively convert changes in contact force into changes in displacement, making it suitable for use as the sensor's sensitive element. Additionally, the advantages of paper also include its great flexibility, low cost, wide availability, and biodegradability. Performance testing on this flexible sensor showed good repeatability, hysteresis, sensitivity, and consistency. When used in experiments for monitoring human motion and respiration, this sensor also exhibited great detection performance. The proposed inductive paper-based flexible contact force sensor, with its simple structure, easy manufacturing process, cost-effectiveness, eco-friendliness, and good sensing performance, provides new insights into research for contact force sensors. [ABSTRACT FROM AUTHOR]

Electromagnetic tracking (EMT) can benefit image-guided interventions in cases where line of sight is unavailable. However, EMT can suffer from electromagnetic distortion in the presence of metal instruments. Metal instruments are widely used in laparoscopic surgery, ENT surgery, arthroscopy and many other clinical applications. In this work, we investigate the feasibility of tracking such metal instruments by placing the inductive sensor within the instrument shaft. We propose a magnetostatic model of the field within the instrument, and verify the results experimentally for frequencies from 6 kHz to 60 kHz. The impact of the instrument’s dimensions, conductivity and transmitting field frequency is quantified for ranges representative of typical metal instruments used in image-guided interventions. We then performed tracking using the open-source Anser EMT system and quantify the error caused by the presence of the rod as a function of the frequency of the eight emitting coils for the system. The work clearly demonstrates why smaller tool diameters (less than 8 mm) are less susceptible to distortion, as well as identifying optimal frequencies (1 kHz to 2 kHz) for transmitter design to minimise for distortion in larger instruments.

Copyright of Journal of Vibration, Measurement & Diagnosis is the property of Nanjing Hangkong Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents a study on an electromagnetic inductive sensor for detecting and locating faults in protective coatings. The accuracy of the sensor was tested by means of periodic signals of various frequency. A number of measurements were performed for selected signals in order to select required frequencies and to determine the sensitivity and accuracy of the inductive sensor. The possibility of minimising measuring errors was also addressed. Once the frequency and shape of the signal is selected, a multi-frequency binary signal is generated for testing multi-layer anticorrosion coatings. Performing a measurement with a number of different frequencies at a time makes it possible to eliminate sources of errors, such as the necessity to repeat measurements at the same place. The measuring system employs the programming package DasyLab by National Instruments. [ABSTRACT FROM AUTHOR]

Inductive contact force sensors, known for their high precision and anti-interference capabilities, hold significant potential applications in fields such as wearable and medical monitoring devices. Most of the current research on inductive contact force sensors employed novel nanomaterials as sensitive elements to enhance their sensitivity and other performance characteristics. However, sensors developed through such methods typically involve complex preparation processes, high costs, and difficulty in biodegradation, which limit their further development. This article introduces a new flexible inductive contact force sensor using paper as a sensitive element. Paper inherently possesses micro- and nanostructures on its surface and interior, enabling it to sensitively convert changes in contact force into changes in displacement, making it suitable for use as the sensor’s sensitive element. Additionally, the advantages of paper also include its great flexibility, low cost, wide availability, and biodegradability. Performance testing on this flexible sensor showed good repeatability, hysteresis, sensitivity, and consistency. When used in experiments for monitoring human motion and respiration, this sensor also exhibited great detection performance. The proposed inductive paper-based flexible contact force sensor, with its simple structure, easy manufacturing process, cost-effectiveness, eco-friendliness, and good sensing performance, provides new insights into research for contact force sensors.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the prevalence of image-guided interventions increases, electromagnetic tracking (EMT) systems play an important role in modern patient care, as they enable real-time instrument positioning and navigation inside the human body without line-of-sight restrictions. Miniature-size inductive coils are the gold standard in clinical settings, as they provide accurate, passive sensing of the magnetic field. To compensate for their small dimensions, such sensors are designed with an elongated shape, where the coil length is usually 10 to 20 times larger than the diameter. In this article, the benefits of a field model based on the magnetic scalar potential formulation are demonstrated for EMT applications where elongated tracking sensors are used. The novel method resolves the single-point approximation error when the coil length is not negligible, and demonstrates improvements in terms of speed and storage requirements. A detailed analysis is proposed where alternative formulations of the magnetic model used in the tracking algorithm are compared. Although this work does not resolve any substantial limits of EMT used in a clinical environment, which are mainly caused by the presence of magnetic distortions, the proposed method is an improvement over existing EMT systems because it enables more accurate and faster tracking. The method might facilitate the use of longer tracking sensor coils which can achieve high sensitivities without the requirement of a magnetic core. In the envisioned application, such coils may be wound around flexible instruments, such as endoscopes or catheters.

