technologia: Metal detector

Evidence: 100 • authority: 72

A metal detector is an instrument that detects the nearby presence of metal. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector typically consists of a control box, an adjustable shaft, and a variable-shaped pickup coil. When the coil nears metal, the control box signals its presence with a tone, numerical reading, light, or needle movement. Signal intensity typically increases with proximity or metal size and composition. A common type are stationary "walk through" metal detectors used at access points in prisons, courthouses, airports and psychiatric hospitals to detect concealed metal weapons on a person's body. The simples…

Evidence: 68 • authority: 72

A magnetometer is a device that measures magnetic field (B) or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of the magnetic B-field at a particular location. A compass is one such device, one that measures the direction of an ambient magnetic field, in this case, the Earth's magnetic field. Other magnetometers measure the magnetic dipole moment of a magnetic material such as a ferromagnet, for example by recording the effect of this magnetic dipole on the induced current in a coil. The invention of the magnetometer is usually credited to Carl Friedrich Gauss in 1832. Earlier, more primitive instruments were developed by Christo…

Evidence: 54 • authority: 72

An inductive sensor is an electronic device that operates based on the principle of electromagnetic induction to detect or measure nearby metallic objects. An inductor develops a magnetic field when an electric current flows through it; alternatively, a current will flow through a circuit containing an inductor when the magnetic field through it changes. This effect can be used to detect metallic objects that interact with a magnetic field. Non-metallic substances, such as liquids or some kinds of dirt, do not interact with the magnetic field, so an inductive sensor can operate in wet or dirty conditions.

Evidence: 54 • authority: 72

Spacecraft magnetometers are magnetometers used aboard spacecraft and satellites, mostly for scientific investigations, plus attitude sensing. Magnetometers are among the most widely used scientific instruments in exploratory and observation satellites. These instruments were instrumental in mapping the Van Allen radiation belts around Earth after its discovery by Explorer 1, and have detailed the magnetic fields of the Earth, Moon, Sun, Mars, Venus and other planets and moons. There are ongoing missions using magnetometers, including attempts to define the shape and activity of Saturn's core. The first spacecraft-borne magnetometer was placed on the Sputnik 3 spacecraft in 1958 and the mos…

Evidence: 54 • authority: 92

Live magnetomyography and robotic-hand proxy control using a wearable triaxial optically pumped magnetometer.. Zero-field optically pumped magnetometers (OPMs) represent a promising modality in biomagnetism research due to their ultra-sensitive capabilities contained within compact sensor packages that enable contactless biomagnetic measurements. In this study, we utilized a zero-field OPM to simultaneously measure three-axis components of biomagnetic fields produced by muscle activity in the human forearm caused through independent finger movements, with the goal of recognizing multiple gestures using only a single magnetic sensor. We recorded muscle activity caused by the opening and clos…

Evidence: 47 • authority: 88

Induction magnetometer using a high-Tc superconductor coil. An induction magnetometer consisting of a search coil and an inverting operational amplifier is simple in structure and in signal transferring mechanism from the magnetic field input to the voltage output. Because this magnetometer is based on Faraday’s law of induction, it has a lower cutoff frequency r/(2πL), where r is the resistance of the coil and L is its inductance. An attempt has been made to lower the cutoff frequency of the induction magnetometer by using a high-Tc superconductor coil. With a pancake coil (inner diameter ≈18 cm and outer diameter ≈23 cm, 92 turns, 3.23 mH) made of a Bismuth strontium calcium copper oxide…

Evidence: 47 • authority: 72

A MEMS magnetic field sensor is a small-scale microelectromechanical systems (MEMS) device for detecting and measuring magnetic fields (magnetometer). Many of these operate by detecting effects of the Lorentz force: a change in voltage or resonant frequency may be measured electronically, or a mechanical displacement may be measured optically. Compensation for temperature effects is necessary. Its use as a miniaturized compass may be one such simple example application.

Evidence: 39 • authority: 92

Optimized 90° Pulse for Fast Measurement of Overhauser Magnetometer.. Overhauser magnetometer (OVM) is a proton precession magnetometer (PM) enhanced by electron resonance, and it is widely used in earthquake prediction, UXO detection, geological exploration, etc. For fast measurement, high cycling rate is necessary for OVM to enhance spatial resolution. Due to the impossibility to receive Larmor signal during the polarization process, traditional intermittent measurement is limited in fast mobile measurement applications owing to the long polarization time. Since it is difficult for proton magnetization to align rapidly for the long longitudinal relaxation time of liquid proton, we combine…

Evidence: 39 • authority: 92

Inductive Microsensor for Magnetic Field Detection: Application in Wireless Power Transfer Systems.. Wireless Power Transfer (WPT) has emerged as a compelling alternative to wired charging; however, efficiency and safety are highly dependent on magnetic field distribution and leakage. This work presents a compact MEMS-based magnetic field induction sensor, including its design, fabrication, and electrical characterization, for real-time diagnosis in WPT systems. The sensor employs a Ni/Cr metallic inductor fabricated on a SiO 2 substrate using standard photolithography and occupies a footprint of 5 mm × 5 mm. The device is electrically characterized through impedance, quality factor, and fr…

Evidence: — • authority: 72

Demining or mine clearance is the process of removing land mines from an area. In military operations, the object is to rapidly clear a path through a minefield, and this is often done with devices such as mine plows and blast waves. By contrast, the goal of humanitarian demining is to remove all of the landmines to a given depth and make the land safe for human use. Specially trained dogs are also used to narrow down the search and verify that an area is cleared. Mechanical devices such as flails and excavators are sometimes used to clear mines. A great variety of methods for detecting landmines have been studied. These include electromagnetic methods, one of which (ground penetrating rada…

Evidence: — • authority: 72

An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in devices such as electric motors, generators, inductors, electromagnets, transformers, sensor coils such as in medical MRI imaging machines. Either an electric current is passed through the wire of the coil to generate a magnetic field, or conversely, an external time-varying magnetic field through the interior of the coil generates an EMF (voltage) in the conductor. A current through any conductor creates a circular magnetic field around the conductor due…

Evidence: — • authority: 92

Superconducting Quantum Magnetometers for Brain Investigations.. This review article aims to provide an overview of superconducting magnetic quantum sensors and their applications in the biomedical field, particularly in the neurological field. These quantum sensors are based on superconducting quantum interference devices (SQUIDs), the operating principles of which will be presented along with the most relevant characteristics. Emphasis will be placed on the magnetic flux and magnetic field noise, which are essential for applications, especially brain investigations requiring ultra-high magnetic field sensitivity. The main configurations of SQUID magnetometers used for highly sensitive app…