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Nanobiosensors contribute to point-of-care (POC) efforts to make routine biodiagnostics more accessible to patients with respect to both expense and convenience. However, devices whose operation is based on magnetic phenomena appear delayed in their progress toward POC commercialization despite their promise of better sensitivity, as compared to devices based on optical, mechanical, or electrochemical phenomena. This review aims to elucidate the technical challenges preventing magnetic nanobiosensors from reaching market readiness. The following types of magnetic nanobiosensor operation are reviewed: giant magnetic impedance (GMI), superconducting quantum interference device (SQUID), anisotropic magnetoresistance, giant magnetoresistance (GMR), resonant coil, Hall effect, and microcantilever. In particular, a careful comparison of each type in terms of their advantages, disadvantages, recently overcome challenges, and sensitivities will be presented. For example, a disadvantage of GMI sensors, and certain others reviewed here, is the fact that ferromagnetic materials used in their construction directly impact the biosensing event since magnetic nanoparticle (MNP) labels are involved in the strategy. Other challenges associated with use of MNP labels will be addressed. Furthermore, some of the more interesting state-of-the-art magnetic nanobiosensor efforts will be discussed in order to provide an overview of target analytes and sample media under consideration. This review identifies GMR sensors as poised to dominate the market owing to their good sensitivity and ease of use. On the other hand, SQUID sensors, at their current stage of development, are revealed as unsuitable for POC applications due to their high operational cost and unwieldy instrumentation. Magnetics experts endeavoring to progress the field toward commercialization will find this review indispensable.

To ensure safety, vehicle companies require position sensors that maintain accuracy and avoid target loss even in harsh automotive environments. Most vehicle position sensors are Hall-based, but even improved gradiometric 3D Hall sensors using the arctangent operation are vulnerable to external magnetic fields (EXMFs) and encounter difficulty at long-stroke (LS) positions. An ISO26262-compliant inductive position sensor (IPS) employing a 3.5 MHz-induced magnetic field source (much higher in frequency than vehicle–environment EXMFs) is proposed in this study as an alternative. To meet the safety goal, a threshold LS distance of 12 mm was set. Then the IPS was compared to existing Hall-based sensors. The B field of the existing 3D sensor was weak at LS and the airgap between sensor face and magnet target caused a large error in accuracy, whereas the IPS was not affected by LS. Because of its high excitation frequency, the IPS was also largely unaffected by EXMFs, as was demonstrated by ISO11452-8 and 0.1 T immunity tests. The proposed IPS outperformed existing 3D Hall sensors, achieving stable accuracy within ±0.85% for different airgaps (1.5–2.5 mm) and proving robust to magnetic and LS effects.

This paper reviews the application of Hall position sensors in control and position estimation of permanent magnet synchronous motors (PMSMs). Accurate rotor position and motor speed data are essential for the high-efficiency control of PMSMs in modern industry. Rotor position and motor speed can be measured by mechanical position sensors, which are costly and less reliable, or by rotor position observers, which are sensitive to system models and changes in motor parameters. This paper examines the benefits, limitations, challenges, and uses of low-resolution Hall position sensors in PMSM drives, presenting them as a cost-effective solution for achieving a balance between performance and expense. In addition, the paper discusses recent solutions to issues related to misplaced Hall position sensors and fault-tolerant control algorithms, and gives an outlook to future developments in this area.

In order to improve the reliability, safety and whole digestive applicability of the gastrointestinal microrobot (GMR), a novel inchworm-like GMR is proposed in this paper. The expanding mechanism of the robot adopts an overlapping expanding arm structure. This structure increases the variable diameter ratio (ratio of fully expanded diameter to fully folded diameter) of the robot to 3.3, making the robot more applicable to the intestines in various parts of the human body. The mechanical model of the expanding arm is established, and the expanding force at different expanding radii is obtained. And then the expanding force is tested by a force test platform. The force test results: the maximum expanding force is 6.5 N, and the minimum expanding force is 1.3 N. The trend of the experimental and theoretical values is the same, and the experimental value is less than the theoretical value. A position limiting device based on Hall sensor is designed, which detects whether the mechanism reaches the limit position by non-contact method. This device alleviates the problem of sharp voltage drop caused by motor stall and improves the stability of the control circuit. The results of the Hall-type position limiting device (HPLD) testing show that the working currents of the expanding mechanism and the telescoping mechanism with HPLD are respectively 0.066A and 0.110A, and the robot control circuit works stably. Finally, the robot is tested in the intestine of the living pig, and the safety and reliability of the robot are verified. However, due to the decrease of the efficiency of wireless power transmission in vivo experiments and the change of the position of the receiving coil relative to the transmitting coil, sometimes the power supply is insufficient.