We demonstrate how resonant planar coils may be used as sensors to detect and quantify magnetic nanoparticles reliably. A coil's resonant frequency depends on the adjacent materials' magnetic permeability and electric permittivity. A small number of nanoparticles dispersed on a supporting matrix on top of a planar coil circuit may thus be quantified. Such nanoparticle detection has application detection to create new devices to assess biomedicine, food quality assurance, and environmental control challenges. We developed a mathematical model for the inductive sensor response at radio frequencies to obtain the nanoparticles' mass from the self-resonance frequency of the coil. In the model, the calibration parameters only depend on the refraction index of the material around the coil, not on the separate magnetic permeability and electric permittivity. The model compares favourably with three-dimensional electromagnetic simulations and independent experimental measurements. The sensor can be scaled and automated in portable devices to measure small quantities of nanoparticles at a low cost. The resonant sensor combined with the mathematical model is a significant improvement over simple inductive sensors, which operate at smaller frequencies and do not have the required sensitivity, and oscillator-based inductive sensors, which focus on just magnetic permeability. [ABSTRACT FROM AUTHOR]

Monitoring the wear debris in lubricant systems is an effective method of reflecting the health of mechanical equipment. With the advantages of being simply structured, noninvasive, and insensitive to oil quality, inductive sensors are often deployed for debris detection. However, induced voltages generated by wear debris are usually contaminated by noise and other undesired components, thereby limiting the reliability and availability of the sensors. In this article, a new debris-detection framework is proposed based on an inductive sensor with parallel dual coils. With the aid of a reference signal, a multi-least-mean-square adaptive weighting filtering method was developed, and good noise suppression was achieved with little violation of the debris signatures. The algorithm is illustrated through numerical simulations, and the effectiveness of the proposed framework was verified by an oil experiment. Two traditional denoising algorithms were also analyzed for comparison. The experimental results demonstrated that the proposed strategy had an excellent capability for extracting and identifying debris features. [ABSTRACT FROM AUTHOR]

The use of information and measurement systems in the food industry can improve the quality of products, reduce the cost of equipment maintenance, and reduce the consumption of raw materials by reducing scrap. The production of ice cream with some changes is carried out according to the general technological scheme and consists of the following operations: receiving raw materials, preparing raw materials, assembling the mixture, pasteurizing the mixture, homogenizing the mixture, cooling and maturing the mixture, freezing the mixture, packaging and hardening, packaging and storage of ice cream. The use of modern instrumentation improves the accuracy of supporting the technological parameters of ice cream production. The developed system, due to the precise measurement of the movement parameters of the technological equipment and its more accurate positioning, allows reducing the time spent on the operation of equipment for ice cream packaging, helps to reduce the production of defective products. By reducing the time for packaging, eliminating equipment delays to eliminate the simultaneous entry of two or more packs of ice cream into the packaging machine, the rhythm of the packaging line is achieved. The Siemens S7-1200 controller was chosen as a programmable logic controller. The system was programmed using the standard software package Siemens TIA Portal V16. During the operation of the system, technological parameters are continuously monitored and, if deviations from normal values are detected, a warning sound and light alarm is activated with a text message displayed on the monitor screen, switching to backup equipment is performed and the main electric drives are turned off to protect equipment from possible damage.

The objective of this paper is to provide a solution to a serious issue in today's world of transportation through railways. The practice to examine the flaws which leads to serious effects in rail track is rail inspection. Among the world countries, Indian railways are the fourth-longest, but when it comes to reliability and safety it lags to provide world standard. As a result, if the track is damaged, it leads to severe loss of valuable human lives and property. This derailment in tracks is caused due to cracks in the rails. Therefore, an early crack detection and protection system is required to save the lives. This paper proposes a customized design of an inductive transducer and crack detection system on railroad tracks to avoid the train accidents. Existing method uses the manpower to identify the cracks and this involves human errors. So, the drawbacks in the existing method can be reduced by the automatic system. Customized inductive sensor is designed and developed using ANSYS. A scaled down model of a cart is fabricated and the inductive sensor is assembled at beneath surface of the cart. The track is acting as a part of the magnetic core for the inductive sensor and voltage is induced in the sensor. The sensor voltage is calibrated to distinguish the magnitude of voltage from the normal to crack. [ABSTRACT FROM AUTHOR]

Wear debris in lubrication oil provides important information for marine engine condition monitoring and faults diagnosis. Inductive sensors have been widely used to detect wear debris in lubrication oil. To improve the sensitivity, the inductive coil is always connected with a capacitor in parallel to form parallel LC resonance-sensing circuit. A previous study optimized the parallel resonance circuit by adjusting the excitation frequency. However, multiple parameters (namely, excitation signal, signal detection circuits, and signal-processing program, etc.) need to be adjusted accordingly for a series of the testing frequencies. To simplify the optimization, we propose a method based on adjusting the parallel capacitance in this work. The impedance (inductance and internal resistance) of the sensing coil and its variation induced by particles are first measured, which are the necessary parameters for establishing the function relationship between the parallel capacitance and the relative impedance variation. With the function relationship, the relative impedance variation is calculated directly, and the optimal capacitance is located at the highest absolute value of it. The experimental results for the ferrous and nonferrous particles match the calculation results well. Interestingly, the optimal capacitance for the nonferrous particle was larger than that of the ferrous particle. We speculate that the difference is generated due to the increased resistance induced by the eddy current effect. [ABSTRACT FROM AUTHOR]

