A Comprehensive Review of Integrated Hall Effects in Macro-, Micro-, Nanoscales, and Quantum Devices

A novel small-animal locomotor activity recording device for biological clock research

The rodent running-wheel recording apparatus is a reliable approach for studying circadian rhythm. This study demonstrated how to construct a simple and intelligent running-wheel recording system. The running wheel was attached to the cage's base, whereas the Hall sensor was attached to the cage's cover. Then, the RJ25 adaptor relayed the running signal to the main control board. Finally, the main control board was connected to the USB port of the computer with the USB connection. Data were collected using the online-accessible, self-created software Magturning. Through Magturning, generated data were saved and exported in real time. Afterward, the device was validated by collecting data on the locomotor activities of mice under different light conditions. In conclusion, this new device can record circadian activity of rodents. Our device is appropriate for interdisciplinary investigations related to biological clock research.

Unconventional Piezoelectricity of Two-Dimensional Materials Driven by the Hall Effect

Piezoelectricity has been widely explored for nanoelectromechanical applications, yet its working modes are mainly limited in polar directions. Here we discover the intrinsic electro-mechanical response in crystal materials that is transverse to the conventional polarized direction, which is named unconventional piezoelectricity. A Hall-like mechanism is proposed to interpret unconventional piezoelectricity as charge polarization driven by a built-in electric field for systems with asymmetric Berry curvature distributions. Density functional theory simulations and statistical analyses justify such a mechanism and confirm that unconventional piezoelectricity is a general property for various two-dimensional materials with spin splitting or valley splitting. An empirical formula is derived to connect the conventional and unconventional piezoelectricity. The extended understanding of the piezoelectric tensor in quantum materials opens an opportunity for applications in multidirectional energy conversion, broadband operation, and multifunctional sensing.

Engineering of Advanced Materials for High Magnetic Field Sensing: A Review

Advanced scientific and industrial equipment requires magnetic field sensors with decreased dimensions while keeping high sensitivity in a wide range of magnetic fields and temperatures. However, there is a lack of commercial sensors for measurements of high magnetic fields, from ∼1 T up to megagauss. Therefore, the search for advanced materials and the engineering of nanostructures exhibiting extraordinary properties or new phenomena for high magnetic field sensing applications is of great importance. The main focus of this review is the investigation of thin films, nanostructures and two-dimensional (2D) materials exhibiting non-saturating magnetoresistance up to high magnetic fields. Results of the review showed how tuning of the nanostructure and chemical composition of thin polycrystalline ferromagnetic oxide films (manganites) can result in a remarkable colossal magnetoresistance up to megagauss. Moreover, by introducing some structural disorder in different classes of materials, such as non-stoichiometric silver chalcogenides, narrow band gap semiconductors, and 2D materials such as graphene and transition metal dichalcogenides, the possibility to increase the linear magnetoresistive response range up to very strong magnetic fields (50 T and more) and over a large range of temperatures was demonstrated. Approaches for the tailoring of the magnetoresistive properties of these materials and nanostructures for high magnetic field sensor applications were discussed and future perspectives were outlined.

Democratization of PV Micro-Generation System Monitoring Based on Narrowband-IoT

Power system configuration and performance are changing very quickly. Under the new paradigm of prosumers and energy communities, grids are increasingly influenced by microgeneration systems connected in both low and medium voltage. In addition, these facilities provide little or no information to distribution and/or transmission system operators, increasing power system management problems. Actually, information is a great asset to manage this new situation. The arrival of affordable and open Internet of Things (IoT) technologies is a remarkable opportunity to overcome these inconveniences allowing for the exchange of information about these plants. In this paper, we propose a monitoring solution applicable to photovoltaic self-consumption or any other microgeneration installation, covering the installations of the so-called ’prosumers’ and aiming to provide a tool for local self-consumption monitoring. A detailed description of the proposed system at the hardware level is provided, and extended information on the communication characteristics and data packets is also included. Results of different field test campaigns carried out in real PV self-consumption installations connected to the grid are described and analyzed. It can be affirmed that the proposed solution provides outstanding results in reliability and accuracy, being a popular solution for those who cannot afford professional monitoring platforms.

Design and Calibration of a Hall Effect System for Measurement of Six-Degree-of-Freedom Motion within a Stacked Column

This paper presents the design, development and evaluation of a unique non-contact instrumentation system that can accurately measure the interface displacement between two rigid components in six degrees of freedom. The system was developed to allow measurement of the relative displacements between interfaces within a stacked column of brick-like components, with an accuracy of 0.05 mm and 0.1 degrees. The columns comprised up to 14 components, with each component being a scale model of a graphite brick within an Advanced Gas-cooled Reactor core. A set of 585 of these columns makes up the Multi Layer Array, which was designed to investigate the response of the reactor core to seismic inputs, with excitation levels up to 1 g from 0 to 100 Hz. The nature of the application required a compact and robust design capable of accurately recording fully coupled motion in all six degrees of freedom during dynamic testing. The novel design implemented 12 Hall effect sensors with a calibration procedure based on system identification techniques. The measurement uncertainty was ±0.050 mm for displacement and ±0.052 degrees for rotation, and the system can tolerate loss of data from two sensors with the uncertainly increasing to only 0.061 mm in translation and 0.088 degrees in rotation. The system has been deployed in a research programme that has enabled EDF to present seismic safety cases to the Office for Nuclear Regulation, resulting in life extension approvals for several reactors. The measurement system developed could be readily applied to other situations where the imposed level of stress at the interface causes negligible material strain, and accurate non-contact six-degree-of-freedom interface measurement is required.

Frontiers of graphene-based Hall-effect sensors

Hall sensors have become one of the most used magnetic sensors in recent decades, performing the vital function of providing a magnetic sense that is naturally absent in humans. Various electronic applications have evolved from circuit-integrated Hall sensors due to their low cost, simple linear magnetic field response, ability to operate in a large magnetic field range, high magnetic sensitivity and low electronic noise, in addition to many other advantages. Recent developments in the fabrication and performance of graphene Hall devices promise to open up the realm of Hall sensor applications by not only widening the horizon of current uses through performance improvements, but also driving Hall sensor electronics into entirely new areas. In this review paper we describe the evolution from the traditional selection of Hall device materials to graphene Hall devices, and explore the various applications enabled by them. This includes a summary of the selection of materials and architectures for contemporary micro-to nanoscale Hall sensors. We then turn our attention to introducing graphene and its remarkable physical properties and explore how this impacts the magnetic sensitivity and electronic noise of graphene-based Hall sensors. We summarise the current state-of-the art of research into graphene Hall probes, demonstrating their record-breaking performance. Building on this, we explore the various new application areas graphene Hall sensors are pioneering such as magnetic imaging and non-destructive testing. Finally, we look at recent encouraging results showing that graphene Hall sensors have plenty of room to improve, before then discussing future prospects for industry-level scalable fabrication.