Fabrication Advancements in Integrated Fluxgate Sensors: A Mini Review

Abstract

Research on magnetic sensors has been carried out in recent years to enhance sensing capability, enabling us to understand the Earth's magnetic field changes [1] with better sensitivities of 10 À10 to 10 À2 T. [2] Magnetic field sensors have been extensively investigated according to their operating principles and actions in various applications. Sensitivity and selectivity are the two essential properties crucial in the evolution of magnetic field sensors to achieve high fidelity outputs. The former is strengthened by increasing the sensor area and improvements to the planar surface with various Nano-materials. In contrast, the latter is improved by using multiple materials and techniques to enhance interfacial interactions.Magnetic sensors detect disturbances and changes in magnetic fields such as force, direction, and flux. It is a transducer that converts a magnetic field into an electrical voltage. There are several types of magnetic field sensors, each with its own sensitivity range. In addition to sensitivity, the temperature range, the physical size of the sensor, and its on-chip manufacturability must all be considered. Magnetic fields of less than 100 pT are extremely weak and far below the earth's magnetic field. Earth magnetic field sensors have a sensitivity range of 10 μT to a few micro-Tesla, while bias magnet field (high field) sensors have a sensitivity of more than 1 mT.Magnetic fields of less than 100 pT are extremely weak and far below the earth's magnetic field. Earth magnetic field sensors have a sensitivity range of 10 μT to a few micro-Tesla, while bias magnet field (high field) sensors have a sensitivity of more than 1 mT. The most sensitive low-field sensor is the superconducting quantum interference device (SQUID). It is based on Brian J. Josephson's research on a point-contact connection for measuring extremely low currents.The SQUID ring, the radio-frequency coil, and the big antenna loop are all superconducting components of the SQUID sensor. All three must be cooled to the point where they become superconducting. The SQUID itself is small, but the requirement for liquid helium cooling makes the entire apparatus big and hefty. Magnetoresistive sensors (MR) have a high sensitivity, are inexpensive to manufacture, and are small in size. However, they have poor noise performance and linearity, as well as a small dynamic range, making them unappealing and unsuitable for many low-noise applications. Furthermore, as the power usage is reduced, their sensitivity degrades.Search-coil or induction sensors are high-sensitivity, lowpower sensors, but their sensitivity decreases as the cross-section area decreases, making miniaturization ineffective. Because search coils can detect an alternating current magnetic field, they cannot detect a static magnetic field like the Earth's magnetic field. Magnetic sensors based on semiconductors, such as Hall-Effect sensors, magnetotransistors, and magnetodiodes, are very small in size. Because of its low manufacturing cost

Flexible Magnetic Field Nanosensors for Wearable Electronics: A Review

“…This asymmetry results in even harmonics in the induced voltage. The magnitude and phase of the even harmonics in the sensing coils can be measured and used to determine the strength and direction of the external magnetic field. − The fluxgate principle allows for highly sensitive and accurate measurement of magnetic fields, making it suitable for a wide range of applications such as compasses, geophysical exploration, and nondestructive testing. ,,,, …”

“…Numerous attempts have been undertaken to streamline the fabrication methods of fluxgate sensors, employing techniques such as printed circuit board (PCB) technologies ,− and microengineering technologies. ,,, Recent advancements in diverse printing techniques have enabled fluxgate sensors and other microfabricated devices to acquire desirable characteristics such as flexibility, seamless integration, environmental sustainability, and more. Flexible fluxgate sensors can be fabricated using different methods, including thin film deposition techniques, screen printing, and flexible PCB technologies.…”