As the prevalence of image-guided interventions increases, electromagnetic tracking (EMT) systems play an important role in modern patient care, as they enable real-time instrument positioning and navigation inside the human body without line-of-sight restrictions. Miniature-size inductive coils are the gold standard in clinical settings, as they provide accurate, passive sensing of the magnetic field. To compensate for their small dimensions, such sensors are designed with an elongated shape, where the coil length is usually 10 to 20 times larger than the diameter. In this article, the benefits of a field model based on the magnetic scalar potential formulation are demonstrated for EMT applications where elongated tracking sensors are used. The novel method resolves the single-point approximation error when the coil length is not negligible, and demonstrates improvements in terms of speed and storage requirements. A detailed analysis is proposed where alternative formulations of the magnetic model used in the tracking algorithm are compared. Although this work does not resolve any substantial limits of EMT used in a clinical environment, which are mainly caused by the presence of magnetic distortions, the proposed method is an improvement over existing EMT systems because it enables more accurate and faster tracking. The method might facilitate the use of longer tracking sensor coils which can achieve high sensitivities without the requirement of a magnetic core. In the envisioned application, such coils may be wound around flexible instruments, such as endoscopes or catheters. [ABSTRACT FROM AUTHOR]

Bio‐inspired soft robots provide a promising solution for robots working in human‐centered scenarios and interacting with unstructured environments. However, the functional versatility and multimodal sensing of soft robots still need improvements. On one hand, the configuration of a soft robot is predefined during manufacturing; on the other hand, the multimodal perception of the deformable soft actuator is challenging. In this work, a reconfigurable and proprioceptive soft origami module is presented, where two kinds of basic actuation modes (i.e., extension and bending) are realized, and multimodal perception is enabled using a novel foldable self‐inductance sensor. As a result, the origami module can be reconfigured to assemble multifunctional robots that can measure interaction force, body configuration, and other environmental information. Dedicated experiments are performed to validate the performance of the proposed origami module. An intelligent gripper assembled using three origami modules is designed with the capabilities of grasping mode adjustment, grasping force measurement, and the grasping target's size measurement. An intelligent jellyfish is assembled using five origami modules, and equipped with buoyancy adjustment and underwater grasping capabilities. The proposed proprioceptive modular soft origami provides an effective solution for versatile and intelligent soft robot design. [ABSTRACT FROM AUTHOR]

This paper presents a new water-level-sensing mechanism based on planar coils fabricated on a printed circuit board (PCB). In addition to level, the sensor detects any relative increase in conductivity compared to that of clean water, which is an indicator of its quality. The sensing mechanism utilizes the eddy current induced in the water column, the corresponding change in the coil inductance, and the change in the turn-to-turn capacitance of the coil in the presence of water. Although several level sensors are available, there is none that gives the level and quality information using a single sensing element. Since both water quantity and quality measurements are fundamental in realizing efficient water and wastewater management, obtaining these two parameters from the same sensor is very beneficial. A scalable, planar coil-based sensor that helps achieve this goal is designed, fabricated, and tested in a laboratory setting. The results illustrate that the reactance of the sensor coil measured at a frequency (1 kHz for the prototype) much lower than the self-resonance of the coil gives reliable information about the level of water, while the measurement made at resonance, using an inductance-to-digital converter, is a clear indicator of its conductivity and, hence, quality. [ABSTRACT FROM AUTHOR]

Bio‐inspired soft robots provide a promising solution for robots working in human‐centered scenarios and interacting with unstructured environments. However, the functional versatility and multimodal sensing of soft robots still need improvements. On one hand, the configuration of a soft robot is predefined during manufacturing; on the other hand, the multimodal perception of the deformable soft actuator is challenging. In this work, a reconfigurable and proprioceptive soft origami module is presented, where two kinds of basic actuation modes (i.e., extension and bending) are realized, and multimodal perception is enabled using a novel foldable self‐inductance sensor. As a result, the origami module can be reconfigured to assemble multifunctional robots that can measure interaction force, body configuration, and other environmental information. Dedicated experiments are performed to validate the performance of the proposed origami module. An intelligent gripper assembled using three origami modules is designed with the capabilities of grasping mode adjustment, grasping force measurement, and the grasping target's size measurement. An intelligent jellyfish is assembled using five origami modules, and equipped with buoyancy adjustment and underwater grasping capabilities. The proposed proprioceptive modular soft origami provides an effective solution for versatile and intelligent soft robot design.