In this study, a simple, adjustable, bidirectional tilt sensor was designed using a pair of linear Hall effect sensors and magnets. Theoretical analysis and experimental results of the sensor system were presented. The working principle of the designed sensor is based on sensing the magnetic field of a mobile magnet which displaces with respect to the tilt angle. Two magnet sets were placed at the two ends of the system to apply repulsive restoring forces on the mobile magnet. The mobile magnet was coated with a light hydrocarbon based ferrofluid as a lubricant to reduce friction. Fixed Hall effect sensors were placed face to face at the two sides of the mobile magnet to monitor the magnetic field of the mobile magnet. It was shown that both experimentally and theoretically, it is possible to measure the approximate tilt angle linearly and quadratically by calculating the sum and difference of the Hall sensor voltages for the relatively small movements of the mobile magnet. Moreover, the system was also examined for the different sets of side magnets. For three different side magnet configurations, approximately 0.7, 1.1 and 1.68 V/rad sensitivity values were observed in the linear range.

Self-inoculation takes major part for the transmission of infections. Basically self-inoculation is nothing but a type of contact transmission. A person’s contaminated hands make contact with other parts of the body by Self-inoculation. Many infections mainly respiratory infections (e.g., influenza, coronavirus) can transmit via self-inoculation. In this pandemic situation it is very necessary to resist the transmission of infection (corona virus) via self-inoculation. In this paper a module of personal protective intelligent hat has been proposed for the protection of human being. The protective intelligent hat fabricates with two ends (i) Face Side End System (FSES) and (ii) Hand Side End System (HSES). FSES is made up with hall sensor whereas HSES is set up with magnet set ring or band. The novel corona virus enters the human body by eyes, nose and mouth when all are touched by infected hand. Avoid touching of contaminated hand is one of the key to survive from the attack of corona virus as well as other bacteria. The smart hat not only applicable to protect COVID-19, it is also applicable to protect various diseases which caused by contaminated hand like Influenza, Common cold, Chicken Pox etc.

This manuscript analyzes the effects of design parameters, such as aspect ratio, doping concentration and bias, on the performance of a general CMOS Hall sensor, with insight on current-related sensitivity, power consumption, and bandwidth. The article focuses on rectangular-shaped Hall probes since this is the most general geometry leading to shape-independent results. The devices are analyzed by means of 3D-TCAD simulations embedding galvanomagnetic transport model, which takes into account the Lorentz force acting on carriers due to a magnetic field. Simulation results define a set of trade-offs and design rules that can be used by electronic designers to conceive their own Hall probes.

Detection of corrosion at rivet sites in a multilayer structure of an aircraft is an essential task to ensure the flight safety of an aircraft. It is challenging to detect the corrosion due to the influence on the signal of the rivet and the multiple fastened layers in the structure. In this letter, an electromagnetic testing method is used in conjunction with principal component analysis (PCA) to detect corrosion around fasteners. Multiple Hall sensors were used for efficient measurement of the magnetic field distribution at the rivet sites. The features of the scanned magnetic image were automatically extracted by the PCA in orthogonal subspaces. The proposed method shows potential results of features extraction and corrosion signal extraction for further development of electromagnetic testing systems in multilayer engineering structures.

A kind of discrimination method of fault signal for wire rope of Multi-array weak magnetic inspection based on Hall Sensor was proposed to increase discrimination accuracy of fault signal for wire rope. Firstly, influence of motion speed for wire rope could be effectively overcome to use Hall Sensor, and a kind of undamaged detection system for wire rope based on Hall Array Sensor was designed. Accurate axial positioning of defects for wire rope can not only be realized for the system, but also defect detection of different axial positions can be realized, thus dimension of defect detection for wire rope is increased; Secondly, good detection effect was achieved through binarizing local grey value of leakage flux leakage data to realize quantitative analysis of defect size; finally, effectiveness of the algorithm was verified through simulation experiment.

A new wire rope tester based on principle of magnetic flux leakage is constructed. Two rings of NdFeB are cut in axial direction into 32 equal arc segments such that each arc segment subtends an angle of 22.5° at the centre. These arc segments are then parallely magnetized in magnetizer. A ferromagnetic cylinderical yoke is constructed by hinging two ferromagnetic half cylinders along one axial edge. A fixture consisting of a wooden square base, wooden mandrel, stepped and slotted Aluminium cylinder and Aluminium fillers is made to assemble the NdFeB magnets in a ring on both the ends of the ferromagnetic yoke. A Hall effect sensor is instrumented inside the yoke in the middle at radial distance of 34 mm from the axis of the yoke. A ferromagnetic wire rope with a defect is inserted in the novel wire rope tester. It has been successfully shown by performing Non-destructive testing that whenever a defect in a wire rope passes below the Hall-effect sensor instrumented in the wire rope tester developed in this work, a signal is generated indicating the defect.