Sensors based on chaotic oscillators have a simple design, combined with high sensitivity and energy efficiency. Among many developed schemes of such sensors, the promising one is based on the Duffing oscillator, which possesses a remarkable property of demonstrating chaotic oscillations only in the presence of a weak sine wave at the input. The main goal of this research was to evaluate the maximal sensitivity of a practically implemented metal detector based on the Duffing oscillator and compare its sensitivity with conventional sensors. To achieve high efficiency of the Duffing-based design, we proposed an algorithm which performs a bifurcation analysis of any chaotic system, classifies the oscillation modes and determines the system sensitivity to a change in different parameters. We apply the developed algorithm to improve the sensitivity of the electronic circuit implementing the Duffing oscillator, serving as a key part of a three-coil metal detector. We show that the developed design allows detecting the presence of metal objects near the coils more reliably than the conventional signal analysis techniques, and the developed detector is capable of sensing a large metal plate at distances up to 2.8 of the coil diameter, which can be considered a state-of-the-art result. [ABSTRACT FROM AUTHOR]

The spring structure is stretchable and resilient, enabling electronic devices to be highly stretchable and durable. However, spring objects composed of only soft materials cannot be maintained without a supporting rod inside the coil owing to self‐weight deformation. Therefore, a design strategy should be investigated. In this study, self‐maintaining spring structures with soft materials are designed using physical simulations and soft spring‐type electronic devices (a stretchable conductor, strain sensor, and pressure sensor) with little hysteresis are developed. The spring‐type electronic devices consist of a core–sheath structure, which is a core channel filled with liquid metal and a 3D‐printed elastomeric sheath. The spring‐type conductor can be stretched with a small force (1.25 N) and has a negligible resistance change for up to 400% strain and ≈5.5% resistance increase at 640% strain. Moreover, the inductance induced by the coil structure monotonically decreases in the range of 200% stretching. The device also has high durability with little change in the electrical characteristics during 1000 cycles of 100% stretching. Furthermore, an inductive pressure sensor can measure <250 Pa (50 mN) by compressing the spring. Spring‐type electronic devices composed of soft materials contribute to highly durable and stretchable sensors for robotic applications. [ABSTRACT FROM AUTHOR]

Lateral flow immunoassays for detecting biomarkers in body fluids are simple, quick, inexpensive point-of-care tests widely used in disease surveillance, such as during the coronavirus disease 2019 (COVID-19) pandemic. Improvements in sensitivity would increase their utility in healthcare, food safety, and environmental control. Recently, biofunctional magnetic nanoclusters have been used to selectively label target proteins, which allows their detection and quantification with a magneto-inductive sensor. This type of detector is easily integrated with the lateral flow immunoassay format. Pneumolysin is a cholesterol-dependent cytolysin and one of the most important protein virulence factors of pneumonia produced by Streptococcus pneumoniae. It is recognized as an important biomarker for diagnosis in urine samples. Pneumonia is the infectious disease that causes the most deaths globally, especially among children under five years and adults over 65 years, most of them in low- and middle-income countries. There especially, a rapid diagnostic urine test for pneumococcal pneumonia with high sensitivity and specificity would be helpful in primary care. In this work, a lateral flow immunoassay with magnetic nanoclusters conjugated to anti-pneumolysin antibodies was combined with two strategies to increase the technique's performance. First, magnetic concentration of the protein before the immunoassay was followed by quantification by means of a mobile telephone camera, and the inductive sensor resulted in detection limits as low as 0.57 ng (telephone camera) and 0.24 ng (inductive sensor) of pneumolysin per milliliter. Second, magnetic relocation of the particles within the test strip after the immunoassay was completed increased the detected signal by 20%. Such results obtained with portable devices are promising when compared to non-portable conventional pneumolysin detection techniques such as enzyme-linked immunosorbent assays. The combination and optimization of these approaches would have excellent application in point-of-care biodetection to reduce antibiotic misuse, hospitalizations, and deaths from community-acquired pneumonia. [ABSTRACT FROM AUTHOR]

Sorting of objects is the first step of a waste management process. These objects should be sorted according to the type of material for effective waste recycling. Therefore, the focus of this work is to design and produce an automated sorting machine that can be used to sort metals and non-metals autonomously. The automatic sorting machine with a smart digital counter was designed to use a microcontroller (Arduino Mega) to control the conveyor systems which consist of the conveyor support, driving unit and the driven unit. The sorting mechanisms consist of the inductive sensor, infrared Sensor and the actuating system using servo motor. The conveyor system helps in the conveyance of objects towards the sorting chute. The actuating system receives signal from the microcontroller and the device does the sorting of the objects based on their characteristics while the digital counter counts the number of metallic objects dropping into the designated cart. The time taken for the inductive sensor to sense an object, the waiting period for the servo motor to be actuated and the time taken for the counter to count after a metallic object is sensed are 1s, 2s and 1s respectively. After its development, it was tested and observed to meet the design requirements. [ABSTRACT FROM AUTHOR]

We demonstrate how resonant planar coils may be used as sensors to detect and quantify magnetic nanoparticles reliably. A coil’s resonant frequency depends on the adjacent materials’ magnetic permeability and electric permittivity. A small number of nanoparticles dispersed on a supporting matrix on top of a planar coil circuit may thus be quantified. Such nanoparticle detection has application detection to create new devices to assess biomedicine, food quality assurance, and environmental control challenges. We developed a mathematical model for the inductive sensor response at radio frequencies to obtain the nanoparticles’ mass from the self-resonance frequency of the coil. In the model, the calibration parameters only depend on the refraction index of the material around the coil, not on the separate magnetic permeability and electric permittivity. The model compares favourably with three-dimensional electromagnetic simulations and independent experimental measurements. The sensor can be scaled and automated in portable devices to measure small quantities of nanoparticles at a low cost. The resonant sensor combined with the mathematical model is a significant improvement over simple inductive sensors, which operate at smaller frequencies and do not have the required sensitivity, and oscillator-based inductive sensors, which focus on just magnetic permeability.

This articledevelops a novel probe-type inductive angular displacement sensor based on time-grating, which is suitable for large-diameter hollow rotary table position detection of the heavy-duty machine tools. It abandons the traditional sensor precise marking lines in spatial domain, and integrates the tested mechanical component with the sensor, which realizes the angular displacement measurement directly. The sensor is divided into three parts: 1) a permalloy probe, which is adopted the simple structure to reduce the assembly errors; 2) a 45-steel rotor, which is a standard spur gear in a heavy-duty machine tool rotary table transmission system; 3) three groups of copper coils, which include sinusoidal coils, cosine coils and inductive coils. The theoretical model of angular displacement measurement is derived by means of mathematical equation in detail. Then the feasibility of the sensor structure is verified by finite element simulation. After that, a sensor prototype is built and tested in the laboratory, showing that the sensor has an original error of ±0.018° (approximately ± $64^{\prime \prime }$) over a full 360° range. The error analysis found that the systematic error is the main component. As a result, the mechanical structure and angular displacement algorithm of the sensor are optimized, which can significantly reduce the original errors of the sensor. After optimization, the final accuracy of the sensor is within ±0.0012° (approximately ± $4.4^{\prime \prime }$) in the range of 0°–360°. [ABSTRACT FROM AUTHOR]

This paper proposes a new planar inductive sensor with printed circuit boards (PCB) based stator and rotor, which can perform more precision measurement than traditional inductive angular displacement sensors. The sensor uses PCB technique to realize accurately configured planar coils. The stator consists of a ferromagnetic base plate and a PCB with three groups of circular excitation coils and two groups of sine shape pickup coils working as two sense channels. The rotor consists of a ferromagnetic base plate and a PCB with two circles of copper pieces. Copper pieces on the rotor PCB produce eddy current in the time-varying magnetic field and alter the outputs of two sense channels of pickup coils cyclically with the rotor’s rotation. Two sense channels can make incremental angle measurement individually and work together to make absolute angle measurement. A prototype with 63 and 64 period sense channels was designed and developed for experiments, and test results show that it was finally examined with short-period error of $14.7^{\prime \prime }$ and full range error of $20.6^{\prime \prime }$ . The possessed characteristics of inductive principle, absolute measuring and good accuracy make this type of sensor is very suitable for high precision, reliable measurement in harsh environments.

The detection of metal particles in oil is of great significance to the fault diagnosis of mechanical equipment. Real domain detection methods cannot simultaneously identify the sizes and materials of particles. Because a metal particle in an alternating magnetic field induces a complex domain signal whose strength relates to the particle properties, this article introduces a double lock-in amplifier circuit (DLAC) into a triple-coil inductive particle sensor to detect the complex domain signal under noise interference conditions. Furthermore, various sizes of red copper, brass, aluminum, iron, and type 403 steel particles are chosen as the experimental materials. For the first time, the complex domain signals induced by the five kinds of particles are detected. Hence, in the complex plane, a method is proposed to identify the size and material of a particle based on the amplitude and phase of these signals. With the high sensitivity and strong antinoise ability of the DLAC, this system can detect 25- $\mu \text{m}$ iron particles and 70- $\mu \text{m}$ copper particles. This study presents a new strategy for the online detection of particles in oil. [ABSTRACT FROM AUTHOR]

With the advantages of high resolution, structural simplicity, reliability, compact size, and high sensitivity, inductive sensors have been widely used in nanopositioning systems. However, the measuring range of traditional inductive sensors are usually limited to 0.2 mm. A novel analysis and design methodology of the miniaturized inductive sensor with large measuring range and nanoscale resolution is proposed. Firstly, an accurate leakage inductance model is established. Secondly, a design rule of armature size is proposed by considering the fringing effect. Then, the error terms introduced by the measurement circuit of differential inductive sensors are analyzed and the corresponding error suppression methods are illustrated. Moreover, A design rule of selecting the optimal excitation frequency is proposed to meet the requirements of high Q value and high bandwidth, and to minimize the impact of core loss resistance on the performance of the sensor. Validated by the experiments, the proposed analysis and design method can effectively guide the design of the miniaturized inductive sensor with nanoscale resolution in the measuring range of ±0.5 mm. The overall size of the fabricated sensor prototypes is less than 6 mm × 6 mm × 3 mm. Combined with large range, high resolution and ideal miniaturization, this inductive sensor can be well suitable for compact and large stroke nanopositioning systems. [ABSTRACT FROM AUTHOR]

Axial movement measurement is required in various technical tasks. In a range up to several centimeters, inductive sensors are widely used. However, cheap on-the-shelf sensors often suffer from low sensitivity. Instead of them, linear potentiometers, inductive sensors with moving cores, linear magnetic encoders or laser systems are used, but these solutions have their own limitations and higher costs. In this paper, we propose an inductive sensor consisting of a planar coil included in a chaotic circuit based on the Cang system. Coil inductance serves as a bifurcation parameter. When the target moves towards the coil and inductance accordingly changes, the phase volume of system attractor also changes. Nonlinearity of this system allows obtaining a steeper sensitivity characteristic comparing with a harmonic oscillator. The phase volume can be easily measured using analog means, which results in completely analog sensor design. We show that such a system is able to perform proximity measuring tasks with adjustable range and high accuracy.

Inductive oil debris sensors have been widely used in the health monitoring of mechanical equipment. Such sensors are important for fault diagnosis, life prediction, and prevention of catastrophic failures. In this article, the concept that the residual voltage caused by the asymmetry of two incentive coils hinders the improvement of the sensor resolution is theoretically demonstrated for the first time. In order to achieve ultrasensitive detection, a novel two-stage autoasymmetrical compensation circuit (AACC) is introduced into the triple-coil debris sensor to automatically suppress the residual voltage in real time. The experimental results show the successful detection of 70 μm (diameter or D) ferrous particles and 165 μm (D) nonferrous particles in a sensing channel with a diameter of 43 mm. The AACC is verified effectively to maintain the residual voltage at an ultrasmall value even in the presence of environmental fluctuations, and the sensitivity of the sensor using AACC is more than 31 times that of the sensor without AACC. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Machine operating conditions can be obtained through lubrication oil detection; solid metal particles are the primary factor causing mechanical wear. The surface of the friction pair is usually specially treated with the nonferrous metal protective coating. Therefore, there are many kinds of nonferrous particles in the lubricating oil. In this paper, a method for measurement of nonferrous particles sizes independent of materials using the impedance signal of the inductive sensor is presented. Both the imaginary part and real part of the coil impedance signal are studied in this paper, which is different from traditional inductive sensor research only the imaginary part of impedance signal output is considered. Through theoretical analysis, it is found that the real and imaginary parts of coil impedance changes with different materials at the same size are corresponding to an elliptic function. Combining with the coil impedance measured in the experiment, the particle size can be obtained, which is independent of particle material. [ABSTRACT FROM AUTHOR]

Wear debris in lubrication oil provides important information for marine engine condition monitoring and faults diagnosis. Inductive sensors have been widely used to detect wear debris in lubrication oil. To improve the sensitivity, the inductive coil is always connected with a capacitor in parallel to form parallel LC resonance-sensing circuit. A previous study optimized the parallel resonance circuit by adjusting the excitation frequency. However, multiple parameters (namely, excitation signal, signal detection circuits, and signal-processing program, etc.) need to be adjusted accordingly for a series of the testing frequencies. To simplify the optimization, we propose a method based on adjusting the parallel capacitance in this work. The impedance (inductance and internal resistance) of the sensing coil and its variation induced by particles are first measured, which are the necessary parameters for establishing the function relationship between the parallel capacitance and the relative impedance variation. With the function relationship, the relative impedance variation is calculated directly, and the optimal capacitance is located at the highest absolute value of it. The experimental results for the ferrous and nonferrous particles match the calculation results well. Interestingly, the optimal capacitance for the nonferrous particle was larger than that of the ferrous particle. We speculate that the difference is generated due to the increased resistance induced by the eddy current effect.

In this study, a magnetic sensing approach is proposed for detecting air bubbles in intravenous fluids (IVs). To the author's knowledge, this is the first paper to apply magnetic sensing technology for the detection of air bubbles in an IV fluid. The approach is based on a compact, portable, and cost-effective sensor prototype that utilizes an LC resonator and a microcontroller. To validate the detecting system, an IV fluid containing air bubbles is passed through a medical tube, and the tube is passed over a planar coil. The magnetic interaction during the flow of the IV fluid with air bubbles is monitored and logging in real time. Air bubbles of 38, 44, 63 and 75 mm3 in IV fluid were successfully detected by the proposed sensing approach. Besides, the detection system is able to determine the flow direction, which is not encountered in alternatives such as capacitive sensing. The measurements from the established test setup, an average air bubble of 28 mm3 causes an inductance variation of approximately 2.8 nH. [Display omitted] • The proposed inductive sensing tech. detects the flow direction as well as the air bubbles. • One sensor, two detections: 1) Air bubbles and 2) Flow direction. • No need for ready-made instruments, easy integration into health devices. • Simple architecture enables wide application feasibility. • Cost-effective compared to alternatives, ideal for healthcare facilities. [ABSTRACT FROM AUTHOR]

A remote and non-invasive diagnostic of the plasma focus using antennas is presented in this work. The main motivation is the application of such diagnostic in a miniaturized plasma accelerator, based on the plasma focus architecture, as a cube satellite thruster. The evaluation of this proposal was carried out measuring a hundred of joules plasma focus operation simultaneously with the inductive measurement and antennas. Three different antennas tuned in the ultra high frequency range were tested: a monopole, Vivaldi and helical. The high frequency transients detected with the antennas were time correlated to the known inductive measurement features. The initial dielectric breakdown and later plasma pinch and subsequent disruption (i.e. the source of the propulsion) were identified to be the principal phenomena to be detected. Signal parameter correlations between the inductive sensor and the antennas showed that the pinch phenomena can be correlated with the antenna signals. Good correlation results were obtained with the monopole antenna when using peak value and signal energy parameter from the antenna transient. An improvement in the correlation results, for the helical and Vivaldi antennas, was obtained when calculating the frequency band energy. In this case, the Vivaldi antenna achieved the best results. The results of the monopole antenna make it an alternative remote sensor for plasma focus, but for the application of a miniaturized plasma focus as pulsed plasma thruster, the Vivaldi antenna is a more feasible design to replace the inductive diagnostic due to its compact design in comparison to the monopole.

This paper presents a new water-level-sensing mechanism based on planar coils fabricated on a printed circuit board (PCB). In addition to level, the sensor detects any relative increase in conductivity compared to that of clean water, which is an indicator of its quality. The sensing mechanism utilizes the eddy current induced in the water column, the corresponding change in the coil inductance, and the change in the turn-to-turn capacitance of the coil in the presence of water. Although several level sensors are available, there is none that gives the level and quality information using a single sensing element. Since both water quantity and quality measurements are fundamental in realizing efficient water and wastewater management, obtaining these two parameters from the same sensor is very beneficial. A scalable, planar coil-based sensor that helps achieve this goal is designed, fabricated, and tested in a laboratory setting. The results illustrate that the reactance of the sensor coil measured at a frequency (1 kHz for the prototype) much lower than the self-resonance of the coil gives reliable information about the level of water, while the measurement made at resonance, using an inductance-to-digital converter, is a clear indicator of its conductivity and, hence, quality.

Sensors based on chaotic oscillators have a simple design, combined with high sensitivity and energy efficiency. Among many developed schemes of such sensors, the promising one is based on the Duffing oscillator, which possesses a remarkable property of demonstrating chaotic oscillations only in the presence of a weak sine wave at the input. The main goal of this research was to evaluate the maximal sensitivity of a practically implemented metal detector based on the Duffing oscillator and compare its sensitivity with conventional sensors. To achieve high efficiency of the Duffing-based design, we proposed an algorithm which performs a bifurcation analysis of any chaotic system, classifies the oscillation modes and determines the system sensitivity to a change in different parameters. We apply the developed algorithm to improve the sensitivity of the electronic circuit implementing the Duffing oscillator, serving as a key part of a three-coil metal detector. We show that the developed design allows detecting the presence of metal objects near the coils more reliably than the conventional signal analysis techniques, and the developed detector is capable of sensing a large metal plate at distances up to 2.8 of the coil diameter, which can be considered a state-of-the-art result.

Lateral flow immunoassays for detecting biomarkers in body fluids are simple, quick, inexpensive point-of-care tests widely used in disease surveillance, such as during the coronavirus disease 2019 (COVID-19) pandemic. Improvements in sensitivity would increase their utility in healthcare, food safety, and environmental control. Recently, biofunctional magnetic nanoclusters have been used to selectively label target proteins, which allows their detection and quantification with a magneto-inductive sensor. This type of detector is easily integrated with the lateral flow immunoassay format. Pneumolysin is a cholesterol-dependent cytolysin and one of the most important protein virulence factors of pneumonia produced by Streptococcus pneumoniae. It is recognized as an important biomarker for diagnosis in urine samples. Pneumonia is the infectious disease that causes the most deaths globally, especially among children under five years and adults over 65 years, most of them in low- and middle-income countries. There especially, a rapid diagnostic urine test for pneumococcal pneumonia with high sensitivity and specificity would be helpful in primary care. In this work, a lateral flow immunoassay with magnetic nanoclusters conjugated to anti-pneumolysin antibodies was combined with two strategies to increase the technique’s performance. First, magnetic concentration of the protein before the immunoassay was followed by quantification by means of a mobile telephone camera, and the inductive sensor resulted in detection limits as low as 0.57 ng (telephone camera) and 0.24 ng (inductive sensor) of pneumolysin per milliliter. Second, magnetic relocation of the particles within the test strip after the immunoassay was completed increased the detected signal by 20%. Such results obtained with portable devices are promising when compared to non-portable conventional pneumolysin detection techniques such as enzyme-linked immunosorbent assays. The combination and optimization of these approaches would have excellent application in point-of-care biodetection to reduce antibiotic misuse, hospitalizations, and deaths from community-acquired pneumonia.

Introduction: A sensor that detects changes in prosthetic socket fit before they manifest clinically may be helpful towards rehabilitation after limb amputation. Materials and Methods: Participants with transtibial amputation walked on a treadmill wearing a motor-driven, cabled-panel adjustable socket. Socket volume was slowly adjusted away from the neutral socket volume (panels flush). The percent socket volume change at which the practitioner, using visual assessment, first noted fit issues was compared with the percent socket volume change at which the sensor first detected a measurable change in fit. Results: The median percent socket volume change at which the sensor first detected a measurable socket enlargement (0.50%) was significantly less than both the median percent socket volume change at which the research practitioner first noted a change in fit (1.69%) (P = 0.008) and the median percent socket volume change at which the participant would normally add a sock (2.30%) (P = 0.005). During socket reduction, the practitioner noted a change in fit before the participant would normally remove a sock in only 2 of 10 participants. The median percent socket volume change at which the sensor first detected a measurable socket reduction (−0.44%) was significantly smaller in absolute value than the median percent socket volume change at which the participant would normally remove a sock (−2.76%) (P = 0.005). Conclusions: The sensor detected controlled socket fit changes before the research practitioner in this study. A next step will be to determine if the sensor detects unforced socket fit changes, and changes in user free-living environments. [ABSTRACT FROM AUTHOR]

As the working medium of machine, lubrication oil system is a very important component, which can be used to judge the operating conditions of machine, moreover, lubricating oil detection can eliminate the need for costly machine shutdowns for inspection. Metal particle is the most important parameter in lubrication oil detection. Inductance detection is one of the commonly used metal particle detection methods, with the development of micro fabrication technology, which can measure the sizes of metal particles and count the particles. In this paper, the model of ferromagnetic metal particle detection is established based on micro inductive sensor. It is obtained that the inductance change rate is proportional to the magnetic permeability of the metal particle and the cube of the particle size of metal particle. The tests about the metal particles with five different diameters are carried out, it is obtained that the theoretical values are in good agreement with the experimental values, the relative errors are less than 9.47%. And combined with experimental research, the magnetic permeability of ferromagnetic metal particles $\mu \,\,3.907\times 10^{4}$ H/m, $4.246\times 10^{4}$ H/m, $4.092\times 10^{4}$ H/m, $3.718\times 10^{4}$ H/m, $4.07\times 10^{4}$ H/m and $4.4289\times 10^{4}$ H/m is obtained when the radii of particles are $25~\mu \text{m}$ , $50~\mu \text{m}$ , $100~\mu \text{m}$ , $200~\mu \text{m}$ , $500~\mu \text{m}$ and 1 mm, the relative errors ${E}_{\text{r}}=\vert 1- \mu {/} \mu _{\text{AVG}} \vert $ are less than 8.82%. [ABSTRACT FROM AUTHOR]

This paper describes a position sensor with six degrees of freedom (DoF) measurement capability. This sensor is designed for the position sensing of the rotor in a bearingless slice motor to enable active control. The sensor is designed to fit entirely under the rotor and operates by accessing the rotor bottom surface only, enabling packaging of the pump on the top of the rotor. The sensor has two parts; both operate using eddy currents. One of these parts measures the two radial DoF of the rotor. The other part measures the axial, angular rotation and tip/tilt DoF. The sensor utilizes a conductive target fixed to the underside of the rotor. Motion of this target varies the magnetic fields which can then be measured by the sensor as variation in either induced voltage or inductance value. The design and fabrication of the sensor along with the signal processing methods are presented in detail. The radial position measurements are the most critical for active levitation due to the small working gaps in these DoF, hence a resolution of < 1.2 ​   μ m and bandwidth of 1 kHz is achieved. This paper also describes the closed-loop behavior of a bearingless motor using this sensor.

Research on the implementation of inductive proximity sensors in active magnetic bearings is performed in this paper. LDC1000 digital sensors manufactured by Texas Instruments are used since they claim to provide precision measured in microns and simple acquisition of the output data. The Sensor chip is connected with the sensing coil which is placed inside the magnetic bearing, close to electromagnets. This newly developed system created a platform for research in signal quality and its resistance to electrical noise. The controller used in this application was Texas Instruments TMS320F28335 digital signal processor (DSP). Software for data acquisition from LDC1000 was written and implemented in DSP using Code Composer Studio development environment. Two different output data are acquired and processed: proximity data and frequency count. Graphs presented in this paper show different resistance to electrical noise. A conclusion derived from this research can be applied in an industry where electromagnetic noise exists, together with the need for precise distance measurement.

This paper presents a system solution for precise and reliable measurement of the turbomotor angular velocity in a wide dynamic range, from 10.000 to 95.000 rpm. Special attention is dedicated for selection of sensor element and hardware implementation for conditioning the signal obtained at the output of a sensor operating in the environment in which are present exhaust gases, high mechanical vibrations and big temperature changes. The accuracy of implemented system is better than ±0,45% on the whole measuring range.